GBook questions

106. What is the wavelength of 10 MHz sound in sofl tissue? A. 0.77 mm B. 0.15 mm C. 1.54 mm D. l0 mm

B. The wavelength of sound in sofl tissue is delined by the following relationship: wavelength (mm1 = 1.54 7 lr"Ouency (MHz) For 2 MHz sound, the wavelength is 'I .54/10 or 0.15 mm.

DISPLAYS-- 438. A video display that is limited to black and white only, with no shades of gray, is called _. A. binary B. bistable C. monochrome D. inchworm

B. A video display with the ability to show black and white only, without any intermediate shades of gray, is called bistable.

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ullrasound wave The beam is unfocused. Are the following I statements true or false?

False. The depth ol the focus is not delermined solely by the diameter of the piezoelectric crystal producing it.

ARTIFACTS-- 566. True or False? Grating lobes are a result of substantial acoustic energy directed outward from a linear array lransducer, but not along the main axis of the sound beam.

True. This is the exact detinition ol a graling lobe.

121 . True or False? Shorter wavelength sound creates higher quality images with greater detail.

True. Wavelength plays a very importanl role in image quality. Shorter wavelength (higher frequency sound) produces higher quality images with greater detail.

129. Whal is the propagation speed o, a 5 megahertz sound wave in sott tissue? A. 1 ,450 meters per sec B. 1,540 krn/sec C. I .54 rn/s D. 1.54 mm/ps

D. The speed of any sound wave moving through soft tissue, regardless ol frequency, is 1.54 mrn/psec, I ,540 m/sec, or 1.54 krn/sec.

DISPLAYS-- 469. A signal with a 120 dB dynamic range is compressed by 40 dB. What is the dynamic range ol the compressed signal? A. 40 dB B. 120 dB C.3dB D. 80 dB

D. When a signal's dynamic range is compressed. the decibels of compression are simply subtracted. ln this case, 120 - 40 = 80 dB.

ARTIFACTS-- 563. Side lobe artifact usually results in all of the following except _. A. hollow structures appearing "filled in" on the image B. reflectors not appearing on an image C. reflectors appearing in improper locations on the image D. reflectors appearing in multiple locations on the image

B. lt is unlikely that a side lobe arti{act would result in the abs€nce ol a reflector on an image. With side lobes, it is more likely that additional refleclions will appear on the image.

DOPPLER-- 532. The two mosl common color maps used in color flow imaging are: A. variance and direct B. variance and velocity C. turbulence and variance D. power and velocity

B.Two common modes ol color Doppler are velocity and variance modes.

TIME of FLIGHT 255. ln soft tissue, sound travels to a reflector and back to the transducer in 39 ps. How deep is the reflector? A.2cm B.6cm C.3cm D. cannot be determined

C. For each 13 us, sound travels a round trip depth of 1 centimeter. Thus, in 39 us, sound travels to and returns from a depth of 3 cm.

SOUND WAVES— Which of the following 8 selections are acoustic variables? (True or False) 36. Motion of particles in the wave

True

ARTIFACTS-- 550. What causes enhancement artifact? A. sound beams bending B. linear array transducer architecture C. unexpectedly low acoustic attenuation D. acoustic energy radiating in a direction other than the beam's main axis

c. Enhancement artifact appears directly below structures with atypically low attenuation. Cystic structures often create enhancement artifact since fluids within the cyst often attenuate sound to a lesser exlent than surrounding tissues.

TRANSDUCERS 283. Which of the following lists orders the impedance from highest to lowest? A. skin, gel, matching layet, PZT B. PZT, gel, matching layer, skin C. gel, PZT, matching layer, skin D. PZT, matching layer, gel, skin

283. To maximize the transmission of sound energy between the transducer and the body, lhe impedances of the active element, matching layer, gel, and skin must be in decreasing order. The impedance ol the piezoelectric crystal is the highest, the matching layer's impedance is a bit lower, the gel's impedance is lower yet, and the impedance ol the skin is the lowest ol all

INSTRUMENTATION 432. The process of demodulation incorporates which of the following tasks? (More than one answer may be correct.) A. smoothing B. amplilication C. rectification D. decompression

A and C. Demodulation is a two-step process. These steps are rectilication and smoothing

DOPPLER-- 496. When red blood cells move away from a transducer, lhe frequency of the wave reflected from the red cells is _ the lrequency emitted by the transducer. A. greater than B. less than C. equal to

B When red blood cells are moving away lrom a transducer, the Doppler shift is negative. The reflected lrequency is less than the originally transmitted lrequency lrom the transducer

DISPLAYS-- 450. Which of these A. 12211221 B. 10000000 c.98765432 D.01010102 is a binary number?

B. A binary number is a string of zeroes and ones only. Binary numbers are based on two choices. Digital numbers are based on ten choices.

AXIAL RESOLUTION 266. An ultrasonic pulse has a pulse repetition period of 1.2 msec, a spatial pulse length of 2.0 mm, and a wavelength of 0.4 mm. What is the axial resolution ol the system? A. 2.0 mm B. 1.0 mm C. 0.4 mm D. 1.8 mm

B The axial resolution ol an ultrasound system is equal to hal, o, the spatial pulse length produced by the system. ln this example, the spatial pulse length is equal to 2.0 mm, and the axial resolution is 1.0 mm. lmage accuracy is best when the numerical value o, axial resolution is small

ARTIFACTS-- 551 . Unexpectedly low attenuation results in which ol the artifacts listed below? A. refraction B. attenuation C. enhancement D. shadowing

C. Enhancement occurs with unexpectedly low rates ol attenuation.

105. True or False? Lower lrequency sound creates higher quality images with greater detail.

False. Frequency plays a very important role in image quality. Higher f requency sound usually produces higher quality images with greater detail.

140. What determin6s the pulse duration? A. the source o, the wave B. the medium in which the pulse travels C. both A and B D. neither A nor B

.A. The pulse duration is the actual time that a transducer is crealing one sound pulse and is determined by the ultrasound system. Pulse duration does not include the listening time.

DOPPLER-- 514. The inlormation that is processed by a standard duplex ultrasound system includes all of the following except A. attenuation B. amplitude C. frequency D. time of arrival

A A duplex ultrasound system provides both image and Doppler inlormation. lncluded in the data processing is the amplitude of the reflected signal, its time of arrival, and its lrequency content. The pulse's attenuation is not recorded or processed. .

ARTIFACTS-- 573. How does slice thickness artifact commonly express itsell? A. fill in of cystic structures B. improper brightness ol reflectors C. absence of refleclors D. strong linear echoes

A Slice thickness artilact results in reflections placed on the image that do not correlate with the anatomical position ol the reflector. Therefore, anechoic structures in the imaging plane are lilled in with echoes from structures above or below the image slice.

168. The pulse repetition lrequency ol ultrasound produced by a transducer typical of diagnostic imaging systems _ A. can be changed by the sonographer B. depends on the medium through which the sound travels C. is unchanged as long as the same ultrasound system is used D. has nothing to do with clinical imaging

A The pulse repetition lrequency (PRF) is inversely related to the maximum imaging depth that is achieved during an exam. As the sonographer increases the maximum imaging depth, the PRF must decrease. This occurs because the transducer must wait a longer time for echoes to return f rom deeper depths. Sonographers, therefore, alter the PRF when they adjust the maximum imaging depth.

BIOEFFECTS-- 596. Which two of the following devices convert ultrasound energy into heat? A. a calorimeter B. a thermocouple C. a hydrophone D. a Schlieren

A and B. The calorimeter and the thermocouple are two devices that use the principle ol converting acoustic energy into thermal energy to estimate the energy in a sound beam. A hydrophone converts acoustic energy into pressure. A Schlieren uses the interaction of sound and light to evaluate a sound beam profile.

156. A sonographer adjusts the maximum imaging depth of an ultrasound system. Which of the following also changes? (More than one answer may be correct.) A. pulse repetition period B. wavelength C. pulse repetition frequency D. frequency

A and C. As imaging depth is altered, the PRF and pulse repetition period change. The wavelength and frequency remain constant, as lhese terms describe the attributes of a single cycle within the pulse, and are not affected by alterations in imaging depth.

TRANSDUCERS 278. The main purposes of a transducer's case are (more than one may be correct): A. to protect the patient from shock B. to protect lhe Patient from heat C. to protect the internal components of the transducer D. to protect the patient from radiation

A and C. The case of a transducer protects the patient from electrical shock and also protects the internal components of the transducer lrom damage.

TWO DIMENSIONAL IMAGING For the following 6 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) 383. Ultrasound systems using these transducers do not actually steer the ultrasound beams to creale a two- dimensional image. A. linear switched (also called linear sequential) array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer F. vector array transducer

A and E. Linear and convex switched (or sequential arrays) do not steer sound beams. Rather, a small group of elements produce a pulse that travels straight ahead

INSTRUMENTATION 417.Which ol these lunctions are performed by the receiver o, an ultrasound system? (More than one answer may be correct.) A. amplification B. threshold C. compensation D. demodulation

A, B, C, and D. All of the functions listed above are performed by the ultrasound system's receiver.

ARTIFACTS-- 540. Acoustic artilacts include: (More than one answer may be correct.) A. images of reflectors in an inappropriate position B. images ol reflectors with improper shape C. images ol rellectors with incorrect brightness D. images that do not correspond to anatomical structures

A, B, C, and D. An artiJact is an error in imaging. All ol the choices indicate a type ol error, and theref ore, are artifacts.

QUALITY ASSURANCE-- 593. Which of the lollowing statements are true of a tissue equivalent phantom? (More than one answer may be correct.) A. it has the same propagation speed as that o, sott tissue B. il attenuates ultrasound at a rate similar to soft tissue C. embedded in it are solid masses and cystic structures D. it is the device of choice for quality assurance sludies

A, B, C, and D. Tissue equivalent phantoms have characteristics that allow for the optimal evaluation ol ultrasound systems. They are quite similar to soft tissue and are the preferred device to evaluate system performance.

1 18. Propagation speed can be correctly recorded with which ol the lollowing units? (More than one may be correct.) A. miles per hour B. mm/msec C. km/sec D. inches per year

A, B, C, and D. speed is recorded as a distance per unit of time, such as miles per hour, or leevsec. Any relationship of distance per time is an acceptable answer.

DISPLAY MODES For the following 3 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) 358. These transducers focus the ultrasound beam electronically. A. linear switched array lransducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer

A, B, D, and E. Electronic tocusing techniques are used in linear phased array and annular phased array transducers. A focused acoustic beam produces images with greater detail. Some linear and convex array transducers tocus the beam electronically, whereas others do not.

179. While using the same ultrasound machine and transducer, which ol the lollowing can a sonographer alter? (More than one answer may be correct.) A. pulse repetition period B. PRF C. frequency D. duty cycle E. pulse duration

A, B, and D. While adjusting the desired maximum imaging depth in an exam, the sonographer adjusts the pulse repetition period and the PRF. The duty factor is also altered. Unlike choices A, B and D, the lrequency of the ultrasound and the pulse duration are fixed once a transducer is selected. These parameters cannot be allered.

DISPLAY MODES For the following 3 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) 359. With these transducers, the ultrasound beam is locused with an acoustic lens, a mirror, or by milling the piezoelectric crystal in a curved shape. A. linear switched array lransducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer

A, C, and E. Acoustic beams can be locused with techniques similar to those that focus light waves, including using an acoustic lens, a focusing mirror, or a curved piezoelectric crystal. Mechanical transducers, and some linear and curvilinear array lransducers, use these techniques to focus acoustic beams.

169. ln diagnostic imaging, what establishes the pulse repetition frequency? A. the source ol the sound B. the medium through which the sound travels C. both A and B D. neither A nor B

A, The sole determinant ol the pulse repetition frequency is the source ol the acoustic wave, the ultrasound system. The medium through which the sound travels does not directly affect the pulse repetition frequency.

LOGARITHMS and DECIBELS 187. Which of the following reports the relative strength of an ultrasound wave? A. decibels B. watts C. W/cm2 D. pascals

A, the relative strength ol a sound beam may be reported in decibels. The term "relative" indicates a comparison belween two values, such as a beam has decreased in strenglh by 50%. Choices B, C, and D are not comparisons, but absolute measuremenls.

LATERAL RESOLUTION and FOCUSING 341 . Which of the following techniques is extemal focusing? A. lens B. curved crystal C. electronic

A. Focusing with a lens is known as external focusing

ATTENUATION, REFLECTION, and SCATTERING 202. A sound wave reaches a rough or irregular A. border between two media. Under these explicit circumstances, which process is most likely to occur? A. backscatter reflection B. specular reflection C. Rayleigh scattering D. refraction

A. The smoolhness or roughness of a boundary will help to determine whal form of rellection takes place. Backscatter is likely to occur when the boundary has irregularities that are larger than the wavelength of the incident acoustic pulse. Difluse refleclion is another name for backscatter.

TWO DIMENSIONAL IMAGING 388 What is the advantage ol using a 1/z dimensional array transducer? A. improvedelevational resolution B. improved lateral resolution C. improved axial resolution D. improved temporal resolution

A. A 1/2 dimensional array transducer creates a thinner imaging plane. Thin imaging planes have superior elevational, or slice thickness, resolution.

LOGARITHMS and DECIBELS 196. What does a 3 dB change in a value intensity mean? A. the value has doubled B. ths value has tripled C. the value has increased 3070 D. the value has increased ten times

A. A 3 decibel change in the intensity indicates that the value has doubled.

DOPPLER-- 520. A system has three transducers with Irequencies ol 7.5 MHz, 5 MHz, and 3.25 MHz. Aliasing appears while using the 5.0 MHz transducer during a pulsed Doppler exam. What should the sonographer do? A. use the 3.25 MHz transducer B. use the 7.5 MHz transducer C. nothing; the other transducers do nol provide solutions to the problem

A. A transducer producing ultrasound at a lower frequency will produce smaller Doppler shifts, which are less likely to alias Thus, one potential solution Ior aliasing is to use a lower frequency transducer.

DISPLAY MODES 352. Which imaging technique usually disptays a single jagged line of varying heights? A. A-mode B. B-mode C. C-mode D. l-mode

A. A-mode displays reflected echoes as spikes of varying height. Echo amplitude appears on the y-axis, and rellector depth on the x-axis. The spike's location on the x-axis is based on the pulse's time ot flight. The height of the peak is determined by the rellection's strength. Stronger ref lections create higher spikes.

INSTRUMENTATION 414. Which one of the tollowing does not belong in the group below? A. receiver gain B. energy output C. pulser power D. acoustic power E. transmitler output F. output gain

A. All of the terms listed as answers, except for choice A, reler to the strength ol the signal produced by the transducer and transmitted into the body. Receiver gain is not synonymous with the other live choices.

AXIAL RESOLUTION 258. Axial resolution describes the accuracy related to visualizing two structures that are to a sound beam's main axis A. parallel B.-perpendicular C. oblique D. normal

A. Axial resolution is related lo structures that are parallel to the beam's main axis. ln other words, the structures are arranged front to back.

DISPLAYS-- 462. All ol the following are true of read zoom except A. preprocessing function of a receiver B. same number ol pixels are in the original ROI and the zoomed image C. on the screen, the pixels in the zoomed image are larger than those in the ROI D. the same number of ultrasound pulses are used to create the original ROI and the zoomed image

A. Bead zoom is a postprocessing function of the receiver. The data originally in the region of interest (ROl), before zoom, remains intact. New inrormation is not acquired.

ARTIFACTS-- 585. What is a comet tail artifact's fundamental mechanism of tormation? A. reflection B. rarefaction C. refraction D. attenuation

A. Comet tail artifacts appear on an image as a result ol numerous reflections between two closely spaced reflectors.

DOPPLER-- 51 1 . All o, the lollowing are related to dedicated continuous wave Doppler transducers except A. wide bandwidth B. high quality lactor C. higher sensitivity D. range ambiguity

A. Continuous wave transducers have a narrow bandwidth. Backing material in pulsed wave transducers creates a wide bandwidth. Since dedicated continuous wave transducers do not use backing material, they have a narrow bandwidth.

TWO DIMENSIONAL IMAGING 390What is the use of a greater number of channels to receive echoes from ever increasing depths called? A. dynamic aperture B. apodization C. dynamic frequency tuning D. subdicing

A. Dynamic aperture is a technique ol receive focusing that uses lewer crystals to identify echoes from superficial depths and many more crystals to monitor echoes from greater depths. Dynamic aperture is also known as variable aperture.

ARTIFACTS-- 589. What is true of acoustic speckle? A. its effects are mild and it tends to slightly degrade images B. it is a rare artifact that does not occur in real{ime imaging C. its effects are dramatic D. it is eliminated with apolarization

A. Even though it does not accurately represent reflectors in the medium, acoustic speckle is often considered "tissue texture." lt tends to contribute to overall image degradation.

LATERAL RESOLUTION and FOCUSING 344. All of the following occur with locusing except A. lower intensity at the focus B. shorter near zone length C. more compact focal zone D. smaller diameter beam diameter at the end of the near zone

A. Focusing does not lower lhe beam's intensity at the focus. With focusing, the near zone is shallower, the focal zone is smaller. and the beam is narrower at the focus.

TRANSDUCERS 295. All ol the following are true about transducers except A. it is necessary to sterilize transducers belore use B. most transducers simply require disinfection as they do not penetrate mucous membranes C. slerilization could depolarize PZT D. they are unlikely to transmit infection

A. Generally, il is unnecessary to sterilize most ultrasound transducers since they do not penetrate mucous membranes. Typically, simple disinfection is all that is needed.

DOPPLER-- 524.Which ol the following determines the gray scale in a Doppler spectrum? A. number of reflectors B. velocity C. frequency shift D. laminar flow

A. Gray scale in a Doppler spectrum is related to the number of red blood cells creating the reflection.

326. Which ot the following explains the difference in sound beam shape created by a disc-shaped crystal from that of a small chip of PZT? A. Huygens' Principle B. Snell's Law C. Bernoulli's Law D. Murphy's Law

A. Huygens' Principle explains the difference between the beam shape lrom tiny chips of PZT and disc crystals ol a larger dimension

ARTIFACTS-- 554. Which process causes mirror image artifact? A. reflection B. refraction C. propagation speed error D. atlenuation

A. Mirror imaging is created by an unexpected and uncorrected reflection of the ultrasound pulse off a strong reflector.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 396. Which two factors determine lemporal resolution? A. speed of sound and depth ot view B. pixel size and sector size C. focal zones and sector depth D. propagation speed and lrame rate

A. Of the 4 choices, propagation speed and depth ol view have the greatest effect upon frame rate and temporal resolution. Frame rale is high with shallow imaging. Frame rate is high when sound travels quickly in a medium.

DISPLAYS-- 467. Which ol the following components typically has the lowest dynamic range? A. display B. pulser C. amplilier D. demodulator

A. Of the four choices, the component of an ultrasound system with the lowest dynamic range is the display.

HEMODYNAMICS-- 477.Which ol the lollowing is not associated . with turbulent flow? A. parabolic B. eddy C. vortex D. swirling E. spectral broadening

A. Parabolic flow is a bullet-shaped llow pattern associated with laminar flow. The remaining terms, B, C, D, and E are all related to turbulent flow.

AXIAL RESOLUTION 269. Which transducer has the best axial resolution? A.2cycles/pulse,4MHz B.4cycles/pulse,4MHz C.4cycleJpulse,2MHz D.2cycleypulse,2MHz

A. Pulses with the lewest cycles and the highest lrequency have the best axial resolution.

REFLECTION and TRANSMISSION 240. An ultrasound wave strikes an inter{ace I between tvo media at a 90'angle. The propagation speeds of the media are identical. However, the densities of the media are diflerent. Which is true? A. reflection will definitely occur B. reflection will definitely not occur C. refraction may occur D. none of the above

A. Reflection will definitely occur. With normal incidence, reflection will occur when the impedances of the media on either side of the boundary are different from each olher. ln this example, the densities of the media are different while their propagation speeds are the same. Since impedance is propagation speed multiplied by density, it follows that the acoustic impedances of the media bordering the interface are indeed diflerent. Reflection will occur.

ARTIFACTS-- 543. Six dlstinct, equally spaced reflections appear on an image at ever increasing depths. What type of artifact is this? A. reverberation B. ring down C. mirror imaging D. longitudinal resolution

A. Reverberations are multiple, equally spaced rellections.

ARTIFACTS-- 565. Grating lobes are produced by the same mechanism as which other artifact? A. side lobes B. reverberation C. transaxial lobes D. acoustic speckle

A. Side lobes and grating lobes are similar in that they represent acoustic energy transmission in a direction other than the main axis of an acoustic beam.

155. On what does the pulse repetition period depend? A. the source of the sound wave B. the medium through which the pulse travels C. both A and B D. neither A nor B

A. Similar to the PBF, the pulse repetition period depends only on the ultrasound system. The pulse repetition period is the time lrom the start of one pulse to the start of the next pulse and includes the pulse duration and the receiving time. When the sonographer adjusts the depth ol view, the pulse repetition period is altered. To be more exact, the listening time is lengthened with deeper imaging and shortened with shallower imaging.

135. The characterislics of four media are described below. Which of the media has the slowest propagation speed? A. high density and high elasticity B. low density and high stitfness C. low stiffness and low density D. low compressibility and low stiffness

A. Speed is determined by density and stiflness of a medium (the opposite of stitfness is elasticity). When a medium has high elasticity, its speed is slow. A medium with a high density also has a slow speed. The medium described in choice A has the lowest propagation speed.

ARTIFACTS-- 579. Two small cysts, positioned perpendicular to the main axis ol a sound beam, arc 2.4 mm apart. What determines whether they appear as two distinct images on the system's display? A. the beam width B. the pulse length C. the PRF D. rhe TGC

A. The ability to correctly image structures that lie close to each other in a direction perpendicular to lhe main axis ol the ultrasound beam is called lateral resolution Laleral resolution is primarily determined by the width of the acoustic pulse.

ATTENUATION, REFLECTION, and SCATTERING 210. The attenuation of an acoustic wave traveling through bone is its attenuation through soft tissue. A. greater than B. less than C. equal to

A. The attenuation of ullrasound in bone is greater than its attenuation in sott tissue

DISPLAYS-- 449. What is the smallest amount ol digital storage called?

A. The bit is the smallest amount ol digital storage or computer memory. The term bit is derived lrom the words "binary digit." A combination of eight bits makes a byte. Computer memory is called random access memory, or BAM.

HEMODYNAMICS-- 488.What happens to the diaphragm when an individual breathes out? A. it ascends into the thorax B. it descends into the abdomen

A. The diaphragm moves upward into the chest cavity (the thorax) when a subject exhales.

TRANSDUCERS 281. The impedance ol a transducer's matching layer is 2.6 MRayls and the impedance of the piezoelectric crystal is 3.4 MRayls. lf this is assumed to be a good imaging system, what is the best estimate lor the impedance ol the skin? A. 1 .5 MRayls B. 3.8 MBayls C. 3.4 MRayls D. 2.8 MRayls

A. The impedance of a transducer's matching layer should be between the impedance ol skin and the impedance of the piezoelectric crystal.

INCIDENCE 226. What are the units of the intensity reflection coefficient? A. none B. Wcm2 C. watts D. dB

A. The intensity reflection coetficient is delined as the percentage or proportion of an ultrasound beam's intensity that is reflected as the sound wave strikes a boundary between two media. The intensity rellection coefficient is reported as a percentage and therefore is unitless.

LATERAL RESOLUTION and FOCUSING 329. The lateral resolution of an ultrasound system is primarily determined by the _ A. width of the sound pulse B. length ol the ultrasound pulse C. duration of the sound pulse D. none ol the above

A. The lateral resolution achieved by an imaging system is approximately equal to the widlh of the ultrasound pulse.

BIOEFFECTS-- 609. Which of the lollowing terms best describes the mechanistic investigation of bioetlects? A- cause-etfect B. exposure-response C. cause-response D. exposure-cure

A. The mechanistic approach to lhe study ol bioeftects is properly called cause and effecl. For example, a researcher might propose that vibration causes harmful bioeffects and then conducts research to see whether this is indeed the case.

DISPLAY MODES 369. . The pattern of electrical signals exciting the piezoeloctric crystals of a linear phased array transducer _. A. typically changes from one acoustic pulse to the next B. changes every fourth or litth acoustic pulse C. changes only when the maximum imaging depth changes D. none of the abov

A. The patlern of the electrical signals that excite the PZT crystals of a linear phased array transducer changes from one pulse to the next. The electrical patterns determine the direction and focusing of each acouslic pulse. Each sound wave is direcled in a slightly diflerent direction to creale a two-dimensional imaging plane. Thus, the electrical signals vary for each acoustic pulse. The electronics that creates the varying patterns is called the beam former.

DISPLAYS-- 445. What happens to a digital image when the pixel density increases? A. spatial detail improves B. temporal resolulion increases C. the field ol view expands D. there are more shades of gray

A. The pixel density, the number ol pixels per inch, determines the detail that a digital picture can illustrate. With greater pixel density, spatial detail imProves. Alternatively, the image has less detail with fewer pixels per inch.

DISPLAYS-- 468. Why is it necessary for the receiver to perform compression on lhe electrical signals that it processes? A. the dynamic range ot the system's electronics is less than the dynamic range of the received sound rellection B. the display's dynamic range exceeds the transducer's dynamic range C. the dynamic range of the receiver is less than the dynamic range ol the image processor D. the dynamic range o, the display exceeds the dynamic range of all other components of the ultrasound system.

A. The process of compression decreases the dynamic range ol a signal. Ultrasound systems compress signals because the dynamic range of the reflected signals received by lhe transducers is lar greater than the dynamic range of any of the other components of the system. Thus, compression matches the dynamic range of the signal to the dynamic range of the system's electrical components.

123. The speed ot sound traveling through bone is _ soft tissue. A. higher than B. lower than C. equal lo D. cannot be determined

A. The propagation speed of sound in bone is higher than in soft tissue. Sound travels at a speed of 3 to 5 krn/sec in bone. This is two to three times faster than sott tissue.

142. The pulse duration is expressed in the same units as the _. A. period B. PRF C. wavelength D. density

A. The pulse duration and the poriod are measured in units of time, such as seconds, minutes, or hours. PRF has units of hertz. Wavelength has units ol distance. Density has units of mass per volume.

DISPLAYS-- 444. Two digital scan converters are undergoing evaluation. Both produce images of the same size. System A has 1 ,000,000 pixels, with l0 bits assigned to each. System B has 250,000 pixels, with 12 bits assigned to each. Which system is more likely to have the capability to display very small details in an image? A. System A B. System B C. both are the same D. cannot be determined

A. The scan converter with the greatest number ol pixels assigned lo an image ol fixed size will provide the viewer with the greatest spatial detail. ln this case, system A has a higher pixel density, and therelore has the ability to display greater detail.

ARTIFACTS-- 536. While using a linear sequential array transducer during a color Doppler exam, the shape of the gray scale image is most often _, whereas the shape of the color Doppler portion of the image is _. A. rectangular, parallelogram B. rectangular, sector C. s€ctor, trapezoid D. square, rectangular

A. The shape of a gray scale image using a linear sequential array is rectangular. However, the sound beams used for Doppler are steered at an angle, creating a parallelogram-shaped region.

QUALITY ASSURANCE-- 594. All of the lollowing may be used to evaluate Doppler systems except A. tissue equivalent phantom B. moving belt phantom C. vibrating string phantom D. Doppler phantom

A. The tissue equivalenl phantom is not suitable for evaluating Ooppler systems because all the reflectors within it are stationary. Doppler evaluations require moving reflectors.

DISPLAYS-- 441 . Which of the following is best described as an analog number? A. the weight ol a person B. the number of people in a room C. the number of stars in the sky D. the number ol tires on a car

A. The weight of a person can be considered an analog number because it is continuous and can achieve an unlimited number of values. On the olher hand, the number of people in a room or the number ol tires on an automobile can be represented only by discrete, whole, or integer values.

