ARRT SONOGRAPHY PHYSICS REVIEW!!
how many cycles per pulse are typically used in doppler imaging?
5-30
TRUE OR FALSE: With a mechanical transducer, foci exist at multiple depths as an ultrasound beam propagates through the body.
False **Mechanical transducers support only a single, unalterable focal depth.
With regard to the backing material of a pulsed ultrasound transducer: TRUE OR FALSE: The backing material decreases the quality factor.
True
TRUE OR FALSE: The sonographer cannot change the duration of a sound pulse unless the transducers are switched.
True **Pulse duration depends upon the interaction of the pulser electronics of the machine and transducer.
TRUE OR FALSE: In diagnostic imaging, it is possible to image with 200 lines/frame, 15 frames/second and a maximum imaging depth of 20 cm.
True **# lines/frame X frame rate X imaging depth = >77,000 Pulses can only travel to a depth of 77,000 cm and back in one second.
TRUE OR FALSE: The AIUM considers an ultrasound-induced biologic tissue temperature rise of less than 2 degrees Centigrade above normal body temperature as safe for clinical studies.
True **AIUM guidelines state that an exam is considered free of potential for thermally induced bioeffects if the tissue temperature is within 1 degree Centigrade of normal.
TRUE OR FALSE: The signal-to-noise ratio remains unchanged when a sonographer adjusts receiver gain.
True **Adjustments to the receiver gain alter both the meaningful signal and the destructive noise to the same extent.
TRUE OR FALSE: The appearance of negative velocities on the spectral display of a CW Doppler exam always indicates that RBCs are moving away from the transducer.
True **Aliasing does not occur with CW Doppler, so negative velocities are only displayed with flow moving away from the transducer.
2 waves, a 5 MHz ultrasonic wave and a 5kHz audible wave, travel through soft tissue. TRUE OR FALSE: Both the 5 MHz and 5 kHz waves travel at similar speeds through the medium
True **All sound waves travel at exactly the same speed while moving through a particular medium.
TRUE OR FALSE: An ultrasound system with a shorter PRP will have better temporal resolution that a system with a longer PRP.
True **An US 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. Increased frame rate improves temporal resolution.
TRUE OR FALSE: The empirical approach to the study of bioeffects and ultrasonic safety surveys data involves finding a relationship between exposure and toxic effects.
True **An empirical study is one where investigators look for a relationship between 2 events without necessarily understanding the fundamental cause and effect that relates the two.
What are the units of pulse duration?
Units of time **Pulse duration is the actual time that a transducer is creating a pulse.
Temporal resolution and pulse duration are ______ related.
Unrelated
Lateral resolution and pulse duration are _____ related.
Unrelated Pulse duration affects axial or longitudinal resolution.
What are the units of the transmitted intensity of a sound wave?
W/cm2 All intensities have the same units.
What are the units of intensity?
Watt/cm2 Intensity=power in the beam divided by beam area
Enhancement of echo reflections occur distal to a: -Nonspecular reflector -Strongly reflecting structure -Weakly attenuating structure -Structure of high impedance -Strongly attenuating structure
Weakly attenuating structure
How long does it take for sound to make a round trip to and from the skin's surface to a reflector 1 cm depth in soft tissue?
13 microseconds
In soft tissue, sound travels to a reflector and back to the transducer in 39 microseconds. How deep is the reflector?
3 cm For each 13 microseconds, sound travels a round trip depth of 1 cm.
Assume that the frequency of sound with the greatest power emitted by a transducer is 5 MHz. However, the pulse contains acoustic energy with frequencies as low as 3.5 MHz and as high as 6.5 MHz. What is the bandwidth of the transducer?
3.0 MHz Bandwidth is the range of frequencies that are present within the pulse. It is calculated by subtracting the lowest frequency from the highest frequency. The natural or center frequency of this transducer is 5 MHz.
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?
30% is transmitted. The law of conservation of energy states that the sum of the percentages of transmitted and reflected sound equals 100%.
If it takes 50 microseconds for a pulse to return as an echo, how deep is the reflector?
3cm
Half value layer is equal to an intensity reduction of:
3dB
What does a 3 dB change in a value intensity mean? A. the value has doubled B. the value has tripled C. the value has increased by 30% D. the value has increased ten times
A. the value has doubled
Spatial Pulse Length (SPL) __________ if the frequency is increased
decreases
what determines the impedance of a medium?
density of the medium multiplied by the propagation speed of the medium
which formula determines the impedance of a medium?
density of the medium multiplied by the propagation speed of the medium
Frequency and focal depth are _____ related.
directly-higher acoustic frequencies create deeper foci and lower frequency crystals produce beams with shallow foci.
Mechanical index is lowest with ____ frequency and _____ pressure.
high frequency low pressure
utilization of a piezoelectric membrane is found in a
hydrophone
What is necessary to calculate distance to a reflector?
propagation speed and round trip time
The common intensity during the extent of a pulse defines
pulse average
the common intensity over the extent of a pulse defines:
pulse average
the hydrophone measures:
pulse repetition period (PRP)
acoustic output testing considers only the
pulser and transducer
which intensity is greatest across the sound beam
spatial peak
SPPA denotes
spatial peak pulse average
the ability to identify correctly the absence of disease is
specificity
Demonstration of boundaries between organs are a result of
specular reflection
Which type of cavitation involves the microbubbles already present in tissues?
stable
a change in direction of the ultrasound beam is more commonly a result of:
striking a boundary at an oblique angle
average intensity during the pulse repetition period
temporal average
What are the units of pulse repetition frequency?
PRF has the same units as frequency-Hertz or per second. PRF is the number of pulses that are produced by the ultrasound system in one second.
a HYPERECHOIC region is
Echogenic
Velocity times density equals?
Impedance
(PRF) pulse repetition frequency is proportional to
duty factor
What is another name for the beam uniformity coefficient?
the SP/SA factor
What is the reciprocal of 1,000?
0.001
What is the range of periods commonly found in waves produced by ultrasound systems?
0.1-0.5 microseconds
What is the typical value of pulse duration in diagnostic imaging equipment?
0.3 to 2 microseconds
What is the pulse duration for 5cycles of 5MHz ultrasound?
1.0 microsecond
An ultrasonic pulse has a PRP of 1.2 msec, a SPL of 2.0 mm, and a wavelength of 0.4 mm. What is the axial resolution of the system?
1.0 mm Axial resolution = SPL/2
What is the value of the duty cycle for a continuous wave ultrasound?
1.0 or 100% This is because a CW probe is always transmitting.
What is the reciprocal of 1/10?
10
with an unfocused transducer, which exposure has no confirmed significant biological effects in mammalian tissue?
100 mW/cm2
Pulses can induce cavitation in mammals with a peak intensity exceeding:
10MPa
what is the average velocity of ultrasound in SOFT TISSUE at 5.0 MHZ?
1540 meters per second
A signal with a 120 dB dynamic range was previously compressed by 40 dB. What is the dynamic range of the original uncompressed signal?
160 dB When a signal is already compressed, the original dynamic range is obtained by adding the decibels of compression.
An ultrasound system with a 4.0 MHz transducer is used to image structures as deep as 15 cm. Twenty images are produced each second, each requiring 100 acoustic pulses. What is the PRF of the system?
2, 000 Hz PRF=# of pulses produced by a system in 1 second. Here, 100 pulses are need to construct an image and there are 20 images/second. PRF= 100X20=2000 Hz
With CW ultrasound, which of the following intensities are the same? 1. SPTA 2. SAPA 3. SATA 4. Im
2. SAPA 3. SATA **with CW, pulse average and temporal average intensities are the same. The term temporal means "dealing with time." The temporal terms PA and TA are identical for CW because the beam is always "on."
if the width of the transducer is 5.0cm, what is the width at the focal point?
2.5cm
Exposure of a fetus to ultrasound is dangerous above
41 degrees Celsius
In soft tissue, sound travels to a reflector and back to the transducer in 39 microseconds. What is the total distance that the pulse traveled?
6 cm For each 13 us, sound travels a round trip of 1 cm. So the pulse traveled a round trip depth of 3 cm, which is 6 cm total distance traveled.
What is the Doppler shift frequency in soft tissue if the transmitted frequency is 3MHz and the velocity of a reflector is 20 cm/s ?
780Hz
work related musculoskeletal disorders are defined as injuries that involve musculoskeletal symptoms that remain for
7days or longer
A signal with 120 dB dynamic range is compressed by 40 dB. What is the dynamic range of the compressed signal?
80 dB When a signal's dynamic range is compressed, the decibels of compression are simply subtracted.
The binary # 1011000 equals the decimal #?
88
with perpendicular incidence, what % of the incident beam continues to the next medium
99%
Which 2 of the following devices convert ultrasound energy into heat? A. calorimeter B. thermocouple C. hydrophone D. Schlieren
A and B The calorimeter and the thermocouple are devices that use the principle of converting acoustic energy into thermal energy to estimate the energy in a sound beam. A hydrophone converts acoustic energy into pressure and a Schlieren uses the interaction of light and sound to evaluate a sound beam profile.
The main purposes of a transducer's case are: A. protect the patient from shock B. protect the patient from heat C. protect the internal components of the transducer D. protect the patient from radiation
A and C The case protects the patient from electrical shock and also protects the internal components of the transducer from damage.
Ultrasound systems using these transducers do not actually steer the ultrasound beams to create a 2-D image. A. linear switched(linear sequential) array B. linear phased array C. mechanical D. annular array E. convex or curvilinear array F. vector array
A and E Linear and convex switched arrays do not steer sound beams. A small group of elements produce a pulse that travels straight ahead.
Which of the following techniques is external focusing? A. lens B. curved crystal C. electronic
A. lens
Which of the following is not a potential cause of artifact in diagnostic imaging? A. operator error B. equipment malfunction C. patient motion D. ultrasound physics E. none of the above
A, B, C, and D. These represent the primary explanations of artifacts commonly seen in diagnostic ultrasound.
Which of the following types of waves do not require a medium in order to propagate? A. light B. heat C. sound D. television
A, B, D Sound cannot travel through a vacuum-it must have a medium in order to propagate.
These transducers focus the ultrasound beam electronically. A. linear switched array B. linear phased array C. mechanical D. annular phased array E. convex or curvilinear array
A,B,D, and E Electronic focusing techniques are employed in linear phased and annular phased array transducers. Some linear and convex array transducers focus the beam electronically and some do not.
With these transducers, the ultrasound beam is focused with an acoustic lens, a mirror, or by milling a piezoelectric crystal in a curved shape. A. linear switched array B. linear phased array C. mechanical D. annular phased array E. convex or curvilinear array
A,C, and E Mechanical and some linear and curvilinear array transducers use these techniques to focus acoustic beams.
Which imaging modality places time-of-flight information on the x-axis and echo amplitude on the y-axis?
A-mode or amplitude mode
Which imaging technique usually displays a single jagged line of varying heights?
A-mode, or amplitude mode, displays reflected signals as spikes of varying height. Echo amplitude appears on the y-axis and reflector depth is on the x-axis. The spike's location on the x-axis is based on the pulse's time of flight. The height of the peak is determined by the reflector's strength. Stronger reflectors create higher spikes.
What is the wavelength of a 2 MHz sound in soft tissue? A. 0.77 mm B. it cannot be determined C. 1.54 mm D. 2 mm
A. 0.77 mm **Wavelength=1.54/frequency(MHz)
pulses can induce cavitation in mammals with a peak intensity exceeding: A. 10 MPa B. 20 MPa C. 10 W/cm2 D. 2000 W/cm2 E. 2500 mW/cm2
A. 10 MPa
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. 0 mmHg C. 40 mmHg D. 120 mmHg E. -120 mmHg
A. 100 mmHg **Since the ankle is substantially lower than the heart, the hydrostatic pressure is 100 mmHg.
With a focused transducer, for which of the exposures that follow are there no confirmed significant biological effects in mammalian tissue? A. 1W/cm2 B. 1mW/cm2 C. 100W/cm2 D. 100mW/cm2
A. 1W/cm2
Which transducer has the best axial resolution? A. 2 cycles/pulse, 4 MHz B. 4 cycles/pulse, 4 MHz C. 4 cycles/pulse, 2 MHz D. 2 cycles/pulse, 2 MHz
A. 2 cycles/pulse, 4 MHz Pulses with the fewest cycles and the highest frequencies have the best axial resolution.
The half value layer is the thickness of tissue where sound attenuates by ____ dB. A. 3 dB B. 6 dB C. 1\2 dB D. 10 dB
A. 3 dB **The half value layer is the thickness of tissue where sound intensity is reduced to 1\2 of its original value. A reduction of intensity of this magnitude is -3 dB.
The amplitude of an acoustic wave decreases from 27 pascals to 9 pascals. If the initial power was 27 watts, what is the wave's final power? A. 3 watts B. 9 watts C. 1 watt D. none of the above
A. 3 watts **Alterations in a wave's power are proportional to changes in its amplitude squared. The amplitude is reduced to 1/3 of its original value. 1/3 squared is 1/9. The initial power was 27 watts, and 1/9 of that is 3 watts.
A signal is amplified from 1 mvolt to 1 volt by the amplifier. How many decibels is this? A. 1000 dB B. 20 dB C. 40 dB D. 60 dB E. 100 dB
A. 60 dB A voltage increase from 1 mV to 1 V is 60 dB. This signal is increased by a factor of 1000. For voltages, a 100-fold increase is 60 dB.
All of the following are related to a dedicated CW Doppler transducer except: A. wide bandwidth B. high quality factor C. higher sensitivity D. range ambiguity
A. Continuous wave transducers actually have a narrow bandwidth- they do not use backing material, which creates a wider bandwidth.
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-time 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."
All of the following occur with focusing except: A. lower intensity at the focus B. shorter near zone C. more compact focal zone D. smaller diameter beam diameter at the end of the near zone
A. Focusing does not lower the 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.
Which of the following determines the grayscale in a Doppler spectrum? A. number of reflectors B. velocity C. frequency shift D. laminar flow
A. Grayscale **in a Doppler spectrum is related to the number of RBCs creating the reflection.
Which of 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
What happens to an acoustic beam's intensity when the power in the beam increases by 25% while the cross-sectional area remains the same? A. it increases by 25% B. it increases by 75% C. it increases by 50% D. it decreases by 25%
A. Increases by 25% **Intensity = power/beam area If power increases by 25% and the area is unchanged, the intensity increases by 25%.
The lateral resolution of an ultrasound system is primarily determined by the ____. A. width of the sound pulse B. length of the ultrasound pulse C. duration of the sound pulse D. none of the above
A. Lateral resolution achieved by an imaging system is approximately equal to the width of the ultrasound pulse.
A sonographer adjusts the maximum imaging depth of an ultrasound system. Which also changes? A. PRP B. wavelength C. PRF D. Frequency
A. PRP C. PRF **The wavelength and the frequency remain constant as these terms describe the attributes of a single cycle within the pulse and are not affected by alterations in the imaging depth.
Which of the following is not associated with turbulent flow? A. parabolic B. eddy C. vortex D. swirling E. spectral broadening
A. Parabolic flow is a bullet-shaped flow associated with laminar flow.
The phosphorous of a cathode ray tuBe converts ______ into _____. A. electrons, light B. light, heat C. pressure, electricity D. electricity, pressure
A. Phosphorous coating the inside of a CRT's screen converts electrons into light.
An ultrasound wave strikes an interface between 2 media at a 90 degree angle. The propagation speeds of the media are identical. However, the densities of the media are different. 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 with different impedances. To calculate impedance, you multiply the density by the propagation speed, so even though their speed is the same, their impedances will be different because of the differing densities.
Sound is best described as _____. A. a series of compressions and rarefactions B. a transverse wave C. a wave humans can hear D. an oblique displacement of acoustic energy
A. Sound is composed of a series of compressions and rarefactions. Molecules in the medium are alternately squeezed together (compressed) and stretched apart (rarefied).
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 increases.
What happens to venous flow in the legs when an individual exhales? A. increases B. decreases C. remains the same
A. Venous flow in the legs increases when an individual exhales.
The process of demodulation incorporates which of the following tasks? A. smoothing B. amplification C. rectification D. decompression
A. and C. Demodulation is a 2 step process-rectification and smoothing.
The information 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. attenuation
A sound wave reaches a rough or irregular border between 2 media. Under these explicit circumstances, which process is most likely to occur? A. backscatter reflection B. specular reflection C. Rayleigh scattering D. refraction
A. backscatter reflection **also called diffuse reflection. The smoothness or roughness of a boundary will help to determine what form of reflection will take place
2 small cysts, positioned perpendicular to the main axis of a sound beam, are 2.4 mm apart. What determines whether they appear as 2 distinct images on the system's display? A. beam width B. pulse length C. PRF D. TGC
A. beam width The ability to correctly image structures that lie close together in a direction perpendicular to the beam is called lateral resolution and is determined by the width of the acoustic pulse.
What is the smallest amount of digital storage called? A. bit B. byte C. pixel D. fractel
A. bit The term bit is derived from the words "binary digit." A combination of 8 bits make a byte.
The pulse repetition frequency of 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. can be changed by the sonographer. **When the maximum imaging depth is changed, the PRF is changed.
Which of the following terms best describes the mechanistic investigation of bioeffects? A. cause-effect B. exposure-response C. cause-response D. exposure-cure
A. cause-effect For example, a researcher might propose that vibration causes harmful bioeffects and then conducts research to see whether this is indeed the case.
Which of the following are acceptable units for the amplitude of an acoustic wave? A. cm B. atmospheres C. gauss D. watts
A. cm (particle motion) B. atmosphere (pressure) ** The acoustic variables are pressure, density, and particle motion.
Which of the following reports the relative strength of an ultrasound wave? A. decibels B. watts C. w/cm2 D. pascals
A. decibels **The relative strength of a sound beam may be reported in decibels. The term relative indicates a comparison between 2 values.
As an ultrasound wave travels through the body, its amplitude usually: A. decreases B. increases C. remains the same D. cannot be determined
A. decreases **This process is called attenuation.
Typically, as an ultrasound wave travels through soft tissue, the power of the wave: A. decreases B. increases C. remains the same
A. decreases through attenuation
Which of the following components typically has the lowest dynamic range? A. display B. pulser C. amplifier D. demodulator
A. display
What 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-a technique of receive focusing that uses fewer crystals to identify echoes from superficial depths and many more crystals to monitor echoes from greater depths. It is also known as variable aperture.
What is the primary reason why blood moves from one location to another? A. energy gradient B. anemia C. pressure gradient D. systole E. friction
A. energy gradient Blood moves from regions of higher energy to regions of lower energy.
How does slice thickness artifact commonly express itself? A. fill in of cystic structures B. improper brightness of reflectors C. absence of reflectors D. strong linear echoes
A. fill in of cystic structures Slice thickness artifact results in reflections placed on the image that do not correlate with the anatomical position of the reflector. Therefore, anechoic structures in the imaging plane are filled in with echoes from structures above or below the image slice.
