# Ultrasound Physics

170 Questions  I  By Paga
Ultrasound Physics Questions

Changes are done, please start the quiz.

 1 Which is not an acoustic variable?
 A. Density
 B. Pressure
 C. Distance
 D. Intensity
 2 All of the following are true EXCEPT:
 A. Two waves with identical frequencies must interfere constructively
 B. Constructive interference is associated with waves that are in phase
 C. Out of phase waves interfere destructively
 D. Waves of different frequencies may exhibit both contructive and destructive interference at different times
 3 Put in decreasing order
 A. Deca
 B. Deci
 C. Micro
 D. Centi
 4 Which of the following sound waves is ultrasonic and least useful in diagnostic imaging?
 A. 30 KHZ
 B. 8 MHz
 C. 8,000 Hz
 D. 3,000 kHz
 E. 15 Hz
 5 What is the frequency of a wave with 1msec period?
 A. 10,000 Hz
 B. 1,000 kHz
 C. 1kHz
 D. 1MHz
 6 If the frequency of an US wave is doubled, what happens to the period?
 A. Doubles
 B. Halved
 C. Remains the same
 D. 4 times greater
 7 The units of pulse repetition frequency are:
 A. Per minute
 B. Msec
 C. Mm/us
 D. MHx
 8 The time from the beginning of a pulse until its end is__________?
 A. Period
 B. Pulse duration
 C. Pulse length
 D. PRF
 9 The time that a transducer is pulsing is measured at 18 seconds in one hour of total elapsed time.  What is the duty factor?
 A. 0.3
 B. 0.005
 C. 0.5Hz
 D. 0.005msec
 10 If a wave's amplitude is doubled, what happens to the power?
 A. Nothing
 B. Halved
 C. Dpib;ed
 11 If the level of an acoustic variable ranges from 55 to 105, what is the amplitude?
 A. 105
 B. 50
 C. 25
 D. 55
 12 If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what happened to the power?
 B. Doubled
 C. Halved
 D. Unchanged
 13 Put these intensities in decreasing order
 A. SATP
 B. SPTP
 C. SATA
 D. SPTP, SATP, SATA
 E. SPTP SATA, SATP
 14 The duty factor for continuous wave ultrasound is
 A. 10
 B. 1%
 C. 1
 D. 0.0%
 15 What is the minimum value of the SP/SA factor?
 A. 10
 B. 1%
 C. 1
 D. 0.0%
 16 Which pair of intensities has the same value for continuous wave US?
 A. Spatial peak & spatial average
 B. Temporal peak & spatial peak
 C. Pulse average & temporal average
 D. Spatial average & temporal average
 17 The fundamental frequency of a transcucer is 2.5 MHz.  What is the second harmonic frequency?
 A. 1.25 MHz
 B. 4.5 MHz
 C. 4.8 MHz
 D. 5 cm
 18 A pulse is emitted by a transducer and is traveling in soft tissue.  The go-return time, or time of flight, of a sound pulse is 130 microseconds.  What is the reflector depth?
 A. 10 cm
 B. 10 mm
 C. 10 m
 D. 130 mm
 E. 13 cm
 19 What is the approximate attenuation coefficient of 1MHz US in soft tissue?
 A. 0.5 dBcm
 B. 1cm
 C. 3dBcm
 D. 1dB
 20 The relaive output of an US instrument is calibrated in dB and the operator increases the output by 60 dB.  The beam intensity is increased by which of the following?