TWO DIMENSIONAL IMAGING For the following 6 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) 382. These transducer systems typically produce an image that, throughout its entire depth, is approximately as wide as the ultrasound transducer itsell. A. linear switched (also called linear sequential) array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer F. vector array transducer

A. The width of a linear sequential array transducer determines the width of the 2-D image that it creates.

ATTENUATION, REFLECTION, and SCATTERING 21 1 . Ultrasound waves traveling through lung tissue attenuate to a extent than when traveling through sott tissue. A. greater B. lesser C. nearly equal

A. Ultrasound attenuales more when traveling through lung tissue than when traveling through soft tissue.

INCIDENCE 227. A wave strikes an interlace between two media and intensities are measured at the interface. What results when the reflected intensity is divided by the incident intensity? A. intensity reflection coefficient B. intensity transmission coefficient C. beam uniformity coefficient D. none of the above

A. Under these circumstances, when we divide the rellected intensity by the incident intensity, the result is the intensity ref lection coeff icient. The intensity reflection coefficient is the percentage of the incident intensity that is reflected as a wave strikes a boundary between two media.

HEMODYNAMICS-- 490.What happens to venous flow in the legs when an individual exhales? A. increases B. decreases C. remains lhe same

A. Venous ,flow in the legs increases when an individual exhales

ARTIFACTS-- 557. Which artifact is created by sound moving through a medium with a propagation speed less than soft tissue? A. vertical misregistration B. horizontal misregistration C. lateral resolution D. ring down

A. Vertical misregistration occurs when pulses do not travel at the speed of sound in soft tissue (1 ,540 m/sec.) The reflections on the image will be placed at depths deeper than the actual position of the reflector in the body.

DISPLAYS-- 470. A signal with a 120 dB dynamic range was previously compressed by 40 dB. What is the dynamic range ol the original uncompressed signal? A. 160 dB B. 120 dB C.3dB D. 80 dB

A. When a signal is already compressed, the original dynamic range is obtained by adding the decibels of compression. ln lhis case, 120 + 40 = 160 dB.

LOGARITHMS and DECIBELS 189. What is the decibel representation when an acoustic signal is amplilied? A. positive B. negative C. equal to zero

A. When a signal is amplilied, its magnitude increases and it becomes stronger. ln decibel notation, an increase in signal strength is described with positive decibels. Positive dB means "getting bigger."

SNELL's LAW and REFRACTION 248. An acoustic wave is traveling from medium X into medium Z. Medium X has a propagation speed ol 1,457 m/sec and an impedance ol 1.44 MRayls. Medium Z has a propagation speed of 1,&4 m/sec and an impedance of 1.26 MRayls. The angle of incidence is 32'. What is true of the angle of the transmitted wave? A. il is greater than 32 degrees B. it is equal to 32 degrees c. it is less than 32 degrees D. cannot be determined

A. With refraction, the relationship bohveen the angle of incidence and the angle of transmission is detined by Snell's Law. When the propagation speed of the medium that the sound is sntering exceeds the propagation speed ol the medium that the sound is currently in, the angle ol transmission is greater lhan the incident angle.

TIME of FLIGHT 254. How long does it take for sound to make a round trip to and from the skin's surface to a retlector depth ol I cm in soft tissue? A. 13 ps B. 150 ms C. 15 ps D. 2 seconds

A. ln soft tissue, sound can travel toand return from a depth of 1 cm (a total distance ot 2 cm) in 13 microseconds (13 millionths ol a second).

BIOEFFECTS-- 601 . Some ullrasonic bioeffects studies are performed in vivo. Whal is the meaning ol lhe tetm in vivo? A. observable in a living body B. observalions based on an experiment C. discernible in a iest tube D. estimated in a computer simulation

A. ln vivo observations are made in a living body. For example, increased tissue temperatures in patients following exposure to ultrasound are considered in vlvo observations.

HEMODYNAMICS-- 478. What is the primary reason blood moves . lrom one location to another? A. energy gradient B. anemia C. pressure gradient D. systole E. Iriction

A.Blood flows f rom one location to another when an energy gradient exists. Blood moves ,rom regions of higher energy to regions ol lower energy. Although choice C, pressure gradient, is attractive, it is not the best answer

HEMODYNAMICS-- 483. The arterial blood pressure of a standing individual is 120 mmHg. What is the hydrostatic pressure at the subject's ankle? A. 100 mmHg B.0mmHg C.40mmHg D. -100 mmHg E. -120 mmHg

A.Hydrostatic pressure is related to the difference between heart level and the site of measurement. Since the ankle is substantially lower than heart level, the hydrostatic pressure is 100 mmHg.

TRANSDUCERS 301. Which properties of the piezoelectric crystal of an imaging transducer result in the highest emitted acoustic wave frequency? A. thin, high propagation speed B. thick, slow propagation speed C. thin, slow propagation speed D. none of the above

A.Only pulsed wave transducers can create images. The crystal's thickness and propagation speed determine the frequency of sound created by these transducers. Highest lrequency sound is created by thin crystals in which sound travels quickly.

HEMODYNAMICS-- 486. What happens to venous return to the heart when an individual inhales? A. increases B. decreases C. remains the same

A.Upon inspiration, venous return to the heart increase

DISPLAYS-- 463. All of the following are true of write zoom except: A. preprocessing lunction of the receiver B. the same number o, pixels are in the original ROI and the zoomed image C. the pixel size in the zoomed image and the ROI are the same D. in comparison to the zoomed image, fewer ultrasound pulses are used to create the original ROI

B Write zoom is a preprocessing function of the receiver where new information is acquired lrom the region of interest (ROl). The data originally in the scan converter, before zoom, is discarded. All the pixels in the image are now concentrated into the ROl, thereby increasing the pixel density and image quality o, the zoomed portion.

DISPLAY MODES 365. The minimum number of active elements in a mechanical transducer is: 4.0 B. 1 c.2 D. none of lhe above

B A mochanical transducer may be constructed with a minimum of a single piezoelectric crystal. An imaging plane is created by mechanically steering the single crystal with a motor.

ARTIFACTS-- 552. When enhancement occurs, where does it appear on the image? A. in the near field B. deeper than a weak atlenualor C. in the far field D. shallower than a weak reflector

B Enhancement occurs after an ultrasound pulse has traveled through a low attenuating tissue and appears on the image deeper (distal) than that structure.

451. Two digital scan converters are undergoing evaluation. System A has 1,000,000 pixels, with 4 bits assigned to each. System B has 250,000 pixels, with 12 bits assigned to each. Which system is more likely to display images with very subtle differences in grayscale? A. System A B. System B C. both are the same D. cannot be determined

B Gray scale levels are determined by the number o, bits assigned to each pixel in an image. Since system B has 12 bits assigned to each pixel and system A has only 4, system B wiil display more gray shades and, thus, display subtle differences.

TRANSDUCERS 303. You are asked to labricate a pulsed ultrasound transducer with the lowest possible lrequency. Which piezoelectric crystal would you select? A. 6 mm thick, 4 cm diameter, 4.0 mm/us propagation speed B. 8 mm thick, 2 cm diameter, 2.0 mm/us propagation speed C. 4 mm thick, 9 cm diameter, 5.0 mm/us propagation speed D. 2 mm thick, 6 cm diameter, 6.0 mm/us propagation speed

B The lrequency is lowest when the crystal is thick and its propagation speed is low, so the active element listed in B is the proper choice. The diameter of the active element does not affect the lrequency of the pulse.

INCIDENCE 229. An ultrasound wave strikes an interface between two media. All intensities are measured directly at the interlace. What results when the transmitted intensity is divided by the incident intensity? A. intensity reflection coefficient B. intensity transmission coefficient C. beam uniformity coefficient D. none of the above

B Under these circumstances, when the transmitted intensity is divided by the incident intensity, the result is the intensity transmission coeff icient. The intensity transmission coefficient is the percentage ol the incident intensity that continues to propagate in the forward direction when the incident wave strikes a boundary between two media

170. When a sonographer increases the maximum imaging depth during an exam, what happens to the PBF? A. PRF increases B. PRF decreases C. remains unchanged

B When the depth of view is increased, the system waits and listens a longer time lor reflections. This reduces the system's ability to send out as many pulses per second. Hence, as imaging depth increases, the pulse repetition frequency decreases. lmaging depth and PRF are inversely related.

DISPLAY MODES 364. Which two ol the following terms are associated with phased array transducers? A- lens B. multi{ocus C. mirror D. adjustable E. external

B and D, Phased array is always associated with adjustable or multi-focusing

TEMPORAL RESOLUTION and REAL-TIME IMAGING 401. Which choice will result in increased lrame rate and temporal resolution? A. decreased propagation speed B. decreased sector size C. decreased lateral resolution D. decreased pulse repetition frequency

B, A narrower sector diminishes the number of pulses required to produce each image Frame rate and lemporal resolulion improves when tewer pulses make each image.

TWO DIMENSIONAL IMAGING For the following 6 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) With these transducers, a sector (wedge- shaped or "slice ot pie") image is produced. At the top, the sector is very narrow and tapers to a point. 385.With these transducers, a sector (wedge- shaped or "slice ot pie") image is produced. At the top, the sector is very narrow and tapers to a point. A. linear switched (also called linear sequential) array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer F. vector array transducer

B, C, and D. Transducers that steer beams from a single point usually create sector- shaped images, like spokes on a bicycle wheel that radiate from a single point.

SNELL's LAW and REFRACTION 249. An acoustic wave in medium B is traveling toward medium A. The sound beam strikes the boundary al a 45' angle. The propagation speed is 1 ,547 m/sec lor medium A and 1 ,745 m/sec for medium B. What is true of the angle of transmission? A. it is greater than 45 degrees B. it is less than 45 degrees C. it is equal to 45 degrees D. cannot be determined

B, With relraction, when lhe medium that the sound is in has a greater propagation speed than the propagation speed ol the medium that the wave is entering, the angle ol transmission is less than the angle ol incidence. ln this case, the angle ol transmission is less than 45' because the sound wave is entering a slower medium than the one through which it is currently propagating.

DISPLAYS-- 439. What is the approximate number of frames that must be presented each second for the human eye to perceive the display wilhout flickering? A,2 B. 30 c. 100 D. 500

B,The frame rale required to perceive smooth, flicker{ree motion is in the range of 30 frames,/sec. When the lrame rate is significantly below this value, the viewer experiences flicker. Flicker increases latigue and discomfort and diminishes the perceptive ability of the observer.

TIME of FLIGHT 256. ln soft tissue, sound travels to a reflector and back to the transducer in 39 ps (39 microseconds or 39 millionths of a second). What is the total distance that the pulse traveled? A.2cm B.6cm C.3cm D. cannot be determined

B. Since the pulse traveled round trip, the total distance is 6 cm. For each 13 ps, sound travels a round trip depth of I centimeter. Thus, in 39 ps, sound travels to and returns from a depth of 3 cm.

BIOEFFECTS-- 623. Which ol the following epidemiologic studies is considered most likely to produce meaninglul results? A. retrospective and Prospective B. prospective and randomized C. retrospective and emPirical O. prospective and mechanistic

B. A clinical trial that is both prospective and randomized is most likely to reach a valid and meaningful endpoint.

SOUND BEAMS 319. For a disc-shaped PZT crystal producing continuous sound, which design will create a beam with the deepest focus? A. large diameter, low frequency B. large diameter, high frequency C. small diameter, low frequency D. small diameter, high frequency

B. A continuous wave transducer producing the longest near zone (the deepest focus) will have a large diameter and a high frequency.

SOUND BEAMS 319. For a disc-shaped PZT crystal producing continuous sound, which design will create a beam with the deepest focus? A. large diameter, low frequency B. large diameter, high frequency C. small diameter, low frequency D. small diameter, high frequency

B. A continuous wave transducer producing the longest near zone (the deepest focus) will have a large diameter and a high frequency.

DISPLAYS-- 458. What is the number ol binary digits required to store 29 levels of gray? A.4 B.5 c.6 D. 29

B. A minimum ot 5 bits are required to display 29 shades oI gray. Actually, 5 bits can display a maximum of 32 shades of gray. Because only 16 shades of gray can be represented by 4 bits, a fifth bit must be added to achieve adequate memory to display more than 16 shades.

ARTIFACTS-- 555. Where is a mirror image artifact located? A. sometimes shallower on the image than in the body B. always deeper on the image than in the body C. sometimes lhe same depth on the image as in the body D. never deeper on the image than in the body

B. A mirror image artifacl occurs when a pulse bounces off a strong reflector (such as the diaphragm) and then strikes a second rellector. The pulse's path is lengthened by the mirroring, and the second reflection (artilact) is always displayed at an abnormally great depth.

DISPLAYS-- 452. A byte is composed of _____bits. A word is composed of _____ bytes A. 2,2 8. 8,2 c. 16, 16 D. 8, 16

B. A string of eight bits of computer memory is a byte. Two bytes of computer memory make a word. Since a byte is I bits, a word is 16 bits.

LOGARITHMS and DECIBELS 193. How many decibels represent a 1oojold increase in the intensity of an acoustic pulse? A. 10 B. 20 c. 100 D.6

B. An increase of 100 times the intensity ol a wave is equal to 20 dB. Each 10 dB indicates a tenlold increase. Therefore, 20 dB (two 10 dB increases) means a pair ol tenfold increases, 10 x 10 = 100.

INCIDENCE 219. Which of the following describes an angle with a measure of 45"? A. orthogonal B. acute C. obtuse D- normal

B. Any angle that measures less than 90 degrees 'is an acute angle.

'158. What happens to the pulse repetition period if the sonographer decreases the maximum imaging depth achieved in an ultrasound scan? A. increases B. decreases C. remains the same D. cannot be determined

B. As the maximum imaging depth, or depth ol view, is decreased, the interval of time during which the ultrasound machine listens lor returning echoes is diminished. As a result of this shorter listening time, the pulse repetition period is shortened. Simply stated, pulse repetition period and depth ol view are directly related.

LATERAL RESOLUTION and FOCUSING 334. Two ultrasound systems have near zone lengths ol 8 cm. At their foci, Syslem Q's lateral resolution is 3.0 mm and System H's is 5.0 mm. Which system will correctly display two small structures at a depth of I cm? The ob,ects are side by side and are 0.4 cm apart. A. System H B. System Q C. both produce similar quality pictures

B. At a depth of 8 cm, System Q will produce a more accurale picture of two struclures that are 0.4 cm apart. A system's lateral resolution is approximated by the beam diameter at that depth. System Q's beam diameter is 3.0 mm at its focus and will display this pair of rellectors accurately. System H's beam, with a diameter of 5mm, is too wide to display this pair of reflectors as distinct and separate.

ARTIFACTS-- 578. The lateral resolution of lour ullrasound systems appear below. Which will produce the finest quality picture? A.2cm B.4mm C.6mm D.8hm

B. Besolution is reported in units ot distance, wilh smaller values producing higher quality pictures. Choice B is the smallest number and thoretore represents the system with the best images based on lateral resolution.

'182. What is the importance of describing sound beam intensities in a variety ol ways with regard to space and time? A. it allows better transducer design B. it's important when sludying bioetlects C. it optimizes image quality D. harmonics can be measured

B. Describing the intensity of sound beams as they vary in time and in space is important in the study of bioetfects.

DOPPLER-- 500. Two ultrasound transducers are used to perform Doppler exams on the same patient. The exams are identical except that the transducer frequencies are 5 and 2.5 MHz. Which exam will measure the highest Doppler shift? A. the 2.5 MHz exam B. the 5 MHz exam C. neither D. cannot be determined

B. Doppler shifts are directly related to the transmitled f requency. Higher lrequency transducers produce a greater Doppler shift. Using lower frequency ultrasound will result in lower Doppler shifts. For a specilic velocity, the Doppler shift produced will depend on the lrequency of the incident sound wave, with higher lrequencies yielding higher Doppler shifts.

176. While using a particular imaging system, whal happens to the duty ,actor when the depth of view increases? A. increases B. decreases C. unchanged

B. Duty factor is inversely related to depth of view. As the system images to a greater depth, the system requires more lime lo listen lor reflections, and the duty lactor decreases- The duty factor is the lraction or percentage of time that an imaging system is transmitting. lt is equal to the pulse duration divided by the pulse repetition period. Under normal operation, the pulse duration never changes. However, as depth of view increases, the pulse repetition period increases.

DISPLAY MODES 374. All of the lollowing describe dynamic receive locusing except A. delay pattern changes continuously throughout reception B. may be used by single crystal transducers C. locusing occurs at many depths D. automatically performed by system

B. Dynamic receive focusing is used only with systems using array transducers. Focusing is accomplished automatically during reception and is outside the control of the sonographer.

DISPLAY MODES 366. Which best describes the elements in a linear phased array lransducer? A. rectangular, 1/4 wavelength thick B. rectangular, 1/2 to 1/4 wavelength wide C. circular D. squares, 1/2 wavelength thick

B. Each element of a linear phased array is rectangular. There are approximately 100 lo 200 elements, each having a width of 1/4 to 1/2 wavelength.

BIOEFFECTS-- 621. What is epidemiology the study ol? A. large groups B. the prevalence of disease C. acoustic bioetfects on the fetus D. in vitro effects

B. Epidemiology is a division of medicine that is devoted to the study of the prevalence of diseases or pathology in a delined population.

LATERAL RESOLUTION and FOCUSING 340. Which of the lollowing techniquEs is intomal focusing? A. lens B. curved crystal C. slectronic

B. Focusing with a curved PZT crystal is knorvn as intemal tocusing.

BIOEFFECTS-- 613.Which of the following is nota potential mechanism for production of bioetfects lrom ultrasound exposure to lhe body? A. temperature elevation B. fractionation C. cavitation D. vibration

B. Fractionation means'1o separate a mixture into its ingredients" and has nothing to do with bioetfecls. The other choices are potential mechanisms for acoustic bioeffects.

LATERAL RESOLUTION and FOCUSING 349.The diameter ol a disc-shaped, unfocused piezoelectric crystal is 1.2 cm. The near zone length is 8 cm. What is the best estimate for the lateral resolution at a depth ol 16 cm? A. 0.6 cm B. 1.2cm C.8cm D. 16 cm

B. Generally, unfocused sound beams produced by a disc-shaped crystal have a profile where the beam tapers to a minimum diameter at the tocus and then starts to diverge. At a distance of twice the near zone length, the beam diameter is approximately equal to the piezoelectric crystal diameter. The beam diameter at a depth of 16 cm (which is twice the near zone length) is equal to the crystal diameter, 1 .2 cm. Thus, 1.2 cm is the lateral resolution at that depth

LATERAL RESOLUTION and FOCUSING 348. The diameter of a disc-shaped, unfocused piezoelectric crystal is 1 cm. What is the best estimate lor the minimum lateral resolution of the ultrasound system? A. 1mm B.smm C. 1cm D.5cm

B. Generally, unfocused sound beams produced by a disc-shaped crystal have an hourglass shape. The beam tapers to a minimum diameter al the focus. At the focus, the beam diameter is approximately one-hall the diameter of the PZT crystal. In this example, the minimum beam diameter is 5 mm. and this represents the lateral resolution ol the system.

SOUND BEAMS 321. Two systems are identical except for the trequency of the emitted pulse. Which system will have the deeper focus? A. the lower frequency system B. the higher frequency system C. both Ioci will be at the same depth

B. High frequency piezoelectric crystals tend to produce ultrasound beams with deeper foci. Frequency and focal depth are directly related. Higher acoustic frequencies create deeper foci. Lower lrequency crystals produce beams with shallow foci.

HEMODYNAMICS-- 482. The arterial blood pressure of a supine individual is 120 mmHg. What is the hydrostatic pressure at the subject's hips? A. 100 mmHg B. 0 mmHg C. 40 mmHg D. 120 mmHg E. -120 mmHg

B. Hydrostatic pressure is related to the difference between heart level and the site of measurement. ln the supine patient, hydrostatic pressure is zero.

SOUND BEAMS 322. As sound travels deeply into the far zone, the beam diverges, or spreads out. Which of the lollowing will result in a minimum beam divergence deep in the lar zone? A. small diameter, high lrequency B. high f requency, large diameter C. large diameter, low lrequency D. low frequency, small diameter

B. Large diameter crystals ol high frequency tend to produce sound bea ln contrast, waves lrom small diameter, low lrequency crystals are more divergent in the deep far zone.

SOUND BEAMS 320. Two ultrasound systems are identical except lor the diameter of the transducer's piezoelectric crystal. Which system has the deepest focus? A. the system with the smaller diameter crystal B. the one with the larger diameter crystal C. their foci will be at the same depth

B. Large diameter crystals tend to produce ultrasound beams with more distant foci. The larger the crystal diameter, the deeper the focus. Smaller diameter crystals produce beams with shallower foci.

167. What are the units ol pulse repetition frequency (PBF)? A. seconds B. l/seconds C. mm/ps D. seconds-2

B. Pulse repetition frequency is the number ol pulses that are produced by the ultrasound system in one second. PRF has the same units as frequency, and these units are hertz, Hz, or per second.

AXIAL RESOLUTION 271 .fwo ultrasound systems produce pulses. One pulse is 0.4 USec in duration and the other is 0.2 psec long. Which pulse is most likely to provide the best radial resolution? A. 0.4 l,sec system B. 0.2 psec system C. they are the same D. cannol be determined

B. Radial (or axial) resolution is determined by the pulse duration or the spatial pulse length. The shorter the time span that a pulse exists (or the shorter the length oI the pulse), the better the radial resolution. The device producing the shorter pulse, 0.2 psec, has the best radial resolution. Radial resolution is also called axial, depth, longitudinal, or range resolution.

AXIAL RESOLUTION 260. The axial resolution ol an imaging system is reported to be 0.85 mm at the beam's focus. What is the closest estimate of the system's radial resolution at a location that is 5 cm deeper than the focus? A. less than 0.85 mm B. equal to 0.85 mm C. greater than 0.85 mm

B. Radial resolution is determined by the spatial pulse length or the pulse duration These variables remain constant, regardless ol the depth of the pulse. The radial resolution is the same at all imaging depths.

AXIAL RESOLUTION 259. You are purchasing a diagnoslic ultrasound system. System X has axial resolution of 0.7 mm whereas Syslem D's is 0.4 mm. Based on this information, which system will produce the better quality picture? A. System x B. System D C. they have the same quality D. cannot be determined

B. Resolution is reported in units of distance, such as cm or mm. Higher image quality is achieved by syslems with lower numerical values for resolution. System D has a lower numerical value lor longitudinal resolution, and will produce more detailed, higher quality pictures.

LATERAL RESOLUTION and FOCUSING 332. Two ultrasound systems have near zone lengths of I cm. At the focus, System G's lateral resolution is 3.0 mm, whereas System P's is 5.0 mm. Which system will produce higher quality pictures at their foci? A. System P B. System G C. both will be of similar quality

B. Since System G has a narrower beam than System P at the end of the near field (which is the location of the foci), System G will produce higher quality images at that depth.

152. Two transducers send ultrasound pulses into soft tissue. One transducer emits sound with a 4 MHz frequency, and the other produces sound at a 6 MHz frequency. Each pulse contains 4 cycles. Which has a greater spatial pulse length? A. the 6 MHz pulse B. the 4 MHz pulse C. they are the same D. cannot be determined

B. Since both pulses have the same number ol cycles, the pulse whose individual cycles have a longer wavelength will have the greater overall length. ln a given medium, waves with lower frequencies have longer wavelengths. The 4 MHz wave has a longer wavelength than the 6 MHz wave and therefore will have a longer spatial pulse length.

SNELL's LAW and REFRACTION 243. What event does Snell's Law govern? A. transmission B. refraction C. impedance

B. Snell's Law defines the physics ol refraction.

130. lf sound travels at exactly 1,540 nvsec in a particular medium, then the medium A. must be soft tissue -. B. may be sott tissue C. cannot be soft tissue

B. Sound waves travel exactly 1,540 rn/sec in sott tissue. However, other media have the same propagation speed as that of soft tissue. The medium in question could be soft tissue, or it could be something else.

133. The speed at which a wave travels through a medium is determined by: A. the sound wave's properties only B. the medium's properties only C. properties of both wave and medium D. none ol the above

B. Speed is determined by the characteristics oI the medium only. The characteristics ol the wave do not atlect its speed. All sound waves ot any frequency, period, intensity, and power travel at the same speed in a particular medium

DISPLAYS-- 446. Two digital scan converters are undergoing evaluation. System A has 1 ,000,000 pixels and the picture size is 100 square inches. System B has an image size of 10 square inches composed ol 250,000 pixels. Which image is more likely to display very small details? A. System A B. System B C. both are the same D. cannot be determined

B. System B has a greater ability to display small detail in an image in comparison to system A. System B has 25,000 pixels per square inch, whereas system A only has '10,000 pixels per square inch. System B has a greater pixel density, and this determines the degree o, spatial resolution.

INSTRUMENTATION 425. Which transducer syslem is most likely to have the longest delay in its TGC curve? A. a 5 MHz linear array B. a 2.5 MHz annular array C. a 7.5 MHz mechanical transducer D. a 5 MHz annular array

B. The 2.5 MHz transducer will have a longer delay in the TGC curve. Low frequency ultrasound waves atlenuate to a lesser extent than high frequency waves. Since choice B has the lowest froquency, it will have the least amounl of attenuation and will require less compensation in the near zone. The type ol transducer (e.9., annular, linear) does not atfect the TGC.

ARTIFACTS-- 538. The analysis of Doppler spectra using _ is mosl accurate. A. zero-crossing detectors B. Fast Fourier Transforms C. time interval histograms D. Chirp-Z transforms

B. The Fast Fourier Transrorm, or FFT, is the most accurate spectral analysis technique. Techniques such as zero-crossing, time interval histograms, and Chirp-Z were initially used to assess Doppler spectra, but are now obsolete. Fast Fourier analysis became popular when computers were Incorporated into ultrasound systems.

BIOEFFECTS-- 618. Which ot the following is related to cavitation bio€ff ects? A. TIS B. MI C. cavitation index D. pulsatility index

B. The Ml, or mechanical index, is related to cavitation bioeffects. Higher values of Ml are associated with increased likelihood ol cavitation.

SOUND BEAMS 307. What is the point or location where a beam reaches its smallest dimension? A. near zone B. focus C. penetration depth D. focal zone

B. The actual location where an uttrasound beam reaches its minimum diameter and cross-sectional area is called the

SNELL's LAW and REFRACTION 251. A wave of acoustic energy is leaving soft tissue and transmitting into fat with an 86" incident angle. What is true ol the angle ol transmission? A. it is equal to 86 degrees B. it is less than 86 degrees C. it is greater than 86degrees D. cannot be determined

B. The angle of transmission will be less than the angle of incidence. Fat's propagation speed is less than that ol soft tissue. The angle o, transmission is less than the angle oI incidence when a wave travels inlo a second medium thal reduces the wave's propagation speed. ln this example, the incidence is oblique, and fat has a lower speed than soft tissue.

ATTENUATION, REFLECTION, and SCATTERING 208. What is the amount of attenuation per centimeter lhat a sound wave undergoes called? A. beam uniformity coefficient B. attenualion coeflicient C. attenuation D. duty factor

B. The attenuation coefficienl reports a sound beam's decibels ol attenuation per centimeter. This is a useful tool as its value remains constant, regardless of the actual path length.

ATTENUATION, REFLECTION, and SCATTERING 207. As a pulse passes through sott tissue, a certain amount of acoustic energy remains in the tissue as heat. What is this constituent ol attenuation called? A. scattering B. absorption C. refraction D. rarefraction

B. The conversion of acoustic energy into heat is called absorption. This process deposits a portion of the energy from the b6am into the soft tissues.

BIOEFFECTS-- 610. Which of th6se terms best describes the empirical investigation oI bioeffects? A. cause-etfect B. exposure-response C. cause-response D. exposure-cure

B. The empirical approach to the study of bioetfecls searches for a biologic response following an exposure to ultrasound. An example of an empirical study is the assessment ol a newborn child following an ultrasound study performed while l'h utero-

TRANSDUCERS 298. With pulsed wave ultrasonic imaging, what helps to establish the primary frequency of the acoustic energy discharged by the transducer? A. piezoelectric crystal diameter B. piezoelectric crystal thickness C. damping material density D. ultrasound system electronics

B. The frequency of sound produced by a standard pulsed wave imaging instrument is partly determined by the thickness of the piezoelectric element. Just as ditferent tones are produced when a musician plays different bars on a xylophone, piezoelectric crystals ol various thicknesses produce acoustic pulses of different frequencies.

