Ultrasound Physics
What is the duty factor of a CW Doppler? a. 1 b. 100 c. 1% d. 0.01
a. 1
The binary number 0010011 converts to which decimal equivalent? a. 19 b. 21 c. 10 d. 35
a. 19
Reducing the likelihood of bioeffects from acoustic energy is the mission of the: a. ALARA b. Reynolds number c. Nyquist limit d. Huygens principle
a. ALARA
The formation of a beam from an aperture is explained by: a. Huygens principle b. piezoelectric effect c. Snell's law d. ALARA
a. Huygens principle
Diagnostic ultrasound transducers operate on which of the following theories? Select one: a. Piezoelectric principle (effect) b. ALARA c. Huygen's principle d. Snell's law
a. Piezoelectric principle (effect)
List the intensity ranges from smallest to highest: Select one: a. SATA,SPTA,SATP,SPTP b. SATA,SATP,SPTP,SPTA c. SPTP,SATP,SPTA,SATA d. SATA,SATP,SPTA,SPTP
a. SATA,SPTA,SATP,SPTP
An increase in reflection amplitudes from reflectors behind a weakly attenuating structure is termed: Select one: a. acoustic enhancement b. slice thickness artifact c. comet-tailed artifact d. acoustic shadowing
a. acoustic enhancement
How are ultrasound transducers typically sterilized? Select one: a. cold-sterilization methods b. heating to the Curie temperature c. autoclaving d. alcohol emersion
a. cold-sterilization methods
What is the receiver function that adjusts the image because of the darker appearance of reflectors in the far field as a result of attenuation? Select one: a. compensation b. compression c. condensation d. confirmation
a. compensation
Which of the following controls adjusts the range of displayed signal amplitudes? a. compression b. amplification c. rejection d. compensation
a. compression
Regions of high density in an acoustic wave are termed: Select one: a. compressions b. rarefactions c. transmissions d. reflections
a. compressions
Which of the following is the part of the transducer that stops the ringing of the element? a. damping material b. housing c. matching layer d. insulator
a. damping material
As imaging depth increases, the PRF must: a. decrease b. PRF does not relate to imaging depth c. increase d. not change
a. decrease
The portion of time the transducer is transmitting a pulse is termed: Select one: a. duty factor b. pulse repetition period c. pulse repetition frequency d. period
a. duty factor
Uniform intensity of the sound beam is located in the : Select one: a. far field b. focal point c. center of the beam d. near field
a. far field
Increasing the transducer frequency will: a. increase the amount of attenuation b. decrease contrast resolution c. decrease the sensitivity to Doppler shifts d. increase the penetration depth
a. increase the amount of attenuation
Which of the following is a function of read zoom? a. magnification and display of stored data b. acquisition and magnification of new information c. frame averaging d. increase in the number of pixels per inch
a. magnification and display of stored data
Micro denotes : Select one: a. millionth b. billionth c. million d. hundredth
a. millionth
Which of the following correctly defines acoustic frequency? Select one: a. number of cycles in a second b. length of one cycle c. number of pulses in a cycle d. strength of a compression wave
a. number of cycles in a second
The thickness of the matching layer is equal to: a. one quarter of the wavelength b. the wavelength c. twice the wavelength d. one half of the wavelength
a. one quarter of the wavelength
Axial resolution directly relates to the: a. operating frequency b. spatial pulse length c. temporal resolution d. transducer diameter
a. operating frequency
Which of the following is defined as changing the timing of the shocking of the elements in order to shape and steer the beam? a. phasing b. focusing c. angulation d. bundling
a. phasing
Line density is directly related to the: a. pulse repetition frequency b. imaging depth c. temporal resolution d. pulse repetition period
a. pulse repetition frequency
What is the purpose of the dampening material in the transducer assembly? a. reduction in pulse duration b. improvement in sound transmission into the body c. diminishment of reflections at the transducer surface d. increase in sensitivity
a. reduction in pulse duration
When coursing from a medium of lower propagation speed to a medium of higher propagation speed, the frequency of the sound wave will: a. remain constant b. double c. increase d. decrease
a. remain constant
What component is not present in A-mode but is necessary for B-mode imaging? a. scan converters b. display c. amplifier d. clock
a. scan converters
Which of the following is a method for overcoming aliasing? a. shift the baseline b. increasing image depth c. decrease the Doppler angle d. increase the operating frequency
a. shift the baseline
The number of cycles in a pulse directly relates to the: a. spatial pulse length b. duty factor c. operating frequency d. pulse repetition frequency
a. spatial pulse length
In B-mode imaging, the stronger the return echo, Select one: a. the brighter the dot on the display b. the weaker the transmit power c. the darker the dot on the display d. the worse the temporal resolution
a. the brighter the dot on the display