 A. 5%
 B. Two times
 C. Twenty times
 D. One hundred times
 E. One million times
 21 The more pixels per inch:
 A. The better the temporal resolution
 B. The better is the spatial resolution
 C. The more shades of gray
 D. The higher the reliability
 22 If we increase the transducer diameter, the beam diameter in the far zone is:
 A. Increased
 B. Decreased
 C. Unchanges
 23 If the transducer diameter increases, the lateral resolution at its smallest dimension is
 A. Increased
 B. Decreased
 C. Unchanged
 24 If we increase the frequency the near zone length is
 A. Increased
 B. Decreased
 C. Unchanged
 25 If the frequency is decreased, the numerical value of the radial resolution is
 A. Increased
 B. Decreased
 C. Unchanged
 26 If the spatial pulse length is 10 mm, what is the axial resolution?
 A. 0.5 cm
 B. 5 cm
 C. 10 mm
 D. 1 cm
 27 Which of the following is the best lateral resolution?
 A. 15 mm
 B. 6 mm
 C. 0.06 cm
 D. 2 cm
 28 What is the meaning of thermal index = 37
 A. A tissue temperature may rise 3 degrees Farenheit
 B. Tissue temperature will rise 3 degrees Celcius
 C. Tissue temperature may rise 3 degrees Celcius
 D. Microbubbles 3mm in diameter will burst
 29 The interaction of microscopic bubbles and ultrasound form the basis for cavitation bioeffects.  Which of the following forms of cavitation are most likely to produce microstreaming in the intracellular fluid and shear stresses?
 A. Stable cavitation
 B. Normal cavitation
 C. Transient cavitation
 D. Inertial cavitation
 E. Active cavitation
 30 Which of the following has the greatest output intensity
 A. B-Mode
 B. Gray scale imaging
 C. CW Doppler
 D. Pulsed Doppler
 31 Which of the following best decribes the empirical approach to the study of bioeffects?
 A. Exposure-response
 B. Cause-effect
 C. Risk-benefit
 D. Causation-reaction
 E. Effect-microstreaming
 32 Which of the following best describes the mechanistic approach to the study of bioeffects?
 A. Cause-effect
 B. Exposure-response
 C. Risk-benefit
 D. Causation-reaction
 E. Effect-microstreaming
 33 The propagation speed of US in the AIUM test object is?
 A. 1m/s
 B. 1.54 m/s
 C. 1.54 mm/us
 D. 1 km/s
 34 Enhancement, multipath and side lobes result in:
 A. Image distortion
 B. Clearer images
 C. Artifact
 D. Resolution problems
 35 A mirror image artifact can appear along side of the true anatomy.
 A. True
 B. False
 36 If the lines per frame is increased while the imaging depth is unchanged then:
 A. Frame rate increases
 B. Number of shades of gray decreases
 C. The frame rate decreases
 D. This cannot happen
 37 The more pixels per inch:
 A. The better the temporal resolution
 B. The better the spatial resolution
 C. The more shades of gray
 D. The higher the reliability
 38 If we increase the transducer diameter, the beam diameter in the far zone is
 A. Increased
 B. Decreased
 C. Unchanges
 39 If the transducer diameter increases, the lateral resolution at its smalles dimension is
 A. Increased
 B. Decreased
 C. Unchanged
 40 If we increase the frequency the near zone length is
 A. Increased
 B. Decreased
 C. Unchanges
 41 If the frequency is decreased, the numberical value of the radial resolution is
 A. Increased
 B. Decreased
 C. Unchanges
 42 If the spatial pulse length is 10mm, what is the axial resolution?
 A. 0.5 cm
 B. 5 cm
 C. 10 mm
 D. 1 cm
 43 Which of the following is the best lateral resolution?
 A. 15 mm
 B. 6 mm
 C. 0.06 cm
 D. 2 cm
 44 What are the units of longitudinal resolution?
 A. Hertz
 B. Rayls
 C. M/s
 D. Feet
 45 The range equation relates distant from the reflector to __________ and __________.
 A. Time-of-flight, distance
 B. Frequency, wavelength
 C. Time of flight, propagation speed
 D. Propagation speed, density
 46 Doppler shifts always occur if the source and observer are in motion relative to each other and the angle between the motion and the sound beam is not 90 degrees.
 A. True
 B. False
 47 What is the most typical Doppler shift measured clinically?
 A. 3.5 MHz
 B. 3,500,000 Hz
 C. 2 kHz
 D. 1,000 kHz
 E. 20,000 Hz
 48 Assuming a constant frequency, what happens if the diameter of an unfocused circular transducer is increased?
 A. The distance to the far field is reduced
 B. The beam width is the near field is reduced
 C. The beam width in the near field is increased
 D. The US wavelength is increased
 E. The sensitivity is reduced
 49 Which one of the following sets of properties of a test phantom is most relevant when assessing depth calibration accuracy?