DOPPLER-- 494. ln standard Doppler, what is true about the reflected frequency produced by blood cells traveling away ,rom lhe transducer? A. it is in the audible range B. it is ultrasonic C. it exceeds the transmitted frequency D. it equals the transmitted frequency

B. The frequency of the sound wave reflected by red blood cells back to the transducer is ultrasonic (having a frequency greater than 20,000 hertz). Although the difference between the transmitted and rellected lrequencies is audible, lhe reflected wave has a frequency in the ullrasonic range.

INSTRUMENTATION 428. What does the far gain ol a depth gain compensation curve represent? A. the median amplilication related to compensation B. the maximum amplilication related to compensation C. the minimum amplification related to compensation D. the maximum atlenuation related to compensation

B. The lar gain setting of a TGC curve represents the maximum amplilication that a reflected wave undergoes during the compensation process.

TWO DIMENSIONAL IMAGING 387. When looking at images produced by these transducer systems, which one can be distinguished from all the others? A. linear phased array B. linear switched array C. annular phased array D. mechanical lransducer

B. The linear swilched arrays (or linear sequential arrays) produce an image of rectangular shape. The other three transducers generate sector-shaped images that are essentially indistinguishable f rom each other.

INSTRUMENTATION 413. The output of an ultrasound pulser determines the _ of the acoustic pulse. A. imaging depth B. intensity C. duration D. pulse repetition period

B. The output of the pulser determines the strength or the intensity of the sound beam produced by the transducer. When greater electrical voltages from the pulser strike the PZT crystal of the transducer, pulses with greater intensity are created.

ARTIFACTS-- 567. Which technique of linear array transducer design has virtually eliminated the appearance of grating lobe artifact on modem ultrasound systems? A. demodulation B. subdicing C. deconvolution D. none ot the above

B. The process o, subdicing has almost eliminated the appearance ol grating lobe artifact on linear array transducer systems Subdicing consists of dividing each of the crystals in the array into smaller pieces. The subdiced pieces are then lired simultaneously as il they were a single crystal. This minimizes grating lobes.

INSTRUMENTATION 436.The process of eliminating low amplitude signals from lurther processing is called all of the following except _. A. reject B. subordination C. threshold D. suppression

B. The process ol removing lowlevel signals from further processing or display by an ultrasound system is called re.lect, threshold, or suppression. The term subordination does not describe this process.

LATERAL RESOLUTION and FOCUSING 345. ln which region of a sound beam is focusing most etfective? A. the very shallow near zone B. the end of the near zone C. very deep in the far zone D. throughout its entire length

B. The region of a beam that is most aflected by focusing is close to the end ol the near zone and at the beginning of the far zone. This region is called the focal zone.

LATERAL RESOLUTION and FOCUSING 328. The focus o, an ultrasound beam is the location where the _. A. beam is the broadest B. optimum transverse resolution is C. lrequency is the highest D. finest depth resolulion is obtained

B. The rocus of an ultrasound beam is the location where the beam is most narrow. The narrowest portion oI the beam provides the optimal transverse or lateral resolution.

What is the speed of sound in air? A. 1 ,540 rnls B. 330 rnls C. 100 rn/s D. 3,010 mis

B. The speed oI sound in air is 330 m/s, substanlially lowerthan the speed ol sound in soft tissue

124. Compared to soft tissue, the speed ol an acoustic wave through lung tissue is _ A. faster B. slower C. equal D. cannot be determined

B. The speed of sound in lung tissue is slower than in soft tissue. Sound travels at speeds in the range of 0.5 to 1.0 km/sec in lung tissue.

132. The propagation speeds of ultrasound waves in muscle, liver, kidney, and blood are _. A. exactly the same B. very similar to each other C. vastly ditferent

B. The speed of sound in these media are less than 5% ditlerent from each other. The characteristics of muscle, kidney, liver, and blood that determine the wave's speed in the media are quite similar.

BIOEFFECTS-- 624. What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects? A. 1 mWcm2 B. 1oo mWcm2 C. 1000 mWcm2 D. 1 Wcm2

B. There have been no independently confirmed signilicant bioeffects in mammalian tissue exposed to unfocused ultrasound with intensities below

REFLECTION and TRANSMISSION 241 . An acoustic wave is traveling from medium X to medium Z. Medium X has a propagation speed of 1,457 m/sec and an impedance ol 1.44 MRayls. Medium Z's propagation speed is 1,644 m/sec and its impedance is 1 .26 MRayls. The angle of incidence is 32 degrees. What is true of the angle ol rellection? A. it is greater than 32 degrees B. it is equal to 32 degrees C. it is less than 32 degrees D. cannot be determined

B. This is a tricky question. ln cases ol oblique incidence, the angle of rellection is always equal to the angle ol incidence. Simply put, if the incident angle is 32', then the rellection angle is 32'. All information regarding the propagation speeds and acoustic impedances of media X and media Z are irrelevant in this question.

BIOEFFECTS-- 617. Which ol the lollowing statements regarding cavitation is true? A. it has never been observed in any biologic media B. stable cavitation relates to oscillating bubbles while transient relates to bursting bubbles C. it is a nonlethal bioeffect produced in animal experiments D. waves with peak pressures less than 100 MPa can never induce cavilation

B. This is the principal difference between the lwo torms ol cavitation: stable cavitation means that the microscopic gas bubbles in the tissues are rhythmically swelling, whereas transient cavitation means the microscopic gas bubbles burst.

IMPEDANCE 217. Which two attributes help establish the acoustic impedance of a medium? A. density and temperalure B. density and stitfness C. stitfness and elastance D. elasticity and compressibility

B. To calculate the acoustic impedance, multiply the propagation speed of the medium by the density of the medium. A medium's propagation speed is determined by the density and the stiffness ol the medium. Therefore, acoustic impedance is a property of both density and stiffness.

IMPEDANCE 216. To calculate the acoustic impedance ol a medium, one should _ the _ by the A. divide, propagation speed, density B. multiply, density, propagation speed C. divide, density, propagation speed D. multiply, stiffness, density

B. To obtain the value o, acoustic impedance, multiply the density of a medium by its propagation speed.

SNELL's LAW and REFRACTION 252. An acoustic wave is in medium A and traveling toward medium B. The sound beam's angle of transmission into medium B with relation to the boundary is 79". Sound's propagation speed is 1 ,547 ml sec in medium A and 1,745 m/sec in medium B. lf rellection and transmission both occur at the boundary, what can be said of the reflection angle? A. it is greater than 79 degrees B. it is less than 79 degrees C. it is equal to 79 degrees D. cannot be determined

B. Two steps are required to determine that the angle of reflection is less than 79'. 1. We know that the transmission angle is 79' and that the propagation speed of medium A is less than that of medium B. From this, we can derive inlormation about the angle ol incidence. Since the speed ol medium B is greater than lhe speed ot medium A, the angle of transmission is greater than the angle of incidence. Thus, the angle of incidence must be less than 79". 2. The angle of reflection is equal to the angle of incidence. Since the angle of incidence is less than 79 degrees the angle ol rellection is also less than 79 degrees

INSTRUMENTATION 423. What is the process of adiusting lor path leng(h related attenuation called? A. compression B. compensation C. time-gain compensation D. reconfirmation

B. Ultrasound experiences attenuation as it travels in soft tissue. The deeper that sound travels, the weaker the reflected pulse is. Comp€nsation is the process ol adjusting for path lenglh attenuation.

ATTENUATION, REFLECTION, and SCATTERING 212. Sound traveling through blood attenuates to a _ extent than when traveling through soft tissue. A. greater B. lesser C. relatively equal

B. Ultrasound waves attenuate less when traveling through blood than when lraveling through soft tissue.

HEMODYNAMICS-- 487.What happens to venous flow in the legs when an individual inhales? A. increases B. decreases C. remains the same

B. Upon inspiration, venous flow in the legs decreases.

HEMODYNAMICS-- 489.What happens to venous return to the heart when an individual exhales? A. increases B. decreases C. remains the same

B. Venous return to the heart decreases when an individual exhales. .

TRANSDUCERS 294. Which ol the tollowing actions would cause a PZT crystal to lose its special properlies? A. breaking it in pieces B. exposing it to high temperatures C. exposing it to electrical current D. exposing it to low pressures

B. When a piezoelectric crystal is exposed to high temperatures , il will depolarize and permanently lose its piezoelectric properties. This temperature is known as the Curie temperature or Curie point.

LOGARITHMS and DECIBELS 190. What is the decibel notation for an acoustic signal that is attenuated? A. positive B. negative C. equal to zero

B. When a signal is attenuated, its magnitude decreases and it becomes weaker. ln decibel notation, a decrease in signal strength is described with negative decibels. Negative dB means "getting smaller."

TEMPORAL RESOLUTION and REAL-TIME IMAGING 399. What is the primary disadvantage ol multiple focal zones along each scan line ol a two-dimensional image? A. improved temporal resolution B. decreased temporal resolution C. improved lateral resolution D. improved longitudinal resolution

B. With multiple foci along each scan line, the ultrasound system uses many pulses to create each image. This reduces the number of lrames created per second, A low frame rate results in decreased temporal resolution.

Two sound pulses travel through the same medium. One wave,s frequency is 2 MHz and the other is I 0 MHz. Answer the following 5 questions. 101 . Which pulse has a longer wavelength? A. the 10 MHz pulse B. the 2 MHz pulse C. neither pulse D. cannot be determined

B. ln any specific medium, the wave with the lower ,requency has the longer wavelength. The 2 MHz sound's wavelength is live limes longer than the 10 MHz wave.

ARTIFACTS-- 584. With standard diagnostic imaging instrumentation, which has the higher numerical value? A. axial resolution B. lateral resolution C. neither; they have identical values

B. ln terms of image accuracy, axial resolution is usually better than lateral resolution. The number assigned to lateral resolution is higher than to axial resolution.

180. Which of the following terms does not belong with the others? A. increased depth of view B. increased duty factor C. increased pulse repetition period D. decreased pulse repetition frequency

B. lncreased duty lactors are related to shallower imaging. The other three selections are consistent with deeper imaging.

HEMODYNAMICS-- 481. The arterial blood pressure ol a supine individual is 120 mmHg. What is the hydrostatic pressure at the subject's ankle? A. 100 mmHg B. 0 mmHg C. 40 mmHg D. 120 mmHg E. -120 mmHg

B.Hydrostatic pressure is related to the difference between heart level and the site of measuremenl. ln the supine patient, hydrostatic pressure is zero

TRANSDUCERS 275. Which component of an ultrasound system is made ol lead zirconate titanate (PZT)? A. transducer's matching layer B. lransducer's active element C. transducer's damping material D. scan converter's comPuter chiPs

B.Lead zirconate titanate. abbreviated PZT, is a man-made piezoelectric material commonly used as the active element ol ultrasound transducers.

ARTIFACTS-- 560. ll a s<irnd pulse travels through a large mass at a speed of 1.2 mn/ps, what happens to the position ol echoes from reflectors deeper than th6 mass? A. they are placed in 1oo shallow a location on the image B. they are placed in too deep a location bn the image C. lhey are likely to be placed at the 'correct depth

B.The mass has a slow propagation speed when compared with soft tissue. All structures distal to the mass will be placed at too great a depth on the image. The retlections on the image will be farther than the retlectofs true anatomical position.

HEMODYNAMICS-- 485. What happens to the diaphragm when an individual breathes in? A. it ascends into the lhorax B. it descends into the abdomen

B.Upon inspiration, the diaphragm moves downward into the abdomen.

HEMODYNAMICS-- 480. Which of the following causes the greatest amount of inertial energy loss? A. pulsatile llow B. flow through a stenosis C. phasic tlow D. steady flow E. parabolic flow

B.lnertial loss is substantial when a fluid's velocity increases or decreases. Flow through a stenosis causes the greatest velocity changes, and the greatest inertial loss.

DOPPLER-- 512. A duplex ultrasound system displays________ intormation. - A. M-mode, two-dimensional image, and A-mode B. A-mode and B-mode C. two-dimensional image and Doppler D. two-dimensional image and M-mode

C A duplex scanner displays both Doppler and two-dimensional image data.

DISPLAY MODES For the following 3 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) 357 With these transducers, the ultrasound beam is steered by a motor, a rotating rellecting mirror, or a similar device. A. linear switched array lransducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer

C and D. ln mechanical and annular phased array transducers, an ultrasound beam is steered using mechanical devices such as motors or mirrors.

DISPLAYS-- 465. The relationship between the largest and the smallest signal amplitudes processed by a componenl of an ultrasound system is called the _____and has units of ____. A. decibels, watts B. intensity, Wcm2 C. dynamic range, dB D. proporlionality, dB

C, Dynamic range is delined as the ratio ol the largest to the smallest signal amplitude that a device can process. The units ol dynamic range are decibels, dB.

BIOEFFECTS-- 620. Which sound wave is least likely to create cavitation? A. 5 MHz,2 MPa B. 2 MHz,4 MPa C. 6 MHz,2 MPa D.2MHz,2MPa

C, Low values of mechanical index indicate low likelihood of cavitation. Derived mathematically from a sound wave's frequency and pressure, mechanical index is lowest with high frequency and low pressure.

AXIAL RESOLUTION 270. Which transducer has the worst axial resolution? A.2cycles/pulse,4MHz B.4cycles/pulse,4MHz C.4cycles/pulse,2MHz D.2cycleypulse,2MHz

C, Pulses with the most cycles and the lowest frequency have the worst axial resolulion

BIOEFFECTS-- 629. A comprehensive and scholarly review ol bioeffects is performed by the American lnstitute ot Ultrasound in Medicine for all ol the following reasons except A. ultrasound is a versatile technique B. ultrasound has proven widespread clinical utility C. ultrasound is considered highly toxic D. applications of ultrasound are growing considerably

C, The AIUM examines bioetfects research because diagnostic ultrasound is a clinically relevant, popular, and widely used imaging technique. Diagnostic ultrasound is not, however, considered highly toxic or likely to expose patients to substantial risks.

SOUND WAVES— Waves that exist at the same location and time will combine. What is this called? A. inference B. rarefaction C. interference D. longitudinal interaction

C, The combination ol many waves into a single wave is called interference.

IMPEDANCE 215. Acoustic impedance is a property of the_____and has units of ______ A. source and medium, lmps B. medium, dB C. medium, Rayls D. medium, Ohms

C. Acoustic impedance is a property of the medium through which sound travels. lt is unaffected by the sound source or lhe characteristics of the wave itsell. The units ol impedance are Rayls.

150. ln diagnostic imaging, what determines the spatial pulse length? A. the ultrasound system B. the medium through which the pulse travels C. both A and B D. neither A nor B

C. C, The spatial pulse length is the distance, or length, ol a pulse. lt depends, in part, upon the wavelength of each cycle in the pulse. Wavelength depends upon both the source of the sound and the medium through which the sound travels. The length of the entire pulse also depends upon both the source and the medium

1 36. Compressibility describes a characteristic ol a medium. Which two terms describe the same property as compressibility? A. density and stiffness B. density and conductance C. stiflness and elasticity D. elastance and impedance

C. The compressibility ol a medium describes its ability to reduce its volume when a force is applied to it. For example, a marshmallow is compressible because when it is squeezed, it gets smaller. Elasticity has the same meaning as compressibility. Stiff ness describes this same characleristic; however, stitfness is the opposite of compressibility.

INCIDENCE 234. A sound beam with an intensity of 45 W/cm2 strikes a boundary and 70% of the wave's intensity is reflected. How much is transmitted? A. 45 W/cm2 B. 25 W/cm2 c. 30% D. 100%

C. 30% of the wave's intensity is transmitted. The law of conservation of energy slates that the sum of the percentage ot transmitted sound and the reflected sound equals 100%.

DISPLAYS-- 473. Which ol the following terms is not associated with a wide dynamic range image? A. low contrasl B. many shades of gray C. bistable

C. A bistable image contains only black and white. An image described as wide dynamic range contains many shades of gray and may be called "low contrast."

LOGARITHMS and DECIBELS '194. The intensity ol an ultrasound wave is changed by -6 dB. This means that the current intensity is _ as much as its original level. A. one-tenth B. four times C. one fourth D. one-sixth

C. A change in intensity oI -6 dB indicates that only one-lourth of the initial intensity remains. The minus sign indicates a decrease in signal magnitude. Each -3 dB change means that one-half of the original intonsity remains. Since there are two sets of -3 dB, one-half multiplied by one-half indicates that there is only one-fourth remaining.

SOUND BEAMS 318. For a disc-shaped PZT crystal producing continuous sound, which design will creale a beam with the shallowest focus? A. Iarge diameter, low ,requency B. large diameter, high frequency C. small diameter, low lrequency D. small diameter, high frequency

C. A continuous wave transducer producing the shortest near zone (the most shallow locus) will have a small diameter and a low emitted frequency.

SOUND BEAMS 318. For a disc-shaped PZT crystal producing continuous sound, which design will create a beam with the shallowest focus? A. Iarge diameter, low ,frequency B. large diameter, high frequency C. small diameter, low frequency D. small diameler, high frequency

C. A continuous wave transducer producing the shortest near zone (the most shallow locus) will have a small diameter and a low emitted lrequency.

LOGARITHMS and DECIBELS 185. What is a decibel? A. the absolute value of a number B. a range of values C. a relationship between two numbers D- none ol the above

C. A decibel represents a relationship between two numbers. A decibel is a relative measure of intensity or power. The term "relative" indicates that we are not dealing with an absolute power (such as 600 watts), but rather with how the power is related to a reference level (for example, the current signal is 50% as strong as the relerence level).

DISPLAYS-- 471. Which display is limited to a single pair of brightness or display levels? A. CRT B. binary C. bistabte D. gray scale

C. A display that presents data in one of only lwo colors is bistable. Each dot on the image is either white or black, bright or dark, on or off . Bistable images are considered high contrast.

DISPLAYS-- 456. With 6 bits, what is the largest number of different gray shades that can be stored? A.8 B. 16 c. 64 D.256

C. A maximum number of 64 shades can be stored with the use ol 6 bits. We multiply 2 by itself a total ot 6 times to calculate the answer to this question: 2 \2x2 x2x2x 2 = 64 shades.

DISPLAY MODES 380. What image is created with a two- dimensional array transducer? A. two-dimensional static image B. two-dimensional real-time image C. three-dimensional real-time image D. B-mode

C. A two-dimensional array transducer creates a three-dimensional image

ARTIFACTS-- 588. What is the cause of acoustic speckle? A. refraction B. attenuation C. interference of tiny acoustic wavelets D. resonance of particles in the near

C. Acoustic speckle is produced by the constructive and destructive interference of small acoustic waves reflected from small reflectors in the near lield.

DISPLAYS-- 472. All ot the lollowing are consistent with an image containing black and white only with no shades of gray except A. bistable B. high contrast C. wide dynamic range

C. An image described as wide dynamic range contains many shades ol gray. Wide dynamic range (also called high dynamic range) means "many choices."

LOGARITHMS and DECIBELS 192. The power in a wave is increased to ten times its original value. How many d€cibels describe this change? A.3 B.6 c. 10 D. 20

C. An increase of ten times the original power of a wave is reported as +10 dB.

BIOEFFECTS-- 614. Which of the lollowing ultrasound beams has a characteristic that is most likely to cause temperature elevation in soft tissue? A. strongly focused B. medium focused C. unfocused

C. An unlocused beam is most likely to cause temperature elevation in soft tissues. Temperature elevation with unfocused beams results lrom the broad area over which the beam spreads. With narrower, locused beams, the area insonated by the beam is smaller and therelore heats a smaller mass of tissue.

BIOEFFECTS-- 602. Certain studies of bioetfects are performed in vilro. Whal is lhe meaning ol in vitro? A. visible in a living organism B. observations based on experiments C. discernible in a test tube D. perceptible in a living human being

C. An, in vitro experiment is perlormed out ol the body and in an artificial environment. The observations may be described as "in a test tube."

INCIDENCE 220. Which of the following describes an angle with a measure of 123 degrees? A. orthogonal B. acute C. obtuse D. normal

C. Any angle that measures greater than 90 degrees is an obtuse angle

ATTENUATION, REFLECTION, and SCATTERING 197. As sound propagates through a medium, the total power in the wave decreases. What is lhis entire process called? A. absorption B. scattering C. attenuation D. reflection

C. As a wave propagates through a medium, its power diminishes. This is atlenuation. Choices A, B, and D are all components of or contributors to attenuation.

ARTIFACTS-- 561. What type of artilact causes a refleclion to be placed at an incorrect depth? A. lateral incertitude B. shadowing C. range ambiguity D. indeterminate relaxalion

C. Bange ambiguity means that uncertainty exists regarding the depth o, a structure in the body.

AXIAL RESOLUTION 268. Two ultrasound systems produce acoustic pulses. A pulse from System t has a wavelength of 0.5 mm, 4 cycles per pulse, and a pulse repetition period of 1 .2 msec. The pulses trom System 2 have a wavelength of 1.0 mm, 2 cycles per pulse, and a pulse repetition period of 1.8 msec. Which ultrasound system will have a lower numerical value of axial resolution? A. Syslem 1 B. System 2 C. both are lhe same D. cannot be determined

C. Bange resolution is equal to one-half the spatial pulse length. Spatial pulse length is equal to the number of cycles in the pulse multiplied by the wavelength. System 1's pulse length is 4 x 0.5 mm = 2.0 mm. System 2's pulse length is 2 x I .0 mm = 2.0 mm. Since both syslems have identical pulse lengths, their axial resolutions are also identical.

137. When the elasticity of a medium is high, the _ is high. A. stiffness B. propagation speed C. compressibility D. reflectivity

C. Both elasticity and compressibility describe the ability of a medium to reduce its volume when atlected by a force. High elasticity means lhe same as high compressibility.

BIOEFFECTS-- 616. Research has indicated that cavitation A. never occurs B. cannot o@ur with long pulses C. can be lethal to living things D. etfects are purely theoretical

C. Cavitation resulting from ultrasound exposure is lethal to the fruit fly. Cavitation has the potential for significant and harmful bioeffects under specific circumstances.

324. Two ultrasound systems are identical except for the pulse repetition period (PRP) of the emitted pulse. Which system will have the deeper focus? A. the system with the lower PFIP B. the system with the higher PBP C. their foci will be at the same depth

C. Changes in the pulse repetition period do not affect the depth ol the focus. The frequency ol the sound and the piezoelectric crystal's diameter help to determine the local depth.

DOPPLER-- 513. All of the lollowing are associated with a CW Doppler transducer except A. narrow bandwidth B. increasedsensitivity C. backing material D. high Ojactor

C. Compared to pulsed transducers, continuous wave transducers do not use backing material. As a result, CW has increased sensitivity and is more able to detect small Doppler shitts.

INSTRUMENTATION 424.Wnich receiver function creates an image of comparable brightness lrom top to bottom? A. receiver gain B. output power C. swept-gain compensation

C. Compensation establishes images ol unirorm brightness from top to bottom. Compensation adiusts lor the attenuation of sound with increasing path length.

LOGARITHMS and DECIBELS 188. The scale associated with decibel notation is _. A. linear B. discrete C. logarithmic D. additive

C. Decibel notation is based on the mathematical relationship of logarithms.

ARTIFACTS-- 574. With depth resolution, A. too many reflectors appear on the image B. reflectors are placed too deep on the image C. too few rellectors are on the image D. rellectors appear too shallow on the image

C. Depth resolution is the ability to distinguish two reflectors that lie close to each other along the main axis of the beam. Most errors in depth resolution result in fewer reflections placed on the image than are actually in the body. Depth resolution is another name for axial resolution.

ATTENUATION, REFLECTION, and SCATTERING 203. Which of the following is true of diffuse reflections? A. they're created by smooth boundaries B. they're created by large reflectors C. sound rellects in many directions D. they do not appear in soft tissue

C. Diffuse reflections, also called backscatter, are dispersed in multiple directions.

DOPPLER-- 501. When using a 4 MHz transducer, a Doppler shitt ol 3,000 Hz is recorded. What will the Doppler shift be when a 2 MHz transducer is used? A. 3,000 Hz B.2Hz c. 1,s00 Hz D. 6,000 Hz

C. Doppler shifts are directly related to lransducer frequency. When the frequency is halved, the Doppler shift will be halved.

DOPPLER-- 495. What is the range of Doppler shilts commonly measured in clinical exams? A. -10 kHz to 1 MHz B. -0.5 MHz to 0.5 MHz c. -0.02 MHz to 0.02 MHz D. none ol the above

C. Doppler shifts in clinical imaging typically range lrom -20,000 Hz to +2O,O0O Hz. Choice C has units ot megahertz, but when we examine the values of -0.02 to +0.02 MHz closely, we see that this means exactly the same as -20,000 Hz to +20,000 Hz

DOPPLER-- 497. What intormation does the Doppler shift furnish concerning the blood cells that produce it? A. frequency B. speed C. velocity D. density

C. Doppler shifts produce information regarding velocity. What is the ditlerence belween speed and velocity? Speed is purely a number such as 400 m/s. Velocity is both a number and a direction, such as 200 m/s away lrom the transducer. Doppler shifts indicate direction and a magnitude.

DISPLAY MODES 379. Which best describes the elements in a linear sequential array transducer? A. rectangular, 1/4 wavelength thick B. rectangular, 1/4 to 1/2 wavelength wide C. rectangular, 1 wavelength wide D. squares, 1 wavelenglh thick

C. Each element of a linear sequenlial array is rectangular. There are many elements, each with a width of one wavelength

LATERAL RESOLUTION and FOCUSING 343. Which o, these techniques is consistent with variable or multi-focusing? A. lens B. curved crystal C. electronic

C. Electronic locusing is achieved with phasing of electronic signals. Electronic tocusing, unlike internal or extemal locusing, is adiusted by the sonographer ln addition, it is multi-focus.

ATTENUATION, REFLECTION, and SCATTERING 200. Which of the following is not one ol the physical processes that contributes to attenualion of ultrasound waves passing through sofl tissue? A. rellection B. redirection ol sound in many directions C. focusing D. conversion of acoustic energy to heat

C. Focusing does not contribute to lhe attenuation process. ln contrast, choices A, B, and D reduce the intensity ol a wave as it propagates.

DOPPLER-- 525.Which choice relates to the presence of gray shades in a Doppler spectrum? A. velocity B. frequency shift C. amplitude ot the echo D. laminar flow

C. Gray scale in a Doppler spectrum is related to the number o, red blood cells creating the reflection. The number of red blood cells determines the amplitude ol the reflected signal.

ARTIFACTS-- 577. With which of the lollowing pulses would lateral resolution be worst? A. 10 MHz,4 mm beam diameter, 4 cycles per pulse B. 4 MHz, 4 mm beam diameter, 2 cycles per pulse C. 7.5 MHz, 8 mm beam diameter, 2 cycles per pulse D. 6 MHz, 2 mm beam diameter, 2 cycles per pulse

C. Lateral resolution artilact is related to the diameter of the ultrasound beam. Narrow beams have the best lateral resolution. Wide beams have the worst laleral resolution. Choice C, with a beam diameter ol 8 mm, is most likely to produce a lateral resolution artifact.

DOPPLER-- 503. Two otherwise identical Doppler studies are performed, except that the angle between flow and the sound beam is 0 degrees in the first study and 60 degrees in the second. The velocity measured in the first study is 2 m/s. What velocity will be measured in the second study? A. 2 m/s B. 4 m/s C. 1 m/s D. cannot be determined

C. Maximum velocities are measured at a zero degree angle. Only one-half ol the true velocity is measured when the angle is 60 degrees.

ARTIFACTS-- 586. ln diagnostic imaging, how does multipaih artifact aflect the image? A. poor angular resolution B. creation of hyperechoic regions C. mild image degradation D. gross horizontal misregistration

C. Multipath artiract does not manifest itself in a pronounced manner. The primary result ol this artifact is mild image degradation.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 400. What is lhe primary advantage ot multiple focal zones along each scan line of a two- dimensional image? A. improved temporal resolulion B. decreased temporal resolution C. improved lateral resolution D. improved longitudinal resolution

C. Multiple foci along a single scan line creates a composite beam that is extremely narrow. Narrow sound beams create images with superior lateral resolution at all depths. Single focus syslems use a single sound beam to create each scan line, and lateral resolution is optimal at only one depth.