Clutter can be reduced using which of the following controls? a. wall filter b. dynamic range c. smoothing d. pulse repetition frequency
a. wall filter
Approximately what percentage of the sound beam will reflect from a media boundary with perpendicular incidence, if the impedances are different? a. 50% b. 1% c. 10% d. 99%
b. 1%
Divergence of the sound beam is demonstrated in the: Select one: a. Fresnel zone b. Fraunhofer zone c. focal zone d. dead zone
b. Fraunhofer zone
Which of the following is not associated with laminar flow? Select one: a. aligned b. chaotic c. normal d. layered
b. chaotic
Decibel is the unit of measurement for: a. intensity b. compression c. pressure d. amplitude
b. compression
A disadvantage of duplex imaging is a: a. inability to display peak velocities b. decrease in imaging frame rate c. decrease in maximum penetration depth d. inability to display flow direction
b. decrease in imaging frame rate
In a time-gain compensation curve, the delay represents: a. area of maximum amplification b. depth at which variable compensation begins c. available region for depth compensation d. area of minimum amplification
b. depth at which variable compensation begins
The percentage of time that the ultrasound system is producing pulses of ultrasound describes the: a. pulse duration b. duty factor c. PRF d. PRP
b. duty factor
Which of the following would be considered the narrowest part of a sound beam? a. near zone b. focus c. far zone d. near zone length
b. focus
Holding a single image of sonographic information for display is termed a: a. pixel b. freeze frame c. scan line d. cine loop
b. freeze frame
The objective of the matching layer in the assembly of an ultrasound transducer is to reduce the: a. pulse duration b. impedance difference between the element and the skin c. spatial pulse length d. number of cycles in each pulse
b. impedance difference between the element and the skin
The sonographer can improve lateral resolution by: a. increasing the frame rate b. increasing the number of focal zones c. increasing the image depth d. decreasing the spatial pulse length
b. increasing the number of focal zones
Which of the following is most likely to improve axial resolution? Select one: a. increasing the frame rate b. increasing the transducer frequency c. decreasing the angle of incidence d. decreasing the beam width
b. increasing the transducer frequency
The harmonic signal ..... Select one: a. is produced by the transducer b. is produced by the patient c. is of a stronger amplitude than the fundamental signal d. has worse lateral resolution than the fundamental signal
b. is produced by the patient
Which of the following is true of the diameter of the sound beam in the Fresnel zone? a. it is unpredictable b. it decreases c. it does not change d. it increases
b. it decreases
If red blood cells are traveling toward a transducer, the frequency emitted by the transducer is _____the frequency reflected from the red blood cells Select one: a. equal to b. less than c. greater than d. same as
b. less than
The mechanical index is inversely proportional to the: a. acoustic pressure b. operating frequency c. beam width d. acoustic output
b. operating frequency
Operating frequency is determined by the: a. thickness of the crystal b. propagation speed and thickness of the element c. frequency of the active element d. diameter of the crystal
b. propagation speed and thickness of the element
The duty factor in pulse ultrasound is proportional to the: Select one: a. operating frequency b. pulse duration c. pulse repetition period d. penetration depth
b. pulse duration
Which of the following determines the number of scan lines per frame? Select one: a. temporal resolution b. pulse repetition frequency c. contrast resolution d. operating frequency
b. pulse repetition frequency
The greater the impedance difference between two structures , the greater the: a. transmission b. reflection c. attenuation d. refraction
b. reflection
Artifacts consisting of parallel equally spaced lines are characteristic of : a. grating lobes b. reverberation c. multipath d. range ambiguity
b. reverberation
Which imaging technique is most likely to visualize structures beneath a highly attenuating structure? Select one: a. pixel interpolation b. spatial compounding c. harmonic frequencies d. pulse inversion
b. spatial compounding
Heat sterilization of ultrasound transducers is not recommended , because: a. transducers stability decreases b. the piezoelectric properties will be lost c. heat will damage the electric cables d. transducer assembly cannot withstand the temperature
b. the piezoelectric properties will be lost
What pulse wave transducer displays a trapezoidal image? a. endocavity b. vector c. convex d. linear
b. vector
Reducing a 30 dB compensation gain by one half would display a new gain setting of: Select one: a. 15 dB b. 10 dB c. 27 dB d. 24 dB
c. 27 dB
Which of the following are even harmonic frequencies of a 2 MHz transducer? Select one: a. 4, 6, 8 b. 2, 4, 6 c. 4 ,8 ,12 d. 3, 5, 7
c. 4 ,8 ,12
What is the minimum number of memory bits necessary to display 128 shades of gray? Select one: a. 10 b. 2 c. 7 d. 5
c. 7