 A. Reflector spacing and reflection coefficient
 B. Attenuation and speed of the US in the medium
 C. Reflector spacing and US attenuation in the medium
 D. Reflector reflection coefficient and US attenuation in the medium
 E. Reflector spacing and propagation speed
 50 Doppler shifts are always created when the source and receiver are in motion relative to each other.
 A. True
 B. False
 51 Fill in of an anechoic structure such as a cyst is known as all of the following EXCEPT?
 A. Partial volume artifact
 B. Slice thickness artifact
 C. Section thickness artifact
 D. Ghosting artifact
 52 According to the AIUM statement on bioeffects, there have been no concirmed bioeffects below intensities of _________ watts per square centimeter SPTA.
 A. 10
 B. 0.01
 C. 0.1
 D. 1
 E. 100
 53 What component of the US unit contains the memory bank?
 A. Transducer
 C. Display
 D. Scan converter
 54 Changing which of the following would not cause any change in a hard copy image output?
 A. TGC
 B. Overall gain
 C. Output power
 D. Display brightness & contrast
 E. Depth of view
 55 What are typical clinical Doppler frequencies?
 A. 1 - 10, 000 Hz
 B. 1 - 10 MHz
 C. 2 - 1,000 kHz
 D. 40 - 45 kHz
 56 If 3 MHz sound has 2DB of attenuation in 1cm of tissue, what is the amount of attenuation of 6MHz sound in 0.5cm of the same tissue
 A. 5dB
 B. 2dB
 C. 10dB
 D. 1.5dB
 57 The distance to a target is doubled.  The time of flight for a pulse to travel to the target and back is
 A. 4 times
 B. 8 times
 C. The samce
 D. 2 times
 58 The gray scale can be changed by the sonographer
 A. True
 B. Fales
 59 How many bits are needed to represent 14 shades of gray?
 A. 14
 B. 1
 C. 4
 D. 3
 E. 8
 60 The manufacturer increases the number of lines per frame.  As a result, which of the following may have to decreased.  Frequency
 A. True
 B. False
 61 The manufacturer increases the number of lines per frame.  As a result, which of the following may have to decreased. FRAME RATE (TRUE OR FALSE)
 A. True
 B. False
 62 The manufacturer increases the number of lines per frame.  As a result, which of the following may have to decreased.  (Sector Angle)
 A. True
 B. False
 63 The manufacturer increases the number of lines per frame.  As a result, which of the following may have to decreased. (IMAGING DEPTH)
 A. True
 B. False
 64 The manufacturer increases the number of lines per frame.  As a result, which of the following may have to decreased. Power Output
 A. True
 B. False
 65 All of the following will improve temporal resolution EXCEPT:
 A. Increase line density
 B. Single rather than multi focus
 C. Higher frame rate
 D. Shallower depth of view
 E. Slower speed in a medium
 66 What artifact has a grainy appearance and is caused by the interference effects of scattered sound?
 A. Spackle
 B. Reverberation
 C. Slice tickness
 D. Speckle
 E. Section thickness
 67 Multiple reflections that are equally spaced are called:
 A. Refractions
 B. Reverberations
 D. Comets
 68 Axial resolution is affected by focusing.
 A. True
 B. False
 69 Which of the following choces determines the signal amplitude in the transducers of an ultrasound system?
 A. Reflected intensity of the sound beam
 B. Post processing
 C. Edge enhancement filtering
 D. Persistence
 E. Demodulation
 70 The angle between an US pulse and the boundary between two media is 90 degrees.  What is this called?
 A. Direct incidence
 B. Oblique incidence
 C. Indirect incidence
 D. Orthogonal incidence
 71 Refraction only occurs if there is :
 A. Normal incidence and differenct impedances
 B. Indirect intensity and differenct propagation speeds
 C. Oblique incidence and different propagation speeds
 D. Oblique frequency and identical impedances
 72 The most likely amount of reflection at a boundary between soft tissue is:
 A. 1 %
 B. 22 %
 C. 33%
 D. 99%
 73 Sound is traveling from medium 1 to medium 2.  Propagation speeds of M1 and M2 are 1600m/s and 1500m/s respectively.  There is oblique incidence.
 A. Angle of incidence > angle of reflection
 B. Angle of incidence = angle of reflection
 C. Angle of incidence < angle of reflection
 74 Depth calibration of a machine measures 100 mm spaced wires to be 90 mm apart.  Scanning reflectors 50 mm apart, what will the machine calculate the distance to be?