Ultrasound waves traveling through lung tissue attenuate to a ____ extent than when traveling through soft tissue. A. greater B. lesser C. nearly equal
A. greater
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. greater than
Which of the following media has the slowest propagation speed? A. high density and high elasticity B. low density and high stiffness C. low stiffness and low density D. low compressibility and low stiffness
A. high density and high elasticity Elasticity is the opposite of stiffness.
The speed of sound traveling through bone is ____ soft tissue. A. higher than B. lower than C. equal to D. cannot be determined
A. higher than **Sound travels at a speed of 3-5 km/sec in bone, which is 2-3 times faster than in soft tissue.
which uses a small transducer element? A. hydrophone B. beam profiler C. AIUM test object D. force balance system E. tissue-equivalent phantom
A. hydrophone
What is the advantage of a 1 1/2 dimensional array transducer? A. improved elevational resolution B. improved lateral resolution C. improved axial resolution D. improved temporal resolution
A. improved elevational resolution-this transducer has a thinner imaging plane, which has superior slice thickness resolution.
Some ultrasound bioeffects studies are performed in vivo. What is the meaning of the term in vivo? A. observable in a living body B. observations based on an experiment C. discernible in a test tube D. estimate in a computer simulation
A. in vivo observations are made in a living body
What happens to the diaphragm when an individual breathes out? A. it ascends into the thorax B. it descends into the abdomen
A. it ascends into the thorax
All of the following are true about transducers except: A. it is necessary to sterilize transducers before use B. most transducers require disinfection since they do not penetrate mucous membranes C. sterilization could depolarize PZT D. they are unlikely to transmit infection
A. it is generally unnecessary to sterilize most ultrasound transducers since they do not penetrate mucous membranes. Typically, simple disinfection is all that is needed.
An acoustic wave is traveling from medium X into medium Z. Medium X has a propagation speed of 1,457 m/sec and an impedance of 1.44 MRayls. Medium Z has a propagation speed of 1,644 m/s and an impedance of 1.26 MRayls. The angle of incidence is 32 degrees. What is true of the angle of the transmitted wave? 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
A. it is greater than 32 degrees When the propagation speed of the medium that the sound is entering exceeds the propagation speed of the medium that the sound is currently in, the angle of transmission is greater than the incident angle.
These transducers typically produce an image that, throughout its entire depth, is approximately as wide as the ultrasound transducer itself. A. linear switched(linear sequential) array B. linear phased array C. mechanical D. annular array E. convex or curvilinear array F. vector array
A. linear sequential array
Propagation speed can be correctly recorded with which of the following units? A. miles per hour B. mm/msec C. km/s D. inches per year
A. miles per hour B. mm/msec C. km/s D. inches oer year **Speed is recorded as a distance per unit of time.
Which of the following are appropriate to describe the period of an acoustic wave? A. minutes B. microseconds C. meters D. mm/us
A. minutes B. microseconds *** The units of period must be a measure of time.
The pulse duration is expressed in the same units as the ______. A. period B. PRF C. wavelength D. density
A. period **Pulse duration is measured in units of time.
What is the decibel representation when an acoustic signal is amplified? A. positive B. negative C. equal to zero
A. positive **When a signal is amplified, its magnitude is increasing and it becomes stronger. In decibel notation, an increase in signal strength is described with positive decibels. Positive decibels means "getting bigger."
All of the following are true of read zoom except: A. pre-processing function of a receiver B. same # of 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 # of ultrasound pulses are used to create the original ROI and the zoomed image
A. read zoom is a post-processing function of the receiver. The data originally in the region of interest, before zoom, remains intact. New information is not acquired.
Which of the following doesn't belong in the group below? A. receiver gain B. energy output C. pulser power D. transmitter output E. output gain
A. receiver gain **The other choices all relate to the strength of the signal produced by the transducer and transmitted into the body.
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. sector, trapezoid D. square, rectangular
A. rectangular, parallelogram
What process causes mirror image artifact? A. reflection B. refraction C. propagation speed error D. attenuation
A. reflection Mirror imaging is caused by an unexpected and uncorrected reflection of the pulse off of a strong reflector.
What is the comet tail artifact's fundamental mechanism of formation? A. reflection B. rarefaction C. refraction D. attenuation
A. reflection They appear on an image as a result of numerous reflections between 2 closely spaced objects.
6 distinct, 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. reverberation, which are multiple, equally spaced reflections.
2 pulses are created by different transducers. The pulses have different duration's. Which pulse is likely to create the best image? A. the shorter duration pulse B. the longer duration pulse C. the qualities will be the same
A. shorter duration pulse **Shorter pulses are desirable for imaging since they provide greater axial resolution and create images of greater accuracy.
Grating lobes are produced by the same mechanism as which other artifact? A. side lobes B. reverberations C. trans-axial lobes D. acoustic speckle
A. side lobes and grating lobes are similar in that they represent energy transmission in a direction other than along the main axis of the beam.
On what does the pulse repetition period depend? A. sound source B. the medium C. both A and B D. neither A nor B
A. sound source **PRP is the time from the start of one pulse to the start of the next pulse and includes the pulse duration and the listening time. When maximum imaging depth is altered, PRP is altered.
What happens to a digital image when the pixel density increases? A. spatial detail increases B. temporal resolution increases C. the field of view expands D. there are more shades of gray
A. spatial detail increases The pixel density, the number of pixels per inch, determines the detail that a digital picture can illustrate.
Which 2 factors determine temporal resolution? A. speed of sound and depth of view B. pixel size and sector size C. focal zones and sector depth D. propagation speed and frame rate
A. speed of sound and depth of view
Why is it necessary for the receiver to perform compression on the electrical signals that it processes? A. dynamic range of the system's electronics is less than the dynamic range of the received sound signal B. display's dynamic range exceeds the transducer's dynamic range C. dynamic range of the receiver is less than the dynamic range of the image processor D. dynamic range of the display exceeds the dynamic range of all other components of the ultrasound system
A. the dynamic range of the systems's electronics is less than the dynamic range of the received sound reflection. The process of compression decreases the dynamic range of a signal. Compression is necessary because the dynamic range of the transducers is far greater than the dynamic range of any of the other components of the system.
In diagnostic imaging, what establishes the pulse repetition frequency? A. the source of the sound B. the medium C. both A and B D. neither A nor B
A. the source **The sole determinant of the PRF is the source of the acoustic wave. The medium does not directly affect the PRF.
What determines the initial intensity of an ultrasound beam? A. the source of 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 sound wave **The source determines the INITIAL intensity
What determines the pulse duration? A. the source of the wave B. the medium through which the pulse travels C. Both A and B D. neither A nor B
A. the source of the wave **Pulse duration does not include the listening time.
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. thin, high propagation speed Only pulsed wave transducers can create images. The crystal's thickness and frequency of sound determine the frequency of sound created by these transducers
All of the following may be used to evaluate Doppler systems except: A. tissue equivalent phantom B. moving belt phantom C. vibrating string phantom D. Doppler phantom
A. tissue equivalent phantom It is unsuitable because all items in it are stationary and to evaluate Doppler, you must have a moving object.
What establishes the frequency of an ultrasound wave? A. transducer B. the medium through which the sound travels C. both A and B D. neither A nor B
A. transducer **Only the sound source establishes a wave's frequency.
What determines the initial amplitude of an ultrasound wave? A. transducer B. medium through which the sound travels C. both A and B D. neither choice A nor B
A. transducer **the initial strength or amplitude of a sound wave is determined by the vibration of the piezoelectric crystal in the transducer. The greater the vibration of the crystal, the larger the amplitude of an us wave.
What determines the period of an ultrasound wave? A. the transducer B. the medium through which the sound travels C. both A and B D. neither A nor B
A. transducer **the sound source that produces the acoustic signal determines the period of a wave.
If the power of the beam is tripled while the cross-sectional area remains the same, the intensity ____. A. triples B. increases nine-fold C. remains the same D. none of the above
A. triples **when the cross-sectional area of a beam remains unchanged, the change in the intensity of a beam is proportional to the change in the power.
The pattern of electrical signals exciting the piezoelectric crystals of a linear phased array transducer _______. A. typically changes from one acoustic pulse to the next B. changes every fourth or fifth acoustic pulse C. changes only when the maximum imaging depth changes D. none of the above
A. typically changes from one acoustic pulse to the next. The pattern of the electrical signals that excite the PZT crystals determine the direction and focusing of each acoustic pulse. Each sound wave is directed in a slightly different direction to create a 2-D imaging plane. The electronics that create the varying patterns is called the beam former.
transient cavitation is most dependent on : A. ultrasound pulse B. size of gas bubbles C. type of contrast agent used D. expansion rate of the microbubble
A. ultrasound pulse
A system has 3 transducers with frequencies of 7.5 MHz, 5 MHz, and 3.25 MHz. Aliasing appears when using the 5.0 MHz transducer during a pulsed Doppler exam. What should the sonographer do? A. use the 3.25 MHz B. use the 7.5 MHz C. nothing; the other transducers do not provide solutions to the problem
A. use the 3.25 MHz **probe A transducer producing ultrasound at a lower frequency will produce smaller Doppler shifts, which are less likely to alias.
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 In this example, the reflections on the image would be placed at depths deeper than the actual position of the reflector in the body.
What is coaptation? A. vessel collapse B. blood clotting C. Bernoulli's flow D. capillary filtration
A. vessel collapse Coaptation means that the opposing walls of a vessel come into contact.
Which of the following is best described as an analog number? A. weight of a person B. number of people in a room C. number of stars in the sky D. number of tires on a car
A. weight of a person **It is continuous and can achieve an unlimited number of values.
While using the same machine and transducer, which of the following can a sonographer alter? A. PRP B. PRF C. frequency D. duty cycle E. pulse duration
ALL **While using the same ultrasound machine and transducer, the sonographer can alter the PRP, PRF, and the duty cycle. All are altered by adjusting the maximum imaging depth. Frequency and pulse duration are fixed one a transducer is selected.
Acoustic artifacts include: A. images of reflectors in an inappropriate position B. images of reflectors with improper shape C. images of reflectors with incorrect brightness D. images that do not correspond to anatomical structures
All of these are artifacts. An artifact is an error in imaging.
Which of the following statements are true of a tissue equivalent phantom? A. it has the same propagation speed as that of soft tissue B. it 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 QA studies
All of these are true
Which of these functions are performed by the receiver of the ultrasound system? A. amplification B. threshold C. compensation D. demodulation
All of these functions are performed by the system's receiver.
Steering of the sound beam is accomplished by
Altering the excitation of the active elements
Axial resolution = ?/2
Axial resolution = SPL/2
Which of the following terms are associated with phased array transducers? A. lens B. multi-focus C. mirror D. adjustable E. external
B and D Phased array is always associated with adjustable or multi-focusing.
What is the amount of attenuation per centimeter that a sound wave undergoes called? A. beam uniformity coefficient B. attenuation coefficient C. attenuation D. duty factor
B attenuation coefficient **This is a useful tool as the value remains constant, regardless of the actual path length.
A wave of acoustic energy is leaving soft tissue and transmitting into fat with an 86 degree incident angle. What is true of the angle of transmission? A. 86 degrees B. less than 86 degrees C. greater than 86 degrees D. it cannot be determined
B less than 86 degrees Fat's propagation speed is less than that of soft tissue. The angle of transmission is less than the angle of incidence when a wave travels into a second medium that reduces the wave's propagation speed.
Which imaging modality places dots of dissimilar gray-scale on the display?
B-mode, or brightness mode. B-mode displays reflected echoes as spots of varying brightness. The depth of the dot is based on the time of flight. Stronger reflectors create bright dots and weaker reflectors create darker ones.
The arterial pressure of a supine individual is 120 mmHg. What is the hydrostatic pressure at the patient's hips? A. 100 mmHg B. 0 mmHg C. 40 mmHg D. 120 mmHg E. -120 mmHg
B. 0 mmHg **Hydrostatic pressure is related to the difference between heart level and the site of measurement. In the supine patient the hydrostatic pressure is zero.B. 0 mmHg Hydrostatic pressure is related to the difference between heart level and the site of measurement. In the supine patient the hydrostatic pressure is zero.
The arterial blood pressure of 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. 0 mmHg **Hydrostatic pressure is related to the difference between the heart level and the site of measurement. In a supine patient, hydrostatic pressure is zero.
What is the wavelength of 10 MHz sound in soft tissue? A. 0.77 mm B. 0.15 mm C. 1.54 mm D. 10 mm
B. 0.15 mm Wavelength(mm)=1.54/frequency(MHz) Wavelenth=1.54/10.0=0.15mm
The process of eliminating low amplitude signals from further processing is called all of the following except ____. A. reject B. subordination C. threshold D. suppression
B. subordination
The minimum number of active elements in a mechanical transducer is : A. 0 B. 1 C. 2 D. none of the above
B. 1 A mechanical transducer may be constructed with a minimum of a single piezoelectric crystal. An imaging plane is created by mechanically steering the crystal with a motor.
What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects? A. 1 mW/cm2 B. 100 mW/cm2 C. 1000 mW/cm2 D. 1 W/cm2
B. 100 mW.cm2
Which of these is a binary number? A. 12211221 B. 10000000 C. 98765432 D. 01010102
B. 10000000 A binary number is a string of zeroes and ones only. Thus binary numbers are based on 2 choices and digital numbers are based on 10 choices.
which frequency is within the audible range? A. 15 Hz B. 15 KHz C. 25 KHz D. 5.0 MHz E. 25,000 Hz
B. 15 KHZ
Which transducer system is most likely to have the longest delay in its TGC curve? A. 5 MHz linear array B. 2.5 MHz annular array C. 7.5 MHz mechanical D. 5 MHz annular array
B. 2.5 MHz Low frequency waves attenuate to a lesser extent than high frequency waves. The type of transducer does not affect the TGC.
How many decibels represent a 100-fold increase in the intensity of an acoustic pulse? A. 10 B. 20 C. 100 C. 6
B. 20 dB **Each 10 dB indicates a tenfold increase. 20 dB means of pair of tenfold increases-10 X 10= 100.
An 8 MHz sound beam travels in soft tissue through a path length of 5 cm. What is the value of the attenuation? A. 8 dB B. 20 dB C. 4 dB D. 40 dB
B. 20 dB **Total attenuation=path length X attenuation coefficient Attenuation coefficient=frequency/2
What is the approximate number of frames that must be presented each second for the human eye to perceive the display without flickering? A. 2 B. 30 C. 100 D. 500
B. 30 When the frame rate is significantly below this value, the viewer experiences flicker, which increases fatigue and discomfort and diminishes the perceptive ability of the observer.
What is the speed of sound in air? A. 1,540 m/s B. 330 m/s C. 100 m/s D. 3,010 m/s
B. 330 m/s **which is substantially lower than the speed through soft tissue
2 transducers send ultrasound pulses into soft tissue. One transducer emits sound with a 4 MHz frequency, and the other produces sound at 6 MHz frequency. Each pulse contains 4 cycles. Which has a greater spatial pulse length? A. 6 MHz pulse B. 4 MHz pulse C. they are the same D. cannot be determined
B. 4 MHz pulse **Since both have the same number of cycles, the pulse whose individual cycles have a longer wavelength will have the longer length. In a given medium, the wave with the lower frequency will have a longer wavelength.
The lateral resolution of 4 ultrasound systems appear below. Which will produce the finest image quality? A. 2 cm B. 4 mm C. 6 mm D. 8 mm
B. 4mm Smaller values produce higher quality pictures.
What is the number of binary digits required to store 29 levels of gray? A. 4 B. 5 C. 6 D. 29
B. 5 5 bits can display a maximum of 32 shades of gray.
2 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. 2.5 MHz B. 5 MHz C. neither D. cannot be determined
B. 5 MHz **Doppler shifts are directly related to transmitted frequency. Higher frequency transducers produce a greater Doppler shift.
The diameter of a disc-shaped, unfocused piezoelectric crystal is 1 cm. What is the best estimate for the minimum lateral resolution? A. 1 mm B. 5 mm C. 1 cm D. 5 cm
B. 5 mm **Generally, unfocused sound beams produced by a disc-shaped crystal have an hourglass shape. The beam tapers to a minimum diameter at the focus. At the focus, the beam diameter is approximately half the diameter of the PZT crystal.
You are asked to fabricate a pulsed ultrasound transducer with the lowest possible frequency. Which piezoelectric crystal would you select? A. 6.0 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. 8 mm thick, 2 cm diameter, 2.0 mm/us The frequency is the lowest when the crystal is thick and the propagation speed is low. The diameter of the active element does not alter the frequency of the probe.
A byte is composed of _____ bits. A word is composed of _____ bytes. A. 2, 2 B. 8, 2 C. 16, 16 D. 8, 16
B. 8,2 A sting of eight bits of computer memory is a byte. 2 Bytes of computer memory make a word. Since a byte is 8 buts, a word is 16 bits.
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 degrees. Sound's propagation speed is 1,547 /sec in medium A and 1,745 m/sec in medium B. If reflection and transmission both occur at the boundary, what can be said of the reflection angle? A. > 79 degrees B. < 79 degrees C. = 79 degrees D. cannot be determined
B. < 79 degrees 2 steps are required to determine that the angle is less. From the info given, we can determine that the angle of incidence must be less than 79 degres, because the wave is moving into a medium with a faster speed. Second, the angle of reflection is equal to the angle of incidence, so the angle of reflection must also be less than 79 degrees.
Which of the following epidemiologic studies is considered most likely to produce meaningful results? A. retrospective and prospective B. prospective and randomized C. retrospective and empirical D. prospective and mechanistic
B. A clinical trial tat is both prospective and randomized is most likely to reach a valid and meaningful endpoint.
Analog scale converters have all of the following limitations except: A. image fade B. low spatial resolution C. image flicker D. tube deterioration
B. Analog scan converters have excellent image detail.
Absorption of the sound beam is highest in? A. air B. bone C. fluids D. muscle E. soft tissue
B. Bone
all can be controlled by delays in the transmitted pulse EXCEPT: A. aperture B. suppression C. apodization D. beam steering E. beam focusing
B. suppression
All of the following describe dynamic receive focusing except: A. delay pattern change continuously throughout reception B. may be used by single crystal transducers C. focusing occurs at many depths D. automatically performed by system
B. Dynamic receive focusing is used only with systems using array transducers, not single crystal transducers.
What is epidemiology the study of? A. large groups B. the prevelance of disease C. acoustic bioeffects 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 defined population.
To calculate the acoustic impedance of 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. Impedance=density X propagation speed
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 along the image D. reflectors appearing in multiple locations on the image
B. It is unlikely that a side lobe artifact would result in the absence of a reflector on an image. It is more likely that there would be extra reflectors on the image.
Which of the following is related to cavitation bioeffects? A. TIS B. MI C. cavitation index D. pulsatility index
B. MI Higher values of the mechanical index are associated with increased likelihood of cavitation.
when researching the biological effects of diagnostic ultrasound which intensity is most commonly used? A. SATA B. SPTA C. SATP D. SPTP
B. SPTA
All of the following are true about sound waves except: A. they are mechanical B. they are transverse C. they carry energy from place to place D. they generally travel in a straight line
B. Sound waves are not transverse-they are longitudinal.
What does the beam uniformity coefficient measure? A. special distribution of the sound energy B. Spatial distribution of acoustic energy C. temporal distribution of sound energy D. none of the above
B. Spatial distribution of acoustic energy ** The beam uniformity coefficient is an index of how evenly an ultrasound beam is distributed throughout space. The term spatial means "throughout space."