INCIDENCE 224.Which term has a meaning other than normal incidence? A. orthogonal incidence B. perpendicularincidence C. oblique incidence

C. Oblique incidence has a meaning thal is different f rom normal incidence. Oblique incidence occurs when a wave strikes a boundary at any angle other than 90 degrees, while normal incidence occurs when the wave strikes a boundary at exactly 90 degrees

ARTIFACTS-- 556. Which artilact is not affected by the shape or dimensions of an ultrasound pulse? A. lateral resolution B. slice thickness C. mirror imaging D. longiludinal resolution

C. Of the artifacts listed, only mirror imaging is unrelated to the size, shape, or geometry of the ultrasound pulse. The others depend in some way on lhe pulse's characteristics.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 405. Of the following, which imaging modality has the poorest temporal resolution? A. two-dimensional, real-time B. A-mode C. color llow imaging D. M-mode

C. Of the choices, color flow imaging has the lowest temporal resolulion. Many pulses are required to create a single color flow image. The large number of pulses required for each image results in a low trame rate and poor temporal resolution.

DISPLAYS-- 466. Which of these components typically has the greatest dynamic range? A. display B. pulser C. amplifier D. demodulator

C. Of the four choices, lhe component of an ultrasound system with the greatest dynamic range is the amplifier.

TWO DIMENSIONAL IMAGING For the following 6 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) 381. These transducers steer the beam with a motor and focus the beam with an acoustic lens or a curved PZT element . A. linear switched (also called linear sequential) array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer F. vector array transducer

C. Only a mechanical scanner has these characteristics.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 403. An ultrasound system with a 4.0 MHz transducer is used to image structures as deep as l5 cm. Twenty images are produced each second, each requiring 100 acoustic pulses. What is the PRF ol the system? A. 1 ,500 Hz B. 300 Hz c. 2,000 Hz D- 4 MHz

C. Pulse repetition frequency is defined as the number of pulses produced by an ultrasound system in one second. ln this example, 100 pulses are required to construct a single image, and 20 images are displayed each second. Thus, a total of 2,000 pulses are used each second to meet the imaging requirements ol this system; this is the PRF. ln this question, frequency and imaging deplh are unimportant.

ATTENUATION, REFLECTION, and SCATTERING 201 . An acoustic pulse rellects from a very smooth boundary where the irregularities on the surface of the boundary are much smaller than the pulse's wavelength. What type of reflection is most likely to occur under these circumstances? A. partial B. Rayleigh C. specular D. total

C. Reflections rrom a smooth boundary are specular. A mirror is a specular refloclor. The waves strike this smooth boundary and reflect in an organized, systematic manner. A boundary is consid€red smooth when irregularities in its surface are smaller than the wavelength ot the incident ultrasonic beam.

ARTIFACTS-- 569.Which artitact results in improper side-by- side positioning of rellectors? A. multipath B. comel tail C. relraction D. reverberation

C. Refraction artilact results rrom an acoustic pulse bending and changing direction. This change ol direction is not corrected by the ultrasound system and results in an improper lateral location of rellectors on the image.

ARTIFACTS-- 544. Which siluation will commonly produce reverberation artiract? A. two masses that lie perpendicular to the sound beam's main axis B. two weak reflectors that lie close to each other along the axis of lhe beam C. two strong reflectors that lie along the main axis ol the beam D. a single highly reflective mass

C. Reverberations are commonly produced by a pair of strong rellectors that lie along the main axis of an ultrasound beam.

DISPLAY MODES 378. How are the piezoelectric crystals excited when using an ultrasound system with a sequential linear array transducer? A. singly and in order: the first crystal, second, then the third, etc. B. in pairs: the Iirst two crystals, the 3rd and 4th, the sth and 6th, etc. C. in a specific order D. in a random sequence

C. Sequential linear array transducers fire small groups of piezoelectric crystals in a specilic succession or progression. The order of firing is determined by lhe manufacturer, and is chosen to produce the highest quality image. There is, however, no specific order that all linear arrays use. The firing pattern is best described as "in a specific order."

ARTIFACTS-- 547. Where are shadowing artifacts commonly seen on an acoustic scan? A. deeper than a structure with a high impedance B. shallower than a structure with a low propagation speed C. deeper than a structure with a high attenuation D. alongside of a structure with a low elaslance

C. Shadowing occurs on an image at locations beneath strong attenuators. For example, a region deeper than a gallstone may be aflected by shadowing.

ARTIFACTS-- 576. Which ol these pulses is least likely 1o produce an axial resolution artilact? A. 10 MHz, I mm beam diameter, 6 cycles per pulse B. 4 MHz, 4 mm beam diameter, 2 cycles per pulse C. I MHz, 8 mm beam diameter, 2 cycles per pulse D. 6 MHz, 2 mm beam diameter, 2 cycles per pulse

C. Short pulses are least likely to produce an axial resolution artifact. Short pulses are those with a high frequency and few cycles per pulse. Although choice C does not have the highest trequency, it has only 2 cycles per pulse, and therelore is the shorlest of the 4 pulses.

ARTIFACTS-- 572. What artifact results lrom an ultrasound beam having a finite and measurable three-dimensional prolile? A. acoustic speckle B. multipath artifact C. slice lhickness artifact D. grating lobe artifact

C. Slice artifact occurs because a sound beam has a thickness. Although the sonographer imagines that the imaging plane is extremely thin, the beam actually has a measurable thickness. Thickness artilact resulls in some reflectors appearing in the image even though they are positioned above or below the idealized imaging plane.

120. What is lhe best estimate of the distance that sound can travel in sotl lissue in one second? A. one yard B. one hundred yards C. one mile D. ten miles

C. Sound travels at a speed ol 1,540 meters per second in soft tissue. This is approximately one mile per second.

'125. What is the best estimate for the speed of sound in tendon? A. 1,000 rn/s B. 1, 0 rn/s C. 1,754 rnls D. 5,400 rn/s

C. Sound travels slightly faster in tendon than in soft tissue.

131. lf sound doesn't travel al 1,540 rn/soc in a medium, then the medium A. must be soft tissue -. B. may be soft tissue C. cannot be soft tissue

C. Sound waves travel exactly 1,540 rn/sec in soft tissue. Since the propagation speed of sound in this medium is not 1,540 m/sec, the medium cannot be sott tissue.

149. The spatial pulse length describes certain characteristics of an ultrasound pulse. What are its units? A. time B. hertz C. meters D. none; it is unitless

C. Spatial pulse length is the distance that a pulse occupies in space. lts length is measured lrom the beginning to the end of the pulse. lt can be reported in any unit ol distance

INSTRUMENTATION 429. At which imaging depth is the slope oI the TGC curve most effective? A. the region very close to the transducer B. the lar zone C. the tocal zone

C. TGC is most effective in improving image quality in the focal zone. Compensating lor attenuation in the local zone allows the ultrasound system to produce high-quality scans with detailed information.

TRANSDUCERS 276. How thick is the active element of a 3 MHz pulsed wave transducer? A. I .54 mm B. 0.51 mm C. half the wavelength of the sound wave in the PZT D. one-quarter the wavelength of sound in the matching layer

C. The PZT is hall a wavelength thick. That isJ the thickness is equal to one-hall the wavelength of sound in the PZT.

183. Which intensity is most closely correlated to tissue heating? A. SPTP B. SATP C. SPTA D. SATA

C. The SPTA intensity relates most closely to tissue temperature elevation.

DOPPLER-- 522. During a pulsed Doppler exam, aliasing is c observed. All of the following may eliminate aliasing except A. selection of another imaging view with a shallower sample volume B. selection of another transducer with a lower frequency C. selection of another imaging view that provides a greater pulse repetition period D. use of a continuous wave system

C. The actions that will reduce the likelihood of aliasing are: 1. selecting a shallower imaging depth to increase the PRF 2. using a transducer with a lower frequency, and 3. using a continuous wave Doppler system that cannot alias lf the sonographer selects an imaging view with a greater pulse repetition period, the pulse repetition frequency will decrease and the likelihood ol aliasing will increase.

INSTRUMENTATION 422. Which oI the following is a typical value lor the amplilication ol a signal by the receiver? A. 50 to 100 watts B. -50 lo -100 dB C. 50 to 100 dB D. 5 to 25 Wcm2

C. The amplification ol the weak eleclrical signals that first reach the receiver range from 50 to '100 decibels. This prepares the signals for turther processing.

TRANSDUCERS 279. Which component of an ultrasound transducer is made lrom a slab ol epoxy embedded with tungsten particles? A. the matching layer B. the piezoelectric crystal C. the damping material D. the computer chips

C. The backing material, or damping material, ot a transducer assembly is often Iabricated of tungsten-embedded epoxy.

DISPLAYS-- 447.Whal is the smallest part of a digital picture called? A. bir B. byte C. pixel D. fractal

C. The basic element ol a digital representation ol an image is the pixel. The term is derived from the words "picture elemenf'.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 404. Which ol the following sector imaging systems will have the best image detail if all oth€r parameters are identical? A. a 90' sector with 100 pulseyimage B. an 80' soctor with 40 pulses/image C. a 70' sector with 84 pulseyimage D. a 60' sector with 60 pulseMmage

C. The best image detail is provided by the system with the highest line density. Line density is defined as the number ot acoustic lines per degree ol sector angle. The more lines per sector degree, the closer together the scan lines are, and the greater the anatomic detail displayed. Choice C has 1.2 acoustic pulses per degree (8410), choice A has a line density ol 1.11 (100/90) lineddegree, choice B has 0.5 (40/80) lineydegree, and choice D has 1 (60/60) line/degree. Choice C has the highest line density and the best spatial resolution.

TRANSDUCERS 293. Damping material is secured to piezoelectric material during the fabrication ol an ultrasonic imaging transducer. Which ol the following is not a consequence ol this attachment? A. bandwidth increases B. quality factor decreases C. sensitivity increases D. transducer case is longer

C. The damping material of an imaging transducer decreases the transduce/s sensitivity. The backing material increases bandwidth, decreases the Q-factor, and lengthens the transducer case.

ATTENUATION, REFLECTION, and SCATTERING 206. To which ol the following is Rayleigh scattering related? A. half of the wavelength B. square root of propagation speed C. frequency 4 D. PRF2

C. The degree to which a wave exhibits Rayleigh scattering is related to frequency raised to the fourth power. That is, if the frequency is twice as high, Rayleigh scattering is increased 16-fold: 2^4=2x2x2x2=16

TWO DIMENSIONAL IMAGING 389Which transducer possesses the best slice thickness resolution? A. linear phased arrays B. 2-D arrays C. 1ll2 dimensional arrays D. linear sequential arrays

C. The greatest advantage of 1/2 dimensional arrays is that they create very thin ultrasound slices.

ARTIFACTS-- 587. Which ol the following determines the spatial resolution of an image on a monitor? A. strength of the electron beam B. form of phosphor coating of the screen C. number of lines of the monitols display D. the pulse duration

C. The image displayed on a monitor is composed of a number of horizontal lines. The detail within the image, called spatial resolution, is determined by the number ol TV lines on the screen.

ARTIFACTS-- 559. lf an ultrasound pulse travels through a large mass in the body at a speed of 1.2 mrn/ps, what happens to the position of all echoes produced lrom reflectors shallower than the mass? A. they are placed In too shallow a location on the image B. they are placed in too deep a location on the image C. they are likely to be placed at the correct depth

C. The mass has a propagation speed ditferent than that of soft tissue. Only structures deeper than the mass will be affected. However, this question asks about reflectors that are shallower than the mass. Reflections from structures shallower than the mass are not atlected by this speed difference.

INCIDENCE 232. What is the maximum permissible value tor both the intensity rellection coefficient and the intensity transmission coefficient? A. 100 B. 1 % c. 1 D. infinity

C. The maximum percentage of the incident intensity that either reflects or transmits is 1 .0 or 100%. At the extremes, total ref lection occurs (intensity ref lection coefficient = L0) or complete transmission occurs (intensity transmission coetficient = 1.0). The upper limit of both of these coefficients is 1.0.

BIOEFFECTS-- 619. Which selection has the highest mechanical index? A. high frequency, high power B. high PRF, high intensity C. low frequency, high pressure D. high spatial pulse length, high PRF

C. The mechanical index is derived mathematically from the pressure in a sound beam and the sound's frequency Mechanical index is highest with a high pressure sound beam of low frequency.

Two sound pulses travel through the same medium. One wave,s frequency is 2 MHz and the other is I 0 MHz. Answer the following 5 questions. 102. Which pulse has a lower propagation speed? A. the 10 MHz pulse B. the 2 MHz pulse C. neither pulse D. cannol be determined

C. The propagation speeds of all sound waves are identical while traveling in a specilic medium.

PULSED ULTRASOUND 139. What are the units of pulse duration? A. units ol frequency (Hz, etc.) B. msec only C. units of time (sec, years, etc.) D. units of distance (feet, etc.)

C. The pulse duration is the actual time that a transducer is creating one pulse. Hence, it has units ol time. The typical range of pulse durations found in diagnostic imaging equipment is 0.3 to 2 psec, but it is valid to report pulse duration in any unit ol time.

157. Which ol the following correctly doscribes pulse repetition period? A. the product of wavelonglh and propagation speed B. the reciprocal ot the frequency C. the sum of the pulse's "on" lime and the listening "otf time D. the time that the transducer is pulsing

C. The pulse repetition period is the actual time from the start of one pulse to the start of the neld pulse. lt is equal to the time that the transducer is pulsing (the pulse duration) plus the time thal lhe ultrasound system is listening for reflected echoes.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 408. A sonographer reduced the sector size from 90 dagrees to 30 degrees. Frame rate, however, did not change. What else happened? A. imaging depth decreased B. pulse duration increased C. multiJocus was turned on D. PBF was increased

C. The question states that sector size was decreased. By itsell, this would increase lrame rate. Thus, lhe correct answer to this question is something that would decrease frame rate. The only selection that decreases frame rate is the use of multiple focal points, choice C.

SOUND BEAMS 304. What is the region from the transducer to the smallest cross-sectional area of a sound beam called? A. tocus B. half-valuethickness C. near zone O. Fraunhofer zone

C. The region lrom the transducer to the narrowest portion ol an ultrasound beam is delined as the near zone, or Fresnel zone.

INSTRUMENTATION 427. Which term best describes the region ol minimum amplification on a standard TGC curve? A. far field B. focus only C. area close to the transducer D. local zone

C. The region of minimum amplification on a TGC curve, often called the "delay," is always associated with the area close to the transducer.

INSTRUMENTATION 41 I . What is a typical pulser output voltage that exciles a piezoelectric crystal? A. 0.1 volts B. 500 millivolts C. 40 volts D. 10 microvolts

C. The signal typically produced bythe pulser of an ultrasound system, used lo excite the lransducers's piezoelectric crystals, may be in the range of tens ol volts.

I 19. The propagation speed of continuous wave ultrasound is 1.8 kilometers per second. The wave is then pulsed with a duty factor ol 50ol". What is the new propagation speed? A. 0.5 knvsec B. 0.9 krn/sec C. 1 .8 krn/sec D. 3.6 krdsec E. cannot be determined

C. The speed of sound in a medium is determined only by the medium. There is no ditference in sound's speed whether the wave is continuous or pulsed. Thus, the new and old speeds will be identical, 'I .8 km/sec.

ARTIFACTS-- 537. What is the meaning of the term "analysis" in the context of spectral analysis ol Doppler signals? A. building a sophisticated signal from componenls B. building a simplilied signal from components C. identifying the building btocks or components of a complex signal D. measuring a complex signal, then modifying its inrormation content

C. The term anarsis derines the act ol scrutinizing an object to determine what individual components are incorporated within it. ln Doppler analysis, the complex signal is broken down into its more basic ingredients.

BIOEFFECTS-- 597. The measures beam intensity at specific locations, whereas a A. calorimeter, thermocouPle B. Schlieren, thermocouPle C. thermocouple, calorimeter D. thermometer, hydrometer

C. The thermocouple is a small electronic thermometer that measures the sound beam's energy at specific locations. The calorimeter absorbs all the beam's energy, converting it to heat. The calorimeler measures all the beam's energy.

SNELL's LAW and REFRACTION 246. Whal conditions are necessary for retraclion to occur at a boundary between two media? A. unequal acoustic impedances and normal incidence at the boundary B. unequal densities ol the media and normal incidence at the boundary C. dissimilar propagation speeds and oblique incidence at the boundary D. ditferent elasticities of the media and oblique incidence

C. The two conditions required for retraction are: 1. a sound wave must be obliquely incident to the border between two media, and 2. the media on either side ot the border must have dissimilar propagation speeds. Relraction occurs during transmission of a wave from one medium lo another.

138. Two sound waves with frequencies of 5 and 3 MHz travel to a depth of 8 cm in a medium and then retlect back to the surface ol the body. Which acoustic wave arrives tirst at the surface ol the body? A. the 5 MHz wave B. the 3 MHz wave C. neither D. cannot be determined

C. They both travel at the same speed and reach the surface ol the body at exactly the same time. All sound waves, regardless of their features, travel al the same speed in a specific medium.fho lact that these waves have different frequencies is irrelevant

ATTENUATION, REFLECTION, and SCATTERING 209. A sound beam travels 9 cm in soft tissue. The attenuation coefficient is 3 dB/cm. What is the total attenuation that the sound beam experienced? A.gdB B.3dB c. 27 dB D. 18 dB

C. To calculate total attenuation, multiply path length by attenuation coetficient. ln this example, the overall attenuation is 3x9=27dB.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 392. Which of the following will improve a system's temporal resolution? A. increased sector angle B. increased line density C. increased PRF D. increased frequency

C. To improve temporal resolution, increase the number of images produced each second. lf the number of pulses emitted per second is increased (choice C) then the system can increase the frame rate. lncreased PRF is obtained by decreasing the maximum imaging depth. A, B, and D all decrease frame rate and decrease temporal resolution.

AMPLITUDE, POWER, and INTENSITY 79. Mathematically, when a number is squared, the number is multiplied by A.2 B. 0.5 C. itsel, D. 1.5

C. To square a number means to multiply the number by itself. Hence, the term live squared" means 5 times 5, or 25. Ten squared is 10 times 10, or 100.

ARTIFACTS-- 542. Ultrasound systems are designed to automatically? A. display similar structures with equal brighhess, regardless of depth B. position structures at the correct depth, regardless ol the medium C. display all reflections on a line corresponding to the main axis of the sound bsam, regardless of refraction D. select the optimal beam width based on the clinical application

C. Ultrasound systems assume that all reflections are created lrom rellectors that lie directly along the main axis oI the ultrasound beam. An artifacl is created when pulses refract and change direction.

ARTIFACTS-- 570.What assumption is violated when a refracted sound wave is processed? A. wav6s trav€l directly to and from a reflector B. sound travels at an average speed of 1.54 mm/ps C. sound travels in a straight line D. the acouslic imaging plane is very lhin

C. Ultrasound systems create images on the basis of certain assumptions. Artitacts occur when these assumptions are invalid. Refraction artifact results from sound traveling in a crooked or bent line while the ultrasound system assumes a straight path.

REFLECTION and TRANSMISSION 235. ll the _ of two media are differenl and sound strikes a border between the media at 90' incidence, then rellection will occur. A. conductances B. densities C. impedances D. propagation speeds

C. Under the conditions of orthogonal or normal incidence, reflection depends on ditferences in the acoustic impedances of the media on either side ol the boundary. With normal incidence, as long as the impedances are dissimilar, rellection will always occur.

ATTENUATION, REFLECTION, and SCATTERING 199. An acoustic wave is traveling through sofl tissue. lts intensity undergoes six decibels ot attenuation. How does the final intensity ol the wave relate to the intensity of the wave when it started its journey? A. it is now four times larger B. it is now six times larger C. it is now one-fourth as large D. it is now one-tenth as large

C. When a wave undergoes 6 dB ol atlenuation, the intensity ol the wave is decreased to one-fourth of its initial value. The term attenuation means "to weaken, or reduce." Attenuation always describes a reduction in the intensity of the wave. Six decibels of attenuation is made up of two groups oI -3 dB. Each -3 dB indicates a halving of intensity. One-half multiplied by one-half means that only one-fourth ol the original intensity remains.

DISPLAY MODES 353. With B-mode, on which axis is the strength of the retlection input? A. x-axis B. y-axis C. z-axis

C. With B-mode, reflection strength is input into the z-axis

ARTIFACTS-- 571.With standard diagnostic imaging instrumenlation, which has the higher numerical value? A. axial resolution B. Iateral resolulion C. elevational resolution

C. ln terms ol image accuracy, elevational resolution, determined by slice thickness, is the cause ol greatest image degradation. The numerical value assigned to elevational resolution is higher than the others.

DOPPLER-- 505. A maximum Doppler shift is obtained when the angle between the direction of blood flow and the direction of the sound beam is A. 10 degrees B. 90 degrees C. 180 degrees D. 270 degrees

C.Maximum Doppler shifts occur when red blood cells travel directly toward or directly away lrom a transducer. An angle ol 180' between the sound source and the direction ol molion exists when the cells travel directly away from the transducer.

ATTENUATION, REFLECTION, and SCATTERING 204. What is the uniform dispersion of a sound wave in many different directions after striking a very small particle? A. microscattering B. backscattering C. Rayleigh scattering D. total absorption

C.Rayleigh scattering is the redirection of an acouslic wave in many different directions as a result ol striking a small particle. When Rayleigh scattering occurs, the dimension of the reflecting particle is usually less than the wavelength of the ultrasound wave. The amount of Rayleigh scattering also depends on the frequency of the ultrasound.

DOPPLER-- 504. What is true of the Doppler shift when the sound beam is normally incident to the velocity ol the red blood cells? A. it is at maximum B. it is hall of maximum C. it is absent D. it is at minimum

C.The Doppler shift is related to the angle between the directions of the blood flow and the sound wave. The cosine ol this angle indicates the percentage of the true velocity that is measured by Doppler. Normal incidence indicates a 90' angle between blood llow and the sound beam. The cosine of 90" is zero. Theretore, zero percent of lhe velocity is measured; the Doppler shitt is absent.

TRANSDUCERS 300. What is the best estimate of the propagation speed ol the ferroelectric element of a transducer used in a lypical diagnostic imaging laboratory? A. 1 .2 mm/psec B. 4.0 m/sec C. 4.0 mm/psec D. 1 .0 km/sec

C.The active element of a typical diagnostic imaging transducer has a propagation speed that is approximately three to five times greater than the speed of ultrasound through soft tissue. This range is approximately 4 to 8 km/sec. Other ways of stating this are 4 to 8 mm/psec, or 4,000 to 8,000 m/sec. Choices A, B. and D are att too low to be the speed ol sound in an imaging crystal.

BIOEFFECTS-- 612. of th6 following choices, which is considered the mosl important ,or the sonographer with regard to bioettecls? A. pulse repetition lrequency B. frequency C. duration of the study D. imaging mode

C.The exam duration is most significant because the sonographer directly controls it. Exams should always be of high quality and should provide relevant diagnostic inlormation with a secondary goal ot minimizing output power level and time exposure to the patient

SOUND BEAMS 305. The area that starts at the beam's smallest diameter and e)dends deeper is: A. the distant zone B. the Fresnel zone C. the Fraunhofer zone D. the depth of penetration

C.The region that extends deeper from an ultrasound beam's narrowest diameler and deeper is called the tar zone, or Fraunholer zone.

153. Using a specific transducer, what happens to the spatial pulse length as the sonographer increases the maximum imaging depth? A. increases B. decreases C. remains the same D. cannot be determined

C.The spatial pulse length is determined by the number of cycles in the pulse and the wavelength of each cycle. With the same system, these lactors are unchanged, and the spatial pulse length remains the same

148. What happens to the pulse duration when C. a sonographer decreases the maximum imaging depth in an ultrasound scan? A. increases B. decreases C. remains the same D. cannot be determined

C.The time that a transducer is "pulsing" does not change with alterations in depth ol view

151 . Which of the following best describes the spatial pulse length? A. frequency multiplied by wavelength B. PRF multiplied by wavelength C. wavelength multiplied by the number of cycles in the pulse D.duty factor multiplied by the wavelength

C.The total length of a pulse equals the length of each cycle in the pulse multiplied by the number ol cycles in the pulse. lmagine the pulse as a train made up of a number of boxcars. The train's length (the spatial pulse length) equals the length of each car (the wavelength) multiplied by the number of cars in the train (the number of cycles in the pulse)

DOPPLER-- 499. Two ultrasound transducers are used to perform Doppler exams on the same patient. The exams are identical except that the transducer frequencies are 5 and 2.5 MHz. Which exam will measure the highest velocities? A. the 2.5 MHz exam B. the 5 MHz exam C. neither D. cannot be delermined

C.The velocities measured by Doppler exams are the same, regardless ol the frequency of the transducer. Although the Doppler shifts associated with the velocities may vary with different transmitted frequencies. the measured velocities are identical.

TRANSDUCERS 291. Assume that the lrequency ol sound with the greatest power emitted by a transducer is 5 MHz. However, the pulse contains acoustic energy with lrequencies as low as 3.5 MHz and as high as 6.5 MHz. What is the bandwidth ol the transducer? A. 6.5 MHz B. 5.0 MHz C. 3.5 MHz D. 3.0 MHz

D The bandwidth ot a pulse is defined as the range o, frequencies that are present within the pulse. To calculate bandwidth, subtract the lowest lrequency from the highest frequency in the acoustic signal (6.5 - 3.5 = 3.0 MHz). The bandwidth is 3.0 MHz. The natural or center lrequency of this transducer is 5 MHz.

LOGARITHMS and DECIBELS 191 . The intensity ol a signal declines from 1.5 mWcm2 to 0.75 mWcm2. How many decibels is this change in intensity? A.3dB B. 0.75 dB c. -0.75 dB D. -3 dB

D A decline in intensity to one-half of the original level is a change of -3 dB. When the new level is less than the reference level, the reported decibels must be negative. When the new intensity is greater than the reference level, the change in decibels is positive

ARTIFACTS-- 575. Axial resolution artifacts are due to which ol the following? A. multiple reflections B. beam width C. attenuation D. pulse length

D The critical factor that influences axial resolution is pulse length. Shorter pulses produce more accurate images than longer pulses. Shorter pulses have improved axial resolution.

ATTENUATION, REFLECTION, and SCATTERING 198. Attenuation is determined by which of the following lactors? A. density and stiffness ol the medium B. lrequency ol sound and propagation speed C. PRF ot sound and path length D. path length and frequency of sound

D The factors that determine lhe degree to which a sound beam weakens are: 1 . the distance that the sound travels, and 2. the frequency of the sound.

TRANSDUCERS 302. You are asked to fabricate a pulsed ultrasound lransducer with the highest possible f requency. Which piezoelectric crystal would you select? A. 6 mm thick, 4 cm diameter, 4.0 mm/ps propagation speed B. 8 mm thick, 2 cm diameter, 6.0 mm/ps propagation speed C. 4 mm thick, 9 cm diameter, 5.0 mm/ps propagation speed D. 2 mm thick, 6 cm diameter, 6.0 mm/us propagation speed

D The main frequency (also called resonant, natural, or center frequency) emitted by a piezoelectric crystal operating in the pulsed mode is principally determined by the lhickness and propagation speed of the crystal. The lrequency is greater when the crystal is thin and its propagation speed is high, so the active element listed in D is the proper choice. The diameter ol the active element does not affect the frequency of the pulse.

Two sound pulses travel through the same medium. One wave,s frequency is 2 MHz and the other is I 0 MHz. Answer the following 5 questions. 104. Which pulse has a longer spatial pulse length? A. the 10 MHz wave B. the 2 MHz wave C. neither wave D. cannot be determined

D The spatial pulse length is equal to the wavelength multiplied by the number of cycles in the pulse. We know that 2 MHz sound has a longer wavelength than 10 MHz ultrasound. However, the number ol cycles that comprise each pulse is unknown. The information provided is insufficient to answer the question.