 A. 40 mm
 B. 45 mm
 C. 60 mm
 D. 65 mm
 75 In an analog scan converter, what component stores the image data?
 A. Computer memory
 B. Video tape recorder
 C. Dielectric matrix
 D. None of the above
 76 When the US machine displays only strong reflecting objects and nothing else, the sonographer should
 B. Increase output power
 C. Increase lateral resolution
 77 If a reflector is moved twice as far away from the tranducer, how will this affect the time of flight of a sound pulse?
 B. Double it
 C. No change
 D. Halve it
 78 You are performing a quality assurance study on an ultrasound system using a tissue equivalent phantom.  You make an adjustment using a knob on the system console that changes the appearance of reflector brightness from fully bright to barely visible.  What are you evaluating?
 A. Resolution
 B. Dynamic range
 C. System sensitivity
 D. Vertical calibration
 E. Slice thickness
 79 At what location in a sound beam is the SPTA intensity the highest?
 A. Focal point
 B. Focal zone
 C. Fresnel zone
 D. Fraunhofer zone
 E. Half value depth
 80 What determines the frequency of a sound beam from a pulsed transducer?
 A. Voltage applied to the PZT
 B. PZT thickness
 C. Frequency of the system
 D. PRF of the pulser
 81 The impredance of tissue is 3 x 10^5 rayls and for the PZT crystal is 6 x 10 ^6 rayls.  What is the best impedance for the matching layer?
 A. 36 X 10 ^6
 B. 3,600
 C. 10,000
 D. 9.5 x 10^5
 E. 9 x 10 ^4
 82 What can pulsed Doppler measure that continuous wave cannot?
 A. Duration
 B. Speed
 C. Velocity
 D. Location
 E. Frequency
 83 What is the fraction of time that sound is transmitting?
 A. Duty factor
 B. Pulse duration
 C. Period
 D. PRF spatial duration
 84 If the SPTA of the following were equal, which would have the lowest SPPA?
 A. Doppler
 B. Annular array real time
 C. Static B-scan
 D. Linear arry
 E. Continuous wave
 85 The dB is defined as the _______________ of two intensities
 A. Sum
 B. Difference
 C. Product
 D. Ratio
 86 If the power of a sound wave is increased by a factor of 8 how many decibles is this?
 A. 3 dB
 B. 6 dB
 C. 9 dB
 D. 8 dB
 87 An ultrasound system is set at 0 dB and is transmitting at full intensity.  What is the output power when the system is transmitting at 50% of full intensity?
 A. -3dB
 B. -50 dB
 C. 10 dB
 D. 3 dB
 E. -10 dB
 88 An ultrasound system is set at 0 dB and is tranmitting at full intensity. What is the output power when the system is transmitting at 10% of full intensity?
 A. - 3dB
 B. -50 dB
 C. 40 dB
 D. 3 dB
 E. -10 dB
 89 What may be a unit of amplitude?
 A. Cm
 B. Hz
 C. Msec
 D. Watts
 E. None of the above
 90 A Doppler exam is performed with a 5MHz probe and a PRF of 15kHz.  Which of these Doppler shifts will create aliasing?
 A. 2 kHz
 B. 2.5 kHz
 C. 7.5 kHz
 D. 14 kHz
 91 According to the AIUM statement on bioeffects, there have been no confirmed bioeffects below intensities of __________ watts per square centimeter SPTA.
 A. 10
 B. 0.01
 C. 0.1
 D. 1
 E. 100
 92 Which of the following is not a measure of area?
 A. Square cm
 B. Meters squared
 C. Cubic meters
 D. Feet x feet
 93 Which of the following is true of all waves?
 A. They travel through a medium
 B. All carry energy from one side to another
 C. Their amplitudes do not change
 D. They travel in a straight line
 94 Is Intensity an acoustic variable?
 A. True
 B. False
 95 A force is applied to a surface.  If the force is tripled and the surface area over which the force is applied is also tripled, what is the new pressure?
 A. Three times larger than the original
 B. One third of the original
 C. Six times more than the original
 D. Unchanged
 96 Which of the following units are appropriate to describe the period of an acoustic wave?  More than one answer maybe correct.
 A. Minutes
 B. Microseconds
 C. Meters
 D. Mm/us
 97 Two waves arrive at the same location and interfere.  The resultant sound wave is smaller that either of the two original waves.  What is this called?