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 the medium and the wave D. none of the above
B. Speed is determined by the characteristics of the medium only. All sound waves of any frequency, period, intensity, and power travel at the same speed in a particular medium.
Which of the following 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 100Mpa can never induce cavitation
B. This is the principal difference between the 2 forms of cavitation: stable cavitation means that the microscopic bubbles in the tissues are rhythmically swelling, while transient cavitation means that they burst.
What happens to the diaphragm when an individual breathes in? A. it ascends into the thorax B. it descends into the abdomen
B. Upon inspiration, the diaphragm moves downward into the abdomen.
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.
What happens to the 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.
All of the following are true of write zoom except: A. pre-processing function of the receiver B. the same number of 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 usd to create the original ROI
B. Write zoom is a pre-processing function of the receiver where new information is acquired from the region of interest. The data originally stored in the scan converter, before zoom, is discarded. All of the pixels in the image are now concentrated into the ROI thereby increasing the pixel density and image quality of the zoomed image.
Which of 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 no change D. they travel in a straight line
B. all carry energy from one site to another
Where is the mirror image artifact located? A. sometimes shallower on the image that in the body B. always deeper on the image than in the body C. sometimes the same depth on the image as in the body D. never deeper on the image than in the bod
B. always deeper on the image than in the body A mirror image artifact occurs when a pulse bounces off of a strong reflector and then strikes a second reflector. The pulse's path is lengthened by the mirroring and the second reflection is always displayed at an abnormal great depth.
A video display that is limited to only black and white, with no other shades of gray is called ____. A. binary B. bistable C. monochrome D. inchworm
B. bistable
What is the process of adjusting for path length related attenuation called? A. compression B. compensation C. TGC D. reconfirmation
B. compensation
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. crystal thickness
Which of the following techniques is internal focusing? A. lens B. curved crystal C. electronic
B. curved crystal
Which choice will result in increased frame rate and temporal resolution? A. decreased propagation speed B. decreased sector size C. decreased lateral resolution D. decreased PRF
B. decreased sector size A narrower sector diminishes the # of pulses required to produce each image, which improves frame rate and temporal resolution.
What is the primary disadvantage of multiple focal zones along each scan line of a 2-D image? A. improved temporal resolution B. decreased temporal resolution C. improved lateral resolution D. improved longitudinal resolution
B. decreased temporal resolution With multiple foci, the system uses many pulses to create each image. This reduces the number of frames created per second, which reduces temporal resolution.
When enhancement occurs, where does it appear on the image? A. in the near field B. deeper than a weak attenuator C. in the far field D. shallower than a weak reflector
B. deeper than a weak attenuator
Which two attributes help establish the acoustic impedance of a medium? A. density and temperature B. density and stiffness C. stiffness and elasticity D. elasticity and compressibility
B. density and stiffness **Impedance is calculated by multiplying the density by the propagation speed. A medium's propagation speed is determined by the density and the stiffness of the medium. Therefore, impedance is a property of both the density and the stiffness.
Which of the following actions would cause a PZT crystal to lose its special properties? A. breaking it in pieces B. exposing it to high temperature C. exposing it to electrical current D. exposing it to low pressure
B. exposing it to high temperature When a piezoelectric crystal is exposed to high heat, it will depolarize and permanently lose its piezoelectric properties. This is known as the Curie temperature or the Curie point.
Which of these terms best describes the empirical investigation of bioeffects? A. cause-effect B. exposure-response C. cause-response D. exposure-cure
B. exposure-response An example is the assessment of a newborn child following an ultrasound study performed in utero.
The analysis of Doppler spectra using _______ is more accurate. A. zero-crossing detectors B. fast Fourier transforms C. time interval histograms D. Chirp-Z transforms
B. fast Fourier transforms **FFT is the most accurate spectral analysis technique. zero-crossing, time interval histograms, and Chirp-Z were initially used to assess Doppler spectra, but are now obsolete. FFT because popular when computers were incorporated into US systems.
Which of the following causes the greatest amount of inertial energy loss? A. pulsatile flow B. flow through a stenosis C. phasic flow D. steady flow E. parabolic flow
B. flow through a stenosis **Inertial loss is significant when a fluid's velocity increases or decreases. Flow through a stenosis causes the greatest velocity changes and therefore the greatest inertial loss.
What is the point or location where a beam reaches its smallest diameter? A. near zone B. focus C. penetration depth D. focal zone
B. focus
Which of the following is not a potential mechanism for production of bioeffects from ultrasound exposure to the body? A. temperature elevation B. fractionation C. cavitation D. vibration
B. fractionation, which means to separate a mixture into its ingredients and has nothing to do with bioeffects. The other choices are potential mechanisms for acoustic bioeffects.
The amplitude of an acoustic wave is increased. which of the following will most likely remain unchanged? A. power B. frequency C. period D. intensity
B. frequency C. period **Amplitude relates to the strength of a wave. Frequency and period are unrelated to amplitude.
The intensity of M-mode imaging is greater than the intensity of: A. color doppler B. gray scale imaging C. pulsed wave doppler D. continuous wave doppler
B. gray-scale imaging
2 systems are identical except for the frequency of the emitted pulse. Which system will have the deepest focus? A. the lower frequency system B. the higher frequency system C. both foci will be at the same depth
B. higher frequency system High frequency crystals tend to produce ultrasound with deeper foci.
clinical trials are examples of which A. in situ studies B. in vivo studies C. ex vivo studies D. in vitro studies
B. in vivo studies
Which of the following terms doesn't belong with the others? A. increased depth of view B. increased duty factor C. increased PRP D. decreased PRF
B. increased duty factor **Increased duty factor is related to shallower imaging. The other 3 selections are consistent with deeper imaging.
What happens to the intensity of an ultrasound beam when the beam's cross-sectional area remains unchanged while the amplitude of the wave triples? A. it triples B. increases nine-fold C. remains the same D. none of the above
B. increases nine-fold **A change in intensity of a wave is proportional to the change in the amplitude of a wave squared.
The output of the ultrasound pulser determines the _______ of the acoustic pulse. A. imaging depth B. intensity C. duration D. pulse repetition period
B. intensity **The output of the pulser determines the strength or the intensity of the sound beam produced by the transducer.
If the power in an ultrasound beam is unchanged, while at the same time, the beam area doubles, then the beam's intensity: A. doubles B. is halved C. is quartered D. remains the same
B. is halved **intensity=power/beam area
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 of 1.44 MRayls. Medium Z's propagation speed is 1,644 m/s and its impedance is 1.26 MRayls. The angle of incidence is 32 degrees. What is true of the angle of reflection? 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. it is equal to 32 degrees In cases of oblique incidence, the angle of reflection is always equal to the angle of incidence. All information regarding the propagation speeds and impedances are irrelevant for this question.
What is the importance of describing sound beam intensities in a variety of ways with regard to space and time? A. it allows better transducer design B. it's important when studying bio-effects C. it optimizes image quality D. harmonics can be measured
B. it is important when studying bio-effects
In standard Doppler, what is true about the reflected frequency produced by blood cells traveling in a direction away from the 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. it is ultrasonic **The frequency of the wave reflected back to the transducer is ultrasonic. The difference between the transmitted and reflected frequency is audible, the reflected wave back is in the ultrasonic range.
2 ultrasound systems are identical except for the diameter of the transducer's 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 crystal-they tend to produce beams with more distant foci. The larger the diameter, the deeper the focus
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. large diameter, high frequency
As sound travels deeply into the far zone, the beam diverges or spreads out. Which of the following will result in a minimum beam divergence deep in the far zone? A. small diameter, high frequency B. high frequency, large diameter C. large diameter, low frequency D. low frequency, small diameter
B. large diameter, high frequency In contrast, waves from small diameter, low frequency crystals are more divergent in the deep far zone.
With standard ultrasound imaging instrumentation, which has the higher numerical value? A. axial resolution B. lateral resolution C. neither, they have identical values
B. lateral resolution In terms of image accuracy, axial resolution is usually better than lateral resolution. The number assigned to lateral resolution is higher than to axial resolution.
When RBCs move away from a transducer, the frequency of the wave reflected from the red cells is ______ the frequency emitted by the transducer. A. greater than B. less than C. equal to
B. less than **When RBCs move away from the transducer the shift is negative. The reflected frequency is less than the originally transmitted frequency from the transducer.
Infrasound is defined as 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. less than 20Hz **Infrasound is sound so low that it is inaudible to humans. It has a frequency less than 20 Hz.
An acoustic wave in medium B is traveling toward medium A. The sound beam strikes a boundary at a 45 degree angle. The propagation speed is 1,547 m/sec for medium A and 1,745 m/sec for medium B. What is true of the angle of transmission? A. > 45 degrees B. < 45 degrees C. = 45 degrees D. cannot be determined
B. less than 45 degrees With refraction, when the medium that the sound is in has a greater propagation speed than that of the medium that the wave is entering, then the angle of transmission is less than the angle of incidence.
Sound traveling through blood attenuates to a ____ extent than when traveling through soft tissue. A. greater B. lesser C. relatively equal
B. lesser
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 transducer
B. linear switched array-it produces a rectangular shaped image. These others produce a sector shaped image.
What does the far gain of a depth gain compensation curve represent? A. median amplification related to compensation B. maximum amplification related to compensation C. minimum amplification related to compensation D. maximum attenuation related to compensation
B. maximum amplification related to compensation
If sound travels at exactly 1,540 m/sec in a particular medium, then the medium ____. A. must be soft tissue B. may be soft tissue C. cannot be soft tissue
B. may be soft tissue **their could be other media with the same propagation speed
the use of contrast agents in diagnostic sonography: A. have induced cell changes B. may increase the risk of cavitation C. does not increase the risk of biological effects D. demonstrate a rapid increase in tissue temperature E. determines the conditions under which thermal effects occur
B. may increase the risk of cavitation
What is the decibel notation for an acoustic signal that is attenuated? A. positive B. negative C. equal to zero
B. negative **When a signal is attenuated, its magnitude is decreasing and it becomes weaker. In decibel notation, a decrease in signal strength is described with negative decibels. Negative dB means "getting smaller."
The focus of an ultrasound beam is the location where the ____. A. beam is the broadest B. optimum transverse resolution is C. frequency is the highest D. finest depth resolution is obtained
B. optimum transverse resolution is, because it is the narrowest portion of the beam.
Which of the following are acoustic variables? A. frequency B. pressure C. propagation speed D. wavelength E. voltage F. intensity G. motion of particles in the wave H. density
B. pressure G. motion of particles in the wave H. density
Which best describes the elements in a linear phased array transducer? A. rectangular, 1/4 wavelength thick B. rectangular, 1/2 to 1/4 wavelength wide C. circular D. squares, 1/2 wavelength thick
B. rectangular, 1/2 to 1/4 wavelength wide There are approximately 100 to 200 elements in a linear phased array.
Compared to soft tissue, the speed of an acoustic wave through lung tissue is _____. A. faster B. slower C. equal D. cannot be determined
B. slower **Sound travels at a speed of 0.5-1.0 km/sec in lung.
Which technique of linear array transducer design has virtually eliminated the appearance of grating lobe artifact on modern ultrasound systems? A. demodulation B. subdicing C. deconvolution D. none of the above
B. subdicing The process of subdicing has almost eliminated the appearance of grating lobes. Subdicing consists of dividing each of the crystals in the array into smaller pieces. The subdiced pieces are then fired simultaneously as if they were a single crystal.
Repeated gripping of the transducer is more commonly associated with
de Quervain's syndrome
n which region of a sound beam is focusing most effective? 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 end of the near zone-this is the focal zone.
The wavelength of a cycle in an ultrasound wave can be reported with which units? A. units of time B. units of distance C. units of area D. mm only
B. units of distance **Wavelength is the distance from the beginning to the end of one cycle.In diagnostic us, the values usually range from 0.15-0.75 mm.
The 2 most common color maps used in color flow imaging are: A. variance and direct B. variance and velocity C. turbulent and variance D. power and velocity
B. velocity and variance maps
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 different
B. very similar to each other **the speed of sound in these media are less that 5% differenct from each other.
What term is used to describe the effects of an ultrasound wave on living tissue?
Biological effects or bioeffects
Poiseuille's equation states that the volume rate of flow through a vessel is inversely proportional to
Blood viscosity
With these transducers, the ultrasound beam is steered by a motor, a rotating reflecting mirror, or similar device. A. linear switched array B. linear phased array C. mechanical D. annular phased array E. convex or curvilinear array
C and D Steering an ultrasound beam is achieved with mechanical devices such as motors or mirrors, in both mechanical and phased array transducers.
For short pulses, the quality (Q) factor is equal to: A. the distance of one pulse B. one half of the frequency C. the number of cycles in the pulse D. the intensity of the sound beam E the propagation fpeed of the medium
C. # of cycles in a pulse
What is the duty factor if the pulse duration is 1 microsecond and the PRP is 1 millisecond? A. 0.1 B. 0.01 C. 0.001 D. 0.0001
C. 0.0001 **Duty factor=pulse duration/PRP 0.000001/0.001=0.0001
What is the maximum permissible value for both the intensity reflection coefficient and the intensity transmission coefficient? A. 100 B. 1% C. 1 D. infinity
C. 1 **The maximum percentage of the incident intensity that either reflects or transmits is 1 or 100%. At extremes, total reflection occurs (intensity reflection coefficient = 1.0) or complete transmission occurs (intensity transmission coefficient = 1.).
Which transducer possesses the best slice thickness resolution? A. linear phased arrays B. 2-D arrays C. 1 1/2 dimensional arrays D. linear sequential arrays
C. 1 1/2 dimensional arrays
2 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 study. 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. it cannot be determined
C. 1 m/s **Maximum velocities are measure at a zero degree angle. Only 1/2 of the true velocity will be measured when the angle is 60 degrees.
When using a 4 MHz transducer, a Doppler shift of 3,000 Hz is recorded. What will the Doppler shift be when a 2 MHz transducer is used? A. 3,000 Hz B. 2 Hz C. 1,500 Hz D. 6,000 Hz
C. 1,500 Hz **Doppler shifts are directly related to transducer frequency. If the frequency is halved, the Doppler shift will be halved.
What is the best estimate for the speed of sound in tendon? A. 1,000 m/s B. 1,540 m/s C. 1,754 m/s D. 5,400 m/s
C. 1,754 m/s **Sound travels slightly faster in tendon than in soft tissue.
The propagation speed of continuous wave ultrasound is 1.8 kilometers per second. The wave is then pulsed with a duty factor of 50%. What is the new propagation speed? A. 0.5 km/sec B. 0.9 km/sec C. 1.8 km/sec D. 3.6 km/sec E. cannot be determined
C. 1.8 km/sec **The speed of sound in a medium is determined by the properties of the medium only. There is no difference in sound's speed whether the wave is continuous or pulsed. The new and old speeds will be the same
The power in a wave is increased to ten times its original value. How many decibels describe this change? A. 3 B. 6 C. 10 D. 20
C. 10 dB
Which of the following values can correctly designate both the duty cycle and the beam uniformity coefficient? A. 1% B. 0 C. 100% D. none of the above
C. 100% **The BUC is equal or greater than 1. The duty cycle ranges from one to zero. The only number common to both is one, which can be expressed at 100%.
What is the typical output voltage that excites a piezoelectric crystal? A. 0.1 volts B. 500 millivolts C. 110 volts D. 10 microvolts
C. 110 volts The signal typically produced by the pulser of an ultrasound system may be in the range of hundreds of volts.
A maximum Doppler shift is obtained when the angle between the direction of blood flow and the direction of sound beam is A. 10 degrees B. 90 degrees C. 180 degrees D. 270 degrees
C. 180 degrees Maximum Doppler shifts occur when RBCs travel directly toward or directly away from the transducer.
The characteristics of a pulse are as follows: the pulse repetition period is 100 usec and the listening or dead time is 998 usec. What is the pulse duration? A. 1950 usec B. 2 msec C. 2 usec D. 0.95
C. 2 usec **The transmission time is the pulse duration. The sum of the talking and listening times is the PRP. If the PRP is 1000 usec and the receiving time is 998 usec, then transmitting time must be 2 usec.
Which of the following waves is ultrasonic and least useful in diagnostic ultrasound? A. 2 MHz B. 2,000 Hz C. 24 kHz D. 7.5 MHz
C. 24 kHz **which is an ultrasonic wave, but it is too low to be useful for diagnostic imaging.
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 experiences? A. 9 dB B. 3 dB C. 27 dB D. 18 dB
C. 27 dB **total attenuation=path length X attenuation coefficient
Which transducer has the worst axial resolution? A. 2 cycles/pulse, 4 MHz B. 4 cycles/pulse, 4 MHz C. 4 cycles/pulse, 2 MHz D. 2 cycles/pulse, 2 MHz
C. 4 cycles/pulse, 2 MHz Pulses with the most cycles and the lowest frequency have the worst axial resolution.
An 8 MHz sound beam travels in soft tissue through a path length of 5 cm. What is the value of the attenuation coefficient? A. 8 dB/cm B. 20 dB/cm C. 4 dB/cm D. 40 dB/cm
C. 4 dB/cm **In soft tissue, the attenuation coefficient (dB/cm) is approximately 1/2 of the frequency measured in MHz. In soft tissue, it is determined by the frequency of the sound only.
What is the best estimate of the propagation speed of the ferroelectric element of a transducer used in a typical diagnostic imaging laboratory? A. 1.2 mm/usec B. 4.0 m/sec C. 4.0 mm/us D. 1.9 km/sec
C. 4.0 mm/us The active element of a typical diagnostic imaging transducer has a propagation speed that is approximately 3-4 times greater than the speed of ultrasound in soft tissue. The range is approximately 4-8 km/sec. Other ways of stating this are 4-8 mm/us, or 4000-8000 m/sec.
An ultrasound system can accurately process voltages in a range from 4 volts to 400 volts. What is the system's dynamic range? A. 396 volts B. 20 dB C. 40 dB D. 60 dB E. 80 dB
C. 40 dB **The ratio between these signals is 100:1. For voltages, a ratio of 100:1 is 40 dB.
The frequency of continuous acoustic wave is 5 MHz. The wave is then pulsed with a duty factor of 0.1. What is the new frequency? A. 0.5 B. 0.5 MHz C. 5 MHz D. 10 MHz
C. 5 MHz **The fact that a wave is pulsed rather than continuous does not change the frequency of the signal. The new and the old are the same-5 MHz.
Which of the following is a typical value for the amplification of a signal by the receiver? A. 50 to 100 volts B. -50 to -100 volts C. 50 to 100 dB D. 5 to 25 W/cm2
C. 50 to 100 dB **The amplification of the weak electrical signals that first reach the receiver range from 50 to 100 dB. This prepares the signals for further processing.