REFLECTION and TRANSMISSION 237. A sound pulse strikes a boundary between two media with normal incidence. The spe€d of sound in the two media are very different; however, the impedances of the media are identical. what will happen? A. a big echo will be produced B. a medium echo will result C. a small echo will result D. there will be no echo at all

D When a sound wave is normally incident at a boundary, reflection will occur only when the media have dissimilar impedances. ln this example, the wave is normally incidenl but the media have identical impedances. Under these circumslances, no rellection will occur and 100"/. of the sound will be transmitted.

DOPPLER-- 492. ln clinical imaging, which reflectors produce most relevant Doppler shifts? A. blood vessels B. blood plasma C. platelets D. red blood cells

D ln clinical imaging, red blood cells are the primary reflectors that produce Doppler shifts. Blood cells constantly move through the circulatory system and make up nearly 45olo of the volume of the blood.

'181 . Which of the following terms does not belong with the others? A. increased depth of view B. decreased duty lactor C. increased pulse repetition period D. decreased spatial pulse length

D, Spatial pulse length is unrelated to alterations in depth of view. The other three selections are all related to deeper imaging.

DISPLAY MODES 350. Which imaging modality places time-of- flight inlormation on the x-axis and echo amplitude on the y-axis? A. M-mode B. L-mode C. J-mode D. A-mode

D. A-mode, or amplitude mode, displays reflector depth on the x-axis. Reflector depth is determined by a pulse's time of flight. The strength ol the rellection is displayed on the y-axis.

INCIDENCE 231. What remains when the rellected intensity is subtracted lrom the incident intensity? A. 1.0 B. incident intensity C. transmitted intensity coefficient D. transmitted intensity

D. At any point in time and space, there must be conservation of energy. ln other words, all energy must be accounted for. The intensity in a wave as it reaches a border between two media is called the incident intensity. As the wave strikes the boundary, a portion of the wave's intensity is redirected toward the sound source. This is called the reflected intensity. The remainder of the energy continues to propagate and is called the transmitted intensity.

172. The pulse repetition frequency is the _. A. product ol the wavelength and propagation speed B. reciprocal of the period C. sum of pulse duration and listening time D. reciprocal ol pulse repetition period

D. The PRF and the pulse repetition period are reciprocals. For example, if the PBF is 100 per second, then the pulse repetition period is one-hundredth ol a second. ll the system creates five hundred pulses per second, then the pulse repetition period is 1/500 of a second.

147. What is the pulse duration equal to? A. Irequency multiplied by period B. period mulliplied by wavelength C. the number ol cycles in the pulse divided by the wavelength D. period multiplied by the number of cycles in the pulse

D. The pulse duration is the total time that the transducer is producing a pulse. The pulse duration is equal to the time to make a single cycle (the period) multiplied by the number ol cycles that make up the pulse. For example, if there are 6 cycles in a pulse, each with a period of 0.2 psec, then the pulse duration is 6 x 0.2 = 1.2 tisec.

ATTENUATION, REFLECTION, and SCATTERING 205. Which of the following is considered a Rayleigh scatterer? A. bone B. liver C. muscle D. blood cell

D. A blood cell is a Rayleigh scatterer. A red blood cell is smaller than the wavelength of the typical acoustic wave used in diagnostic imaging. When an acoustic wave strikes a blood cell, the energy within the puls6 is scattered in many directions.

ARTIFACTS-- 545. What are the characteristics of a medium that produces comel tail artifact? A. weak reflectors, closely spaced, low propagation speeds B. strong reflectors, widely spaced, high propagation speeds C. strong reflectors, closely spaced, low propagation speed D. strong reflectors, closely spaced, high propagation speed

D. A comet tail artilact is similar to a reverberalion except that the reflection is a solid hyperechoic line. The comet tail is a solid jet because of strong rellectors with high propagation speeds lying close to each other

TRANSDUCERS 297. What helps to determine the trequency ol the sound produced by the transducer ol a continuous wave ultrasound system? A. piezoelectric crystal diameter B. piezoelectric crystal thickness C. damping material density D. ultrasound system electronics

D. A continuous wave (CW) transducer produces an acoustic wave with a frequency equal to the lrequency of the electrical signal that excites the crystal. When the pulser's electrical signal has a lrequency ol 6 MHz, then the emitted acoustic wave is also 6 MHz. The electronics ol a CW system determine the frequency of the sound wave.

DISPLAYS-- 455. What is the maximum number of shades of gray that are represented with 4 bits? A.4 B.8 c. 12 D. 16

D. A maximum of 16 shades ol gray can be represented with 4 bits. To calculate this, multiply 2 by itselt the same number of times that there are bits. ln this example, multiply 2 by itsell a total of 4 times (there are 4 bits):2x2x2x2 = 16 shades.

HEMODYNAMICS-- 474. Which ol the lollowing llow patterns is associated with cardiac contraction? A. phasic B. spontaneous C. steady D. pulsatile E. continuous

D. A pulsatile llow pattern describes blood moving at a variable velocity as a result ot contraction of the heart. As a result, arterial flow is often described as pulsatile.

ARTIFACTS-- 548. How is shadowing artifact expressed? A. positioning structures too deep on the imaqe B. locating structures in improper lateral position C. placing reflections in multiple locations O. reflectors being absent on the image

D. A shadow artilact results from unexpectedly high attenuation. The ultrasound beam deeper than the strong attenuator is so weak that significant anatomical information does not appear on the image.

ARTIFACTS-- 562What causes side lobe artitact? A. sound beams bending B. linear array transducer architecture C. unexpectedly low acoustic attenuation D. acoustic energy radiating in a direction other than the beam's main axis lobe artilact usually results in all of

D. A side lobe is produced when a significant amount of acoustic energy is directed along a line other than the main axis of the acoustic pulse

DISPLAY MODES 351. Which imaging mode accurately displays rellector depth? A. Fmode B. L-mode C. C-mode D. A-mode

D. A-mode, or amplitude mode, displays the reflector depth accurately. A-mode is used in ophthalmology, which requires precise measures oI deplh or thickness.

LATERAL RESOLUTION and FOCUSING 342. Which ol theso t6rms means adiustable toatsing or multi-focusing? A. dynamac aperturo B. harmonics C. trsquency agility D. phased anay

D. All phased array transducers share one of these two featurgs: 1. they have multi-tocus capabilitiss or 2. the local depth can be changed by the sonographer.

INSTRUMENTATION 409. Which of the lollowing is not considered a component o, an ultrasound system? A. master synchronizer B. pulser C. receiver D. image intensilier

D. An ultrasound system is considered to have six components: transducer, pulser, receiver, image processor, display, and master synchronizer. An image intensilier is part of an x-ray imaging system.

Display modes 377. What is true of the electrical pulses that excite the active elements of an annular phased array transducer? A. they arrive at each piezoelectric crystal at exactly lhe same time B. they vary in amplitude based on the direction ol the steering and focusing C. they excite the crystals at diflerent times, nanoseconds apart D. they arrive at each PzT crystal at difterent times, microseconds apart

D. Annular array lechnology fires the piezoelectric crystals in a particular sequence to produce a locused ultrasound beam. The electrical pulses that excite the ringed elements of the array arrive at slightly difterent times, separated by only very small lractions o, a second.

DISPLAY MODES 375. What is the shape of the elements in an annular phased array transducer? A. rectangles B. squares C. wedges D. circles

D. Annular array transducers have piezoelectric crystals that are donut or ring shaped. They are arranged as a collection of concentric rings.

SOUND BEAMS 306. Which of, these terms have the same meaning? 1) far zone 2) near zone 3) Fresnel zone 4) focal zone 5) Fraunhofer zone 6) lateral zone A. 1 and 2, 3 and 4 B. 1 and 4, 2 and 3 C.4 and 6, 5 and 1 D.2 and 3, 5 and 1

D. Another name ior the Fresnel zone isthe near zone. The Fraunhofer zono can also be called the far zone. (Hint): Fresnel is the short name-it is the near zone. Fraunhofer is the long name-it is the far zone.

LOGARITHMS and DECIBELS 195. What units are used to describe attenuation? A. watts B. watts/cm2 C. macro D. decibels

D. Attenuation is measured in decibels Attenuation is reported as a relative change in strength, not an absolute change.

BIOEFFECTS-- 611. When studying bioeffects, which research approach is more important? A. empirical B. mechanistic C. neither is important D. both are equally important

D. Both the empirical and the mechanistic approaches are important. The strongest bioeffects conclusions are reached when the results of both approaches are in agreement. .

LOGARITHMS and DECIBELS 186. Decibel notation is a ______ between two numbers. A. difference B. sum C. product D. ratio

D. Decibels are calculated by dividing the final strength of a signal by the starting strength. Thus, decibel notation is a ratio between two numbers.

INSTRUMENTATION 418.Which of the following tasks is not performed by the receiver of an ultrasound system? (More than one answer may be correct.) A. rectilication B. smoothing C. compression D. degaussing

D. Degaussing is the only task listed above that is not performed by the syslem's receiver.

INSTRUMENTATION 433. Which ol the lollowing best describes the demodulation process? A. changing the gray scale of an image B. changing the frequency of a signal C. changing the form of a sound pulse D. changing an electrical signal's form

D. Demodulation alters the lorm or shape ol electrical signals within the receiver.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 397. Which two controls determine a system's temporal resolution? A. lrame rate and sector size B. focal zones and sector depth C. propagation speed and frame rate D. depth of view and pulses per image

D. Depth of view and number of pulses per image determine the frame rate (and temporal resolution) ol an ultrasound system. The sonographer can alter both ol these lactors.

173. What is a typical value lor the duty lactor (also called the duty cycle) of pulsed sound waves used in diagnostic imaging? A. 0.001 msec B. 0.001 kg/cm3 c.0.75 D. 0.001

D. Duty factor, or duty cycle, is the percentage or lraction ol time that an ultrasound system produces an acouslic signal, or is transmitting. Typically, ultrasound transducers spend the vast maiority ol time receiving, and only a small fraction of time transmitting an acoustic signal.

DISPLAY MODES 373 . Which of the lollowing forms of focusing is diflerent from the others? A. lens B. mirror C. phased D. dynamic receive

D. Dynamic receive locusing is accomplished during reception of reflected sound. The other lhree techniques are lorms ol focusing during transmission.

BIOEFFECTS-- 615. According to the AIUM, at what ln situ tissue temperature is there danger to a fetus? A. 100. c B. 98.6' F C. 1' F over normal temperature D.41"C

D. Elevation of letal tissue in excess of 41" C is considered potentially harmful

ARTIFACTS-- 553. Acoustic tocusing of an ultrasound beam may create which artilact? A. side lobes B. refraction C. speckle D. enhancement

D. Focusing ol an ultrasound beam may result in very strong reflections lrom anatomic structures at the depth of the locus. The powerrul reflections result in a hyperechoic band that is called focal enhancement or local banding.

DISPLAYS-- 457. How many bits are required to display 10 different shades ol gray? 14 shades? '15 shades? A.4bits,5bits,6bits B. 10 bits, 14 bits, 15 bits C.4bits,4bits,2bits D.4bits,4bits,4bits

D. Four bits of memory are required to display 10, 14, or 15 shades of gray. Three bits can display a maximum ol I gray shades (2 x 2 x 2 = 8). Adding a single bit to the collection increases the number o, gray shades to 16 (2x2x2 x 2 = 16).

126. As a general rule, which of the following lists media in increasing order of propagation speeds? A. gas, solid, liquid B. liquid, solid, gas C. solid, liquid, gas D. gas, liquid, solid

D. Generally, sound travels slowest in gases, faster in liquids, and fastest in solids.

ARTIFACTS-- 564. Grating lobes are most common with which type of transducer technology? A. annular array B. continuous wave C. mechanical scanners D. linear arrays

D. Grating lobe artifacts ar€ associated with linear array transducers.

327. Huygens' Principle is based on _. A. refraction B. constructive indices C. lransverse waves D. interference

D. Huygens' Principle explains the ditference between the beam shape from tiny pieces of PZT and disc crystals ol a larger dimension. The hourglass-shaped beam is caused by the interference of spherical waves.

ARTIFACTS-- 580. Which artifact is not related to the unexpected rellection ol an acoustic wave? A. multipath B. comet tail C. reverberation D. lateral resolution

D. Lateral resolution is an artifact that is not associated with abnormal reflection. Lateral resolution artifacts are related to beam diameter.

BIOEFFECTS-- 622. Epidemiologic studies ol ,n utelo exposure to ultrasound have included all ol the following lindings except A. birth weight -. B. cancer C. structural abnormalities D. none oI the above

D. Many epidemiologic studies on the effects of ultrasound have been reported. End points of birth weight, cancer, and structural abnormalities have all been studied. There is no correlation between ultrasound exposure and these events.

SNELL's LAW and REFRACTION 253. Sound propagates from one medium with a density of 1 .1 6 kg/m3 to a second medium with a density of t.O2 kg/m3. lf the angle of transmission is 49', what can be correctly stated about the angle of incidence? A. it is less than 49 degrees B. it is equal to 49 degrees C. it is greater than 49 degrees D. it cannot be determined

D. No delinite statement can be made about the angle of incidence. Since the propagation speeds ot the media are unknown, we cannol make any conclusions about the incident angle. The density of a medium helps to determine the propagation speed, but knowledge of only the density without knowledge ol a tissue's stiftness is insufficient to deduce which of the two media has a higher propagation speed.

INCIDENCE 223. A sound wave strikes a boundary between two media at a 60" angle. This is called _ incidence. A. orthogonal B. angular C. obtuse D. oblique

D. Oblique incidence is always present when the angle between the direction of a wave's propagation and the boundary between two media is different than 90". Oblique incidence is a definition of exclusion. That is, il the incidence is not perpendicular, it is oblique.

INCIDENCE 221. The angle between the direction ol propagation and the boundary between two media is 90'. What term describes the form of incidence of the wave? A. not normal B. direct C. oblique D. orthogonal

D. Orthogonal incidence is attained when a sound wave strikes a boundary between media at exactly 90 degrees

LATERAL RESOLUTION and FOCUSING 339. Which ol the following ,ocusing techniques is ditferent lrom the others? A. lens B. curved crystal C. fixed D. phased

D. Phased focusing is achieved with the electronics of an ultrasound system. Phased focusing is adluslable. Focusing with either a lens or curved crystal is tixed.

ARTIFACTS-- 546. What is the most likely cause oI ring down artifact? A. refraction B. inversion C. reabsorption D. reflection

D. Ring down artifact is thought to result lrom multiple r6flections.

ARTIFACTS-- 549. Which of these produces shadowing? A. reverberation B. multipath C. rellection D. attenuation

D. Shadowing results from atypical attenuation, the weakening ol ultrasound pulses.

SOUND BEAMS 323. As sound travels deeply into the far zone, the beam diverges, or spreads out. Which will result in the grealest beam divergence deep in the far zone? A. small diameter, high frequency B. high frequency, large diameter C. large diameter, low lrequency D. low frequency, small diameter

D. Small diameter crystals ot low frequency tend to produce sound beams thal diverge most in the deep far zone.

SNELL's LAW and REFRACTION 244. Which of the following best describes the process described by Snell's law? A. reflection with normal incidence B. reflection with oblique incidence C. transmission with normal incidence D. transmission with oblique incidence

D. Snell's Law defines the physics of refraction. Ref raction describes the behavior of sound beams that transmit after striking a boundary obliquely. Relraction is "transmission with a bend."

TEMPORAL RESOLUTION and REAL-TIME IMAGING 406. Which ultrasound imaging modality has the best tomporal resolution? A. B-scanning B. duplex imaging C. color flow imaging D. M-mode

D. Temporal resolution is the ability to accurately record the position of moving reflectors. With M-mode, the ultrasound pulse tracks retlector position in only a single dimension (depth only) and delivers extremely fine temporal resolution. The remaining choices all operate in two dimensions and do so by compromising temporal resolution.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 395. Two imaging systems produce acoustic pulses; one pulse is 0.4 psec long and the other is 0.2 psec long. Which is most likely to provide the best temporal resolution? A. 0.4 psec system B. 0.2 Usec system C. they are the same D. cannot be determined

D. Temporal resolution is unrelated to pulse duration. Temporal resolution is determined by the number of frames, or images, that are produced each second. There is insufficient information to answer the queslion.

DOPPLER-- 517. The highest Doppler lrequency without the appearance of aliasing is called the _ and is equal to _. A. aliasing limit, half ol the emitted lrequency B. pulse repetition frequency, the pulse repetition frequency C. Nyquist limit, half of the emitted ,requency D. Nyquist limit, half of the emitted PRF

D. The Nyquist limit is the highest Doppler shift that can be displayed without aliasing The Nyquist limit is equal to half of the pulse repetition frequency (PRF).

INCIDENCE 228. An ultrasound wave strikes a boundary between two media. All intensities are measured directly at the boundary. What results when the transmitted intensity is divided by the reflected intensity? A. intensity reflection coefficient B. intensity transmission coefficient C. beam uniformity coeflicient D. none ol the above

D. The choices of A, B, and C are all incorrect. When the transmitted intensity is divided by the rellected intensity, a number is obtained. This number has no special meaning in ultrasound physics, and is not identified by a special name.

174. What is the value ol the duty cycle for continuous wave ultrasound? A. 100 B. 1vo c. 1000% D. none ol the above

D. The duty factor lor continuous wave ultrasound is 1 .0 or 100%. This means that the transducer is producing an acoustic signal at all times. None ol the answers indicate this: 100 is not 100%, 1% means one-hundredth and is incorrect, and 1 000% means 10 times and is also false.

REFLECTION and TRANSMISSION 239. An ultrasound wave approaches an interface between two media at a 90" angle. The propagation speeds and the densities of the two media are different. Which is correct? A. reflection will definitely occur B. reflection will definitely not occur C. refraction may occur D. none of the above

D. The facts presented indicate that the propagation speeds and the densities of the two media are different, but this information is insufficient to determine whether reflection will take place. The important lact is whether the impedances ol the media are diflerent. lf the impedances of the media are different, then reflection will occur. lf the impedances are lhe same, then retlection will not occur ln this case, since we are unsure as to whether the impedances o, the media are the same, we are unsure whether choices A or B are correct. Choice C is incorrect because relraction will never occur when a sound wave strikes a boundary at a 90' angle. The only appropriate answer is D.

SOUND BEAMS 308. All of the following are true of the focus except A. it is at the end of ths noat zone B. it is at lhe b€ginning of the Fraunholer zone C. it has ths highosl spatial peak intensity D. it is at the start ot the Fresnol zone

D. The focus is located at the end of the near or Fresnel zone. The Fresnel zone starts at the transducer.

TRANSDUCERS 296. Which properties of the piezoelectric crystal of a continuous wave transducer result in the highest emitted acoustic wave frequency? A. thin, high propagation speed B. thick, slow propagation speed C. thin, slow propagation speed D. none ol the above

D. The frequency ot sound emitted by a continuous wave transducer is determined only by the trequency ol the electrical signal that excites the piezoelectric crystal. The crystal's lhickness and propagation speed do not affect the ,requency ol sound from a continuous wave transdu

IMPEDANCE 218. Which value is closest to the impedance of soft tissue? A. 1 .5 kiloRayls B. 2.5 deciRayls C. 19 megaRayls D. 2,000,000 Rayls

D. The impedance of soft tlssue is in the range of 1 .5 to 2.5 million Rayls. Choices A and B are far too low, and choice C is too high.

INCIDENCE 225. What are the units ol the intensity transmission coeff icient? A. watts/square cm B. watts C. dB D. none of the above

D. The intensity transmission coefficient is defined as the percentage ol an ultrasound beam's intensity that is transmitted as the sound wave passes through a boundary between two media. The intensity transmission coefficient is a percentage, and is reported without units.

DISPLAYS-- 440. What was the original purpose for the ultrasound system's analog scan converter? A. to increase the dynamic range of ultrasound systems B. to make real-time imaging possible C. to increase the sensitivity of ultrasound systems D. to allow for gray scale imaging

D. The introduction of scan converter technology in ultrasound allowed for the presentation of gray scale images. That is, the images were not limited to black and white (bistable), but had various shades of gray within them. Additionally, the scan oonverter changed the lormal o, the system's data trom penetrations to a format suitable for display.

INSTRUMENTATION 426. All of the following are used to describe compensation except A. swept gain B. depth gain C. time gain D. amplitude gain

D. The lerms swept gain, depth gain, and time gain are used interchangeably when describing compensation. The term amplitude gain is not synonymous with the other three terms.

LOGARITHMS and DECIBELS 184. The logarithm ol a numeral is defined as how many times _ must be multiplied togelher to get that numeral. A 1 B 2 C 5 D 10

D. The logarithm of a numeral is equal to the number of tens that ar€ multiplied together to result in thal number.

AXIAL RESOLUTION 261 . Two systems are undergoing evalualion. System A has 1,000,000 pixels, each with 4 bits. System B has 750,000 pixels, each with 12 bits. Which system has the best longitudinal resolulion? A. System A B. System B C. both are the same D. cannot be determined

D. The longitudinal resolution of an ultrasound system is determined primarily by the pulse duration or the spatial pulse length. Since no information is provided on the length ol the pulse, it is impossible to determine which ol the systems will have superior longitudinal resolution. Hint: Longitudinal resolution is also called axial resolution.

TRANSDUCERS 284. What is the thickness of the matching laye( of a2 MHz pulsed wave transducer? A. 1.54 mm B. 0.77 mm C. half the wavelength of lhe sound wave in the PzT D. one-quarter the wavelength ol sound in the matching layer

D. The matching layer is one-quarter wavelength thick. That is, the thickness is equal to one-quarler the wavelength ol sound in the malching layer.

INCIDENCE 233. What is the minimum permissible value for both the intensity reflection coefficient and the intensity transmission coefficient? A. different from each other B. -1 c. 100% D.0

D. The minimum value for the intensity transmission and the intensity reflection coefficients is zero. At one extreme, it is possible to have total transmission and no reflection (intensity reflection coefficient = 0). At the other extreme, it is possible lor total reflection to occur. No transmission would exist and the intensity transmission coefficient = 0.

Two sound pulses travel through the same medium. One wave,s frequency is 2 MHz and the other is I 0 MHz. Answer the following 5 questions. '103. Which pulse has the lowest power? A. the 10 MHz pulse B. the 2 MHz pulse C. neither pulse D. cannot be determined

D. The power of a wave is not related to its lrequency. The power relates to lhe strength of the wave, and in this case, no information is provided about the power. Therelore, we cannot answer this question based on the inlormation provided.

INSTRUMENTATION 4'12. What is the typical voltage of the signal that is the input to the receiver ol an ultrasound system? A. 0.1 volts B. 500 mvolts C. 250 volts D. 10 pvolts

D. The signal produced by the transducer upon reception and sent to the receiver of the ultrasound system is extremely small and is in the micro- to millivolt range.

INCIDENCE 230. What results when the intensity transmission coefficient and the intensity reflection coetficient are added together? A. incident intensity coefficient B. acoustic impedance C. total intensity D. 1.0

D. The sum of the intensity reflection coefficient (lRC) and the intensity transmission coetficient (lTC) equals one o( 100yo. The ITC is the percentage ol a sound wave's intensity that is transmitted at a boundary. The IBC is the percentage ol a wave's intensity that is reflected at a boundary. Since there is conservation ol energy at the boundary, these percentages added together equal 100% (or 1 .0).

THE BASICS— 9.A sack contains 6 pounds of flour. The contents of the bag are increased by a factor of 5. How much flour is in the bag? A. 6 pounds B. 11 pounds C. 60 pounds D. 30 pounds

D. The term "increase by a factor means to multiply. 6x5=30pounds.

TRANSDUCERS 299. An ultrasonic pulse is traveling in soft tissue. Which of the lollowing is most important in the determination ol the frequency of the sound? A. the propagation speed of the ultrasound transducer's matching layer B. the thickness of the transducer's backing material C. the impedance ol lhe transducer's matching layer D. the propagation speed of the transducer's active element

D. The two characteristics lhat determine the frequency of sound in a pulse are: c. 1. the thickness of the ultrasound crystal and 2. the propagation speed ol the crystal. The speed and impedance of the matching layer and the thickness ot the backing material are unrelated to the frequency of an ultrasound pulse.

134. What two properties establish sound's propagation speed in a given medium? A. elasticity and stiflness B. stitlness and impedance C. conductance and density D. density and stitfness

D. The two properties ol the medium that affect sound's propagation speed are density and stiffness.

325. All ot the following terms describe the shape of a sound wave created by a tiny fragmenl of PZf except A. spherical B. Huygens'wavelet C. V-shaped D. hourglass shaped

D. The waves are not hourglass in shape. Small pieces of PZT create V-shaped waves. Choices A and B have the same meaning as V-shaped.

LATERAL RESOLUTION and FOCUSING 347. Two ultrasound systems have near zone lengths ot 8 cm. At the focus, System S's lateral resolution is 3.0 mm, whereas System C's is 5.0 mm. Which sYstem is most likely to appropriately display two small body structures that lie, one in front of the other, at depths of 8.6 and 9.0 mm? System C B System S C both have comparable quality D cannot be determined

D. There is insuff icient inlormation to answer the question. The information provided gives insight into the lateral resolution of the systems. However, the question asks about the ability to distinguish two structures that lie one in front of the other, or parallel to the sound beam's main axis. This depends upon axial resolution, and no information is provided about this.

ATTENUATION, REFLECTION, and SCATTERING 213. Which ol these lists indicates media with increasing attenuation of ultrasound? A. water, lung, sott tissue, bone, air B. lung, air, soft tissue, bone C. lung, fat, muscle D. water, blood, fat, muscle, bone, air

D. This list orders tissues with increasing attenuation rates of ultrasound.

TIME of FLIGHT 257. One retlector is 5 times deeper than another. The time ot llight of sound to the deeper structure is the time ol flight of the shallower rellector. - A. one fifth as much as B. equal to C. less than D. five times more than

D. Time ol flight and reflector depth are directly related. When a reflector is five times deeper than anolher, the pulse's time of flight is live times greater.

LATERAL RESOLUTION and FOCUSING 338. What will lower the value of an ultrasound syst€m's lateral resolution? A. decrease the # of cycles in the pulse B. increase the €ftective damping material C. incroase the pulse repetition period D. use an a@uslic lens

D. To lower the numerical value of lateral resolution of an ultrasound system, the diameter ol the b6am must be reduced. A commonly used technique to decrease the diameter of lhe b6am is to focus the bsam with an acoustic lens.

DISPLAY MODES 368. How are the piezoelectric crystals of a linear phased array transducer fired? A. in a single specilic pattern B. in order, lrom top to bottom C. at exactly the same time D. at almost exactly the same time

D. To steer and focus the ultrasound beam that a linear phased array transducer produces, the PZT crystals are excited by electronic pulses at almost the same time Only billionths ol seconds separate the electronic pulses that strike the PZT crystals in the transducer.

ARTIFACTS-- 558. While imaging a test object, an ultrasound system displays one image 1.8 cm deeper than another. Upon measuring the test object, il is lound that it is actually 2.0 cm de6per. What conclusion caln be drawn trom this? A. speed oI sound in the tesl obiect is the same as soft lissue B. speedln the test obiect is less than thaf in sott tissue C. attenuation ol sound in the test obiect is less than that in soft tissue D. speed in soft tissue is less than that ot the test obiect

D. When vertical misregistration occurs, it is likely lhat the speed oI sound in the medium diflers lrom 1,540 rn/sec. lf the measurements on the image are less than the true distances, then the spe€d of sound in the medium is gr€ater lhan that oI soft tissue.

REFLECTION and TRANSMISSION 238. Two acoustic wavss strike a boundary behveen two media. The waves are traveling in a direclion 90" to the boundary. Reflection ol these waves depends on differences in the _. A. Irequencies ol the two waves B. propagation speeds of the two media c. amplitudes of the two waves D. impedances ot lhe two media

D. With normal incidence, reflection will occur at a boundary when the media on eilher side of the boundary have ditferent acoustic impedances. Rellection is not dependent on the waves' characterislics such as amplitude and frequency. With normal impedance, only one condition must be met for reflection to take place: the impedances ol the media on either side of the boundary must be difrerent.