 A. Constructive interference
 B. Angular interaction
 C. Destructive interference
 D. In-phase waves
 98 Ultrasound is defined as a sound with a frequency of
 A. Greater thatn 20,000 kHz
 B. Less thatn 1 kHz
 C. Greater than 10 MHz
 D. Greater thatn 0.02 MHz
 99 Compare two sound waves. A and B.  The frequency of a wave A is one-third that of wave B.  How does the period of a wave A compare the period of wave B?
 A. A is one-third as long a B
 B. A is the same as wave B
 C. A is three times as long as B
 D. Cannot be determined
 100 Which of the following wave is ultrasonic and least useful in diagnotic ultrasound?
 A. 2 MHz
 B. 2000 Hz
 C. 24 kHz
 D. 7.5 MHz
 101 True of False:  With standard diagnostic imaging instrumentation, the sonographer has the ability to vary the amplitude of a sound wave produced by the transducer.
 A. Ture
 B. False
 102 The power of an ultrasound wave can be reported with which of the following units? More than one answer maybe correct.
 A. Watts/square centimeter
 B. DB/Cm
 C. Watts
 D. Kg/cm^2
 103 The maximum value of the density of an acoustic wave is 60 lb/in^2 while the minimum density is 20 lb/in^2.  What is the amplitude of the wave?
 A. 20 lb/in^2
 B. 40 lb/in^2
 C. 60 lb/in^2
 D. None of the above
 104 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
 105 The amplitude of an acoustic wave decreases from 27 pascals to 9 pascals.  If the initial power in the wave was 27 watts, what is the wave final power?
 A. 3 watts
 B. 9 watts
 C. 1 watt
 D. None of the above
 106 What are the units of intensity?
 A. Watts
 B. Watts/cm
 C. Watts/cm^2
 D. DB
 107 If the power in an ultrasound beam is unchanged, while at the same time, the beam area doubles, then the beams's intensity
 A. Doubles
 B. Is halved
 C. Is quartered
 D. Remains the same
 108 What happens to an acoustic beams's intensity when the power in the beam increases by 25% while the cross sectional area of the beam remain the same?
 A. It increased by 25%
 B. Increases by 75%
 C. It increases by 50%
 D. Decreases by 25%
 109 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 time larger
 110 What determines the intensity of an ultrasound beam after it has traveled through the body?
 A. The sound wave's source
 B. The medium throught which the sound travels
 C. Both A and B
 D. Neither choice A nor B
 111 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 ninefold
 C. Remains the same
 D. None of the above
 112 The wavelength of a cycle in an ultrasound wave can be reported with which units?
 A. Units of time (seco, min, etc)
 B. Units of distance (feet, cm)
 C. Units of area (m^2, etc
 D. Mm only
 113 Which of the following terms best describes the relationship between frequency and wavelength for sound traveling in soft tissue?
 A. Receiprocal
 B. Direct
 C. Related
 D. Inverse
 114 (TRUE OR FALSE) The power in the wave increases as it travels through the mass. (An ultrasound pulse propagates from soft tissue through a mass.  Sound's propagation speed in the mass is 1575 m/s.)
 A. True
 B. False
 115 The frequency closest to the lower limits of US is:
 A. 19,000kHz
 B. 10,000 MHz
 C. 20,000 msec
 D. 15,000 Hz
 116 Which of the following sound waves is ultrasonic and least useful in diagnostic imaging?
 A. 30 KHz
 B. 8 MHz
 C. 8,000 Hz
 D. 3,000 kHz
 E. 15 Hz
 117 _____________ is the distance covered by one cycle
 A. Pulse length
 B. Wavelength
 C. Cycle distance
 D. Cycle duration
 118 If the frequency of US is increased from 0.77 MHz to 1.54 MHz, what happens to the wavelength?
 A. Doubles
 B. Halved
 C. Remains the same
 D. 4 times greater
 119 If the frequency is decreased, the numberical value of the radial resolution is
 A. Increased
 B. Decreased
 C. Unchanged
 120 If we increase the frequency, the near zone length is
 A. Increased
 B. Decreased
 C. Unchanged
 121 The digital scan converter has a number of pixels assigned to each bit.
 A. True
 B. False
 122 The more bits per pixel
 A. The better the resolution
 B. The higher the pizel density
 C. The more shades of gray
 D. Higer reliability
 123 What is the actual time that an US machine is creating a pulse?
 A. Duty factor
 B. Period
 C. Pulse period
 D. Pulse duration
 124 The angle of incidence of an US beam is perpendicular to an interface.  The two media have the same propagation speeds.  What process cannot occur?