How many horizontal scan lines make up an image on a tv monitor used in the United States? A. 2,500 B. 500 C. 525 D. 1,000
C. 525 the electron beam is rapidly steered across the face of the CT from left to right and from top to bottom and "paints" an image on the screen.
Which wave is least likely to create cavitation? A. 5 MHz, 2 MPa B. 2 MHz, 4 MPa C. 6 MHz, 2 MPa D. 2 MHz, 2 MPa
C. 6 MHz, 2 MPa Low values of MI indicate low likelihood of cavitation. MI is lowest with high frequency and low pressure.
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. 64 To calculate this, we have to multiply 2 by itself 6 times. 2 X 2 X 2 X 2 X 2 X 2 = 64
With which of the following pulses would lateral resolution be worst? A. 10 MHz, 4 mm beam diameter, 4 cycles/pulse B. 4 MHz, 4 mm beam diameter, 2 cycles/pulse C. 7.5 MHz, 8 mm beam diameter, 2 cycles/pulse D. 6 MHz, 2 mm beam diameter, 2 cycles/pulse
C. 7.5 MHz, 8 mm beam diameter, 2 cycles/pulse Lateral resolution artifact is related to the diameter of the ultrasound beam. Narrower beams have the best lateral resolution. Wider beams have the worst.
Which of the following sector imaging systems will have the best image detail if all other parameters are identical? A. a 90 degree sector with 100 pulses/image B. an 80 degree sector with 40 pulses/image C. a 70 degree sector with 84 pulses/image D. a 60 degree sector with 60 pulses/image
C. 70 degree sector with 84 pulses/image The best image detail is provided by the system with the highest line density. Line density is the number of acoustic lines per degree of sector angle. The more lines per sector degree, the closer the scan lines are squeezed together and the greater the anatomic detail displayed.
Which of these pulses is least likely to produce an axial resolution artifact? A. 10 MHz, 8 mm beam diameter, 6 cycles/pulse B. 4 MHz, 4 mm beam diameter, 2 cycles/pulse C. 9 MHz, 8 mm beam diameter, 2 cycles/pulse D. 6 MHz, 2 mm beam diameter, 2 cycles/pulse
C. 9 MHz, 8 mm beam diameter, 2 cycles/pulse 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 C doesn't have the highest frequency, it has only 2 cycles/pulse and therefore is the shortest of the 4 pulses. Beam diameter is irrelevant with regard to axial resolution.
Which choice relates to the presence of gray shades in a Doppler spectrum? A. velocity B. frequency shift C. amplitude of the echo D. laminar flow
C. AMPLITUDE OF THE ECHO **Grayscale in a Doppler spectrum is related to the number of RBCs creating the reflection. The number of RBCs determines the amplitude of the reflected signal.
What is the cause of acoustic speckle? A. refraction B. attenuation C. interference of tiny acoustic wavelets D. resonance of particles in the near field
C. Acoustic speckle is produced by the constructive and destructive interference of small acoustic waves reflected from small reflectors in the near field.
Spectral analysis of color flow Doppler is most commonly performed by which of the following techniques? A. zero-crossing detectors B. fast Fourier transforms C. autocorrelation D. Chirp-Z transforms
C. Autocorrelation **Autocorrelation is better suited to process the enormous amount of data acquired in a color Doppler study.
All of the following are associated with a CW Doppler transducer except: A. narrow bandwidth B. increased sensitivity C. backing material D. high Q-factor
C. CW transducers don't use backing material and as a result, the have increased sensitivity and is more able to detect small Doppler shifts.
When the elasticity of a medium is high, the ______ is high. A. stiffness B. propagation speed C. compressibility D. reflectivity
C. Compressibility **Both elasticity and compressibility describe the ability of a medium to reduce its volume when affected be a force.
A comprehensive and scholarly review of bioeffects is performed by the American Institute of Ultrasound in Medicine for all of 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. Diagnostic ultrasound is not considered highly toxic or likely to expose patients to substantial risks.
A duplex ultrasound system displays _____ information. A. M-mode, 2-D image, and A-mode B. A-mode and B-mode C. 2-D image and Doppler D. 2-D image and M-mode
C. Doppler and 2-D image
During a pulsed doppler exam, aliasing is 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 PRP D. use of a continuous wave system
C. If you select a transducer with a greater PRP then the PRF will decrease, making aliasing more likely.
These transducers steer the beam with a motor and focus the beam with an acoustic lens or a curved PZT element. A. linear switched(linear sequential) array B. linear phased array C. mechanical D. annular array E. convex or curvilinear array F. vector array
C. Only the mechanical scanner has these characteristics.
Which situation will commonly produce reverberation artifact? A. 2 masses that lie perpendicular to the sound beam's main axis B. 2 weak reflectors that lie close to each other along the axis of the beam C. 2 strong reflectors that lie along the main axis of the beam D. a single highly reflective mass
C. Reverberations are commonly produced by a pair of strong reflectors that lie along the main axis of the beam.
Which intensity is most closely correlated to tissue heating? A. SPTP B. SATP C. SPTA D. SATA
C. SPTA
Sound can be characterized as: A. energy flowing 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.
Which of the following is a correct description of the pulse repetition period? A. the product of wavelength and propagation speed B. the reciprocal of frequency C. the sum of the pulse's "on" time and the listening "off" 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 next pulse. It is equal to the time that the transducer is pulsing (the pulse duration) plus the time that the ultrasound system is listening for reflected echoes.
What is the range of Doppler shifts commonly measured in clinical exams? A. -10 kHz to 1 MHz B. -0.5 MHz to 0.5 MHz C. -0.01 MHz to 0.01 MHz D. none of the above
C. The range of Doppler shifts in clinically imaging typically range from -10,000 Hz to 10,000 Hz, or -0.01 to 0.01 MHz.
Of the following, which imaging modality has the poorest temporal resolution? A. 2-D, real-time B. A-mode C. color flow imaging D. M-mode
C. color flow imaging Many pulses are required to create a single color flow image. The large number of pulses required for each image results in a low frame rate and poor temporal resolution.
What is the meaning of the term "analysis" in the context of spectral analysis of Doppler signals? A. building a sophisticated signal from components B. building a simplified signal from components C. identifying the building blocks or components from a complex signal D. measuring a complex signal, then modifying its information content
C. The term analysis defines the act of scrutinizing an object to determine what individual components are incorporated within it? in Doppler analysis, the complex signal is broken down into its more basic ingredients.
What conditions are necessary for refraction to occur at a boundary between two media? A. unequal acoustic impedances and normal incidence at the boundary B. unequal densities of the media and normal incidence at the boundary C. dissimilar propagation speeds and oblique incidence at the boundary D. different elasticities of the media and oblique incidence
C. The two conditions for refraction are: 1. sound wave must be obliquely incident to the border between 2 media AND 2. the media on either side of the border must have dissimilar propagation speeds.
Which of the following is true of diffuse reflection? A. they're created by smooth boundaries B. they're created by large reflections C. sound reflects in many directions D. they do not appear in soft tissue
C. They are dispersed in many different directions.
Ultrasound systems are designed to automatically ______. A. display similar structures with equal brightness, regardless of depth B. position structures at the correct depth, regardless of the medium C. display all reflections on a line corresponding to the main axis of the sound beam, regardless of refraction D. select the optimal beam width based on the clinical application
C. Ultrasound systems assume that all reflections are created from reflectors that lie directly along the main axis of the beam. An artifact is created when pulses refract and change direction.
What image is created with a 2-D array transducer? A. 2-D static image B. 2-D real time image C. 3-D real time image D. B-mode
C. a 2-D array transducer creates a 3-D image
What is a decibel? A. the absolute value of a number B. range of values C. a relationship between 2 numbers D. none of the above
C. a relationship between two numbers. It is a relative measure of intensity or power.
Which of these components typically has the greatest dynamic range? A. display B. pulser C. amplifier D. demodulator
C. amplifier
Which of the following 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 unfocused beam is most likely to cause temperature elevation in soft tissues.With narrower, focused beams, the area insonated by the beam is smaller and therefore heats a smaller mass of tissue.
Which term best describes the region of minimum amplification on a standard TGC curve? A. far field B. focus only C. area closest to the transducer D. focal zone
C. area closest to transducer, which is often called the "delay."
As sound propagates through a medium, the total power in the wave decreases. What is this entire process called? A. absorption B. scattering C. attenuation D. reflection
C. attenuation **Absorption, scattering, and reflection are components or contribute to attenuation.
Which of the following is different for a tissue equivalent phantom and an AIUM 100mm test object? A. propagation speed of sound B. wavelength of sound C. attenuation of sound D. frequency of sound
C. attenuation of sound In the tissue equivalent phantom, sound attenuates at a rate similar to soft tissue. Sound attenuates at a much slower rate in the AIUM test object.
Which of the following terms is not associated with a wide dynamic range? A. low contrast B. many shades of gray C. bistable
C. bistable **A bistable image contains only black and white.
Which display is limited to a single pair of brightness or display levels? A. CRT B. binary C. bistable D. grayscale
C. bistable **Each dot on the image is either black or white, bright or dark, on or off. Bistable images are considered high contrast.
In diagnostic imaging, what determines the spatial pulse length? A. the ultrasound system B. medium through the pulse travels C. both A and B D. neither A nor B
C. both system and the medium **SPL is the distance, or length, of a pulse. It depends on part on the wavelength of each individual cycle in the pulse. Wavelength depends on both the source and the medium, so the length or the SPL depends upon both the source and the medium.
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. both the source and the medium Wavelength is determined in part by the wave's frequency, which is determined by the source, and by the speed of sound in the wave, which is established by the medium.
Research has indicated that cavitation _____. A. never occurs B. cannot occur with long pulses C. can be lethal to living things D. effects are purely theoretical
C. can be lethal to living things Cavitation resulting from ultrasound exposure is lethal to the fruit fly. Cavitation has the potential for significant and harmful bioeffects under specific circumstances.
If sound doesn't travel at 1,540 m/s in a medium, then the medium ____. A. must be soft tissue B. may be soft tissue C. cannot be soft tissue
C. cannot be soft tissue
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, deci, deca, hecto
which of the following reduces occupational injuries: A. chin slightly raised B. eyes are even with the middle of the monitor C. chin is slightly tucked D. eyes are even with top of the monitor
C. chin is slightly tucked
which differentiate similar or dissimilar tissues? A. axial resolution B. lateral resolution C. contrast resolution D. temporal resolution E. elevational resolution
C. contrast resolution
Doppler does not always provide a valid estimate of the speed of blood cells because the shift is related to the ____ of the angle between the direction of the beam and the direction of blood flow. A. sine B. tangent C. cosine D. cotangent
C. cosine
Where are shadowing artifacts commonly seen on a 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 high attenuation D. along side of a structure with a low elastance
C. deeper than a structure with high attenuation
Certain studies of bioeffects are performed in vitro. What is the meaning of 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. discernible in a test tube In vitro experiments are performed out of the body and in an artificial environment.
Of the following choices, which is considered the most important for the sonographer with regard to bioeffects? A. PRF B. frequency C. duration of the study D. imaging mode
C. duration of the study, because it is directly controlled by the sonographer. Exams should always be of high quality and should provide relevant diagnostic information with a secondary goal of minimizing output power level and time exposure to the patient.
The relationship between the largest and the smallest signal amplitudes processed by a component of an ultrasound system is called the ____ and has units of _____. A. decibels, watts B. intensity, W/cm2 C. dynamic range, dB D. proportionality, dB
C. dynamic range, dB
Which of these techniques is consistent with variable or multi-focusing? A. lens B. curved crystal C. electronic
C. electronic Electronic focusing is achieved with phasing of electronic signals. Electronic focusing, unlike internal or external focusing, is adjusted by the sonographer. It is also multi-focusing.
With standard diagnostic imaging instrumentation, which has the higher numerical value? A. axial resolution B. lateral resolution C. elevational resolution
C. elevational resolution In terms of image accuracy, elevational resolution, which is determined by slice thickness, is the cause of the greatest image degradation. The numerical value is then higher than the others.
Unexpectedly low attenuation results in which of the artifacts listed below? A. refraction B. attenuation C. enhancement D. shadowing
C. enhancement
Which of the following is not one of the physical processes that contribute to attenuation of ultrasound waves passing through soft tissue? A. reflection B. redirection of sound in many directions C. focusing D. conversion of acoustic energy to heat
C. focusing
To which of the following is Rayleigh scattering related? A. half of the wavelength B. square root of propagation speed C. frequency to the fourth power D. PRF squared
C. frequency raised to the fourth power.
The Doppler effect is observed as a change in _____ and has units of ____. A. amplitude, watts B. power, watts C. frequency, per second D. wavelength, mm
C. frequency, per second **The Doppler effect is a change in a wave's frequency when the sound source and the receiver of sound are in motion relative to each other. Frequency may be expressed in hertz, Hz, cycles/sec, or per second.
How thick is the active element of a 3 MHz pulsed wave transducer? A. 1.54 mm B. 0.51 mm C. half of the wavelength of the sound wave in the PZT D. one quarter the wavelength of sound in the matching layer
C. half the wavelength of the sound wave in the PZT
If the ____ of 2 media are different and sound strikes a border between the media at 90 degree incidence, then reflection occur. A. conductance's B. densities C. impedance's D. propagation speeds
C. impedance's **With normal incidence, as long as the impedance's are dissimilar, reflection will always occur.
What is the primary advantage of multiple focal zones along each scan line of a 2-D image? A. improved temporal resolution B. decreased temporal resolution C. improved lateral resolution D. improved longitudinal resolution
C. improved lateral resolution 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.
How are the piezoelectric crystals excited when sing an ultrasound system with a sequential linear array transducer? A. singly and in order: the first crystal, the second crystal, etc B. in pairs: the first 2 crystals, the 3rd and 4th, etc C. in a specific order D. in a random sequence
C. in a specific order Sequential linear arrays fire small groups of piezoelectric crystals in a specific succession or progression. The order of firing is determined by the manufacturer and is choseN to produce the highest image quality. There is, however, no specific order that ALL linear arrays use. The firing pattern is best described as "in a specific order."
Which of the following actions will improve the signal-to-noise ratio? A. increase dynamic range B. increase receiver gain C. increase output power D. increase TGC
C. increase output power **When the pulse's strength is increased, reflections arriving at the transducer are stronger as well. Strong reflections are less susceptible to the image degrading effects of noise.
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. increased PRF **improved temporal resolution is achieved by increasing the # of images produced each second. The other choices all decrease temporal resolution.
What is true of the Doppler shift when the sound beam is normally incident to the velocity of the RBCs? A. it is at a maximum B. it is half of maximum C. it is absent D. it is at a minimum
C. it is absent **The Doppler shift is related to the angle between the directions of the blood flow and the sound wave. The cosine of this angle indicates the percentage of the true velocity that is measured with Doppler. Normal incidence indicates a 90 degree angle between blood flow and the sound beam. The cosine of 90 degrees is zero. Therefore, zero percent of the velocity is measured-the doppler shift is absent.
Which imaging modalities demonstrates highest intensity? A. color doppler B. real time imaging C. puled wave doppler D. Continuous doppler
C. pulsed wave doppler
If RBCs are traveling toward a transducer, the frequency emitted by the transducer is ____ the frequency reflected from the RBCs. A. greater than B. equal to C. less than
C. less than **When RBCs are approaching a transducer, a positive Doppler shift results. The emitted frequency is less than the received frequency.
In the case of pulsed ultrasound, what is the maximum value of the duty factor? A. 100% B. 1 C. less that 100% D. none of the above
C. less that 100% **When dealing with pulsed ultrasound, at least a small amount of time must be spent listening rather than transmitting. Therefore the percentage of time transmitting must be less than 1 or 100%.
The scale associated with the decibel notation is _______. A. linear B. discrete C. logarithmic D. additive
C. logarithmic
2 pulses are created by different transducers. Both waves have the same frequency. The pulse containing more cycles has a _______. A. lower PRF B. shorter pulse duration C. longer pulse duration D. longer PRP
C. longer PRP (pulse repetition period) **longer pulse duration Pulse duration=# of cycles in a pulse X period If the frequency is the same, the period is the same, therefore the pulse with more cycles has a longer pulse duration.
2 pulses are created by different transducers. Both have the same number of cycles. The pulse containing cycles of a lower frequency has a _______. A. lower pulse repetition frequency B. shorter pulse duration C. longer pulse duration D. longer pulse repetition period
C. longer pulse duration **The pulse duration is calculated by multiplying the number of cycles in a pulse by the period of each cycle. When frequency is lower, a longer period results. When the period is longer and the number of cycles is the same, the pulse duration is also longer.
Which selection has the highest mechanical index? A. high frequency, high power B. high PRF, high intensity C. low frequency, high pressure D. high SPL, high pressure
C. low frequency, high pressure
The term IM defines the ______ and has units of ______. A. medium's maximum impedance, Rayls B. transducer's minimum input, watts C. maximum intensity, watts/cm2 D. minimum inductance, Rayls/ sec
C. maximum intensity that is observed in an ultrasound wave when averaged over the largest one-half cycle. As is true of all intensities, the units are watts/cm2.
Half value layer depends upon which of these features? A. path length and frequency B. path length and propagation speed C. medium and frequency D. PRF and medium
C. medium and frequency **Path length is irrelevant with regard to the half value later thickness.
Acoustic impedance is a property of the ____ and has units of ____. A. source and medium, Imps B. medium, dB C. medium, Rayls D. medium, Ohms
C. medium, Rayls **Impedance is unaffected by the sound source or the characteristics of the wave itself.
In diagnostic imaging, how does multipath artifact affect the image? A. poor angular resolution B. creation of hyperechoic regions C. mild image degradation D. gross horizontal mis-registration
C. mild image degradation It does not manifest itself in a pronounced manner.
Which artifact is not affected by the shape or dimensions of an ultrasound pulse? A. lateral resolution B. slice thickness C. mirror imaging D. longitudinal resolution
C. mirror imaging
A sonographer reduced the sector size from 90 degrees to 30 degrees. Frame rate, however, didn't change. What else happened? A. imaging depth increases B. pulse duration increased C. multi-focus was turned on D. PRF was increased
C. multi-focus was turned on Decreasing sector size would normally increase the frame rate, so you have to look for something that would decrease frame rate. The only selection that does is C.
What is the region from the transducer to the smallest cross-sectional area of a sound beam called? A. focus B. half-value thickness C. near zone D. Fraunhofer zone
C. near or Fresnel zone
2 sound waves with frequencies of 5 and 3 MHz travel to a depth of 8 cm in a medium and then reflect back to the surface of the body. Which acoustic wave arrives first at the surface of the body? A. the 5 MHz B. the 3 MHz C. neither D. it cannot be determined
C. neither **they both travel at the same speed and reach the surface of the body at exactly the same time. All sound waves, regardless of their features, travel at the same speed in a specific medium.
2 transducers are used to perform Doppler exams on the same patient. The exams are identical except the transducer frequencies are 5 and 2.5 MHz. Which exam will measure the highest velocities? A. 2.5 MHz B. 5 MHz C. neither D. it cannot be determined
C. neither **The velocities measure by Doppler exams are the same, regardless of the frequency of the transducer. Although Doppler shifts associated with the velocities may vary, the measured velocities are identical.