DISPLAYS-- 454. What happens to an image when the number ol bits allocated to each pixel increases? A. spatial detail improves B. frame rate increases C. field of view expands D. more shades of gray

D. ln a digital representation of an image, as the number of bits assigned to each pixel increases, the number ol diflerent shades oI gray in the image increases.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 407. All ol the following reduce temporal resolution by increasing the number ol pulses per image except A. increasing the number of foci B. increasing line density C. increasing field of view D. increasing depth of view

D. lncreasing the depth of view does not alter the number ol pulses per image. lncreasing depth ol view decreases temporal resolution by changing the pulse repetition period while leaving the number of pulses in each image unchanged.

BIOEFFECTS-- 600. Under which condition is it permissible to perform a diagnostic ultrasound exam? A. when the patient will benefit B. when the patient has insurance C. when the exam is perfectly safe D. when the benefits outweigh the risks

D. lt is proper to perform a diagnostic ultrasound exam when the benefit to the patient outweighs the risks that may be present.

BIOEFFECTS-- 603. Which component of an ultrasound system exposes a patient to greatest risk? A. thE CRT B. the electric cord C. the pulser D. the transducer

D.Although the risk is small, the transducer exposes the patient to the greatest risk during an ultrasound scan. However, the risk will be substantially greater if the system is not functioning properly or being used in a responsible manner.

DOPPLER-- 498. Blood moving at a velocity of 2 rnls creates a Doppler frequency ol 3,000 Hz what will the Doppler shift be if the velocity increases to 4 m/s? A. 3,000 Hz B.2Hz C. 1 ,500 Hz D. 6,000 Hz

D.Doppler shifts are directly related to reflector velocity. Higher velocities create higher Doppler shifts. Lower velocities create lower Doppler shifts. When the velocity doubles, the Doppler shift doubles.

LATERAL RESOLUTION and FOCUSING 330. Two ultrasound systems produce acoustic pulses. One pulse is 0.4 psec in duration and lhe other is 0.2 psec. Which pulse will most likely provide the best lateral resolution? A. 0.4 psec pulse B. 0.2 psec pulse C. they are the same D. cannot be determined

D.The duration of a pulse is unrelated to the lateral resolution. Pulse duration atf€cts axial (longitudinal) r6solution. lt is not possible to answer the question with the inlormation provided.

DOPPLER-- 521 . The frequency of a pulsed Doppler wave is 6 MHz, and the PRF is 5 kHz. What is the maximum Doppler shift that can be recorded without aliasing? A. 6 MHz B. 5 kHz C. 3 MHz D- 2.5 kHz

D.The lrequency at which aliasing occurs is called the Nyquist limit and is one-hall the pulse repetition lrequency. ln this example, the pulse repetition ,requency is 5 kHz or 5,000 pulses/sec. Thus, the Nyquist limit is 2.5 kHz. Aliasing will occur when Doppler frequencies exceed this value

BIOEFFECTS-- 625. The upper limit for the SPTA intensity ol a Iocused ultrasound wave where there have been no observed bioeflects is A. 1 mwcm2 B. l0 mWcm2 C. 100 mWcm2 D. 1 Wcm2

D.There have been no independentlY conf irmed signif icant bioeff ects in mammalian tissue exposed to focused ultrasound with intensities below 1 Wcm2

HEMODYNAMICS-- 479. All of the following decrease the flow energy of a fluid except A. lriclional loss B. viscous loss C. inertial loss D. velocity loss

D.Three energy losses associated with llow through the circulalion are lrictional, viscous, and inertial loss.

DOPPLER-- 516. With pulsed Doppler, what term is used to D describe a very high posrtive Doppler shitt that is displayed as a neqative waveform? A. attenuation B. filtering C. demodulation D. aliasing

D.ln pulsed Doppler exams, the phenomenon where high velocities are displayed as negative velocities is called aliasing. The term alias means "having a false identity".

QUALITY ASSURANCE-- 595. Which modes of Doppler may be assessed with a Doppler phantom? A. color flow Doppler B. pulsed Doppler C. power mode Doppler D. continuous wave Doppler E. all of the above

E A Doppler phantom is a versatile device that evaluates all Doppler modes including pulsed, continuous wave, color flow, and power mode.

HEMODYNAMICS-- 476. Which of the following is not associated with laminar f low? A. layered B. normal C. aligned D. smooth E. chaotic

E. Chaotic does not describe laminar flow. Chaotic flow is associated with turbulent flow.

TWO DIMENSIONAL IMAGING For the following 6 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) 384. A special sector shape is produced when this transducer is used. lt looks like a wedge or a slice ol pie, but it doesn't originate at a point. The sector has a blunted, curved shape at the top. The arc at the top of lhe image may be a few centimeters wide. A. linear switched (also called linear sequential) array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer F. vector array transducer

E. Curved array transducers create a special form seclor that starls at an initial width and gets progressively larger. ll the PZT crystals are arranged in an arc of 2 to 4 cm, the image will be 2 to 4 cm wide al its top. From that dimension, the image becomes progressively wider.

HEMODYNAMICS-- 484. The arterial blood pressure of a standing individual is 120 mmHg at the level of the heart. What is the measured blood pressure at the subject's ankle? A. 100 mmHg B. 0 mmHg C. 40 mmHg D. -100 mmHg E. 220 mmHg

E. Measured blood pressure is equal tothe sum of actual blood pressure at heart level and hydrostatic pressure. ln this example, 120 mmHg + 100 mmHg = 220 mmHg.

AXIAL RESOLUTION 272. A sonographer is performing a study on a patienl and desires superior depth resolution. Which of the following changes would create such a system? A. higher lrequency B. shorter wavelength C. lewer cycles per pulse D. less ringing E. all of the above

E. Systems that produce shorter pulses create better pictures and have lower numerical values for depth resolution. Higher frequency, shorter wavelength, and fewer cycles per pulse all shorten the spatial pulse length, decrease the numerical depth resolution, and create more accurate images.

ARTIFACTS-- 541. Which ol the following is not a potential cause ol artifact in diagnostic imaging? A. operator error B. equipment mallunction C. patient motion D. ultrasound physics E. none of the above

E. The four choices, A through D, represent the primary explanations of artilacts commonly seen in diagnostic ultrasound.

TWO DIMENSIONAL IMAGING For the following 6 statements, indicate which of the transducer types are appropriate answers. (More than one answer may be correct.) 386. With these transducers, a trapezoidal image shape is produced. The image is flat at the top and becomes progressively wider at increasing depths. A. linear switched (also called linear sequential) array transducer B. linear phased array transducer C. mechanical transducer D. annular phased array transducer E. convex or curvilinear array transducer F. vector array transducer

F. Vector arrays create this image shape. The vector transducer is a combination ol linear phased and linear switched array technologies.

BIOEFFECTS-- 604. True or False? The AIUM suggests that ln vitro research confirming bioetfects is valuable and valid. Their results are significant and should be directly applied to the clinical arena.

False, Although in vitro experiments results are extremely important, it is dit icult to assess their direct clinical signiticance. Further studies should be performed before applying these conclusions clinically.

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ullrasound wave The beam is unfocused. Are the following I statements true or false?

False, The sound beam created by a disc- shaped continuous wave crystal is smaller than the crystal in the near zone and the initial part o, the far zone.

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ultrasound wave The beam is unfocused. Are the following I statements true or false? 317. The thicker a continuous wave transducer's piezoelectric crystal, the longer the near zone length is.

False, increasing the thickness of a piezoelectric crystal does not alter the length of the near zone of a conlinuous wave ultrasound beam.

Two waves, a 5 MHz ultrasonic wave and a 5 kHz audible wave, travel through sott tissue. Are the following 4 statements true or false? 109. The ultrasound wave travels much faster lhan the audible wave.

False. All sound waves, regardless ol their frequencies, travel at exactly the same speed in a particular medium. Both waves propagate at the same speed. ln sotl tissue, sound propagates at a speed ol 1,540 rnlsec.

Two waves, a 5 MHz ultrasonic wave and a 5 kHz audible wave, travel through sott tissue. Are the following 4 statements true or false? 108. The wavelength of the 5 MHz wave is greater than the wavelength oI the 5 kHz wave.

False. When two sound waves travel lhrough the same medium, the higher frequency wave has a shorter wavelength. The wave with the lower frequency has a longer wavelength. ln this question, the 5 MHz wave has a higher frequency and theretore has a shorter wavelength. Specifically, the wavelength of the 5 kHz wave is 1,000 times that ol the 5 MHz wave.

BIOEFFECTS-- 607. True or False? A bioeffect identified through the mechanistic approach rather than the empirical approach is more likely to have clinical significance.

False. A bioeffect identified only by a mechanistic methodology is not likely to have greater clinical signilicance than a bioeffect identilied empirically. The mosl clinically relevant bioeffect would be one identified both mechanistically and empirically.

AXIAL RESOLUTION 267. True or False? The more cycles there are in a pulse, the greater the detail that will be visualized in the ultrasound scan.

False. A pulse with many cycles is long. Systems with long pulses cannot produce images with fine detail. When many cycles are in a pulse, less detail is presented on the scans. Transducers with pulses composed of more cycles can be described as "more ringing.'

INSTRUMENTATION 410. True or False? The pulser ol a mechanical transducer is typically more complex than the pulser of a phased array transducer.

False. A single electrical signal excites the PZT crystal ol a mechanical transducer. With phased array technology, many crystals are excited nearly simultaneously to produce an acoustic pulse. Phased array systems use this technique to steer and locus sound beams. Thus, phased anay systems have more complex pulsers.

Are the following 4 statements regarding pulse duration true or false? 146. The pulse duration cannot be changed under any circumstances or by any action of the sonographer.

False. A sonographer can alter the pulse duration by using a different imaging transducer or ultrasound system

Are the following 4 statements regarding pulse duration true or false? 144. A sonographer can adjust lhe duration of an acoustic pulse since it depends upon the maximum imaging depth.

False. A sonographer cannot change the pulse duration. lt has a constant value, and is not dependent on imaging depth

Are the following 4 statements regarding pulse duration true or false? 143. A sonographer can adjust the duration of an acoustic pulse since it depends upon the pulse's propagation speed.

False. A sonographer cannot change the pulse duration. lt is a fixed leature of the transducer and ultrasound system. lt does not depend upon propagation speed.

SNELL's LAW and REFRACTION 247. True or False Refraction always occurs at the interface between two media when the propagation speeds of the media are unequal

False. A sound wave refracts at the boundary between two media when two conditions are satisfied: 1. the sound beam must be obliquoly incident, and 2. the propagation speeds of the two media must be ditferent from each other

DISPLAY MODES With regard to mechanical transducers, a re the next 4 statements true or false? 363. Foci exist at multiple depths as an ultrasound beam propagates through the body.

False. A standard mechanical transducer cannot focus at multiple depths or provide Ior variable or userselectable focal depths. Mechanical transducers support only a single, unalterable local depth.

PROPAGATION SPEED An ultrasound pulse propagates from soft tissue through a mass. Sound's prop- agation speed in the mass is 1,575 m/s. Are these 4 statements lrue or false? 111. The ,requency of the wave increases as it travels through the mass

False. A wave's frequency is delermined by the sound source only, and is unaflected by the tissues through which it travels.

The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. Are the next 4 slatements true or false? 166. The lrequency is increased

False. Afler reading the inlormation in the question, you will note that nothing is stated regarding the lrequency of sound emitted by the transducer. Therefore, nothing can be concluded regarding Irequency.

With regard to CW Doppler, are the following 4 statements true or false? 508. Problems with aliasing significantly limit its clinical utility.

False. Aliasing is an artifact where high Doppler shifts are misidentified as llow in the opposite direction. Aliasing is produced in pulsed Doppler exams when the PBF is low compared to the Doppler frequency. Aliasing does not appear with CW Doppler

ARTIFACTS-- 583. True or False? All artilacts are errors in imaging that do not represent the true anatomy of the imaged organ. Theretore, they are all undesirable and should be eliminated if possible.

False. All artifacts are indeed errors in imaging. However, they may provide useful information. An artifact can provide insight into lhe physical characteristics of a struclure, and help the clinician make a delinitive diagnosis. Eliminating all artilacts may exclude important inlormation from appearing on the exam.

DOPPLER-- 531 . True or False? Absence of color on a color Doppler image always indicates a region ol no blood flow.

False. Although this statement may be true, it is not always true. Even with blood flow, if the direction of the sound beam is 90" to the direction ol blood flow, no Doppler shifl will be created. The region will remain colorless even when flow is present.

DOPPLER-- 530. True or False? On a color Doppler image, red always represents llow toward the transducer, whereas blue indicates IIow away from the transducer.

False. Although this statement may be true, it is not always true. The color associated with flow toward the transducer appears in the upper half of the color map. The color associated with llow away f rom the transducer appears in the lower portion of the color map.

AXIAL RESOLUTION 263. True or False? One way that a sonographer can alter the axial resolution achieved during an exam is to adjust the maximum imaging depth.

False. Depth of view and axial resolution are unrelated. A sonographer cannot adiust imaging depth to change a system's axial resolution.

DISPLAYS-- 443. True or False? Digital scan converters do not use computer technology to process electronic data into images.

False. Digital scan converters use computer technology to process data.

DISPLAY MODES 371. True or False? The "curved pattern" of delays in the electrical spikes used in a linear phase array transducer locuses the beam during reception

False. Focusing using time delays of the electrical spikes is a form of transmit, not receive, focusing.

AXIAL RESOLUTION 262.f rue or False? The lower the numerical value of the longitudinal resolution, the worse the picture.

False. Higher quality images are associated with lower values ol longitudinal resolution. The numerical value indicates how close two structures can be and still produce two distinct images on the ultrasound display. Lower numbers identify ultrasound systems that display images with fine detail.

DOPPLER-- 515. True or False? The appearance ol negative velocities in a pulsed Doppler display always indicates that red blood cells are moving away lrom the transducer.

False. Negative velocities on the spectral display of a pulse Doppler exam may indeed indicate that red blood cells are traveling away from the transducer. However, aliasing may also cause negative velocities in the spectrum. Aliasing occurs when very high Doppler shifls are processed incorrectly as llow in the opposite direction

INSTRUMENTATION 421. True or False? The sonographer can make an image of unilorm brightness by ad,usting both output power and receiver gain.

False. Neither output power nor receiver gain can creale images of uniform brightness because they do not @rrect lor attenuation. The function that corrects for attenuation is called time-gain compensation, or TGC.

QUALITY ASSURANCE-- 591. True or False? Ouality assurance evaluations ol ultrasound systems can only be performed by biomedicat engineers or physical scientists.

False. Ouality assurance evaluations should be performed by the sonographers who use the system. Although other individua ls may be capable ol evaluating system performance, the sonographer plays an essential role in the quality assurance program

DISPLAYS-- 460. True or False? Preprocessing of image data occurs atter lhe data has been stored in the scan converter.

False. Preprocessing of image data is achieved before image storage in the scan converter. TGC and write magnification are examples of preprocessing.

The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. Are the next 4 slatements true or false? 163. The pulse repetition period is increased

False. Pulse repetilion period is determined by the depth of view. ln this case, the maximum depth is unchanged, so the pulse repetition period is also unchanged.

The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. Are the next 4 slatements true or false? 164. The pulse repetition frequency is increased.

False. Pulse repetition Irequency and pulse repetition period are reciprocals. ll the pulse repetition period is unchanged, then the PRF must also remain unchanged.

QUALITY ASSURANCE-- 590. True or False? Quality assurance evaluations of ultrasound systems should be performed weekly.

False. Quality assurance evaluations must be performed routinely. The actual time between evaluations is determined by the pattern ol use of the system.

SNELL's LAW and REFRACTION 250. True or False? The period of a sound wave determines whether refraction will occur.

False. Relraction does not depend upon the characteristics ol a wave. Belraction only depends upon the incidence of the sound beam and the speeds o, the media.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 393. True or False? An ultrasound system with a longer pulse duration will generally have better temporal resolution.

False. Temporal resolution ol a system is unaffected by the pulse duration.

Two ultrasound systems, one producing sound with a lrequency of 3 MHz and the other at 6 MHz, are used to image a patient. The maximum imaging depth ol both exams is 8 cm. Are the lollowing 4 statements true or false? 162. The PRF ol the 6 MHz transducer is greater than the PRF of the 3 MHz transducer.

False. The PRF is derived from the maximum imaging depth as established by the sonographer. The PRF changes only when the imaging depth changes. Since the depth of view for both systems is the same, the PRFS are also the same.

TRANSDUCERS 280. True or False? The characteristic impedance of acoustic gel is greater than the matching laye/s impedance but less than the piezoelectric element's impedance.

False. The acoustic impedance of gel is lower than the impedances of both the active element and the matching layer. The gel increases the efficiency ol sound transmission at the transducer/skin boundary. Consequently, the gel must have an impedance that is between those of the matching layer and the skin.

TRANSDUCERS 285. True or False? The acoustic impedance ol the skin is greater than the acoustic impedances of both the matching layer and the piezoelectric element.

False. The acoustic impedance ol the skin is lower than the impedances ol both the matching layer and the piezoelectric crystal.

TRANSDUCERS With regard to the backing material of a pulsed ultrasound transducer, are the following 5 statements true or false? 288. The pulse duration is increased as a resull o, the presence of backing material.

False. The backing material inhibits the crystal's oscillations and shortens the pulse duration. When a ferroelectric crystal does not have backing material, it can vibrate freely and ring lor a long time.

BIOEFFECTS-- 598. True or False? The biological etfects ol ultrasound are thought to be negligible and thus, few investigations have been performed on the subject.

False. The biologicaI effects of ultrasound are studied extensively by scientists throughout the world. Under specific circumstances, bioeffects have been conlirmed and are the subject ol many discussions, investigations, and publications.

Three sound waves with identical frequencies ol 3 MHz have powers of 2 mW, 5 mW and 15 mW. They all travel though three media-wood, brick, and tat- with identical thicknesses of 5 cm. Are the following 3 statements true or false? 115. The waves travel through all three media at the same speed since they have identical f requencies.

False. The determinant of the propagation speed in a medium is the medium only. The fact that these three waves have the same frequency is irrelevant. The waves are traveling in media with vastly different densities and stitfnesses and as a result will travel at ditferent speeds through the wood, brick, and fat.

178. True or False? The duty factor is a characteristic of an ultrasound and transducer system and does not change as long as the system components remain unchanged.

False. The duty cycle changes when the sonographer adjusts the maximum imaging depth during an exam

DOPPLER-- 528.True or False? Color flow Ooppler relies on pulsed Doppler principles and is immune to aliasing artifact.

False. The first portion ol the statemenl is lrue color llow does indeed rely on pulsed Doppler principles. However, the second part ol the statement is lalse. lt is continuous wave Doppler, not pulsed Doppler, that is immune to aliasing.

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ullrasound wave The beam is unfocused. Are the following I statements true or false?

False. The focus gets deeper as the frequency of the wave increases. With low frequency sound, the focus is shallower.

Three sound waves with identical frequencies ol 3 MHz have powers of 2 mW, 5 mW and 15 mW. They all travel though three media-wood, brick, and tat- with identical thicknesses of 5 cm. Are the following 3 statements true or false? 116. The sound waves travel through all three media at diflerent speeds because the waves have different powers.

False. The lact that the waves have dissimilar powers is not the reason they travel at diflerent speeds. The waves travel at different speeds because of the dissimilarities in the densities and stiffnesses of the

DISPLAYS-- 453. True or False? The greater the number ol bits assigned lo each pixel ol a digital image, the greater the spatial resolution ol the image is.

False. The number of bits assigned to each pixel of a digital image does not directly affect the spatial resolution ol the image

PROPAGATION SPEED An ultrasound pulse propagates from soft tissue through a mass. Sound's prop- agation speed in the mass is 1,575 m/s. Are these 4 statements lrue or false? 112. The p€riod ol the sound wave decreases as it travels through the mass.

False. The period of a wave is determined by the sound source only, and is unaffected by the tissues lhrough which it travels. Recall that period and lrequency are reciprocals. Since the frequency r€mained unchanged, so too must th6 period.

DOPPLER-- 535. True or False? Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent.

False. The principal difterence belween velocity and variance modes is that variance mode maps are able to identify turbulent flow. Turlculent llow appears on the image as a third color, such as green. that is located on the right side of the color map. When turbulent flow exists, the variance color will appear. Since there is no variance color with velocity mode, the variance and velocity mode images will differ.

TRANSDUCERS With regard to the backing material of a pulsed ultrasound transducer, are the following 5 statements true or false? 286. The damping material helps to decrease the pulse repetition period achieved at a given imaging depth.

False. The pulse repetition period (PRP) is the time lrom the start ol one pulse to the start ol the subsequent pulse. The pulse repetition period is determined by the maximum imaging depth established by the sonographer. PBP is unrelated to the presence of backing material.

PROPAGATION SPEED An ultrasound pulse propagates from soft tissue through a mass. Sound's prop- agation speed in the mass is 1,575 m/s. Are these 4 statements lrue or false? 114. The power in the wave increases as it travels through lhe mass.

False. Typically, the power of a beam diminishes as it travels. This is a result o, attenuation. lf anything, the wave's pow6r diminishes as it propagales through the mass.

BIOEFFECTS-- 599. True or False? lt is generally believed that the etfects ol ultrasound on biologic media are minimal.

False. Ultrasonic bioeffects are substantial under certain conditions, including, but not limited to, therapeutic ultrasound and lithotriPsy.

122. True or False? The wavelength of an acoustic wave is shorter when it is pulsed rather than continuous.

False. Wavelength reports the length of one cycle in a wave. The wavelength does not change based on whether the cycle is part of a pulsed or continuous wave.

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ullrasound wave The beam is unfocused. Are the following I statements true or false?

False. When a continuous wave is produced by a disc-shaped crystal, the beam's diameter equals the crystal's diameter at a depth of twice the near zone length

INSTRUMENTATION 430. True or False? The lower the frequency of the ultrasound beam, the shallower is the delay of the TGC curve.

False. With lower sound frequencies, the delay of the TGC curve is deeper. There is less attenuation with low lrequency sound, and this allows lor a deeper TGC delay.

INSTRUMENTATION 435. Typically the sonographer can control the demodulation process performed by a receiver

False. With the majority of ultrasound systems, the process of demodulation is not under the sonographer's control. The parameters ol demodulation are set within the ultrasound system and cannot be adjusted

REFLECTION and TRANSMISSION 242.Itue u False? When reflection occurs with oblique incidence, the angle of reflection equals the angle of incidence. This is known as Snell's Law.

False. lt is indeed true that the angle ol reflection is equal to the angle of incidence when reflection occurs at an oblique incident angle. The lalsehood in this statement is that this is not Snell's Law.

ARTIFACTS-- 568. True or False? Grating lobes are attributed only to array transducers.

Tlue. Grating lobes are associated with array transducers.

LATERAL RESOLUTION and FOCUSING 346.True or False? ln comparison to other locations along the length of an ultrasound beam, locusing is generally ineffective in the far zone.

True Focusing is a technique that narrows the width of a sound beam to improve image quality. When a beam undergoes focusing, it narrows in the region in the focal zone but not in the deep lar zone.

REFLECTION and TRANSMISSION 236. True or False? The proportion ol the incident intensity that is retlected at a border between two media will increase as the impedances of the media become increasingly dissimilar.

True, As sound waves strike the border belween two media, reflection occurs i, their impedances are ditterent. Greater ditferences between the two impedances create stronger reflections. lf the impedances are only slightly different, then a weak reflection will be produced

DOPPLER-- 518. True or False? ln a pulsed Doppler exam, the use of a higher transducer frequency increases the likelihood that aliasing will appear.

True, The Doppler shift depends on the lrequency ol the incident sound wave. The stalement is true because a higher emitted lrequency produces a higher Doppler shift, and a high Doppler shift is more likely to alias.

Three sound waves with identical frequencies ol 3 MHz have powers of 2 mW, 5 mW and 15 mW. They all travel though three media-wood, brick, and tat- with identical thicknesses of 5 cm. Are the following 3 statements true or false? 1 17. The waves travel through all three media at differenl speeds because the media are diflerent.

True, This is correct! Finally, we have a statement that attributes variations in propagation speeds to the differences in the media. Again, the characteristics ot the media alone determine the speed that sound can lravel through it.

SOUND WAVES— Which of the following 8 selections are acoustic variables? (True or False) 31 Pressure

True.

Two waves, a 5 MHz ultrasonic wave and a 5 kHz audible wave, travel through sott tissue. Are the following 4 statements true or false? 107. The period of the 5 MHz wave is less than the period of the audible wave

True. The period and frequency of any wave are inversely proportional. That is, the higher the frequency of wave, the shorter the period. ln this case, the 5 MHz wave has a higher lrequency than the 5 kHz

Two waves, a 5 MHz ultrasonic wave and a 5 kHz audible wave, travel through sott tissue. Are the following 4 statements true or false? 110. Both the 5 MHz and the 5 kHz waves travel at similar speeds through the medium.

True. All sound waves travel at exactly the same speed while moving though a particular medium.

LATERAL RESOLUTION and FOCUSING 331 . True or False? The pulse duration does not profoundly influence the lateral resolution.

True. Generally, the primary determinant of lateral resolution is the sound beam's diameter. The pulse length, or duration, does not dramatically alter the lateral resolution.

DISPLAYS-- 442. True or False? A digital representalion of a number can achieve only specilic fixed values.

True. A digital representation of a number is limited to discrete values and cannot take on unlimited values. Because of this, digital scan converlers can store only a lixed number of gray shades.

BIOEFFECTS-- 608. True or False? The AIUM considers an ultrasound-induced biologic tissue t€mporature rise ol less than 2' Centigrade above normal body tempsrature as sate tor clinical studies

True. AIUM guidelines state that an exam is considered lree of the potential for thermally induced bioeffects it the tissue temperature is within 2" C of normal.

INSTRUMENTATION 420. f (ue or False? The signal-to-noise ratio remains unchanged when a sonographer adjusts receiver gain.

True. Adjustments to receiver gain alter both the meaninglul signal and the destructive noise to the same extent. Therefore, the signal-to-noise ratio is unaltered.

DOPPLER-- 506. True or False? The appearance of negative velocities on the spectral display ol a continuous wave Doppler exam always indicates that red blood cells are moving away from the transducer.

True. Aliasing does not occur with continuous wave Doppler. Negative velocities appear on the spectral display only when red blood cells travel away lrom the transducer.

DISPLAYS-- 461 . True or False? Postprocessing of image data occurs after the data has been stored in the scan converter.

True. All processing that occurs after the image is stored in the scan converter is called postprocessing. Examples ol postprocessing are read magnirication and the various forms ol gray scale assignment. Any manipulation ol a lrozen image is postprocessing.

Two ultrasound systems, one producing sound with a lrequency of 3 MHz and the other at 6 MHz, are used to image a patient. The maximum imaging depth ol both exams is 8 cm. Are the lollowing 4 statements true or false? 161 . The pulses produced by both systems travel at the same speed in the patient

True. All sound waves travel in the same medium at identical speeds. Frequency and speed are unrelaled.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 398. True or False? An ultrasound system with a shorter pulse repetition period (PRP) will have better temporal resolution than a system with a longer PRP.

True. An ultrasound system with a shorter PRP has the ability to produce more pulses each second. With more pulses per second, the system creates many images per second. lncreased frame rate improves temporal resolution.

ARTIFACTS-- 582. True or False? Artifacts are likely to appear when the dimensions of the sound beam area are larger lhan the dimensions of the reflectors in the body.

True. Artifacts are crealed for many reasons. Some artifacts, such as slice thickness and axial resolution, result from the sound beam being larger than the reflectors.

ATTENUATION, REFLECTION, and SCATTERING 214.ftue or False? Attenuation and propagation speed are unrelated

True. Attenuation and propagation speed are entirely unrelated. Attenuation is the weakening of a beam as it travels and has nothing to do with how fast it travels.