The unit of impedance is the: Select one: a. watt/cm b. Joule c. Rayl d. Newton
c. Rayl
Reduction in the intensity of the sound wave is a result of: a. scattering, refraction and absorption b. absorption, scattering and refraction c. absorption, scattering and reflection d. heat, reflection and transmission
c. absorption, scattering and reflection
Varying the excitation voltage to each element in the array forming the ultrasound pulse is termed: a. spatial compounding b. dynamic focus c. apodization d. subdicing
c. apodization
Firing delays found in array systems are determined by the: a. transducer b. reciever c. beam former d. master synchronizer
c. beam former
Depth gain compensation is necessary to: a. decrease contrast resolution b. increase axial resolution c. counteract attenuation d. store echo amplitudes and locations
c. counteract attenuation
At a stenosis, pressure will: Select one: a. remain unchanged b. double c. decrease d. increase
c. decrease
Which of the following uses a variable recieving focus? Select one: a. subdicing b. dynamic aperature c. dynamic focusing d. apodization
c. dynamic focusing
Which of the following is the resolution in the third dimension of the beam? a. lateral resolution b. contrast resolution c. elevational resolution d. longitudinal resolution
c. elevational resolution
Wavelength depends on what two factors? a. period and frequency b. frequency and amplitude c. frequency and propagation speed d. amplitude and intensity
c. frequency and propagation speed
Which adjustable system control affects the frame rate? a. compensation b. transmit power c. image depth d. compression
c. image depth
All of the following are true of wavelength except: Select one: a. it is inversely related to frequency b. it is directly related to period c. it is equal to the period divided by the frequency d. it is determined by both the medium and the sound source
c. it is equal to the period divided by the frequency
Which of the following would have the lowest propagation speed? a. bone b. water c. lung tissue d. soft tissue
c. lung tissue
What type of blood flow demonstrates a constant speed across the vessel? Select one: a. turbulent b. pulsatile c. plug d. parabolic
c. plug
Which of the following instruments generates the pulse of sound? a. beam former b. transducer c. pulser d. master synchronizer
c. pulser
Which part of the US machine does not affect the amount of energy entering the patient? a. transmitter b. beam former c. receiver d. pulser
c. receiver
Image quality is improved by: a. decreasing the output b. increasing the beam width c. shortening the pulse length d. decreasing the frame rate
c. shortening the pulse length
The ability of a sonogram to identify the true absence of disease is a test's : a. positive predictive value b. accuracy c. specificity d. sensitivity
c. specificity
The speed at which a wave travels through a medium is determined by the: a. resistance and impedance of the medium b. amplitude and intensity of the sound beam c. stiffness and density of the medium d. distance of the sound source
c. stiffness and density of the medium
When voltage is applied to the piezoelectric crystal, the crystal will: a. increase in size b. decrease in size c. vibrate d. increase or decrease according to the polarity
c. vibrate
Which Doppler angle yields the greatest Doppler shift? a. 10 degrees b. 60 degrees c. 45 degrees d. 0 degrees
d. 0 degrees
Which of the following transducers will produce a longer focal length if the crystal diameter remains constant? Select one: a. 5 MHz focused transducer b. 10 MHz focused transducer c. 5 MHz unfocused transducer d. 10 MHz unfocused transducer
d. 10 MHz unfocused transducer
Blood moving at a velocity of 2 m/s creates a Doppler frequency of 3000 Hz. What will the Doppler shift be if the velocity increases to 4 m/s? Select one: a. 3000 Hz b. 1500 Hz c. 2 Hz d. 6000 Hz
d. 6000 Hz
Which of the following is equal to one half of the pulse repetition frequency? a. Reynolds number b. attenuation coefficient c. pulsitility index d. Nyquist limit
d. Nyquist limit
Frequency is proportional to: a. penetration depth b. wavelength c. period d. attenuation
d. attenuation
Which of the following types of resolution does the wavelength have the greatest effect on? Select one: a. contrast b. temporal c. lateral d. axial
d. axial
Which color always represents the baseline in color Doppler imaging? a. red b. blue c. yellow d. black
d. black
Which of the following would have the highest propagation speed? Select one: a. soft tissue b. air c. water d. bone
d. bone
Equal intensity for all similar structures regardless of the depth is a function of: Select one: a. rectification b. amplification c. suppression d. compensation
d. compensation
A large packet size in color-flow imaging will: a. increase the volume flow rate b. increase the frame rate c. decrease the Doppler sensitivity d. decrease the temporal resolution
d. decrease the temporal resolution
Which of the following would cause an increase in frame rate? Select one: a. increased line density b. increased imaging depth c. multifocusing d. decreased imaging depth
d. decreased imaging depth