Which term has a meaning other than normal incidence? A. orthogonal incidence B. perpendicular incidence C. oblique incidence
C. oblique incidence **occurs when a wave strikes a boundary at any angle other than 90 degrees.
What is the best estimate of the distance that sound can travel in soft tissue in one second? A. one yard B. one hundred yards C. one mile D. ten miles
C. one mile **Sound travels at a speed of 1.540 meters per second in soft tissue, which is approximately one mile per second.
The intensity of an ultrasound wave is changed by -6 dB. This means that the current intensity is ______ as much as the original level. A. one-tenth B. four times C. one-fourth D. one-sixth
C. one-fourth
What is the smallest part of a digital picture called? A. bit B. byte C. pixel D. fractel
C. pixel The term "pixel"is derived from the words picture element.
The intensity of an ultrasound beam is defined as the ____ in a beam _____ by the ____ of the beam. A. power, multiplied, diameter B. amplitude, divided, area C. power, divided, area D. amplitude, multiplied, circumference
C. power, divided by area **The intensity of an ultrasound beam is the concentration of the power within the beam area.
Which of the following terms doesn't belong with the others? A. phasic B. spontaneous C. pulsatile D. venous
C. pulsatile The other 3 describe venous flow, or flow that is moving at a variable velocity as a result of the mechanics of breathing.
What type of artifact causes a reflection to be placed at an incorrect depth? A. lateral incertitude B. shadowing C. range ambiguity D. indeterminate relaxation
C. range ambiguity, which means that uncertainty exists regarding the depth of a structure in the body.
Which best describes the elements in a linear sequential array transducer? A. rectangular, 1/4 wavelength thick B. rectangular, 1/2 to 1/4 wavelength wide C. rectangular, 1 wavelength wide D. squares, 1/2 wavelength thick
C. rectangular, 1 wavelength wide
________is a Rayleigh scatter? A. lung B. liver C. red cell D. diaphragm
C. red cell
Which artifact results in improper side-by-side positioning of reflectors? A. multipath B. comet tail C. refraction D. reverberation
C. refraction Refraction artifact results from an acoustic pulse bending and changing direction. This change of direction is not corrected by the system and results in improper lateral location of reflectors on the image.
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. remains the same **SPL is determined by the # of cycles in the pulse and the wavelength of each cycle. With the same system, these factors are unchanged and the SPL remains the same.
Damping material is secured to piezoelectric material during the fabrication of an ultrasonic imaging transducer. Which of the following is not a consequence of this attachment? A. bandwidth increases B. quality factor decreases C. sensitivity increases D. longer transducer case
C. sensitivity increases The damping material actually decreases the sensitivity.
What artifact results from an ultrasound beam having a finite and measurable 3-D profile? A. acoustic speckle B. multipath artifact C. slice thickness artifact D. grating lobe artifact
C. slice thickness artifact Slice artifact occurs because a sound beam has a thickness. Thickness artifact results in some reflectors appearing in the image even though they are above or below the idealized imaging plane.
For a disc-shaped PZT crystal producing continuous sound, which design will create a beam with the shallowest focus? A. large diameter, low frequency B. large diameter, high frequency C. small diameter, low frequency D. small diameter, high frequency
C. small diameter, low frequency
What determines the intensity of an ultrasound beam after it has traveled through the body? A. the sound source B. the medium through which the sound travels C. both A and B D. neither A nor B
C. sound source & the medium through which sound travels **The combination of the source and the medium ultimately determine the residual intensity of an ultrasound beam following passage through the body.
What assumption is violated when a refracted sound wave is processed? A. waves travel directly to and from a reflector B. sound travels at an average of 1.54 mm/us C. sound travels in a straight line D. the acoustic imaging plane is very thin
C. sound travels in a straight line Refraction artifact results from sound traveling in a crooked or bent line while the system assumes a straight path.
An acoustic pulse reflects 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? A. partial B. Rayleigh C. specular D. total
C. specular **The waves strike this smooth boundary and reflect in an organized, systematic manner. A boundary is considered smooth when the irregularities in its surface are smaller than the wavelength of the incident ultrasonic beam.
Which of the following occur when a sound wave strikes a smooth large surface at a 90 degree angle? A. refraction B. reverberation C. specular reflection D. Rayleigh's scatter E. non-specular reflection
C. specular reflection
Compressibility describes a characteristic of a medium. Which 2 terms describe the same property as compressibility? A. density and stiffness B. density and conductance C. stiffness and elasticity D. elastance and impedance
C. stiffness and elasticity **Compressibility of a medium describes its ability to reduce its volume when a force is applied to it. Elasticity has the same meaning as compressibility, but stiffness is the opposite.
Which receiver function creates an image of comparable brightness from top to bottom? A. receiver gain B. output power C. swept-gain compensation
C. swept-gain compensation
which is greatest during the pulse: A. spatial peak B. pulse average C. temporal peak D. spatial average
C. temporal peak
The area that starts at the beam's smallest diameter and extends deeper is: A. the distant zone B. the Fresnel zone C. the Fraunhofer zone D. the depth of penetration
C. the far or Fraunhofer zone
At which imaging depth is the slope of the TGC curve most effective? A. the region very close to the transducer B. the far zone C. the focal zone
C. the focal zone
The ____ measures beam intensity at specific locations, whereas a _____ measures the entire energy in a sound beam. A. calorimeter, thermocouple B. Schlieren, thermocouple C. thermocouple, calorimeter D. thermometer, hydrometer
C. thermocouple, calorimeter 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 calorimeter measures all of the beam's energy.
Pulse average is defined as the average intensity: A. of the pulse B. over the pulse area C. throughout the duration of a pulse D. across the entire sound beam
C. throughout the duration of a pulse
With depth resolution, _______ . A. too many reflections appear on the image B. reflections are placed too deep on the image C. too few reflections are on the image D. reflectors appear too shallow on the image
C. too few reflectors are on the image Depth resolution is the ability to distinguish two reflectors that lie close to each other alone the main axis of the beam. Most errors in depth resolution result in fewer reflections placed on the image that are actually in the body.
which are types of cavitation? A.stable and thermal B. in vivo and stable C. transient and stable D. spatial and transient
C. transient and stable
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. unexpectedly low attenuation Enhancement artifact appears directly below structures with atypically low attenuation.
What information does the Doppler shift furnish concerning the blood cells that produce it? A. frequency B. speed C. velocity D. density
C. velocity Velocity is both a speed and a direction. Doppler shifts indicate direction and a magnitude.
Which of these lists indicates media with increasing attenuation of ultrasound? A. water, lung, soft tissue, bone, air B. lung, air, soft tissue, bone C. water, blood, fat, muscle, bone, air D. lung, fat, muscle
C. water, blood fat, muscle, bone, air
The power of an ultrasound wave can be reported with which of the following units? A. watts/square centimeter B. dB/cm C. watts D. kg/cm2
C. watts
All of the following are consistent with an image containing only black and white and no other shades of gray except: A. bistable B. high contrast C. wide dynamic range
C. wide dynamic range, which contains many shades of gray and means "many choices."
multipath artifact
Created when sound pulses glance off a second structure on the way to or from the primary reflector. As a result, the transmit path length differs from the return path length.
TRUE OR FALSE: Intensity of the ultrasound beam is proportional to the square root of the acoustic pressure
False
TRUE OR FALSE: The Reynolds number predicts aliasing?
False
The intensity of a signal declines from 1.5mW/cm2 to 0.75 mW/cm2. How many decibels is this change in intensity? A. 3 dB B. 0.75 dB C. -0.75 dB D. -3 dB
D. -3 dB **When the new level is less than the reference level, the reported decibels must be negative.
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. 0 **At one extreme, it is possible to have total transmission and no reflection and at the other total reflection with no transmission.
What is a typical value for the duty factor of pulsed sound wave in diagnostic imaging? A. 0.001 msec B. 0.001 kg/cm3 C. 0.75 D. 0.001
D. 0.001 **Duty factor is the percentage of time that the system is producing an acoustic signal or transmitting. Typically, ultrasound transducers spend the vast majority of time receiving and only a small fraction of time transmitting.
What is the duty factor of a wave that has a PRP of 30 Microseconds and a pulse duration of 0.3 microseconds? A. 0.03 B. 0.90 C. 30.3 D. 0.01
D. 0.01 **Duty factor=pulse duration/PRP 0.3/30=0.01
The upper limits for the SPTA intensity of a focused ultrasound wave where there have been no bioeffects is _____. A. 1 mW/cm2 B. 10 mW/cm2 C. 100 mW/cm2 D. 1 W/cm2
D. 1 W/cm2
What results when the intensity transmission coefficient and the intensity reflection coefficient are added together? A. incident intensity coefficient B. acoustic impedance C. total intensity D. 1.0
D. 1.0
What is the propagation speed of a 5 megahertz sound wave in soft tissue? A. 1,450 meters per second B. 1,540 km/sec C. 1.54 m/s D. 1.54 mm/us
D. 1.54 mm/us **The speed of any sound wave moving through soft tissue, regardless of frequency, is 1.54 mm/us, 1,540 m/s, or 1.54 km/sec.
What is the typical voltage of the signal that is input to the receiver of an ultrasound system? A. 0.1 volts B. 500 mvolts C. 250 volts D. 10 uvolts
D. 10 uvolts 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.
What is the maximum number of shades of gray that are represented with 4 bits? A. 4 B. 8 C. 12 D. 16
D. 16 To calculate this, multiply 2 by itself the same number of times that there are bits. In other words, the number of shades of gray is 2 to the power of the number of bits.
You are asked to fabricate a pulsed ultrasound transducer with the highest possible frequency. Which piezoelectric crystal would you select? A. 6.0 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
D. 2 mm thick, 6 cm diameter, 6.0 mm/us The main frequency emitted by a piezoelectric crystal operating in the pulsed mode is principally determined by the thickness and propagation speed of the crystal. The frequency is greater when the crystal is thin and has a high propagation speed.
Which value is the closest to the impedance of soft tissue? A. 1.5 kiloRayls B. 2.5 deciRayls C. 19 megaRayls D. 2,000,000 Rayls
D. 2,000,000 Rayls **The impedance of soft tissue is in the range of 1.5-2.5 million Rayls.
What is the range of frequencies emitted by transducers used in ultrasonic imaging? A. 1-3 MHz B. 1 to 1,000 khz C. -10,000 to +10,000 Hz D. 2,000,000 to 10,000,000 Hz
D. 2,000,000 to 10,000,000 Hz **Frequencies commonly used in diagnostic imaging range from approximately 2-10 megahertz or 2-10 million cycles per second.
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. 2.5 kHz **The frequency at which aliasing occurs is the Nyquist limit and occurs at 1/2 the PRF.
How many bits are required to display 10 different shades of gray? 14 shades? 15 shades? A. 4 bits, 5 bits, 6 bits B. 10 bits, 14 bits, 15 bits C. 4 bits, 4 bits, 2 bits D. 4 bits, 4 bits, 4 bits
D. 4 bits of memory are required to display 10, 14, or 15 shades of gray. 3 bits can display a maximum of 8 shades of gray. Adding a single bit to the collection increases the number of gray shades to 16.
Assume that the frequency of sound with the greatest power emitted by a transducer is 5 MHz. However, the transducer produces acoustic energy with frequencies as low as 3.5 MHz and as high as 6.5 MHz. What is the quality factor of the transducer? A. 5 B. 5/3.5 C. 5/6.5 D. 5/3
D. 5/3 Quality factor is defined as the main frequency divided by the bandwidth. The main frequency is 5 MHz and the bandwidth is 6.5-3.5 =3.0 MHZ. The Q-factor is therefore 5/3.
Blood moving at a velocity of 2 m/s creates a Doppler frequency of 3,000 Hz. What will the Doppler shift be if the velocity increases to 4 m/s? A. 3,000 Hz B. 2 Hz C. 1,500 Hz D. 6,000 Hz
D. 6,000 Hz Doppler shifts are directly related to reflector velocity. When the velocity doubles, the Doppler shift doubles.
What causes side lobe artifacts? A. sound beams bending B. linear array transducer architecture C. unexpectedly low attenuation D. acoustic energy radiating in a direction other than the beam's main axis
D. A side lobe is produced when a significant amount of energy is directed along a line other than the main axis of the pulse.
Which imaging mode accurately displays reflector depth? A. I-mode B. L-mode C. C-mode D. A- mode
D. A-mode displays the reflector depth accurately. It is used in ophthalmology, where precise measurements of depth or thickness are required.
Epidemiologic studies of in utero exposure to ultrasound have included all of the following except ____. A. birth weight B. cancer C. structural abnormalities D. none of the above
D. All of these have been studied and there is no correlation between ultrasound and these events.
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 the same time B. they vary in amplitude based on the direction of the steering and the focusing C. they excite the crystals at different times, nanoseconds apart D. they arrive at each PZT crystal at different times, microseconds apart
D. Annular array technology produces a focused ultrasound beam by firing the piezoelectric crystals in a particular sequence. The electrical pulses that excite the ringed elements of the array arrive at slightly different times, separated by only very small fractions of a second.
What 2 properties establish sound's propagation speed in a given medium? A. elasticity and stiffness B. stiffness and impedance C. conductance and density D. density and stiffness
D. Density and stiffness
According to the AIUM, at what in situ tissue temperature is there danger to a fetus? A. 100 degrees Centigrade B. 98.6 degrees Fahrenheit C. 1 degree Fahrenheit over normal temperature D. 41 degrees Centigrade
D. Elevation of fetal tissue in excess of 41 degrees C is considered potentially harmful.
The letters represent the abbreviations for the prefixes of the metric system. Select the sequence that appears in decreasing order. A. m, k, M, g, da B. g, m, k, d, u C. g, k, di, m, u, n D. M, k, da, d, c
D. M(mega), k(kilo), da(deca), d(deci), c(centi)
Which ultrasound imaging modality has the best temporal resolution? A. 2-D, real-time B. A-mode C. color flow imaging D. M-mode
D. M-mode With M-mode the ultrasound pulse tracks reflector position in only a single dimension(depth only) and delivers extremely fine temporal resolution.
Which of the following describes the characteristics of a sound wave? A. longitudinal, non-mechanical B. mechanical, transverse C. transverse, acoustic D. mechanical, longitudinal
D. Mechanical, longitudinal A mechanical wave 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.
The final amplitude of an acoustic wave is reduced to one-half of 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. None of the above **Changes in the power of a wave are proportional to the wave's amplitude squared. When one-half of the wave's original amplitude remains, then only one-fourth of the original power remains.
The highest Doppler frequency without the appearance of aliasing is called the _____ and is equal to ______. A. aliasing limit, half of the emitted frequency B. PRF, PRF C. Nyquist limit, half of the emitted frequency D. Nyquist limit, half of the emitted PRF
D. Nyquist limit, half of PRF
The pulse repetition frequency is the ________. A. product of the wavelength and propagation speed B. reciprocal of period C. sum of the pulse duration and listening time D. reciprocal of pulse repetition period
D. PRF and PRP are reciprocals
Which of the following lists orders the impedance from highest to lowest? A. skin, gel, matching layer, PZT B. PZT, gel, matching layer, skin C. gel, PZT, matching layer, skin D. PZT, matching layer, gel, skin
D. PZT, matching layer, gel, skin To maximize the transmission of sound energy between the transducer and the body, the impedances of the active element, matching layer, gel and skin must be in decreasing order.
In clinical imaging, which reflectors produce most relevant Doppler shifts? A. blood vessels B. blood plasma C. platelets D. RBCs
D. RBCs **In clinical imaging, RBCs are the primary reflectors that produce Doppler shifts. The move constantly through the circulatory system and make up nearly 45% of the volume of blood.
What is the most likely cause of ring down artifact? A. refraction B. inversion C. reabsorption D. reflection
D. Ring down artifact is thought to result from multiple reflections.
Heat is most dependent on which of the following intensities? A. SPPA B. SPTP C. SATP D. SATA E. SPTA
D. SATA
which displays the lowest intensity value in pulsed wave ultrasound A. SPTP B. SAPA C. SPTA D. SATA
D. SATA
As sound travels deeply into the far zone, the beam diverges, or spreads out. Which will result in a greatest beam divergence deep in the far zone? A. small diameter, high frequency B. high frequency, large diameter C. large diameter, low frequency D. low frequency, small diameter
D. Small diameter crystals of low frequency tend to produce beams that diverge most in the deep far zone.
All of the following are true of the focus except: A. it is at the end of the near zone B. it is at the beginning of the Fraunhofer zone C. it has the highest spatial peak intensity D. it is at the start of the Fresnel zone
D. The focus is located at the end of the Fresnel zone.
A sound pulse strikes a boundary between 2 media with normal incidence. The speed of sound in the 2 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 occurs only if their impedances are different. In this example, no reflection will occur-100% of the sound will be transmitted.
Resistance to the propagation of sound through a medium defines: A. speckle B. reflection C. attenuation D. acoustic impedance E. rayleigh's scatter
D. acoustic impedance
With pulsed Doppler, what term is used to describe a very high positive Doppler shift that is displayed as a negative waveform? A. attenuation B. filtering C. demodulation D. aliasing
D. aliasing **which means "having a false identity."
Spatial pulse length (SPL) is determined by the? A. oscillator B. pulser C. pulse oscillator D. all of the above
D. all of the above
The SPTP intensity of a typical pulsed acoustic wave _____. A. exceeds the SATA intensity B. exceeds the SPTA intensity C. exceeds the SATP intensity D. all of the above
D. all of the above **With pulsed wave, the SPTP is the largest intensity. When an acoustic wave is pulsed, the temporal peak always exceeds the temporal average. In addition, a typical acoustic wave has a greater intensity near its center compared to its edges. Therefore, the spatial peak intensity is higher than the spatial average intensity. This leads to the conclusion that for pulsed waves, the SPTP has the highest value of all other intensities.
All of the following are used to describe compensation except: A. swept gain B. depth gain C. time gain D. amplitude gain
D. amplitude gain
The excitation of array elements with dissimilar voltages is called ____ and is used to ____. A. dynamic aperture, reduce refraction B. subdicing, eliminate lobes C. apodization, remove flash artifact D. apodization, reduce lobe artifact
D. apodization, reduce lobe artifact
How are the piezoelectric crystals of a linear phased array transducer fired? A. in a single specific pattern B. in order, from top to bottom C. at exactly the same time D. at almost exactly the same time
D. at almost exactly the same time-only billionths of a second separate the electronic pulses that strike the PZT crystals in the transducer.
Which of these produce shadowing? A. reverberation B. multipath C. reflection D. attenuation
D. attenuation
Which of the following is considered a Rayleigh scatterer? A. bone B. liver C. muscle D. blood
D. blood **A RBC 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 pulse is scattered in many different directions.
When studying bioeffects, which research is more important? A. empirical B. mechanistic C. neither is important D. both are equally important
D. both approaches are equally important. The strongest bioeffects conclusions are reached when the results of both approaches are in agreement.
