Ultrasound Physics
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Ultrasound Physics Questions
- 1.
- 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.
- 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
- D.
Quadrupled
- 11.
- A.
105
- B.
50
- C.
25
- D.
55
- 12.
- A.
Quadrupled
- 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.
- A.
10.0
- B.
1%
- C.
1.0
- D.
0.0%
- 15.What is the minimum value of the SP/SA factor?
- A.
10.0
- B.
1%
- C.
1.0
- 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.
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.
- 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.
- 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.
- 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
- B.
Receiver
- 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
- C.
Shadows
- 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
- A.
Adjust the gain
- B.
Increase output power
- C.
Increase lateral resolution
- D.
Adjust the TGC
- 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?
- A.
Quadruple it
- 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.
- 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.
- 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.
- 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.
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.
- 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
- D.
Receiver
- 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?
- A.
Receiver
- B.
Display
- C.
Hydrometer
- D.
Hydrophone
- 134.Which type of artifact appears most commonly with highly reflective objects?
- A.
Reverberations
- B.
Mirroring
- C.
Shadowing
- 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.
- 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
- B.
Check the scan head
- C.
Check the scan converter
- D.
Adjust the recorder
- 146.Shadowing may result from high amounts of reflection of US energy.
- A.
True
- B.
False
- 147.Where are harmonics created?
- A.
In the receiver
- 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.
10.0
- B.
1%
- C.
1.0
- 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
- B.
Receiver
- 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 a range of frequencies
- B.
It contains sound at the nominal frequency of the transducer only
- C.
It contains sound at the center frequency of the transducer only
- D.
The shorter the pulse the narrower the bandwidth
- E.
Sound engery is continuously transmitted
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