 A. Refraction
 B. Reflection
 C. Transmission
 D. Attenuation
 125 What is the most typical Doppler shift measured clinically?
 A. 3.5 MHz
 B. 3,500,000 Hz
 C. 2kHz
 D. 1,000 kHz
 E. 20,000 Hz
 126 If the frequency is decreased, the numerical value of the radial resolution is
 A. Increased
 B. Decreased
 C. Unchanges
 127 The digital scan converter has a number of pixels assigned to each bit.
 A. True
 B. False
 128 The more bits per pixel
 A. The better the resolution
 B. The higher the pixel density
 C. The more shades of gray
 D. Higher reliability
 129 Increasing the frequency increases the penetration depth.
 A. True
 B. False
 130 All of the following will improve temporal resolution EXCEPT
 A. Increased line density
 B. Single rather than multi focus
 C. Higher frame rate
 D. Shallower depth of view
 E. Slower speed of sound in a medium
 131 What componet of a transducer changes electrial to mechanical and mechanical back to electrical engery?
 A. PZT
 B. Scan converter
 C. Demodulator
 132 What determines the frequency of a sound beam from a pulsed transducer?
 A. Voltage applied to the PZT
 B. PZT thickness
 C. Frequency of the system
 D. PRF of the pulser
 133 What measures the output of the a transducer?
 B. Display
 C. Hydrometer
 D. Hydrophone
 134 Which type of artifact appears most commonly with highly reflective objects?
 A. Reverberations
 B. Mirroring
 D. Enhancement
 E. Defocusing
 135 Which of the following will result in the highest mechanical index?
 A. High frequency and low power
 B. High intensity and high frequency
 C. Low frequency and high signal amplitude
 D. Low intensity and low frequency
 136 All of the following statements reqarding in-vitro bioeffects are true EXCEPT
 A. In vitro bioeffects conclusions are clinically relevant
 B. In vitro bioeffects are always real
 C. In vitro bioeffects are very important
 D. In vitro bioeffects may not be applicable to clinical settings
 137 Which of the following is not used to measure the output of ultrasound systems?
 A. Calibrated absorpterometer
 B. Hydrophone
 C. Thermocouple
 D. Calorimeter
 E. Liquid crystals
 138 Under which circumstance is cavitation most likely to occur?
 A. High frequency and low power
 B. High intensity and high frequency
 C. Low intensity and low frequency
 D. Low frequency and high signal amplitude
 139 Post processing occurs when the image
 A. Is played off the VCT
 B. Entered the A/D converter but before display
 C. After it leaves the A/D converter
 D. After it leaves the can converter
 140 What happens to venous blood flow to the heart during expiration?
 A. Increases
 B. Decreases
 C. Unchanged
 141 Which of the following has a propagation speed closest to "soft tissue"?
 A. Muscle
 B. Fat
 C. Bone
 D. Air
 142 What is displayed on the y axis of an m-mode image?
 A. Time
 B. Time of flight
 C. Echo intensity
 D. Red blood cell velocity
 143 An amplifier of an ultrasound system increases the voltage of a signal from 0.0001 to 0.1 volt.  What is the amplification?