Which of the following 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. changing an electrical signal's form **Demodulation alters the form or shape of electrical signals within the receiver.
What are the units used to describe attenuation? A. watts B. watts/cm2 C. macro D. decibels
D. decibels **Attenuation is reported as a relative change in strength, not an absolute change.
Which of the following terms doesn't belong with the others? A. increased depth of view B. decreased duty factor C. increased PRP D. decreased SPL
D. decreased SPL **SPL is unrelated to alterations in depth of view. The other 3 are related to deeper imaging.
Which of the following tasks is not performed by the receiver of the ultrasound system? A. rectification B. smoothing C. compression D. degassing
D. degassing
What 2 controls determine a system's temporal resolution? A. frame rate and sector size B. foca zones and sector depth C. propagation speed and frame rate D. depth of view and pulses per image
D. depth of view and pulses per image, which may both be altered by the sonographer.
What is the shape of the elements in an annular phased array transducer? A. rectangles B. squares C. wedges D. circles
D. donut or ring shaped They are arranged as a collection of concentric rings.
Which of the following forms of focusing is different from the others? A. lens B. mirror C. phased D. dynamic receive
D. dynamic receive This type of focusing is accomplished during reception of reflected sound. The other 3 are forms of focusing during transmission.
Focusing of an ultrasound beam may create which artifact? A. side lobes B. refraction C. speckle D. enhancement
D. enhancement Focusing may result in very strong reflections from anatomical structures at the depth of the focus. The powerful reflections result in a hyperechoic band that is called focal enhancement or focal banding.
One reflector is 5 times deeper than another. The time of flight of sound to the deeper structure is ___ the time of flight of the shallower reflector. A. one fifth as much B. equal to C. less than D. five times more than
D. five times more than Time of flight and reflector depth are directly related.
When the power in an acoustic beam is doubled and the cross-sectional area of the beam is halved, then the intensity of the beam is: A. doubled B. halved C. quartered D. four times larger
D. four times larger **intensity=power/beam area =2 divided by 1/2, which is 4
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. gas, liquid, solid
Ultrasound is defined as a sound with a frequency of _______. A. greater than 2,000 kHz B. less than 1 kHz C. greater than 10MHz D. greater than 0.02 MHz
D. greater than 0.02MHz **Ultrasound is an inaudible wave with a frequency of at least 20,000 hertz or 0.02 MHz.
What is characteristic of acoustic waves with frequencies exceeding 20,000 Hz when compared with waves having frequencies of less than 20,000 Hz? A. they travel more effectively in soft tissue B. they travel more rapidly C. they attenuate less when traveling in soft tissue D. humans can't hear them
D. humans can't hear them **Waves with frequencies 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 with higher frequencies.
Which of the following is not considered a component of an ultrasound system? A. master synchronizer B. pulser C. receiver D. image intensifier
D. image intensifier **which is part of an x-ray system. The 6 components of an ultrasound system include: transducer, pulser, receiver, image processor, display and master synchronizer.
2 acoustic waves strike a boundary between 2 media. The waves are traveling in a direction 90 degrees to the boundary. Reflection of these waves depends on the differences in the ______. A. frequencies of the 2 waves B. propagation speeds of the 2 media C. amplitudes of the 2 waves D. impedances of the 2 media
D. impedances of the 2 media **With normal incidence, only one condition must be met for reflection to occur-the impedances of the media on either side of the boundary must be different.
All of the following reduce temporal resolution by increasing the number of pulses except: A. increasing the number of foci B. increasing the line density C. increasing the field of view D. increasing depth of view
D. increasing depth of view, which decreases temporal resolution by changing the PRP while leaving the number of pulses the same.
A sonographer adjusts the output power of the wave emitted by the transducer. Which of the following also changes? A. PRP B. PRF C. propagation speed D. intensity
D. intensity **PRP and PRF will only change is the imaging depth changes. Propagation speed only changes if the medium changes.
Huygens' Principle is based on ____. A. refraction B. constructive interference C. transverse waves D. interference
D. interference
Which of the following terms best describes the relationship between frequency and wavelength for sound traveling in soft tissue? A. reciprocal B. direct C. related D. inverse
D. inverse **Higher frequency waves are related to shorter wavelengths.
Which artifact is not related to the unexpected reflection of an acoustic wave? A. multipath B. comet tail C. reverberation D. lateral resolution
D. lateral resolution, which is related to beam diameter.
Grating lobes are most common with which type of transducer architecture? A. annular array B. continuous wave C. mechanical scanners D. linear arrays
D. linear array transducers
What happens to an image when the number of bits allotted to each pixel increases? A. spatial detail improves B. frame rate increases C. field of view expands D. more shades of gray
D. more shades of gray In a digital representation of an image, as the number of bits assigned to each pixel increases, the number of different shades of gray in the image increases.
Sound propagates from one medium with a density of 1.16 km/m3. If the angle of transmission is 49 degrees, 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 definite statement can be made. Since the propagation speeds are unknown, we cannot make any conclusions about the incident angle. The density helps to determine the propagation speed, but knowledge of only density without knowledge of tissue's stiffness is insufficient to deduce which of the two media has a higher propagation speed.
An ultrasound wave approaches an interface between two media at a 90 degree angle. The propagation speeds and the densities of the 2 media are different. What is correct? A. reflection will definitely occur B. reflection will definitely not occur C. refraction may occur D. none of the above
D. none of the above **The facts presented indicate that the propagation speeds and the densities are different, but this information is insufficient to determine whether reflection will take place. If the impedances are the same, reflection will not occur. Refraction will never occur with a 90 degree incidence.
An ultrasound wave strikes a boundary between 2 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 coefficient D. none of the above
D. none of the above **When the transmitted intensity is divided by the reflected coefficient, a number is obtained. This number has no special meaning in ultrasound physics and is not identified by a special name.
Which properties of the piezoelectirc 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 of the above
D. none of the above The frequency of sound emitted by a continuous wave transducer is determined only by the frequency of the electrical signal that excites the piezoelectric crystal.
A sound wave strikes a boundary between 2 media at a 60 degree angle. This is called ____ incidence. A. orthogonal B. angular C. obtuse D. oblique
D. oblique **Oblique incidence is always present when the angle between the direction of a wave's propagation and the boundary between 2 media is different from 90 degrees.
What is the thickness of the matching layer of a 2 MHz pulsed wave transducer? A. 1.54 mm B. 0.77 mm C. half the wavelength of the sound wave in the PZT D. one-quarter the wavelength of the sound in the matching layer
D. one-quarter the wavelength of the sound in the matching layer
The angle between the direction of propagation and the boundary between 2 media is 90 degrees. What term describes the form of incidence in this wave? A. not normal B. direct C. oblique D. orthogonal
D. orthogonal **Orthogonal incidence is attained when a sound wave strikes a boundary between 2 media at exactly 90 degrees.
Attenuation is determined by which of the following factors? A. density and stiffness of the medium B. frequency of sound and propagation speed C. PRF of sound and path length D. path length and frequency of sound
D. path length and frequency of sound
What is the pulse duration equal to? A. frequency multiplied by period B. period multiplied by frequency C. The number of cycles in the pulse divided by the wavelength D. period multiplied by the number of cycles in the pulse
D. period (single cycle) multiplied by the number of cycles in the pulse **The pulse duration is the total time that the transducer is producing a pulse.
Which of the following focusing techniques is different from the others? A. lens B. curved crystal C. fixed D. phased
D. phased Phased focusing is achieved with the electronics of the ultrasound system. It is also adjustable.
Which of these terms means adjustable focusing or multi-focusing? A. dynamic aperture B. harmonics C. frequency agility D. phased array
D. phased array All phased array transducers share one of these 2 features: 1. they have multi-focus capabilities OR 2. the focal depth can be changed by the sonographer
which describes demodulation? A. demodulation suppresses low level echoes B. demodulation changes the gray scale characteristics of an image C. structure boundaries are accentuated when utilizing demodulation D. processing the received signal is made possible by demodulation E. demodulation provides equal amplitude for structures regardless
D. processing the received signal is made possible by demodulation
Which of the following flow patterns is associated with cardiac contraction? A. phasic B. spontaneous C. steady D. pulsatile E. continuous
D. pulsatile
Axial resolution artifacts are due to which of the following? A. multiple reflections B. beam width C. attenuation D. pulse length
D. pulse length The critical factor that influences axial resolution is pulse length. Shorter pulses produce more accurate images.
Decibel notation is a ______ between 2 numbers. A. difference B. sum C. product D. ratio
D. ratio **They are calculated by dividing the final strength of a signal by the starting strength.
the motion of moving structures in a 2 dimensional image display is: A. static imaging B. motion mode C. amplitude mode D. real time imaging E. temporal resolution
D. real time imaging
How is shadowing artifact expressed? A. positioning structures too deep on the image B. locating structures in improper lateral position C. placing reflections in multiple locations D. reflectors being absent on the image
D. reflectors being absent on the image The beam deeper than the attenuator is so weak that significant anatomical information does not appear on the image.
What are the characteristics of a medium that produces comet 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 speeds
D. strong reflectors, closely spaced, high propagation speeds A comet tail artifact is similar to reverberation except that the reflection is a solid hyperechoic line.
An ultrasound pulse is traveling in soft tissue. Which of the following is most important in the determination of the frequency of sound? A. the propagation speed of the ultrasound transducer's matching layer B. the thickness of the transducer's backing material C. the impedance of the transducer's matching layer D. the propagation speed of the transducer's active element
D. the propagation speed of the transducer's active element The 2 characteristics that determine the frequency of sound in a pulse are: 1. thickness of the crystal AND 2. propagation speed of the crystal
Which component of the ultrasound system exposes a patient to the greatest risk? A. the CRT B. the electric cord C. the pulser D. the transducer
D. the transducer
To which of the following do the x-axis of a B-mode, the y-axis of an M-mode and the x-axis of an A-mode all relate? A. depth of view B. echo amplitude C. go time D. time of flight
D. time of flight All 3 of these measurements report the reflector depth. Reflector depth is determined by the pulse's time of flight.
which evaluates the operation of the ultrasound system? A. beam former B. hydrophone C. force-balance system D. tissue-equivalent phantom E. preventive maintenance service
D. tissue-equivalent phantom
which evaluates the operation of the ultrasound system? A. beam former B. hydrophone C. force-balance system D. tissue-equivalent phantom E. preventive maintenance service
D. tissue-equivalent phantom
What was the original purpose for the ultrasound system's analog scan converter? A. to increase the dynamic range of the system B. to make real-time imaging possible C. to increase sensitivity of the system D. to allow for gray-scale imaging
D. to allow for gray-scale imaging. With the introduction of the scan converter, the images were not limited to black and white (bistable). Additionally, the scan converter also changed to format of the system's data from penetrations to a format suitable for display.
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. transmission with oblique incidence **Snell's Law defines the physics of refraction. Refraction describes the behavior of sound beams that transmit after striking a boundary obliquely. Refraction is "transmission with a bend."
What helps to determine the frequency of the sound produced by the transducer of a CW system? A. piezoelectric crystal diameter B. piezoelectric crystal thickness C. damping material density D. ultrasound system electronics
D. ultrasound system electronics A CW transducer produces a wave with a frequency equal to the frequency of the electrical signal that excites the crystal.
All of the following decrease the flow energy of a fluid except: A. frictional loss B. viscous loss C. inertial loss D. velocity loss
D. velocity loss **The 3 energy losses associated with flow through the circulation are frictional, inertial, and viscous.
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. when the benefits to the patient outweigh the risks that may be present
If the PRP increases, duty factor _____________
Decreases
In a Cathode Ray Tube display device the electron beam is steered by?
Deflection plates
Two waves arrive at the same location and interfere. The resultant sound wave is smaller than either of the two original waves. What is this called?
Destructive interference
Mirror image artifact is sometimes seen near the
Diaphragm
Doppler shifts are ______ related to transducer frequency.
Directly
Pulse repetition period and depth of view are ________ related.
Directly
Temporal resolution and frame rate are ____ related.
Directly
Time of flight and reflector depth are ____ related.
Directly
Doppler shifts are ______ related to transmitted frequency.
Directly Higher frequency transducers produce a greater Doppler shift.
Doppler shifts are ______ related to reflector velocity.
Directly Higher velocities create higher Doppler shifts.
A component of an ultrasound system can process voltages in a range from 5 volts to 50 volts. What is the dynamic range of the components? A. 45 volts B. 10 dB C. 15 dB D. 45 dB E. 20 dB
E. 20 dB **The ratio of the largest to the smallest signal is 50:5 or 10:1. For voltages, this is 20 dB
The arterial blood pressure of a standing individual is 120 mmHg at the level of the heart. What is the measured pressure at the subjects ankle? A. 100 mmHg B. 0 mmHg C. 40 mmHg D. -100 mmHg E. 220 mmHg
E. 220 mmHg **Measured pressure = actual blood pressure at the heart level + hydrostatic pressure =120 mmHg + 100 mmHg = 220 mmHg
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. all of the above A Doppler phantom is a versatile device that evaluates all Doppler modes.
A sonographer is performing a study on a patient and desires superior depth resolution. Which of the following changes would create such a system? A. higher frequency B. shorter wavelength C. fewer cycles in a pulse D. less ringing E. all of the above
E. all of the above 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 SPL, decrease the numerical value of depth resolution and create more accurate images.
Which of the following is not associated with laminar flow? A. layered B. normal C. aligned D. smooth E. chaotic
E. chaotic flow is associated with turbulent flow
A special sector shape is produced when this transducer is used. It looks like a wedge or a "slice of 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 the image may be a few centimeters wide. A. linear switched(linear sequential) array B. linear phased array C. mechanical D. annular array E. convex or curvilinear array F. vector array.
E. convex or curvilinear array If the PZT crystals are arranged in an arc of 2-4 cm, then the image will be 2-4 cm wide at its top. From that dimension, the image becomes progressively wider.
which of the following decreases the likelihood of range ambiguity artifact? A. perpendicular incidence B. decreasing the receiver gain C. increasing the overall output D. decreasing the operating frequency E. decreasing the pulse repetition frequency
E. decreasing the pulse repetition frequency
Attenuation of the sound wave is a result of all of the following EXCEPT? A. heat B. reflection C. scattering D. absorption E. transmission
E. transmission
In a standard cathode ray tube used to display ultrasound images, what are the charged particles that are emitted from a "gun" from the rear of the tube?
Electrons The coating on the inner surgace of the screen glows when struck by these electrons and provides the capacity to produce an image.
the study of various factors determining the frequency and distribution of diseases in the human community describes:
Epidemiology
With these transducers, a trapezoidal shaped image is produced. The image is flat at the top and becomes progressively wider at increasing depths. A. linear switched(linear sequential) array B. linear phased array C. mechanical D. annular array E. convex or curvilinear array F. vector array
F. vector array The vector is a combination of linear phased and linear switched array technologies.
which organization regulates ultrasound equipment
FDA
TRUE OR FALSE: A high PRF is needed to image deep structures?
False
TRUE OR FALSE: Aliasing is not a problem with color flow imaging
False
TRUE OR FALSE: Density is not an acoustic variable?
False
TRUE OR FALSE: The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. The frequency is increased.
False **Nothing is stated regarding the frequency of sound emitted by the transducer. Therefore nothing can be concluded regarding frequency.
TRUE OR FALSE: The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. The PRF is increased.
False **PRF and PRP are both affected by the maximum imaging depth. If it is unchanged, then the PRF doesn't change.
TRUE OR FALSE: The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. The pulse repetition period is increases.
False **PRP is determined by the depth of view. In this case, maximum depth is unchanged, so PRP is unchanged.
TRUE OR FALSE: The pulse duration cannot be changed under any circumstances or by any action of the sonographer.
False **Sonographer can alter the pulse duration by using a different transducer or ultrasound system.
TRUE OR FALSE: A bioeffect identified through the mechanistic approach rather than by the empirical approach is more likely to have clinical significance.
False **A bioeffect identified only by a mechanistic methodology is not likely to have a greater clinical significance than a bioeffect identified empirically. The most clinically relevant bioeffect would be one identified both mechanistically and empirically.
TRUE OR FALSE: The pulser of a mechanical transducer is typically more complex than the pulser of a phased array transducer.
False **A single electrical signal excites the PZT crystal of a mechanical transducer. With phased array technology, many crystals are excited nearly simultaneously to produce an acoustic pulse. This technique is used by phased array systems to steer and focus sound beams. Therefore phased array systems have more complex pulsers.
TRUE OR FALSE: A sonographer can adjust the duration of an acoustic pulse since it depends upon the maximum imaging depth.
False **A sonographer cannot change the pulse duration. It has a constant value, and is not dependent on imaging depth.
TRUE OR FALSE: For CW Doppler, problems with aliasing significantly limit its clinical utility.
False **Aliasing is an artifact where high Doppler shifts are misidentified as flow in the opposite direction. Aliasing does not occur with CW Doppler, though it does with PW.
TRUE OR FALSE: All artifacts are errors in imaging that do not represent the true anatomy of the image organ. Therefore, they are all undesirable and should be eliminated if possible.
False **All artifacts are errors in imaging, but they may provide useful information.
2 waves, a 5 MHz ultrasonic wave and a 5kHz audible wave, travel through soft tissue. TRUE OR FALSE: The ultrasound wave travels much faster than the audible wave.
False **All sound waves, regardless of their frequencies, travel at exactly at the same speed in a particular medium. In soft tissue, they travel at a speed of m/s.
TRUE OR FALSE: The AIUM suggests that in vitro research confirming bioeffects is valuable and valid. Their results should be directly applied to the clinical arena.
False **Although in vitro experiments results are extremely important, it is difficult to assess their direct clinical significance. Further studies should be performed before applying these conclusions clinically.
TRUE OR FALSE: Absence of color on a color Doppler image always indicates a region of no blood flow.
False **Although this may be true, it is not always true. Even with blood flow, if the direction of the sound beam is 90 degrees to the direction of blood flow, no Doppler shift will be created.
TRUE OR FALSE: On a color Doppler image, red always represents flow toward the transducer, whereas blue indicates flow 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 flow away from the transducer appears in the lower portion of the color map.
TRUE OR FALSE: Color flow Doppler relies on pulsed Doppler principles and is immune to aliasing artifact.
False **Color flow Doppler does rely on pulsed Doppler principles, but it does alias.
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.
TRUE OR FALSE: Both digital and analog scan converters use computer technology to process electronic data into images.
False **Digital scan converters use computers but analog ones don't
TRUE OR FALSE: The "curved pattern" of delays in the electrical spikes used in a linear phased array transducer focuses the beam during reception.
False **Focusing using time delays of the electrical spikes is a form of transmit, not receive focusing
TRUE OR FALSE: Refraction always occurs at the interface between two media when the propagation speeds of the media are unequal.
False **For refraction to occur, the sound beam must also be obliquely incident as well as the media having different propagation speeds.
TRUE OR FALSE: Lower frequency sound creates higher quality images with greater detail.
False **Higher frequency sound usually produces higher quality images with greater detail.
TRUE OR FALSE: With standard ultrasound pulses, the frequency of the ultrasound changes significantly as the wave propagates through the body.