AXIAL RESOLUTION 264.f rue or False? With a specific ultrasound system and transducer, the system's axial resolution is invariant, and the sonographer can do nothing to improve it.

True. Axial resolution is determined only by the components of the system. When you are using a particular ultrasound system, axial resolulion remains constant

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ullrasound wave The beam is unfocused. Are the following I statements true or false?

True. Beam diameter exceeds transducer diameter only in the lar zone, never in the near zone.

DISPLAYS-- 464. True or False? The assignment oI ditfer€nt shades of gray to the digital numbers stored in the scan converter acts to improve the diagnoslic value ol an ullrasound exam.

True. By using different gray scale maps, the sonographer selects what lissue textures will be distinguished lrom each other on the display. This is very important when ditferent tissues in the body produce reflections that are quite similar. By using an appropriate gray scale map, these tissues appear differently on the screen, thereby enhancing an exams's diagnostic value.

DOPPLER-- 523.True or False? TGC cannot be used with continuous wave Doppler.

True. CW Doppler is not associated with TGC. Unlike pulsed ultrasound, attenuation effects cannot be remedied with continuous wave Doppler.

TRANSDUCERS 277.True ot False? The purpose of the backing material of an ultrasound transducer is to shorten the pulses, thereby creating images with better image quality.

True. Diagnostic imaging transducers are especially effective in creating excellent images when their pulses are short. The backing material reduces the ringing of the active element and shortens the pulse duration.

TRANSDUCERS True or False? ln general, ultrasound imaging transducers have a lower quality lactor and a wider bandwidth than therapeutic ultrasound transducers.

True. Diagnostic imaging transducers have a lower quality factor than therapeutic ultrasound transducers. The backing material acts to shorten the pulse, but concurrently increases the bandwidth and decreases the O-tactor.

The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. Are the next 4 slatements true or false? 165. The duty tactor is increased

True. Duty cycle is calculated by dividing the pulse duration by the pulse repelition period (PFIP). ln this example, the PRP is unchanged. By changing to a lransducer with a longer pulse duration while the PRP stays constant, the duty factor increases

DISPLAY MODES 370. True or False? The "curved pattern" of delays in the electrical spikes used in a linear phase array transducer focuses the beam during transmission.

True. Focusing using time delays of the eleclrical spikes is a lorm of transmit focusing.

LATERAL RESOLUTION and FOCUSING 337. True or False? When using an instrument typical of today's diagnostic imaging devices, a higher frequency transducer is likely to improve the axial resolution.

True. Higher lrequency ultrasound pulses typically have shorter pulse lengths. Short pulse lengths correspond to images with good range resolution.

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ullrasound wave The beam is unfocused. Are the following I statements true or false? 316. The greater the diameter of a transducer's piezoelectric crystal, the longer the near zone length is.

True. Large diameter crystals tend to produce continuous wave sound beams with a deeper focus. The beam's near zone is longer.

ARTIFACTS-- 581 . True or False? Side lobe, grating lobe, and relraction artifacts all reduce lateral resolution.

True. Lateral resolution is related to structures that lie in a plane perpendicular to the sound beam's main axis. These three artifacts all degrade lateral resolution.

LATERAL RESOLUTION and FOCUSING . 333. True or False? When using standard ultrasonic imaging instrumentation, the lateral resolution has a higher numerical value than the axial resolution.

True. Most imaging systems have better axial resolution than lateral resolution. The lateral resolution will have a higher numerical value than the axial resolution because a sound pulse is typically wider than half its length.

With regard to CW Doppler, are the following 4 statements true or false? 509. Frequencies measured at the transducer are produced ,rom many ditlerent locations along the ultrasonic beam.

True. One of the characteristics ol CW Doppler is that the frequencies received by the transducer can come Irom anywhere along the region of overlap between the transmitted and received beams. This is called range ambiguity, which is the inability to distinguish the absolute depth where the Doppler shift was created.

DOPPLER-- 527.True or False? Cotor ttow Ooppte, ,maging incorporates pulsed Doppler principles and provides range resolution.

True. One of the greatest advantages of color flow Doppler is its ability to superimpose two-dimensional color velocities upon a two-dimensional gray scale image ol anatomy. Color flow Doppler provides range resolution and is based on pulsed Doppler principles.

171 . True or False? The pulse repetition frequency and the frequency are unrelated.

True. PRF and ,requency are unrelated. The PRF is determined only by the depth ol view. The frequency is determined by the characteristics of the transducer.

INSTRUMENTATION 431. True or False? Typically, the sonographer can adjust the compression function ol a receiver.

True. Part of the compression lunction involves the assignment of gray scale levels on the display. This is adjusted by the operator.

SNELL's LAW and REFRACTION 245.ftue q False? Relraction occurs at the border between two media if and only if there is oblique incidence ol the wave at the boundary.

True. Refraction cannot occur il a wave is normally incident to the boundary between two media. ll can occur only if the incident wave is oblique to the boundary.

BIOEFFECTS-- 627. True or False? Focused sound beams are considered less likely to create bioeffects because the beams will strike fewer gas bubbles that could potentially cavitate.

True. Small gas bubbles, or gaseous nuclei in tissues, serve as sites ol cavitation. When a beam is focused, its diameter is smaller and is less likely to strike cavitation nuclei.

128. True or False? Soft tissue is an imaginary conslruct that actually does not exist.

True. Soft tissue is an imaginary structure with characteristics thal represent an "average" ol body tissues, including muscle, blood, kidney, and spleen. lt is used as an approximation.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 402. True or False? With seclor scanning, images with greater detail (spatial resolution) are created when the number of acoustic pulses per degree oI sector is increased.

True. Spatial resolution is improved with more pulses per degree of sector. When the line density is low, gaps may exist between adiacent pulses. Reflectors within the gaps will not accurately appear on the image.

TEMPORAL RESOLUTION and REAL-TIME IMAGING 394. True or False? The length ol a pulse does not directly influence the temporal resolution.

True. Temporal resolution is not atfecled by the length of the pulses produced by the system. The ,actors that influence the temporal resolulion are maximum imaging depth, sector angle, line density, and the number ol loci per scan line.

DOPPLER-- 526.True or False? Color flow Doppler exams tend to have lower lemporal resolulion than traditional two-dimensional. real-time imaging.

True. Temporal resolution is the ability to accuralely locate moving structures. Color llow technology reduces the number ol pictures produced each second. Color flow Doppler suffers from poor temporal resolution because of this low f rame rate.

TRANSDUCERS With regard to the backing material of a pulsed ultrasound transducer, are the following 5 statements true or false? 287.The backing material helps to decrease the duty cycle at a particular PRF.

True. The backing material of an imaging transducer tends to shorten the pulse duration. This decreases the percentage of time that the system is 'lalking" and therefore decreases the duty factor.

TRANSDUCERS With regard to the backing material of a pulsed ultrasound transducer, are the following 5 statements true or false? 290. The spatial pulse length is decreased with the application of backing material.

True. The backing material tends lo diminish the "ringing" o, the transducer's active element after it is excited by the electrical signal from the pulser. This shortens the pulse length. The action ol the damping material is similar to the action of a cymbal player in a band. lf a short tone is desired, the musician pinches the cymbals between his arms and ribs. This stops the cymbals Irom vibrating and shortens the spatial pulse length. The terms backing material and damping material are synonymous.

TRANSDUCERS With regard to the backing material of a pulsed ultrasound transducer, are the following 5 statements true or false? 289. The backing material decreases the quality factor.

True. The backing material that is attached to the back of lhe piezoelectric crystal will decrease the transducer's Q-factor.

177. True or False? The sonographer alters the duty cycle when adjusting the maximum imaging depth of a scan.

True. The duty cycle is the percentage of time that an ultrasound system is creating an acoustic wave. Duty lactor is inversely related to depth of view. Duty factor decreases when depth of view increases.

With regard to CW Doppler, are the following 4 statements true or false? 510. The duty cycle ol the continuous wave is 1000/".

True. The duty cycle is the percentage of time that the ultrasound transducer is producing sound. With CW Doppler, one crystal is transmilting continuously and the duty cycle is 100%

TRANSDUCERS 282. True or False? The piezoelectric crystal of a transducer typically has an impedance higher than the impedance ol skin.

True. The impedance of piezoelectric crystals typically exceeds the impedance ol skin. To calculate impedance, multiply the density ol a material by the propagation speed of the material. The density of lead zirconate tilanate (a common piezoelectric material) is greater than the density of skin, The propagation speeds of piezoelectric crystals are usually three to four limes greater than skin.

BIOEFFECTS-- 605. True or False? The mechanistic approach to the study ol bioeffects and safety includes the identification of a theoretical construct that could produce an effect.

True. The mechanistic approach is based on developing a theory as to how something happens. lf the theoretical mechanism is proven correcl, it provades great insight into the system and its component factors. The development of a computer simulation of tissue lemperature and its relation to exposure is such an example. The mechanistic approach is considered "cause and effect."

DISPLAYS-- 448. True or False? The greater the number ol bits assigned to each pixel of a digital image, the greater the number of shades of gray the image has.

True. The number of gray shades in an image increases when lhe number of bits assigned to each pixel increases.

INSTRUMENTATION 415. True or False? The sonographer can alter the pulser power.

True. The output voltage of the pulser and the strength of the acoustic pulse produced by the transducer are in the sonographer's control. The output power has ditferent names depending on the manulacturer, but the sonographer can always alter its level.

154. True or False? While imaging soft tissue, the spatial pulse length does not change as long as the components ol the ultrasound system are the same.

True. The overall length ol a pulse is equal to the wavelength multiplied by the number o, cycles in the pulse. Using a particular ultrasound system and transducer, the pulse length cannot change.

Two ultrasound systems, one producing sound with a lrequency of 3 MHz and the other at 6 MHz, are used to image a patient. The maximum imaging depth ol both exams is 8 cm. Are the lollowing 4 statements true or false? 159. The period of the 3 MHz sound is greater than the period ol the 6 MHz sound.

True. The period of a wave is the time that is required to complete one single cycle. A sound signal's period and frequency are reciprocals; therelore, the lower the frequency, the higher the period. ln this case, the 3 MHz wave has a period twice as long as the 6 MHz wave.

INSTRUMENTATION 434. True or False? The primary purpose of demodulation is the preparation of the electrical signal for display on a television monitor. rapher can control the demodulation process performed by a receiver.

True. The primary purpose for demodulating a signal within an ultrasound system is to prepare it lor ultimate display on a television monitor.

DOPPLER-- 534. True or False? Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood Ilow patterns are laminar.

True. The principal ditference between velocity and variance modes is that variance mode maps identify turbulent llow. Turbulent llow appears on the image as a third color, such as green, that is located on the right side of the color map. l, turbulent flow is not present, then the third color will not appear on the image and the velocity and variance mode images will look identical.

Are the following 4 statements regarding pulse duration true or false? 145. The sonographer cannot change the duration of a sound pulse unless the transducers are switched.

True. The pulse duration depends upon the interaction of the pulser electronics of the machine and the transducer. The pulse duration may change when the sonographer changes transducers.

141 . True or False? The pulse duration of an ultrasound and transducer system does not change significantly as long as the system components remain unchanged.

True. The pulse duration is the timespan lhat a pulse exists. lt is determined by the ultrasound system and the transducer. Generally, it remains constant for a particular transducer.

DISPLAYS-- 459. True or False? For digital image inlormation to be displayed on a conventional television screen. lhe data must be processed by a digital-to-analog converter.

True. The representation of an image in digital format is not suitable for display on a standard television because a TV is an analog device. After all the signal processing is completed, the image data is passed through a digital-to-analog converter. lt is then suitable for TV display.

INSTRUMENTATION 419.True or False? The sonographer can adjust the receiver gain.

True. The sonographer is in direct control o, the receiver gain. The sonographer determines the degree to which the signal retuming from the transducer is amplilied. It is a primary control on the ultrasound system that helps determine the ultimate quality of images.

DISPLAY MODES With regard to mechanical transducers, a re the next 4 statements true or false? 362. There is communication between the pulser of the ultrasound system and the piezoelectric crystal ol the transducer.

True. The transduceis PzT musl be directly connected to the pulser electronics oI the ultrasound system. A wire provides a route lor the electrical signal to travel from the pulser to the PzT. ln addition, the crystal sends dala back to the system regarding the reception o, reflected echoes. This dala goes to the receiver and creates an image.

AXIAL RESOLUTION 274.ftue or False? The shorter the pulse length, the better lhe picture

True. This is the fundamental concept ol longitudinal resolulion. Shorter pulses produce better pictures. One ol the most important design criteria ,or ultrasound systems and transducers is to minimize the pulse duralion and spatial pulse length.

DOPPLER-- 529. True or False? Color flow Doppler systems display anatomical data in gray scale while simultaneously displaying flow information in color.

True. This is the lundamental process by which color flow mapping works. A two- dimensional black and white image provides data on anatomical structures. A two-dimensional color image is displayed simultaneously on top of the black and white image. The color data deals with the Doppler frequencies produced by moving blood cells in the imaging plane.

AXIAL RESOLUTION 265. True or False? The shorter the pulse duration, the better the picture.

True. This restates one of the lundamenlal principles ol ultrasonic imaging. The shorter the pulse duration, the higher the quality ol the images.

QUALITY ASSURANCE-- 592. True or False? Proper quality assurance programs require the assessment of every transducer used in the clinical laboratory.

True. To establish a valid and rigorous quality assurance program, each component in clinical use must be evaluated. Thus, each transducer must be individually assessed.

BIOEFFECTS-- 628. True or False? lt is generally believed that the ultrasound bioeffects are minimal at intensity levels typical ol those produced by diagnostic imaging equipment.

True. Ultrasound is considered safe at levels typical of current diagnostic imaging equipment. The lik6lihood of significant, harmful bioetfects is extremely low.

INSTRUMENTATION 437.rue or False? Typically, the sonographer can adjust the threshold level.

True. Under normal circumstances, the operator adjusts the reject (suppression or threshold) level that is performed during signal processing.

DOPPLER-- 533. True or False? Variance mode color maps may be identilied by side-to-side changes in the color bar, whereas velocity mode color maps only change color vertically.

True. Variance mode maps change colors side to side as well as f rom top to bottom. Velocity mode maps only change color from top to bottom.

PROPAGATION SPEED An ultrasound pulse propagates from soft tissue through a mass. Sound's prop- agation speed in the mass is 1,575 m/s. Are these 4 statements lrue or false? 1 13. The wavelength increases while the wave travels lhrough the mass.

True. Wavelength is dependent on both the sound source and the medium. The speed of sound in soft tissue is 1,540 m/sec, and through the mass is 1,575 m/sec. As a wave travels in a faster medium, its wavelength increases.

Two ultrasound systems, one producing sound with a lrequency of 3 MHz and the other at 6 MHz, are used to image a patient. The maximum imaging depth ol both exams is 8 cm. Are the lollowing 4 statements true or false? 160. . The wavelength o, th6 3 MHz ultrasound is greater than the 6 MHz sound.

True. Wavelength is the distance that a singl€ cycle of a pulse occupies in space. When traveling through a particular medium, cycles lrom waves with lower frequencies have longer wavelengths. Thus, cycles from a 3 MHz wave have longer wavelengths than those from a 6 MHz

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ullrasound wave The beam is unfocused. Are the following I statements true or false?

True. When a continuous wave is produced by a disc-shaped crystal, the beam's diameter equals the crystal's diameter at a depth that is twice the near zone length.

AXIAL RESOLUTION 273. True or False? The higher the frequency of the cycles within a pulse, the lower the numerical value of the axial resolution

True. When traveling through a particular medium, higher frequencies are associated with shorter wavelengths. shorter wavelengths will shorten the spatial pulse length. Since the axial resolulion is equal to one-half the spatial pulse length, the numerical value of the axial resolution will also be reduced.

DISPLAY MODES With regard to mechanical transducers, a re the next 4 statements true or false? 360. The ultrasound beam is directed in many ditferent directions to create an imaging plane.

True. With a mechanical transducer, the active €lement is aimed in several directions so that the pulses creale a two-dimensional picture. Without this beam steering, the pulses would travel in the same direction and display only a single B-mode line.

LATERAL RESOLUTION and FOCUSING 336. True or False? When using an instrument typical of today's imaging devices, a higher ,requency lransducer is likely to mildly improve the system's lateral resolution.

True. With all olher variables being equal, pulses made with higher trequency sound are somewhat narrower than low frequency pulses. Narrow beams improve the lateral resolution of lhe imaging system.

DISPLAY MODES 376. True or False? Annular phased array transducers locus sound beams in all planes and at all depths.

True. With annular arrays, the sound beam has the appearance of a straw. lt is locused in all planes and at all depths.

With regard to CW Doppler, are the following 4 statements true or false? 507. A minimum of two distinct piezoelectric crystals are in the transducer.

True. With continuous wave ultrasound, one crystal is constantly producing sound. A second crystal is required to listen for reflections. ln some pulsed ultrasound systems, the same crystal may be used for both pulsing and receiving.

BIOEFFECTS-- 626. True or False? One reason locused ultrasound beams with low intensities are less likely to caus6 bioetlects is that a focused beam is less efficient in heating a large mass ol tissue to a critical temperature.

True. With focused beams, only a small mass ot tissue is heated, and the heat flows rapidly to cooler neighboring tissues. There is limited accumulation of heat energy and the temperalures tend to stay below critical levels-

DISPLAY MODES With regard to mechanical transducers, a re the next 4 statements true or false? 361. The ultrasound beam is not focused electronically.

True. With mechanical transducers, focusing is not achieved electronically. The beam is locused with an acustic lens (extemal) or by a curved PZT crystal (intemal).

DISPLAY MODES 372 Irue or False? Both linear and phased array lechnologies have the ability to variably locus an ultrasound beam to diflerent depths.

True. With the phased delivery ol electrical pulses to the crystals, the ultrasound beam may be focused at a variety ol different depths.

SOUND BEAMS A PZT crystal in the shape of a disc produces a continuous ullrasound wave The beam is unfocused. Are the following I statements true or false?

True. ln the near zone, the sound beam actually tapers down until it reaches the focus. At depths greater than the near zone, the beam diverges, or spreads out

DISPLAY MODES 367. True or False? All phased array transducer systems direct ultrasound pulses in many directions to create a twc dimensional image.

True: To create a two-dimensional image, the sound beams ol annular, linear, and curvilinear phased array transducers must be steered through a path. The linear and curvilinear phased array syslems steer the beam electronically, whereas the annular phased anay steers the beam mechanically.

BIOEFFECTS-- 606. True or False? The empirical approach to the study of bioeflects and ultrasonic safety suNeys data involves finding a relationship between exposure and toxic effects.

Truo. An empirical study is one where investigalors look for a relationship between two events without necessarily understanding the fundamental cause and etfect that relates the two faclors. An example of an empirical study is examining the possibility that changes in fetal birth weight and ultrasound exposure are associated. Note that no specilic mechanism lor this relationship is postulated. The empirical approach is consider€d 'exposure-response.'

DOPPLER-- 491. The Doppler effect is observed as a change in _ and has units of _. A. amplitude, watts B. power, watts C. Irequency, per second D. wavelength, millimeters

c The Doppler effect is a change in a wave's frequency when the sound source and the receiver ol the sound are in motion relative to each other. Frequency may be expressed as hertz, Hz, cycles/sec, or per second.

DOPPLER-- 493. ll red blood cells are traveling toward a transducer, the frequency emitted by the transducer is _ the frequency reflected from the red blood cells. A. greater than B, equal to C. less than n

c When red blood cells approach a transducer, a positive Ooppler Irequency shift results. The emitted lrequency is less than the reflected lrequency.

LATERAL RESOLUTION and FOCUSING 335. The lateral resolution of an ultrasound system is 4 mm. Two structures are separated by 3 mm and lie side by side in relation to the sound beam's main axis. What will most likely appear on the system's display? A. two weak echoes, 4 mm apart m B. two bright echoes, 3 mm apart C. one echo D. two bright echoes, 7 mm apart

c When two structures are closer together than the resolution ol an ultrasound system, the images of the structures will blur together. Since these structures are 3 mm apart and the lateral resolulion is 4 mm, only a single echo representing both reflectors will appear on the image.

175. ln the case of pulsed ultrasound, what is lhe maximum value of the duty factor? A. 100% B. 1 C. less than 100% D. none of the above

c. This question is a bit tricky. When dealing with a pulsed ultrasound system, al least a tiny bit of time must be spent listening rather than transmitting. Therefore, the percentage of time transmitling must be less than 1 or 100%. lf the percentage equals 100%, the system is continuous wave. The correct choice, c, distinguishes between pulsed and continuous wave by stating that the maximum value o, the duty cycle must be less than 100% for a pulsed system.

HEMODYNAMICS-- 475. Which of the following terms does not belong with the others? A. phasic B. spontaneous C. pulsatile D. venous

c. Arterial flow is often described as pulsatile. Phasic or spontaneous llow patterns describe blood moving at a variable velocity as a result of the mechanics of breathing. Phasic llow is observed in venous circulation.

ARTIFACTS-- 539. Spectral analysis of color flow Doppler is most commonly performed by which ol the following techniques? A. zero-crossing detectors B. Fasl Fourier transtorms C. autocorrelation D. Chirp-Z transforms

c. Autocorrelation is the technique ol choice tor spectral analysis ol color Doppler. Although the most accurate technique is the FFT, autocorrelation is better suited to process the enormous amount of data acquired in a color Doppler study.

INCIDENCE 222. Which term does not belong in the group below? A. orthogonal B. at right angles C. oblique D. 90. E. normal F. perpendicular

c. The five terms: orthogonal, at right angles, 90 degrees, normal, and perpendicular are synonymous. Their meanings are identical

INSTRUMENTATION 416 Which of the following aclions will improve the signal-to-noise ralio? A. increase dynamic range B. increase receiver gain C. increase output power D. increase time-gain compensation

c. lncreasing output power will improve the signal-to-noise ratio. When the pulse's strength is increased, rellections arriving at the transducer are stronger as well. Strong reflections are less susceptible to the image degrading etfects of noise.

PERIOD and FREQUENCY 58. What eslablishes the frequency of an ultrasound wave? A. the transducer B. the medium through which the sound travels C. both A and B D. neither choice A nor B

A When created by a transducer, an ultrasound wave has a specific lrequency. The lrequency is not determined by the medium through which the sound travels. Only the sound source (the transducer) establishes the wave's frequency

PERIOD and FREQUENCY 53. Which o, the following units are appropriate to doscribe the period of an acoustic wave? (More than one answ€r may be correct.) A. minutes B. microseconds C. meters D. mm/ps E. cubic centimeters

A and B, The period of a wave is defined as the time that elapses as a wave oscillates through a single cycle. The units for period must be a measure ol time, such as minutes or seconds. A and B are units ol time. The incorrect selections C, D, and E are units of distance, speed, and volume, respectively.

AMPLITUDE, POWER, and INTENSITY 74. Which of the following are acceptable units lor the amplitude of an acoustic wave? (More than one answer may be correct.) A. cm B. pascals C. gauss D. watts

A and B. The acoustic variables are pressure, density, and particle motion. The units of acoustic wave amplitude are cm lor particle motion and pascals lor pressure.

SOUND WAVES— Match the 3 acoustic variables, pressure, density, and particle motion with their correct units. (More than one answer may be correct.) A. lb/in3 B. Fahrenheit degrees C. miles D. Pa E. cm F. Centigrade degrees G. lb/in2 H. kgr'm3 Density

A and H. Density is the concentration ol mass per unit of volume. Mass is measured in pounds (lbs) or kilograms (kg). Volume has units of length cubed, such as cubic inches (in3) or cubic meters (m3).

AMPLITUDE, POWER, and INTENSITY 73. As an ultrasound wave travels through the body, its amplitude usually: A. decreases B. increases C. remains the same D. cannot be determined

A, As a sound wave travels in the body, its strength or amplitude diminishes. This process is called attenuation. W€ experience attenuation when walking away lrom a person who is speaking. The ,urther away we are from a speaker, the weaker that person's voice becomes.

AMPLITUDE, POWER, and INTENSITY 88. What are the units of the transmitted intensity of a sound wave? A. Wcmz B. watts C. dB D. none; it is unitless

A, As sound propagates, one of the ways to measure its strength is to record its intensity. The intensity of the part ot a beam that continues to propagate in the forward direction as it reaches a boundary is called the transmitted intensity. lt is reported in units w/cm2.

SOUND WAVES— What are the units of a pressure measurement of an acoustic wave? (More than one answer may be correct.) A. atmospheres (atm) B. pascals (Pa) C. millimeters ol mercury (mm Hg) D. pounds6q. inch (lMn2)

A, B, C, and D. All of these terms are appropriate to represent pressure (just as weight can be reported with units of pounds, ounces, tons, or grams). However, the pressure ol sound waves is most often reported in units ol pascals.

SOUND WAVES— 26.Which of the following types of waves do not require a medium in order to propagate? (More than one answer may be correct.) A. light B. heat C. sound D. talevision

A, B, and D. Sound cannot travel through a vacuum; it requires a medium in order to propagate. Other waveforms such as lighi, heat and TV waves are capable ol traveling through A VACUUM.

AMPLITUDE, POWER, and INTENSITY 86. What determines the initial intensity of an ultrasound beam? A. the source ol the sound wave B. the medium through which the sound travels C. both A and B D. neither A nor B

A. The source of the acoustic wave determines the initial intensity (as well as the wave's amplitude and powe4. At its point of origin, the strength of an acoustic wave will not be related to the medium that the sound is about to enler.

AMPLITUDE, POWER, and INTENSITY 77. Typically, as an ultrasound wave lravels through soft tissue, the power ol the wave: A. decreases B. increases C. remains lhe same

A. As a sound wave travels through the body, its power diminishes. This process is called attenuation. Amplitude and power are both measures ol the strength ol an acoustic wave, and tend to decrease as sound travels.

SOUND WAVES— 28. Sound is best described as _ A. a series of compressions and rarelactions B. a transverse wave C. a wave that humans can hear D. an oblique displacement ol acoustic energy

A. Sound is composed of a series of compressions and rarelactions. Molecules in the medium are alternately squeezed together (compressed) and stretched apart (rarefied).

THE BASICS— 13.What are the units associated with the circumference of a circle? A. mm B. mm2 C. cm3 D. m4

A. The circumference of a circle is the length ol the circle's outer boundary and is measured in units of length. B and C are units of area and volume. D has units of length to the fourth power, which has no meaning in geometry.

AMPLITUDE, POWER, and INTENSITY 71 . What determines the initial amplitude of an ultrasound wave? A. the transducer B. the medium through which the sound travels C. both A and B D. neither choice A nor B

A. The initial strength or amplitude ol a sound wave is determined by the vibration ol the piezoolectric crystal in the transducer. The greater the vibration of the cryslal, the larger lhe amplitude oI the ullrasound wave.

AMPLITUDE, POWER, and INTENSITY 90. What happens to an acoustic beam's intensity when the power in the beam increases by 25% while the cross- sectional area of the beam remains the same? A. it increases by 25% B. increases by 75% C. it increases by 50% D. decreases by 25%

A. The intensity is equal to the power divided by the beam area. lf the power increases by 25% while the beam's area is unchanged, then the intensity is also increased by 25%.

SOUND WAVES— A particle within a transverse wave is traveling vertically. What is the direction of lhe wave's propagation? A. horizontal B. vertical C. diagonal; both horizontal and vertical D. cannot be determined

A. The particles within a lransverse wave lravel in a direction that is perpendicular to the direction ol propagation of the wave. lf a transverse wave is traveling vertically, the particles in the wave are traveling horizontally. A water wave is a primarily a transverse wave. The wave propagates sideways along the surface ol the waler, while a ball lloating on top of the water moves up and down as the wave passes.

WAVELENGTH 98. What is the wavelength of 2 MHz sound in soft tissue? A. 0.77 mm B. cannol be determined C. 1.54 mm D.2mm

A. The wavelength of sound in soft tissue is defined by the following relationship: wavelength (mm) = t.54 T lr"Ouency (MHz) For 2 MHz sound, the wavelength is 1.54/2 ot O.77 MHz.