 A. 60 dB
 B. 30 dB
 C. 1,000 dB
 D. 90 dB
 144 Which of the following will result in the greatest number of shades of gray in a digital image display?
 A. Large pixels with many bits/pixel
 B. Small pixels with few bits/pixel
 C. Many TV lines per frame
 D. High contrast
 E. Narrow dynamic range
 145 With good images on the CRT but not on the strip chart recorder, one should
 A. Increase the gain
 C. Check the scan converter
 146 Shadowing may result from high amounts of reflection of US energy.
 A. True
 B. False
 147 Where are harmonics created?
 B. In the transducer
 C. In the tissue
 D. In the beam former
 148 How is range ambiguty artifact eliminated?
 A. Lower the PRF
 B. Raise the PRF
 C. Increase the gain
 D. Use a lower frequency transducer
 149 For Doppler, which incident angle reults in no shift?
 A. 180
 B. 90
 C. 0
 D. 45
 150 Which transducer would be best to image superficial structures?
 A. Small diameter, high frequency
 B. Small diameter, low frequency
 C. Large diameter, high frequency
 D. Large diameter, low frequency
 151 What information does Doppler shift provide?
 A. Flow
 B. Cardiac out put
 C. Velocity
 D. Speed
 152 Circumferences are usually measured in:
 A. Cm
 B. Cm squared
 C. Cubic cm
 D. Cubits
 153 Decimal uses a base of 10, binary uses a base of
 A. 1
 B. 2
 C. 5
 D. 10
 154 If the frame rate increases and the lines per frame is unchanged, what else must happen?
 A. US speed increases
 B. Frequency increases
 C. Depth increases
 D. Depth decreases
 155 How many decibels is related to 90% decrease in imaging power?
 A. -1dB
 B. -10dB
 C. -90dB
 D. -100dB
 156 If the output of an US machine is calibrated in dB and the output is increased by 20 dB, the beam intensity is increased
 A. 100 times
 B. 1,000,000 times
 C. 20 times
 D. 10 times
 157 Which has the greatest amount of attenuation?
 A. Bone
 B. Fat
 C. Water
 D. Muscle
 158 Refraction only occurs if there is :
 A. Normal incidence and different impedances
 B. Indirect intensity and differenct propagation speeds
 C. Oblique incidence and different propagation speeds
 D. Oblique frequency and identical impedances
 159 With normal incidence, what factors affect refraction of US?
 A. Propagation speeds
 B. Frequencies
 C. Attenuation coefficients
 D. None of the above
 160 Which of the following is associated with power mode Doppler?
 A. Poor temporal resolution and flash artifact
 B. Lower sensitivity and good temporal resolution
 C. High sensitivity and high frame rates
 D. Flash artifact and reduced sensitivity
 E. Good temporal resolution and flash artifact
 161 The sonographer cannot change, directly or indirectly, the duty factor of an US machines.
 A. True
 B. False
 162 There have not been biological effects from US found in the laboratory.
 A. True
 B. False
 163 As the impedances of two media become vastly different, the
 A. Reflection increases
 B. Transmission increases
 C. Refraction increases
 D. Absorption increases
 164 What is the minimum value of the duty factor?
 A. 10
 B. 1%
 C. 1
 D. 0.0%
 165 Assuming a fixed frequency, what happens if the diameter of an ultrasound circular transducer is increased?
 A. The distance to the far field is reduced
 B. The beamwidth in the near field is reduced
 C. The beamwidth in the far field is reduced
 D. The ultrasonic wavelength is increased
 E. The sensitivity is reduced
 166 From a safety standpoint, which one of the following methods is best?
 A. Low transmitter output and high receiver gain
 B. High transmitter output and low receiver gain
 C. High near gain and low far gain
 D. Low near gain and high far gain
 E. High reject and high transmitter output
 167 Which one of the following instruments is a component that stores digital echo signal information?
 A. Demodulator
 C. Video monitor
 D. Logarithmic amplifier
 E. Scan converter
 168 The dynamic range of the receiver of an ultrasound instrument refers to the
 A. Ability of the receiver to track a rapidly moving structure
 B. Range of echo signal frequencies that can be processed without distortion
 C. Speed with which the receiver recovers following the excitation pulse to the transducer
 D. Depth range in tissue over which moving echoes can be received
 E. Range of echo signal amplitudes that can be processed without distortion
 169 A sound wave leaves its source and travels through air.  The speed of sound in air is 330 m/sec.  One second later, an echo returns to the source.  At what distance from the source is the reflector that produced the echo?
 A. 1540 meters
 B. 770 meters
 C. 660 meters
 D. 330 meters
 E. 165 meters
 170 Whichone of the following statements is true about a single pulse of ultrasound from a transducer?
 A. It contains sound at the center frequency of the transducer only
 B. The shorter the pulse the narrower the bandwidth
 C. Sound engery is continuously transmitted
 D. It contains a range of frequencies
 E. It contains sound at the nominal frequency of the transducer only
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