False **In diagnostic imaging, the frequency of the wave generally remains constant and does not change as the sound propagates. Slight changes in frequency occur when sound strikes moving structures. This forms the basis for Doppler ultrasonography.
TRUE OR FALSE: When reflection occurs with oblique incidence, the angle of reflection equals the angle of incidence. This is known as Snell's Law.
False **It is true that the angle of reflection is equal to the angle of incidence when reflection occurs at an oblique incidence. However, this is not Snell's Law.
parabolic flow
Has a bullet shaped profile, Velocity is highest in the center of the lumen and gradually decreases to its minimum at the vessel wall
TRUE OR FALSE: The appearance of negative velocities in a pulsed Doppler display always indicates that RBCs are moving away from the transducer.
False **Negative velocities many indicate that RBCs are traveling away, but aliasing may also cause negative velocities.
TRUE OR FALSE: The sonographer can make an image uniform brightness by adjusting both output power and receiver gain.
False **Neither output power nor receiver gain can create images of uniform brightness because they do not correct for attenuation. The function that corrects for attenuation is time-gain compensation, or TGC.
With regard to the backing material of a pulsed ultrasound transducer: TRUE OR FALSE: The damping material helps to decrease the PRP achieved at a given imaging depth.
False **PRP is determined by the maximum imaging depth established by the sonographer and is unrelated to the presence of backing material.
TRUE OR FALSE: Pre-processing of image data occurs after the data has been stored in the scan converter.
False **Pre-processing of data is achieved before image stored in the scan converter. TGC and write magnification are examples of pre-processing.
TRUE OR FALSE: Quality assurance evaluations of ultrasound systems can only be performed by biomedical engineers or physical scientists.
False **QA evaluations should be performed by the sonographers who use the system. Although others may be capable of evaluating the system, the sonographer plays an essential role in the QA program.
TRUE OR FALSE: Quality assurance evaluations of ultrasound systems should be performed weekly.
False **QA exams should be performed routinely. The actual time between evaluations is determined by the pattern of use of the system.
TRUE OR FALSE: The period of a sound wave determines whether refraction will occur.
False **Refraction does not depend upon the characteristics of a wave. It only depends upon the incidence of the sound beam and the speeds of the media.
TRUE OR FALSE: An ultrasound system with a longer pulse duration will generally have better temporal resolution.
False **Temporal resolution of a system is unaffected by pulse duration.
TRUE OR FALSE: 2 ultrasound systems, one producing a sound with a frequency of 3 MHz and one at 6 MHz, are used to image a patient. The maximum imaging depth of both exams is 8 cm. The PRF of the 6 MHz transducer if greater than that of the 3 MHz transducer.
False **The PRF is derived for the maximum imaging depth. It changes only when the imaging depth changes. Since the depth of view for both systems is the same, the PRFs are also the same.
TRUE OR FALSE: The characteristic impedance of acoustic gel is greater than the matching layer'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 of sound transmission at the transducer/skin interface.
TRUE OR FALSE: The acoustic impedance of the skin is greater than the acoustic impedances of both the matching layer and the piezoelectric element.
False **The acoustic impedance of skin is lower than the impedances of both the matching layer and the piezoelectric crystal.
With regard to the backing material of a pulsed ultrasound transducer" TRUE OR FALSE: The pulse duration is increased as a result of the presence of the backing material.
False **The backing material inhibits the crystal's oscillations and shortens the pulse duration.
TRUE OR FALSE: The biological effects of ultrasound are thought to be negligible and thus, few investigations have been performed on the subject.
False **The biological effects of ultrasound are studied extensively by scientists throughout the world. Under specific circumstances, bioeffects have been confirmed and are the subject of many discussions, investigations, and publications.
3 sound waves with identical frequencies of 3MHz have powers 2 mW, 5 mW, and 15 mW. They all travel through 3 media-wood, brick and fat-with identical thicknesses of 5 cm. TRUE OR FALSE: The waves travel through all three media at the same speed since they have identical frequencies.
False **The determinant of the propagation speed in a medium is the medium only. The fact that they all have the same frequency is irrelevant. The waves are traveling in media with vastly different densities and stiffness and as a result will travel at different speeds through the wood, brick and fat.
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 factor changes when the sonographer adjusts the maximum imaging depth during an exam.
TRUE OR FALSE: The greater the number of bits assigned to each pixel of a digital image, the greater the spatial resolution of the image is.
False **The number of bits does not affect the spatial resolution of the image.
TRUE OR FALSE: A diagnostic ultrasound system can produce 20 images per second, to a maximum imaging depth of 20 cm, and create each image with 200 acoustic pulses.
False **The number of lines per frame, frame rate and imaging depths must be multiplied together and equal less than 77,000. Sound travels at exactly 154,000 cm/sec in soft tissue-pulses can only travel to a depth of 77,000 cm and back in one second. 200 X 20 X 20 = 80,000, so it is not possible.
TRUE OR FALSE: Typically, the sonographer can control the demodulation process performed by the receiver.
False **The parameters of demodulation are set within the ultrasound system and cannot be adjusted.
TRUE OR FALSE: Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent.
False **The principle difference between variance and velocity modes is that variance mode maps are able to identify turbulent flow. Turbulent flow appears on the image as a third color, such as green, that is on the color map, is located on the right side. Since there is no variance color with velocity mode, the variance and the velocity mode images will differ.
TRUE OR FALSE: A sonographer can adjust the duration of an acoustic pulse since it depends upon the pulse's propagation speed.
False **The sonographer cannot change the pulse duration-it is a fixed feature of the transducer and the ultrasound system.
3 sound waves with identical frequencies of 3MHz have powers 2 mW, 5 mW, and 15 mW. They all travel through 3 media-wood, brick and fat-with identical thicknesses of 5 cm. TRUE OR FALSE: The sound waves travel through all 3 media at different speeds because the waves have different powers.
False **The speed in the media is based only on the densities and stiffness of the media through which they travel-their power is irrelevant.
TRUE OR FALSE: It is generally believed that the effects of ultrasound on biologic media are minimal.
False **Ultrasonic bioeffects are substantial under certain conditions, including, but not limited to, therapeutic ultrasound and lithotripsy.
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 whether the cycle is part of a pulsed or continuous wave.
2 waves, a 5 MHz ultrasonic wave and a 5kHz audible wave, travel through soft tissue. TRUE OR FALSE: The wavelength of the 5 MHz wave is greater than the wavelength of the 5 kHz wave.
False **When 2 sound waves travel through the same medium, the higher frequency wave has a shorter wavelength. Specifically, the wavelength of the 5 kHz wave is 1,000 times that of the 5 MHz wave.
A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused: TRUE OR FALSE: If the diameter of a sound beam is 8 mm at a depth equal to twice the near zone length, then the PZT crystal has a diameter of 16 mm.
False **When a CW 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.
TRUE OR FALSE: The lower the frequency of the ultrasound beam, the shallower the delay oF the TGC curve.
False **With lower sound frequencies, the delay of the TGC curve is deeper.
TRUE OR FALSE: The sonographer has the ability to alter the period of an ultrasound wave that is produced by a basic transducer.
False The sonographer cannot adjust the period. If the sound beam's frequency or period is not suited for the particular type of imaging, the sonographer must select a new transducer with a different frequency.
TRUE OR FALSE: The higher the PRF of a Doppler exam, the more likely that aliasing will occur.
False Aliasing is less likely to occur with high PRF.
TRUE OR FALSE: The lower the numerical value of the longitudinal resolution, the worse the picture.
False Higher quality images are associated with lower values of longitudinal resolution. The numerical value indicates how close together 2 structures can be and still produce 2 distinct images on the ultrasound display.
Pulsatile flow
Flow the accelerates and decelerates with each cardiac cycle
laminar flow
Flows in parallel lines in a smooth progression
What is the reciprocal of period?
Frequency
What term describes the number of cycles that an acoustic variable completes in a second?
Frequency
Q value is determined by
Frequency & Bandwidth
A particle within a transverse wave is traveling vertically. What is the direction of the wave's propagation?
Horizontal-the particles in a transverse wave travel in a direction that is perpendicular to the direction of propagation of a wave. If the particle in the wave is traveling vertically, the then wave is moving horizontally.
Reflection at a tissue interface depends primarily on
Impedance
Increasing the amplitude of the sound beam by 3dB will:
Increase the signal-to-noise ratio
If the PRF increases, duty factor ___________
Increases
A wave strikes an interface between 2 media and intensities are measured at the interface. What results when the reflected intensity is divided by the incident intensity?
Intensity reflection coefficient= reflected intensity/incident intensity
An ultrasound wave strikes an interface between two media. All intensities are measured directly at the interface. What results when the transmitted intensity is divided by the incident intensity?
Intensity transmission coefficient=transmitted intensity/incident intensity The intensity transmission coefficient is the percentage of the incident intensity that continues to propagate in the forward direction when the wave strikes a boundary between two media.
Wavelength is _________ proportional to frequency.
Inversely
Duty factor is _______ related to the depth of view.
Inversely **As the system images to a greater depth, the system requires more time to listen for echoes, and the duty factor decrease.
Pulse repetition frequency is ______ related to maximum imaging depth.
Inversely When the imaging depth in increased, the transducer must wait a longer time for the echoes to return from deeper depths, so PRF decreases.
turbulent flow
Irregular flow with random variations in pressure.
A specular reflector has surface texture _______ the wavelength of the incident wave
Irrelevant to
2 ultrasound systems have near zone lengths of 8 cm. At the focus, System S's lateral resolution is 3.0 mm while System C's is 5.0 mm. Which system is most likely to display 2 small body structures that lie, one in front of the other, at depths of 8.6 and 9.0 mm?
It cannot be determined-the information given is related to lateral resolution, but the question asked is about axial resolution. We don't have enough information to answer the question.
Two sound pulses travel through the same medium. One's wave's frequency is 2 MHz and the other is 10 MHz. Which pulse has the lowest power?
It cannot be determined. Power is not related to frequency, it is related to the strength of the wave and no information is provided about the power. Based on this, we cannot answer this question.
Two sound pulses travel through the same medium. One's wave's frequency is 2 MHz and the other is 10 MHz.Which pulse has the longer spatial pulse length?
It cannot be determined. SPL is equal to the wavelength multiplied by the number of cycles in the pulse. We know that the 2 MHz wave has the longer wavelength, but we don't know how many cycles compose the pulse, so we have insufficient information to answer the question.
2 ultrasound systems produce acoustic pulses. One pulse is 0.4 usec in duration and the other is 0.2 usec. Which pulse will most likely provide the best lateral resolution?
It cannot be determined. The duration of a pulse is unrelated to the lateral resolution. Pulse duration affects axial resolution.
When the sonographer increases the maximum imaging depth, what happens to the pulse repetition frequency?
It decreases **When depth of view is increased, the system waits and listens for a longer time for reflections. This reduces the system's ability to send out as many pulses per second.
While using a particular ultrasound system, what happens to the duty cycle when the depth of view increases?
It decreases **Duty factor is inversely related to depth of view. As the system images to a greater depth, the system requires more time to listen for reflections.
What event does Snell's Law govern?
It defines the physics of refraction.
What happens to the pulse duration when a sonographer decreases the maximum imaging depth in an ultrasound scan?
It does not change. The time that the transducer is "pulsing" doesn't change with a deeper depth, only the listening time.
What are the units of the intensity reflection coefficient?
It is a unit-less number-it is the percentage of an ultrasound beam's intensity that is reflected as the sound wave strikes a boundary between 2 media.
What happens to the pulse repetition period if the sonographer decreases the maximum imaging depth achieved in an ultrasound sound?
It is shortened. As maximum imaging depth is decreased, the interval of time during which the ultrasound machine listens for returning echoes is diminished. As a result of this shorter listening time, the PRP is shortened.
When a sonographer increases the maximum imaging depth during an exam, what happens to the frequency?
It stays the same. Maximum imaging depth and frequency are unrelated.
Beam diameter determines
Lateral Resolution
Low frequency transducers have
Longer wavelengths and greater penetration, but less image resolution
The mode that produces lines related to the changing position of reflectors in the body with respect to time is called _______.
M-mode, or motion mode. It is the only display that provides reflector position throughout time.
Annular array transducers steer the beam
Mechanically
the AIUM recommends:
Prudent use of ultrasound in the clinical environment
Pulse duration=_______ X ________
Pulse duration=number of cycles in a pulse X period
Aliasing artifacts are unique to
Pulsed Doppler
What artifact improperly displays a true reflectors location?
Range Ambiguity
RED BLOOD CELLS are an example of a
Rayleigh Reflector
What is reflection in multiple directions from a reflector that is small relative to the wavelength
Rayleigh Scattering
What is the dispersion of a sound wave uniformly in many different directions after striking a very small particle?
Rayleigh scattering. When Rayleigh scattering occurs, the dimension of the reflecting particles is usually less than the wavelength of the ultrasound wave. The amount of Rayleigh scattering depends on the frequency of the ultrasound.
Snell's law determines the amount of:
Refraction at an interface
The angle of refraction is described by
Snell's Law
Which has a higher acoustic impedance coefficient? A. solid B. liquid C. gas D. all of the above
Solid
Frame rate is determined by what two factors?
Sounds speed in the medium, depth of imaging
According to Snell's Law, sin(transmission angle/sin(incident angle) =
Speed of medium 2/speed of medium 1
Diffraction is the ?
Spreading out of an ultrasound beam
As a pulse passes through soft tissue, a certain amount of acoustic energy remains in the tissue as heat. What is this constituent of attenuation called?
The conversion of acoustic energy into heat is called absorption. This process acts to deposit a portion of the energy of the beam into the soft tissue.
2 digital scan converters are undergoing evaluation. Both produce images of the same size. System A has 1,000,000 pixels with 10 bits assigned to each. B has 250,000 pixels with 12 bits assigned to each. Which system is capable of displaying very small details in an image?
System A, which has a higher pixel density. The scan converter with the greater number of pixels assigned to an image of fixed size with provide greatest spatial detail.
2 ultrasound systems have near zone lengths of 8 cm. At the focus, System G's lateral resolution is 3.0 mm, while System P's is 5.0 mm. Which system will produce higher quality pictures at their foci?
System G because it has a narrower beam at the focus, so it will have higher quality images at that depth.
Two sound pulses travel through the same medium. One's wave's frequency is 2 MHz and the other is 10 MHz. Which sound has the longer period?
The 2 MHz pulse. Frequency and period are reciprocals, so the wave with the lower frequency will have the longer period.
Two sound pulses travel through the same medium. One's wave's frequency is 2 MHz and the other is 10 MHz. Which pulse has a longer wavelength?
The 2 MHz pulse. In a specific medium, the wave with the lower frequency has the longer wavelength. The 2 MHz wave is five times longer than that of the 5 MHz wave.
Which component of an ultrasound system is made of lead zirconate titanate?
The active element of the transducer. Lead zirconate titanate, or PZT, is a man-made piezoelectric material
Which component of an ultrasound transducer is made from a slab of epoxy embedded with tungsten particles?
The backing material or damping material
What are acceptable units for the beam uniformity coefficient?
The beam uniformity coefficient is a unit less number that indicates the degree that an ultrasound beam's intensity is distributed in space. It is calculated by dividing the peak spatial by the average spatial intensity.
2 acoustic beams have identical SPTP intensities of 400 mW/cm2. One beam is pulsed while the other is continuous wave. which beam has a higher SPTA intensity?
The continuous wave ultrasound will have the higher SPTA intensity. Longer receiving times reduce the SPTA intensity for pulsed waves.
Two sound pulses travel through the same medium. One's wave's frequency is 2 MHz and the other is 10 MHz. Which pulse has the lower propagation speed?
The propagation speeds of all sound waves are identical while traveling in a specific media, regardless of frequency.
What is the coating on the inner surface of a cathode ray tube that glows when struck by charged particles?
The inner surface of a CRT is coated with phosphor that glows when it is struck by electrons. Color televisions has 3 different phosphor coatings on the screen. Each phosphor glows with a different color when excited by electrons, thereby producing a color image.
What are the units of the intensity transmission coefficient?
The intensity transmission coefficient is a unit-less number. It is defined as the percentage of an ultrasound beam's intensity that is transmitted as the sound wave passes through a boundary between 2 media.
The logarithm of a numeral is deemed as how many times _____ must be multiplied together to get that numeral.
The logarithm of a numeral is equal to the number of tens that are multiplied together to result in that number.
Period is?
The time it takes to complete a single cycle
The direction of motion of a particle in a wave is perpendicular to the direction of propagation of the wave. What type of wave is this?
Transverse wave
3 sound waves with identical frequencies of 3MHz have powers 2 mW, 5 mW, and 15 mW. They all travel through 3 media-wood, brick and fat-with identical thicknesses of 5 cm. TRUE OR FALSE: The waves travel through all 3 media at different speeds because the media are different.
True
A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused.: TRUE OR FALSE: The far zone is the only region where the beam diameter exceeds the transducer diameter.
True
A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused: TRUE OR FALSE: The near zone is the only region where the diameter of the sound beam decreases as depth increases.
True
TRUE OR FALSE: A BIT is the smallest part of a digital "word"
True
TRUE OR FALSE: A-Mode is mainly used to measure distance
True
TRUE OR FALSE: A-mode scanning represents the depth of the signal in the horizontal dimension?
True
TRUE OR FALSE: Both linear and phased array technologies have the ability to variably focus an ultrasound beam to different depth.
True
TRUE OR FALSE: Density is an acoustic variable
True
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
TRUE OR FALSE: For digital image information to be displayed on a conventional tv screen, the data must be processed by a digital-to-analog converter.
True
TRUE OR FALSE: Grating lobes are a result of substantial acoustic energy directed outward from a linear array transducer, but not along the main axis of the beam.
True
TRUE OR FALSE: Grating lobes are attributed only to array transducers.
True
TRUE OR FALSE: In soft tissue, attenuation coefficient is determined by the frequency of sound only.
True
TRUE OR FALSE: Receiver demodulation can not be controlled by the sonographer
True
TRUE OR FALSE: Side lobe, grating lobe, and refraction artifacts all reduce lateral resolution.
True
TRUE OR FALSE: Temperature is an acoustic variable
True
TRUE OR FALSE: The "curved pattern" of delays in the electrical spikes used in a linear phased array transducer focuses the beam during transmission.
True
TRUE OR FALSE: The greater the number of bits assigned to each pixel of digital image, the greater the shades of gray in the image.
True
TRUE OR FALSE: The intensity reflection coefficient depends on acoustic impedance mismatch?
True
TRUE OR FALSE: The piezoelectric crystal of a transducer typically has an impedance higher than the impedance of the skin.
True
TRUE OR FALSE: The primary purpose of demodulation is the preparation of the electrical signal for display on a television.
True
TRUE OR FALSE: The purpose of the backing material of an ultrasound transducer is to shorten the pulses, thereby creating images with better image quality.
True
TRUE OR FALSE: Typically, the sonographer can adjust the threshold level.
True
TRUE OR FALSE: Velocity of sound in a medium is constant regardless of frequency?