As the transducer diameter increases, the: a. thickness of the element decreases b. intensity in the focal zone increases c. near zone length decreases d. divergence in the far field decreases
d. divergence in the far field decreases
The ratio of the largest power to the smallest power the ultrasound system can handle describes: Select one: a. compensation b. contrast resolution c. bandwidth d. dynamic range
d. dynamic range
A linear phased array sweeps the ultrasound beam : a. mechanically, by sequential activation of crystals in the array b. electronically, by sequential activation of the crystals in the array c. electronically, by sequential rotation of the crystals in the array d. electronically, by delayed activation of crystals in the array
d. electronically, by delayed activation of crystals in the array
Temporal resolution relates to which of the following? Select one: a. element diameter b. lateral resolution c. range ambiguity d. frame rate
d. frame rate
Transmission of the sound wave from one medium to the next is determined by the media's: a. propagation speed b. density c. stiffness d. impedance
d. impedance
Focusing of the sound beam: Select one: a. creates a spacious sound beam over a specified area b. increases specular reflection c. decreases beam intensity d. improves lateral resolution
d. improves lateral resolution
How would the sonographer improve this image using only one operator control? Select one: a. increase the transducer frequency b. decrease imaging depth c. decrease the number of focal zones d. increase the TGC in the far field
d. increase the TGC in the far field
The purpose of gel in diagnostic imaging is: a. decrease transducer's sensitivity b. make the patient's skin softer c. decrease the efficiency of sound transfer between the transducer's PZT and the patient's skin d. increase the efficiency of sound transfer between the transducer's PZT and the patient's skin
d. increase the efficiency of sound transfer between the transducer's PZT and the patient's skin
What does heat sterilization do to an ultrasound transducer? a. kills all the bacteria and viruses b. gives it better axial resolution c. improves lateral resolution of the transducer d. kills pathogens and destroys the transducer
d. kills pathogens and destroys the transducer
The Fresnel zone is another name for: Select one: a. dead zone b. far zone c. focal zone d. near zone
d. near zone
How wide are the elements of a linear-phased array transducer? Select one: a. one tenth wavelength b. one wavelength c. one half wavelength d. one quarter wavelength
d. one quarter wavelength
Averaging the frame rate is operator adjustable using which of the following functions? a. contrast variation b. read zoom c. dynamic range d. persistence
d. persistence
Placement of an echo is determined by the reflector's round trip time and.... a. density b. amplitude c. stiffness d. propagation speed
d. propagation speed
Which of the following is a technique most likely used in harmonic imaging? Select one: a. pixel interpolation b. spatial compounding c. apodization d. pulse inversion
d. pulse inversion
If the amplitude of a wave doubles, the intensity will: a. double b. decrease by one tenth c. decrease by one half d. quadruple
d. quadruple
Which of the following will most likely occur if the pulse repetition frequency is set too high? Select one: a. acoustic speckle b. flash c. aliasing d. range ambiguity
d. range ambiguity
Rayleigh scattering is most likely to occur when encountering the: a. pleura b. liver c. diaphragm d. red blood cells (RBC)
d. red blood cells (RBC)
Which instrument properly locates each series of reflectors in individual scan lines for storage? a. Fast Fourier transfer b. random access memory c. autocorrelation d. scan converter
d. scan converter
Contrast agents improve visualization by increasing: Select one: a. refraction b. reverberation c. reflection d. scatter
d. scatter
Grating lobes are caused by: a. reverberation artifact b. interference phenomenon c. dynamic focusing d. spacing of the array elements
d. spacing of the array elements
Specular reflections occur when the sound wave: a. encounters a small reflector b. encounters a strong reflector c. strikes a rough surface d. strikes a smooth, large reflector
d. strikes a smooth, large reflector
Mirror imaging artifact is a result of a : a. impedance difference b. weak reflector c. strong attenuating structure d. strong reflector
d. strong reflector
The amplitude of the transmitted and received signals is the responsibility of the: Select one: a. transducer b. amplifier c. pulser d. system output
d. system output
The Reynolds number predicts the onset of : a. biological effects b. a Doppler shift c. aliasing d. turbulent flow
d. turbulent flow
The Doppler shift frequency is proportional to the: Select one: a. cosine values b. operating frequency c. Doppler angle d. velocity of the reflector
d. velocity of the reflector
Proximal to, at, and distal to a stenosis , which of the following must remain constant? a. pressure b. velocity c. resistance d. volumetric flow rate
d. volumetric flow rate
In the Fraunhofer zone, the beam Select one: a. intensity is greatest b. intensity is inconsistent c. is conical in shape d. width diverges
d. width diverges