AMPLITUDE, POWER, and INTENSITY 75. The maximum value ol the density of an acoustic wave is 60 lb/in2 while the minimum density is 20 lb/in2. What is the amplitude ol the wave? A. 20 lbtin2 B. 40 lb/in2 C. 60 lb/in2 D. none of the above

A. To calculate the amplitude of a wave, subtract the minimum value o, the acoustic variable from its maximum and then divide that number in half. ln this case, the maximum minus the minimum is 60 - 20 = 40 lblin2. Half of 40 is 20 lb/in2.

THE BASICS— 5.How is weight related to a sonographer's time spent exercising? A. inversely B. conversely C. directly D. unrelated

A. Two variables are related when changes in one variable resull in changes in the other. When the changes follow in the opposite direction (one increases as the other decreases), the variables are inversely related.

AMPLITUDE, POWER, and INTENSITY 93. lf the power of the beam is tripted while the cross-sectional area of the beam remains the same, the intensity _. A. triples B. increases ninefold C. remains th6 same D. none of the above

A. When the cross-sectional area of a beam remains unchanged, the change in the intensity of a beam is proportional to th6 change in the power. The question states thal the power is tripled. ll the power is tripled, then the intensity is also tripled.

METRIC SYSTEM— 20. Match the following prefixes with their meanings. A. mega B. hecto C. milli D. kilo E. nano F. giga 1. hundreds 2. thousands 3. thousandths 4. millions 5. billions 6. billionths

A.4, B-1, C-3, D-2, E-6, F-5. You should be familiar with the abbreviations, prefixes, and meanings for all the terms associated with the metric system.

AMPLITUDE, POWER, and INTENSITY 81. The amplitude ol an acoustic wave decreases lrom 27 pascals to 9 pascals. lt the initial power in the wave was 27 watts' what is the wave's linal Power? A. 3 watts B. 9 watts C. I watt D. none ol the above

A.Alterations in a wave's Power are proportional lo changes in its amplitude squared. The power is reduced to one{hird of its previous value (from 27 to 9 pascals). One-third squared equals one-ninth. Thus, only one-ninth of the wave's original power remains. The initial power in the wave was 27 watls, one-ninth of that is 2719, or 3 watts.

PERIOD and FREQUENCY What determines the period ol an ultrasound wave? A. the transducer B. the medium through which the sound travels C. both A and B D. neither choice A nor B

A.The sound source (the transducer) that produces an acoustic signal determines the period of a wave. The wave's period is unrelated to lhe medium through which the sound travels, and will not change as the wave moves from one medium to another.

PERIOD and FREQUENCY What is the range of periods commonly found in waves produced by ultrasound systems? A. 0.001 to 1 s B. 0.06 to 0.5 us C. 0.2 to 1 ms D. 10 to 100ns

B Ultrasonic imaging waves have a period in the range of 0.06 to 0.5 u.s. The period is the time of a single cycle. Period is the reciprocal of frequency. A wave with a lrequency ol 2 MHz has a period of 0.5 usec. A wave with a trequency of 15 MHz has a period or 0.06 us.

SOUND WAVES— A longitudinal wave propagates lrom east to west at a speed of 2 miles per hour. What is the direction of motion of the particles within the wave? A. lrom east to wesl only B. altemately lrom east to west and then lrom west lo east C. from north to south only D. alternately from south to north and then lrom north to south

B A longitudinal wave is defined as a wave whose particles vibrate back and lorth in the same direction that the wave is propagating. Since the wave is traveling from east to west, the particles in this wave will move alternately lrom east to west and then from west to east.

WAVELENGTH 96. The wavelength ol a cycle in an ultrasound wave can be reported with which units? A. units of time (sec, min, etc.) B. units ot distance (feet, etc.) C. units of area (m2, etc.) D. mm only

B Wavelength is the dislarce from the beginning to the end of one cycle. lt has units of distance. ln soft tissue, and with f requencies typical o, diagnostic imaging. wavelengths range from 0.15 to 0.75 mm Although it may be impractical to record wavelengths in miles or meters, it can be done since they are distances.

SOUND WAVES— 25Which ol the following is true of all waves? A. they travel through a medium B. all carry energy from one site to another C. their amplitudes do not change D. they travel in a straight line

B Waves carry energy from one place to another. A is incorrecl because some waves, such as light, can travel through a vacuum. C is incorrect because many waves gel weaker as they travel. Certain waves do not travel in a straight line, so D is also incorrect.

AMPLITUDE, POWER, and INTENSITY 94. The amplitude o, an acoustic wave is increased. Which of the following will most likely remain unchanged? (More than one answer may be correct.) A. power B. frequency C. period D. intensity

B and C. Amplitude relates to the strength of a wave. The trequency of a wave describes the number of cycles in one second. A wave's period is the time an acoustic variable oscillates though one complete cycle. Frequency and period are not related to amplitude, and remain unaltered when the amplitude changes.

THE BASICS— 16.How much bigger is one billion than one thousand? A. 1 ,000 times B. 1,000,000 times C. 10 times D. 10,000 times

B. A billion is one million times larger than a thousand. A million is 1,000,000.

AMPLITUDE, POWER, and INTENSITY 92 What happens to the intensity of an ultrasound beam when the beam's cross- sectional area remains unchanged while the amplitude ot lhe wave triples? A. it triples B. increases ninefold C. remains the same D. none of the above

B. A change in the intensity ot a wave is proportional to the change in the amplitude ol the wave squared. When the amplitude of a wave is tripled, the intensity is increased ninefold (3 x 3 = 9).

THE BASICS— 8.What is the reciprocal of 1/10? A. one-hundredth B. 10 c. 1/10 D. one-millionth

B. A pair of reciprocal numbers, when multiplied together, have a value of 1 in this case, 10 x 1/10 = 1.

SOUND WAVES— 24.As sound travels through a medium, what term describes the effects of the medium on the sound wave? A. toxic effects B. acoustic propagation properties C- bioeffects D. transmission properties

B. Acoustic propagation properties describes the effects ol the medium on the wave traveling through it. Acoustic means "sound." Propagation means '1o travel."

Two sound pulses travel through the same medium. One wave,s frequency is 2 MHz and the other is I 0 MHz. Answer the following 5 questions. A. the '10 MHz pulse B. the 2 MHz pulse C. neither pulse D. cannot be determined

B. Frequency and period are reciprocals wave with a higher frequency has a shorter period. Lower frequencies have longer periods. The 2 MHz wave has a period live times longer than the 10 MHz wave.

METRIC SYSTEM— 18.How many nanoseconds are in 7 seconds? A.7,000,000 B.7,000,000,000 C. 7 million D.0.00000007

B. Nano means billionth. There are one billion billionths in one second. Therefore, there are seven billion billionths in seven seconds.

SOUND WAVES— All of the following are true about sound waves except _. A. they are mechanical B. they are transverse C. they carry energy lrom place to place D. they generally travel in a straight line

B. Sound waves are not transverse, they are longitudinal.

THE BASICS— 2 what is the name of the horizontal axis of a graph? A. z-axis B. x-axis C. y-axis D. red axis

B. The horizontal axis of a graph is the x-axis. The x-axis extends side to side

AMPLITUDE, POWER, and INTENSITY 83. As sound travels in the body, what typically happens to the intensity ot lhe wave? A. increases B. decreases C. remains the same

B. The intensity of a sound beam decreases as it travels through the body because of attenuation. Amplitude, Power, and intensity are three ditlerent ways to measure the strength ol an ultrasound beam. They all decrease as sound propagates.

PERIOD and FREQUENCY 55. What term describes the number of cycles that an acoustic variable completes in a second? A. period B. frequency C. pulse repetition period D. variable rate

B. This is the definition of the term frequency. Frequency can also be thought of as the number of regularly occurring events in a specific time.

SOUND WAVES— A pair ol waves are in phase. What occurs when these waves interlere? A. reflection B. constructive interference C. refraction D. destructive interf erence

B. Waves that are in phase constructively interfere with each other. The single wave that results from the combination ol the two in-phase waves will always have a higher amplitude than either ol the original waves,

AMPLITUDE, POWER, and INTENSITY 89. What happens when lhe power in an ultrasound beam is unchanged, and al the same time, the beam area doubles? A. doubles B. is halved C. is quartered D. remains the same

B. lntensity is equalto power divided by beam area. ln this case, the pow€r is unchanged while the beam area is doubled. Thorefore, the beam's intensity is halved. For example, il the original power was 2 watts and the initial beam area was 2 cm2, then the starting inlensity was 2 watts divided by 2 cm2, or 1 watttm2. Now, beam area is doubled, trom 2lo 4 cm2. The new intensity is 2 watts divided by 4 cm2 or 0.5 wattstm2. The initial intensity was 1, and lhe linal intensity is 0.5 watts/cm2;

PERIOD and FREQUENCY 62. lnfrasound is defined as a sound with a frequency of A. greater than 20,000 kHz -. B. less than 20 Hz C. greater than 10 MHz D. less than 0.02 MHz

B. lntrasound is defined as an acoustic wave with a frequency so low thal it is not audible to humans. lntrasound is an inaudible wave with a ,requency of less than 20 Hz.

SOUND WAVES— Match the 3 acoustic variables, pressure, density, and particle motion with their correct units. (More than one answer may be correct.) A. lb/in3 B. Fahrenheit degrees C. miles D. Pa E. cm F. Centigrade degrees G. lb/in2 H. kgr'm3 Particle motion

C and E. Particle motion is measured in units of distance, such as miles or cm. These choices are the only ones available that appear simply as distance.

AMPLITUDE, POWER, and INTENSITY The intensity ol an ultrasound beam is defined as the in a beam bY the _ A. power, multiplied, diameter B. amplitude, divided, area C. power, divided, area D. amplitude, multiPlied, circumlerence

C, The intensity of an ultrasound beam is the concentration of the power within the beam area. lt is calculated by dividing the power in a beam by its area. The units ol intensity are watls per centimeter squared, Mcm2.

SOUND WAVES— 48. Two waves arrive at the same location and interfere. The resultanl sound wave is smaller than either of the two original waves. What is this called? A. constructive interference B. angular interaction C. destructive interference D. in-phase waves

C. Destructive interference results when a pair ol out-of-phase waves inlerfere with each other. The sum of the lwo out-of-phase waves has a smaller amplitude than at least one ol the original waves.

SOUND WAVES— 23What term is used to describe the effects. of an ultrasound wave on living tissues? A. toxic effects B. acoustic propagation properties C. biological effects D. transmission properties

C. The etlects of ultrasound on the tissues are called biological eflects or bioetlecls. There have been no confirmed bioeflects on humans with acoustic intensities typical of those used in diagnostic imaging.

METRIC SYSTEM— 22.How can the volume of an irregularly shaped object be measured most accurately? A. by visual inspection B. by its weight C. by immersing it in water D. by ultrasound scanning

C. The volume of any obiect can be accurately measured by immersing it in water and measuring the volume of water that is displaced.

THE BASICS— 6.What is the reciprocal of 1 ,000? A. one-hundredth B. 1 ,000 c.0.001 D. one-millionth

C. A pair of reciprocal numbers, when multiplied together, have a value of 1. In this case, 1 ,000 x 0.001 = 1

THE BASICS— 7. What is the reciprocal of 5? A. one-hundredth B.5 c. 1/5 D. one-millionth

C. A pair ol reciprocal numbers, when multiplied together, have a value ol 1 ln this case, 5 x 1/5 = 1.

PERIOD and FREQUENCY 69. Compare two sound waves, A and B. The frequency of wave A is one-third that of wave B. How does the period of wave A compare with the period of wave B? A. A is one-third as long as B B. A is the same as wave B C. A is three times as long as B D. cannot be determined

C. Frequency and period are reciprocals. lf the frequency ol one wave is one{hird as large as another, then the period of the wave will be three times longer than the other.

PERIOD and FREQUENCY 70. ________ is the reciprocal ol period. A. inverse period B. pulse repetition period C. frequency D. propagation period

C. Frequency is the reciprocal ol period. Reciprocals are related in two ways: . As one increases, the other decreases. . When they are multiplied together, the result is unity. For example, a wave with a period of one- hundredth of a second has a frequency ot 100 per second or 100 Hz.

PERIOD and FREQUENCY 66. The trequency of a continuous acoustic wave is 5 MHz. The wave is then pulsed with a duty lactor oI 0.1. What is the new frequency? A. 0.5 B. 0.5 MHz C. 5 MHz D. 10 MHz

C. Frequency is the reciprocal ol the period. The fact that a wave is pulsed rather than continuous does not alter the frequency of the signal. The new and old trequencies are the same, 5 million/second.

SOUND WAVES— Sound can be characterized as: A. energy traveling through a vacuum B. a variable C. cyclical oscillations in certain variables D. a principle of acoustics

C. Sound is a wave. A wave is the rhythmical variation throughout time.

AMPLITUDE, POWER, and INTENSITY 84. What are the units ol intensity? A. watts B. watts/cm C. watts/cm2 D. dB

C. The intensity of a beam is the power in the beam divided by its cross-sectional area. Power has units ol watts and beam area has units ol square cm. lntensity has units ol watts/cm2.

AMPLITUDE, POWER, and INTENSITY 87. What determines the intensity of an ultrasound b6am after it has traveled through the body? A. the sound wave's source B. the medium through which the sound travels C. both A and B D. neither A nor B

C. The source and the medium both ultimately determine the residual intensity of an ultrasound beam after it passes through the body. Sound waves attenuate as they propagate. The initial intensity o, a sound beam is established by the source ol the sound, the transducer. The trequency, which is also determined by the transducer, affects the rate of attenuation. ln addition, the characleristics of the medium help to determine attenuation. For example, bone and lung have a greater attenuation rate than soft tissue. ln contrast, water has a lower atlenuation rate than soft tissue.

THE BASICS— 10.A bouquet has 30 flowers. The size of the bouquet is decreased by a factor ol 3. How many flowers remain? A. 27 B..0 c. 10 D. 15

C. The term "decrease by a factor means to divide. 30/3=10.

AMPLITUDE, POWER, and INTENSITY 76. The power of an ullrasound wave can be reported with which of the lollowing units? (More than one answer may be correct.) A. wattYsquare centimeter B. dB/cm C. watts D. kg/cm2

C. The units ol power are watts. This is the same measure of power as for light bulbs, stereo systems, and curling irons.

THE BASICS— 1.What is the vertical axis of a graph called? A. z-axis B. x-axis C. y-axis D. time-axis

C. The vertical axis of a graph is called the y-axis and extends up and down.

THE BASICS— 3 How are scores on the ultrasound board exams related to study time? A. inversely B. conversely C. directly D. unrelated

C. Two variables are related when changes in one variable result in changes in the other. When the changes go in the same direc{ion (both increase or both decrease), the variables are directly related. Since scores increase as study time increases, these variablos are directly related.

WAVELENGTH 97. The wavelength of an ultrasonic wave is determined by: A. the sound source B. the medium through which the wave travels C. both A and B D. neither A nor B

C. Wavelength is determined by both the sound source and the medium through which it travels. Wavelength is determined, in part, by the wave's frequency (which is established by the sound source). Wavelength is also atfected by the speed of the sound wave, which is established by the medium. ln a particular medium, higher frequency waves have shorter wavelengths. With a particular f requency, faster propagation speeds create longer wavelengths.

PERIOD and FREQUENCY 60. When a sonographer increases the maximum imaging depth during an exam, what happens to the frequency? A. Irequency increases B. frequency decreases C. remains unchanged

C. lmaging depth and frequency are unrelated. When the depth of view is increased, the frequency of sound remains the same.

PERIOD and FREQUENCY With standard ultrasonic imaging, what happens to the period of a wave as it propagates? A. increases B. decreases C. remains the same

C.. Certain parameters of a wave change as the wave lravels through the body. However, the period and the lrequency ol a wave typically remain constanl as a sound wave propagates.

AMPLITUDE, POWER, and INTENSITY The final amplitude of an acoustic wave is reduced to one-half ol its original value The final power is_______the original power A. the same as - B. one-half C. double D. none of the above

D Changes in the power of a wave are proportional to changes in the wave's amplitude squared. One-half squared equals one-quarte( (112 x 112 = 114). When one-hall of the wave's original amplitude remains, then only one-fourth of the original power remains.

WAVELENGTH 99. Which of the following terms best describes the relationship between lrequency and wavelength for sound traveling in sofl tissue? A. reciprocal B. direct C. related D. inverse

D The relationship between frequency and wavelength is inverse. Higher frequency waves are related to shorter wavelengths Lower lrequency waves are relaled to longer wavelengths.

THE BASICS— The volume of a cystic structure is estimated from sonographic data. Which of the following is an acceptable measurement ol this volume? A.6 B.6cm C. 6 cm2 D. 6 cm3

D The units of volume are length cubed, such as ft3 or cubic centimeters. Volume may also be expressed as length to the third power. A has no units, whereas B and C have units of length and area

SOUND WAVES— Match the 3 acoustic variables, pressure, density, and particle motion with their correct units. (More than one answer may be correct.) A. lb/in3 B. Fahrenheit degrees C. miles D. Pa E. cm F. Centigrade degrees G. lb/in2 H. kgr'm3 Pressure

D and G. Units ol pressure include pascals (Pa) and pounds per square inch (lb/in2).

SOUND WAVES— 27.Which of the following describes the characteristics of a sound wave? A. longitudinal, non-mechanical B. mechanical, transverse C. lransverse, acoustic D. mechanical, longitudinal

D. Sound is a mechanical, longitudinal wave. A mechanical wave, such as sound, actually imparts energy to the molecules of the medium through which it travels. The molecules of the medium vibrate, striking their neighbors, which in turn vibrate. This chain reaction results in the acoustic energy traveling through the medium.

SOUND WAVES— The direction of motion of a particle in a wave is perpendicular to the direction of propagation ol the wave. what type ol wave is this? A. longitudinal B. acoustic C. mechanical D. transverse

D. A characteristic of transverse waves is that the direction ol propagation is perpendicular to the direction of particle motion in the wave. Sound waves are not lransverse, but rather longitudinal.

AMPLITUDE, POWER, and INTENSITY 95. A sonographer adlusts the output power ol the wave emitted by the transducer. Which of the tollowing also changes? (More than one answer may be correct-) A. pulse repetition period B. PRF C. propagation speed D. intensity

D. As a sonographer adiusts the output power, the intensity will change. The PRF and pulse repetition period will change only when the maximum imaging depth (also called depth ot view) changes. The sound's propagation speed will change only if the medium changes.

PERIOD and FREQUENCY What is the range of lrequencies emitted by transducers used in uitrasonic imaging? A. 'l to 3 MHz B. .1 to 1 ,000 kHz C. -10,000 to +10,000 Hz D. 2,000,000 to 15,000,000 Hz

D. Frequencies commonly used in diagnostic imaging range from approximately 2 to 15 megahertz or 2 to '15 million cycles per second

METRIC SYSTEM— 19. The letters below represent the abbreviations for the prefixes of the metric system. Select the sequence that appears in decreasing orde( . A. m, k, M, g, da B. g,m,k,d,u C. g, k, di, m, p, n D. M, k, da, d, c

D. M stands for mega and means 'millions." k stands for kilo and means thousands." da stands for deca and means tens.'d slands tor deci and means 'one-tenth." c stands Ior centi and means "one-hundredth." Thus, this sequence is ol decreasing numbers.

METRIC SYSTEM— 21.Which term is the reciprocal of mega? A. nano B. kilo C. macro D. micro

D. Mega means million. The reciprocal ol million is millionth. Micro means millionth

SOUND WAVES— A force is applied to a surface. lf the force is tripled and the surrace area over which the torce is applied is also tripled, what is the new pressure? A. three times larger than the original B. one third o, the original C. six times more than the original D. unchanged

D. Pressure is defined as an amount of lorce divided by the area to which it is applied. lf the applied force is tripled, and at the same time, the area over which it is applied is tripled, then the pressure remains unchanged.

AMPLITUDE, POWER, and INTENSITY When the power in an acoustic beam is doubled and the cross-sectional area ol the beam is halved, then the intensity ol the beam is: A. doubled B- halved C. quartered D. four times larger

D. The intensity rises to four times its original value. lntensity is equal to power divided by beam ar6a. ln this case, lhe power is doubled and the area is halved. For example, il lhe original power was 4 watts and the initial beam area was 4 cm2, then lhe starting intensity was 4 watts divided by 4 cm2, or 1 watUcm2. Now, lhe power is doubled lrom 4 to 8 watts and the beam area is halved, ,rom 4 to 2 cm2. The new intensity is 8 watts divided by 2 cm2, or 4 wattsi/cm2. Since the initial intensity was I and the final inlensity is 4 watts/cm2, lhe intensity has increased fourfold.

THE BASICS— 4.How are caloric intake and weight related? A. inversely B. partially C. reciprocally D. directly

D. These two terms are directly related. As food intake increases, weight increases. Similarly, as food intake decreases, weight decreases.

PERIOD and FREQUENCY 61. Ultrasound is defined as a sound with a frequency of A. greater than 20,000 kHz B. less than 1 kHz C. greater than 10 MHz D. greater than 0.02 MHz

D. Ultrasound is delined as an acouslic wave with a frequency so high that it is not audible to humans. Ultrasound is an inaudible wave with a frequency of at least 20,000 Hz, 20 kHz ot 0.02 MHz.

PERIOD and FREQUENCY 64. What is characteristic of acoustic waves with trequencies exceeding 20,000 Hz when compared with waves having frequencies of less than 20,000 Hz? A. they travel more ettectively in soft lissue B. they travel more rapidly C. they attenuate less when traveling in soft tissue D. humans can't hear them

D. Waves with frequencies exceeding 20 kHz are inaudible to humans and are called ultrasonic. They travel at the same speed as waves with lower lrequencies and atlenuale at a faster rate than waves with lower trequencies.

PERIOD and FREQUENCY 65. What is characteristic of acoustic waves with frequencies of less than 20 Hz when compared with waves having frequencies of more than 20 Hz? A hey travel less eflectively in soft tssue B hey travel more rapidly c hey attenuate more when lraveling in soft tissue D. humans can't hear them

D. Waves with frequencies of less than 20 Hz are inaudible to humans and are called infrasonic. They travel at the same speed as waves with higher frequencies and attenuate at a lesser rate than waves at higher frequencies.

PERIOD and FREQUENCY 56. Which of the tollowing cannot be considered a unit of frequency? A. per day B. cycles/sec C. Hz D. hertz E. cycles

E. The term cycles informs us of the number of evenls, but does not inform us ol the duration of time required lor those events to occur. Choice E is incomplete, and is not a unit ot frequency. All the othor choices reveal that a number of events took place in a specific time span

SOUND WAVES— Which of the following 8 selections are acoustic variables? (True or False) 30 Frequency

False

SOUND WAVES— Which of the following 8 selections are acoustic variables? (True or False) 32. Propagation speed

False

SOUND WAVES— Which of the following 8 selections are acoustic variables? (True or False) 33. Wavelength

False.

SOUND WAVES— Which of the following 8 selections are acoustic variables? (True or False) 34. Voltage

False.

SOUND WAVES— Which of the following 8 selections are acoustic variables? (True or False) 35. lntensity

False.

PERIOD and FREQUENCY 54. True or False? The sonographer has the ability to alter the period oI an ultrasound wave that is produced by a basic transducer.

False. The sonographer cannot adiust the period (or ,requency) of a wave produced by a basic transducer. Think of striking a key on a piano. The frequency oI sound created by striking a single key is constant. lf the sound beam's trequency and period are not suited for the particular type of imaging, the sonographer must select a new transducer wilh a different ,requency.

PERIOD and FREQUENCY 59. True or False? With standard ultrasound pulses, the lrequency of the ultrasound changes significantly as the wave propagates through the body.

False. ln diagnostic imaging, the frequency of the sound wave generally remains constant and does not routinely change as the sound propagates through the body Slight changes in frequency occur when sound strikes moving structures. This lorms the basis lor Doppler ultrasonography.

AMPLITUDE, POWER, and INTENSITY 78. True or False? A sonographer can routinely change the power of a wave emitted by a transducer used in diagnostic ultrasonic imaging.

True, A sonographer can alter the power of an ultrasound wave by adjusting a control on the ultrasound system. Power and amplitude are related; if the amplitude is increased, then so is the power. When the amplitude decreases, the power also decreases.

SOUND WAVES— Which of the following 8 selections are acoustic variables? (True or False) 37. Density

True. Acoustic variables identily certain wave as sound waves. These quantities are pressure, density and particle motion.

AMPLITUDE, POWER, and INTENSITY 85. True or False? With diagnostic ultrasonic imaging instruments, the operator can alter the intensity ot an ultrasound beam produced by a transducer.

True. Although operators cannot change all the characteristics of an ultrasound beam produced by an individual transducer, they can change the initial power. As the operator increases the output power ol a transducer, the initial intensity increases.

PERIOD and FREQUENCY 63. True or False? Waves in the ultrasound range behave in the same general manner as sound waves that are audible.

True. As stated above, the primary difference between audible and ultrasonic waves is that humans can hear audible waves. A wave's behavior or adherence to physical laws and principles is generally the same, regardless ol whelher it can be heard by humans.

PERIOD and FREQUENCY 68. True or False? lf the periods of two waves are the same, then the frequencies oI the waves must also be the same.

True. Frequency and period are reciprocals. When the periods of two waves are identical, lhe frequencies of the waves must also be identical.

PERIOD and FREQUENCY 67 True or False? The period ol an ullrasound wave is related to the lrequency and is the same, regardless of whether the wave is pulsed or continuous

True. The period ol a wave is a characteristic of each individual cycle in the wave. The period of a wave (as well as frequency and wavelength) remains unchanged, whether the wave is continuous or pulsed.

AMPLITUDE, POWER, and INTENSITY 72. f rue q False? With standard diagnostic imaging instrumentation, the sonographer has the ability to vary the amplitude of a sound wave produced by the transducer.

True. The sonographer can adiust the strength ol the ultrasound signal that a transducer creates. When a sonographer increases the output power, the electrical voltage sent to the transducer is increased. This produces a more violent vibration ol the piezoelectric crystal within the transducer and, in turn, a stronger ultrasound wave.

METRIC SYSTEM— 17.Select the sequence that appears in increasing order A. mega, kilo, hecto, milli, giga B. nano, milli, micro, deci, deca, mega C. centi, deci, deca, hecto D. milli, hecto, centi, deci, nano, giga

c Centi means "one-hundredth", deci means "one{enth", deca means 'len", and hecto means "hundred." Thus, this sequence is increasing, starting from the smallest and ending with the largest.

THE BASICS— 11. which of the following is not a measure of area? A. square cm B. meters squared C. cubic meters D. feet x feet

c. Cubic meters are not used to measure area; they are used to measure volume. An area is measured in units of distance squared. For example, a rectangle's area is its length multiplied by its width, and can be reported in square feet, in2, or square miles.

THE BASICS— 15.The speed of red blood cells traveling through a blood vessel is 750 cm/sec. You are asked to measure this speed in miles per hour. What information would be sutficient Ior you to complete your task? A. how many seconds in a minute and how many blood cells in the vessel B. the number ol miles in a meter C. how many seconds per hour and the number of miles in a centimeter D. the direction ol red blood cell motion and the Doppler shift frequency

c. To convert one unit to another requires a lactor that relates the two terms. For example, to change a measurement ol length lrom feet into inches, we must know how many inches are in a foot. ln this case, we are asked to convert cm per sec into miles per hour. Therefore, we require two pieces ol inlormation: the relationship between seconds and hours (relating one unit of time to anotheo and the relationship between miles and centimeters (relating one unit of distance to another(). When units are changed, the actual amount does not change. For example, ten dimes provide the same purchasing power as four quarters. The units may be different, but the "total picture" remains lhe same.

THE BASICS— 12.A sonographer measures the perimeter of an anatomical structure . Which of the following choices is a reasonable value for the measurement? A. 6 cm2 B. 5cc C. 15 mm D. 18 dB

c. "Perimetef means the length of the outer boundary o, a structure. For example, a square with an edge that is 5 inches long will have a perimeter measuring 20 inches (four sides, each with a length of 5 inches) Units of measurement in A, B, and D are not applicable to length.