True
TRUE OR FALSE: 2 ultrasound systems, one producing a sound with a frequency of 3 MHz and one at 6 MHz, are used to image a patient. The maximum imaging depth of both exams is 8 cm. The pulses produced by both systems travel at the same speed in the patient.
True **As all sound waves travel in the same medium, they travel at identical speeds. Frequency and speed are unrelated.
TRUE OR FALSE: The proportion of the incident intensity that is reflected at a border between 2 media will increase as the impedance's of the media become increasingly dissimilar.
True **As sound waves strike the border between 2 media, reflection occurs if their impedances are different. Greater differences between the 2 impedances create stronger reflections. If the impedances are only slightly different, then a weak reflection will be produced.
TRUE OR FALSE: Attenuation and propagation speed are unrelated.
True **Attenuation is the weakening of the beam as it travels and has nothing to do with how fast it travels.
TRUE OR FALSE: A digital representation of a number can achieve only specific fixed values.
True **Because of this, digital scan converters can only store a fixed number of gray shades.
TRUE OR FALSE: The assignment of different shades of gray to the digital numbers stored in the scan converter acts to improve the diagnostic value of an ultrasound exam.
True **By using different gray-scale maps, the sonographer selects what tissue textures will be distinguished from each other on the display.
TRUE OR FALSE: TGC cannot be used with CW Doppler.
True **CW doppler is not associated with TGC. Unlike PW, attenuation affects cannot be remedied with continuous wave Doppler.
TRUE OR FALSE: The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. The duty factor is increased.
True **Duty cycle is calculated by dividing the pulse duration by the PRP. In this example the PRP is unchanged, so the duty factor increases.
TRUE OR FALSE: Artifacts are likely to appear when the dimensions of the sound beam area are larger than the dimensions of the reflectors in the body.
True **Examples of artifacts caused by beam area being larger than the reflector are slice thickness and axial resolution artifacts.
TRUE OR FALSE: Post-processing of the image data occurs after the data has been stored in the scan converter.
True **Examples of post-processing include read magnification and assignment of various forms of gray-scale assignment. Any manipulation of the frozen image is post-processing.
TRUE OR FALSE: In comparison to other locations along the length of an ultrasound beam, focusing 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 far zone.
TRUE OR FALSE: When using an instrument typical of today's diagnostic imaging devices, a higher frequency is likely to improve the axial resolution.
True **Higher frequency pulses typically have shorter pulse lengths. Short pulse lengths correspond to images with good range resolution.
TRUE OR FALSE: The pulse duration does not profoundly influence the lateral resolution.
True **In general, the primary determinant of lateral resolution is the sound beam's diameter.
TRUE OR FALSE: With a mechanical transducer, there is communication between the pulser of the ultrasound system and the crystal of the transducer.
True **It is essential that the crystal is directly connected to the pulser electronics of the ultrasound system. A wire provides a route for the electrical signal to travel from the pulse to the crystal.
A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused: TRUE OR FALSE: The greater the diameter of a transducer's piezoelectric crystal, the longer the near zone length.
True **Large diameter crystals tend to produce beams with a deeper focus. The beam's near zone is longer.
TRUE OR FALSE: For CW Doppler, frequencies measured at the transducer are produced from many different locations along the ultrasonic beam.
True **One of the characteristics of CW Doppler is that the frequencies received by the Transducer can some from anywhere along the region of overlap between the transmitted and received beam. This is called range ambiguity.
TRUE OR FALSE: Color flow Doppler imaging incorporates pulsed Doppler principles and provides range resolution.
True **One of the greatest advantages of color flow Doppler is its ability to superimpose 2-D color velocities upon a 2-D gray-scale image of anatomy. Color flow Doppler provides range resolution and is based on pulsed Doppler principles.
TRUE OR FALSE:The pulse repetition frequency and the frequency are unrelated.
True **PRF is determined only by the depth of view and the frequency is determined by the characteristics of the transducer.
TRUE OR FALSE: Typically, the sonographer can adjust the compression function of a receiver.
True **Part of the compression function involves the assignment of gray-scale levels on the display, which can be adjusted by the operator.
2 waves, a 5 MHz ultrasonic wave and a 5kHz audible wave, travel through soft tissue. TRUE OR FALSE: The period of the 5MHz wave is less than the period of the audible wave.
True **Period and frequency are inversely proportional. In this case, the 5 MHz wave has a higher frequency and thus a shorter period.
TRUE OR FALSE: 2 ultrasound systems, one producing a sound with a frequency of 3 MHz and one at 6 MHz, are used to image a patient. The maximum imaging depth of both exams is 8 cm. The period of the 3 MHz sound is greater than that of the 6 MHz sound.
True **Period and frequency are reciprocals. The lower the frequency, the higher the period. In this case, the 3 MHz wave has a period twice as long as the 6 MHz wave.
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 **Pulse duration is the time span that a pulse exists. It is determined by the system and the transducer. It remains constant for a particular transducer.
TRUE OR FALSE: Refraction occurs at the border between two media if and only if there is oblique incidence of the wave upon the boundary.
True **Refraction cannot occur if a wave is normally incident to the boundary between two media.
TRUE OR FALSE: Shorter wavelength sound creates higher quality images with greater detail.
True **Shorter wavelengths produce higher quality images with greater detail.
TRUE OR FALSE: Soft tissue is an imaginary construct that actually does not exist.
True **Soft tissue is an imaginary structure with characteristics that represent an "average" of body tissues, including muscle, blood, kidney, spleen, etc.
TRUE OR FALSE: With sector scanning, images with greater detail (spatial resolution) are created when the number of acoustic pulses per degree of 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 adjacent pulses. Reflectors within the gaps will not accurately appear on the image.
TRUE OR FALSE: The length of a pulse does not directly influence the temporal resolution.
True **Temporal resolution is not affected by the length of the pulse produced by the system. The things that affect temporal resolution are maximum imaging depth, sector angle, line density, and the number of foci per line.
TRUE OR FALSE: Color flow Doppler exams tend to have lower temporal resolution than traditional 2-D, real-time imaging.
True **Temporal resolution is the ability to accurately locate moving structures. Color flow technology reduces the number of pictures produced each second. Because of this low frame rate, temporal resolution suffers.
TRUE OR FALSE: In a pulsed Doppler exam, the use of a higher frequency transducer increases the likelihood that aliasing will appear.
True **The Doppler shift depends on the frequency of the incident sound wave. The statement is true because a higher emitted frequency produces a higher Doppler shift, and a high Doppler shift is more likely to alias.
TRUE OR FALSE: In a mechanical transducer, the beam is directed in many different directions to create an imaging plane.
True **The active element is aimed in a variety of directions so that the pulses create a 2-D picture. Without this beam steering, the pulses would travel in the same direction and display only a single B mode line.
TRUE OR FALSE: In general, ultrasound imaging transducers have a lower quality factor and a wider bandwidth than therapeutic ultrasound transducers.
True **The backing material helps to shorten the pulse, which also increases the bandwidth and decreases the Q-factor.
With regard to the backing material of a pulsed ultrasound transducer: TRUE OR FALSE: The SPL is decreased with the application of the backing material.
True **The backing material tends to diminish the "ringing" of the transducer's active element after it is excited by the electrical signal from the pulser. This shortens the pulse length.
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 factor decreases when depth of view increases because the system needs more time to listen for reflections.
TRUE OR FALSE: It is generally believed that the ultrasound bioeffects are minimal at intensity levels typical of those produced by diagnostic imaging equipment.
True **The likelihood of significant, harmful effects is extremely low.
TRUE OR FALSE: The mechanistic approach to the study of bioeffects and safety includes the identification of a theoretical construct that could produce a result.
True **The mechanistic approach is based on developing a theory as to how something happens. If the theoretical mechanism is proven correct, then great insight into the system and its component factors is achieved.
TRUE OR FALSE: While imaging soft tissue, the spatial pulse length does not change as long as the components of the ultrasound system are the same.
True **The overall length of the pulse is equal to the wavelength multiplied by the number of cycles in a pulse. Using a particular ultrasound system and transducer, the pulse length cannot change.
TRUE OR FALSE: The period of an ultrasound wave is related to the frequency and is the same regardless of whether the wave is pulsed or continuous.
True **The period of a wave is characteristic of each individual cycle in the wave. The period of a wave (as well as the frequency and the wavelength) remains unchanged regardless of whether the wave is continuous or pulsed.
TRUE OR FALSE: Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are laminar.
True **The principle difference between variance and velocity modes is that variance mode maps identify turbulent flow. Turbulent flow appears on the image as a third color, such as green, that on the color map is located on the right side. If no turbulent flow is present, the third color will not appear on the image and the velocity and variance mode images will appear identical.
TRUE OR FALSE: With diagnostic ultrasonic imaging instruments, the operator can alter the intensity of an ultrasound beam produced by a transducer.
True **The sonographer can change the initial power. As the output power increases, the initial intensity increases.
TRUE OR FALSE: The sonographer can adjust the receiver gain.
True **The sonographer is in direct control of the receiver gain.
TRUE OR FALSE: The shorter the pulse length, the better the picture.
True **This is the fundamental concept of longitudinal resolution. One of the most important design criteria for ultrasound systems and transducers is to minimize the pulse duration and SPL.
TRUE OR FALSE: Color flow Doppler systems display anatomical data in gray-scale while simultaneously displaying flow information in color.
True **This is the fundamental process by which color flow mapping works.
TRUE OR FALSE: The shorter the pulse duration, the better the picture.
True **This restates one of the fundamental principles of ultrasonic imaging.
TRUE OR FALSE: All phased array transducer systems direct ultrasound pulses in many directions to create a 2-D image.
True **To create a 2-D image, the sound beams of annular , linear, and curvilinear phased array transducers must be steered through a path. The linear and the curvilinear phased array systems steer the beam electronically, whereas the annular phased array steers the beam mechanically.
TRUE OR FALSE: Proper quality assurance programs require the assessment of every transducer in the clinical laboratory.
True **To establish a valid and rigorous QA program, each component in clinical use must be evaluated.
TRUE OR FALSE: Variance mode color maps may be identified by side-by-side changes in the color bar, whereas velocity mode color maps only change color vertically.
True **Variance mode maps change color side to side as well as from top to bottom. Velocity mode maps only change color from top to bottom.
An ultrasound pulse propagates from soft tissue through a mass. Sound's propagation speed in the mass is 1,575 m/s. TRUE OR FALSE: The wavelength increases while the wave travels through 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/s and through the mass is 1,575 m/s. As a wave travels through a faster medium, the wavelength increases.
A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. TRUE OR FALSE: If the diameter of the acoustic beam produced by a crystal is 8 mm at a depth of twice the near zone length, then the PZT crystal has a diameter of 8 mm.
True **When CW 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.
TRUE OR FALSE: With standard diagnostic imaging instrumentation, the sonographer has the ability to vary the amplitude of a sound wave produced by the transducer.
True **When a sonographer increases the output power, the electrical voltage sent to the transducer is increased. This produces a more violent vibration of the piezoelectric crystal within the transducer and, in turn, a stronger ultrasound wave.
TRUE OR FALSE: 2 ultrasound systems, one producing a sound with a frequency of 3 MHz and one at 6 MHz, are used to image a patient. The maximum imaging depth of both exams is 8 cm. The wavelength of the 3 MHz ultrasound is greater than that of the 6 MHz sound.
True **When traveling through a particular medium, cycles from waves with lower frequencies have longer wavelengths.
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 SPL. Since axial resolution is equal to one-half the SPL, the numerical value of the axial resolution will also be reduced.
TRUE OR FALSE: In CW Doppler, a minimum of 2 distinct piezoelectric crystals are in the transducer.
True **With CW ultrasound, 1 crystal is constantly producing sound. A second crystal is required to listen for reflections.
TRUE OR FALSE: When using an instrument typical of today's imaging devices, a higher frequency transducer is likely to mildly improve the system's lateral resolution.
True **With all other variables being equal, pulses made with higher frequency sound are somewhat more narrow than low frequency pulses. Narrow beams improve the lateral resolution of the system.
TRUE OR FALSE: Annular phased array transducers focus sound beams in all planes and at all depths.
True **With annular arrays, the sound beam has the appearance of a straw. It is focused on all planes and at all depths.
TRUE OR FALSE: One reason that focused ultrasound beams with low intensities are less likely to cause bioeffects is that a focused beam is less efficient in heating a large mass of tissue to a critical temperature.
True **With focused beams, only a small mass of tissue is heated and the heat flows rapidly to cooling neighboring tissues. There is limited accumulation of heat energy and the temperatures tend to stay below critical levels.
TRUE OR FALSE: A sonographer can routinely change the power of a wave emitted by a transducer used in diagnostic ultrasonic imaging.
True **power and amplitude are related; if the amplitude is increased, then so is the power.
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 different names depending on the manufacturer, but the sonographer can always alter its level.
With regard to the backing material of a pulsed ultrasound transducer: TRUE OR FALSE: The backing material helps to decrease the duty cycle at a particular PRF.
True The backing material tends to shorten the pulse duration. This decreases the percentage of the time that the system is "talking" and therefore decreases the duty factor.
TRUE OR FALSE: In a mechanical transducer, the beam is not focused electronically.
True. **The beam is focused with an acoustic lens (external) or by a curved crystal (internal).
TRUE OR FALSE: If the periods of two waves are the same, then the frequencies of the waves must also be the same.
True. Frequency and period are reciprocals, so if the periods are the same, the frequencies must also be the same.
The spatial pulse length describes certain characteristics of an ultrasound pulse. What are the units?
Units of length **SPL is the length that a pulse occupies in space. Its length is measured from the beginning to the end of the pulse.
An acoustic wave is traveling through soft tissue. Its intensity undergoes six decibels of attenuation. How does the final intensity of the wave relate to the intensity of the wave when it started on its journey?
When a wave undergoes 6 dB of attenuation, the final power is 1/4 of its original value. Attenuation means to weaken or reduce.
attenuation, is most commonly a result of:
absorption
As sound travels through a medium, what term describes the effects of the medium on the sound wave?
acoustic propagation properties
grating lobe artifact
array t/d, shot off at a large angle from main beam
slice thickness artifact
artifact that occurs as a result of the beam not being razor thing; thus unintended echoes may appear in the image as the beam slices through structures adjacent to intended reflectors; also known as elevational plane artifact
spatial average
average intensity across the entire sound beam
temporal average
average intensity during the pulse repetition period
pulse average
average intensity over the pulse duration
Wavelength has the greatest effect on?
axial resolution
which testing device plots reflection amplitudes received by the transducer?
beam profiler
preventive maintenance service is usually performed by a?
biomedical engineer
tissue mimicking phantoms cannot evaluate?
blood flow
absorption of the sound beam is highest in
bone
Shadowing artifacts are
caused by differences in attentuation
the positive half of a pressure wave corresponds to
compression
A pair of waves are in phase. What occurs when these waves interfere?
constructive interference-the single wave that results from the combination of the two in-phase waves will always have a higher amplitude than either of the original waves.
a sound beam demonstrates the most uniform intensity in the:
far field
Higher intensities are necessary to produce bioeffects with:
focused transducer
higher intensities are necessary to produce bioeffects with:
focused transducers
radiation force
force exerted on the sound beam by an absorber
define radiation force
force exerted on the sound beam on an absorber
# of images per second defines the
frame rate
Weak beams emitted from a linear sequenced array transducer are termed:
grating lobes
temporal peak
greatest intensity during the pulse
The frame rate in real time imaging can be modified by adjusting the __________.
imaging depth
in situ
in its original place
in vivo
in living body
Waves that exist at the same location and time will combine together. What is this called?
interference-the combination of many waves into a single wave
As sound travels in the body, what typically happens to the intensity of the wave?
it decreases through attenuation
With standard ultrasonic imaging, what happens to the period of a wave as it propagates?
it remains the same
Azimuthal resolution is also known as
lateral resolution
the impedance of the matching layer is
less than the impedance of the crystal
Mechanical index indicates the
likelihood cavitation will occur
which of the following transducers operate by applying voltage pulses to groups of linear elements in succession?
linear sequenced array
The % of ultrasound reflected at an air/liquid interface is?
low
cavitation is the result of
pressure changes in soft tissue causing the formation of gas bubbles
Transmission angle is less than the incident angle if the propagation speed of
medium 2 is less than that of medium 1
Cavitation is the interaction of the sound wave with:
microscopic gas bubbles found in tissue
when the doppler gain is too high, what happens
mirror image
Epidemiology studies on the biological effects of diagnostic ultrasound have determined:
no significant biological effects have been detected
Microbubbles will expand and collapse when:
pressure is applied
ex situ
off-site conservation; outside location
which of the following is a disadvantage of the single emulsion x-ray film?
old data files are purged from the system
Heating of soft tissue is proportional to the:
operating frequency
ex vivo
outside the body
pulse average is defined as the average intensity:
over the duration of a pulse
Axial resolution describes the accuracy related to visualizing 2 structures that are ____ to the sound beam's main axis.
parallel In other words, the structures are arranged front-to-back.
Longitudinal waves are
parallel to the axis of the wave propagation
spatial peak
peak intensity found across the sound beam
Transverse waves are
perpendicular to the axis of the wave propagation
negative predictive value is the ability of a diagnostic test to:
predicts normal findings
Scattering is
redirection of the sound beam in many directions
sub-dicing the elements in diagnostic ultrasound transducers is used to
reduce grating lobes
what is a digital matrix
rows & columns of picture elements in a digital image
The ability of a diagnostic technique to identify the presence of genuine disease is termed:
sensitivity
the # of correct positive test results divided by the total # of positive tests calculates:
sensitivity
Plant studies are useful for understanding
the cavitational effects on living tissues
what determines the diameter of the focus?
the diameter of the transducer
acoustic speckle
the interference pattern caused by scatterers that produces the granular appearance of tissue on a sonographic image
power is defined as:
the rate at which work is done
power is defined as
the rate at which work is done (hydrophone)
what receiver function decreases acoustic noise?
threshold
the distance to a reflector is determined by the
time it takes for an echo to return
which testing device will a quality assurance program most likely utilize?
tissue-equivalent phantom
what is the function of T/R switch?
to protect the receiver components from the pulse voltage
Total attenuation = _______ X ____
total attenuation = path length X attenuation coefficient
a device that plots 3dimensional reflection amplitudes received by the transducer evaluates
transducer characteristics
What remains when the reflected intensity is subtracted from the incident intensity?
transmitted intensity At any point in time and space, there must be conservation of energy. In other words, all energy must be accounted for. The intensity in a wave as it reaches a border between 2 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. The is the reflected intensity. The remainder of the energy continues to propagate and is called the transmitted intensity.
biological studies of the cytoskeleton have shown
ultrasound-induced changes are temporary
in vitro
within a glass, observable within a test tube
in utero
womb, uterus
What is the name of the horizontal axis of a graph?
x-axis side to side
What is the Vertical Axis of a graph called?
y-axis-it extends up and down
With B-mode, on what axis of a CRT is the strength of the reflection input?
z-axis
phasic flow
~Venous, respiration, low rate, lower pressure
