Ch. 15-19 Physics questions Flashcards
1
Q
Which electronic component is required for gray scale imaging?
A. VCR
B. non-interlaced display
C. computer memory
D. scan converter
A
Scan converter
2
Q
Which of the following scan converters will provide the best spatial resolution?
A. 256 x 256 pixels
B. 512 x 512 pixels
C. 128 x 128 pixels
D. 1000 x 1000 pixels
A
1000 x 1000 pixels
3
Q
Which of these statements regarding a bit of computer memory is false?
A. it is the smallest element of a image
B. it is bistable
C. Eight bits combine to make a byte
D. it is a component of a digital scan converter
A
it is the smallest element of a image
4
Q
How many gray shades can be represented by a group of:
4 bits?
2 bits?
A
4 bits= 16
2 bits= 4
5
Q
What is the number of shades that can be represented by 3 bits?
A
8
6
Q
What is the number of shades that can be represented by 8 bits?
A
256
7
Q
What is the number of shades that can be represented by 10 bits?
A
1024
8
Q
What is the number of shades that can be represented by n bits?
A
2 is multiplied by itself n times. 2^n different gray shades can be stored using n bits.
9
Q
How many bits are needed to store:
10 shades of gray?
11 shades of gray?
15 shades of gray?
A
10 shades= 4 bits
11 shades= 4 bits
15 shades = 4 bits
10
Q
Which of the following statements regarding a pixel is false?
A. it is the smallest part of a digital image
B. a collection of bits, assigned to each pixel, stores the shade of gray.
C. it displays up to 3 gray shades simultaneously.
A
it displays up to 3 gray shades simultaneously.
11
Q
Are the following procedures usually pre- or postprocessing?
A. Modifying a frozen image
B. read zoom
C. write zoom
D. adjusting the brightness on the monitor
E. increasing the receiver gain
A
Modifying a frozen image= postprocessing
read zoom= postprocessing
write zoom= preprocessing
adjusting the brightness on the monitor= postprocessing
increasing the receiver gain= preprocessing
12
Q
What is the primary disadvantage of video tape and computer disc methods of image archiving?
A. these methods are very costly
B. the information is vulnerable to erasure when exposed to strong magnetic fields
C. only low resolution images are stored
D. only black and white images are stored
A
the information is vulnerable to erasure when exposed to strong magnetic fields
13
Q
Where does coded excitation take place?
A. in the transducer
B. in the receiver
C. in the pulser
D. in the PACS system
A
in the pulser
14
Q
Which of the following is not true about spatial compounding?
A. data is collected from different viewing angles
B. frame rates are reduced
C. shadowing artifact can be eliminated
D. can be performed with a mechanical transducer
A
can be performed with a mechanical transducer
15
Q
All of the following are advantages of PACS systems except:
A. data will not deteriorate over time
B. images can be delivered to distant locations on the imaging network
C. older, archived studies and reports can be reviewed easily
D. images have higher resolution than what appears on the system’s display
A
images have higher resolution than what appears on the system’s display
16
Q
What is DICOM?
A. standards for transducer design
B. standards for patient exposure
C. protocols for two- dimensional imaging
D. protocols for medical image data
A
protocols for medical image data
17
Q
What is the primary storage device on a PACS system?
A. Magneto-optical storage
B. hard disc drives
C. solid state memory
D. compact discs
A
hard disc drives
18
Q
Which of the following technologies uses long sound pulses to create an image?
A. coded excitation
B. harmonics
C. pulse inversion
D. rendering
A
coded excitation
19
Q
With frequency compounding, how many pulses are transmitted down each scan line?
A. 1
B. 2
C. 4
D. cannot be determined
A
1
20
Q
Which of the following techniques is used to create image data where non really exists?
A. edge enhancement
B. temporal compounding
C. fill in interpolation
D. spatial compounding
A
fill in interpolation
21
Q
In modern elastography, how are the tissues deformed?
A. by pressing the transducer into the skin
B. with the use of a second probe
C. automatically
D. As a result of respiration
A
automatically
22
Q
An uncompressed signal within the receiver of an ultrasound system has a dynamic range of 110dB. The signal undergoes 40dB of compression. What is the dynamic range of the compressed signal?
A
110dB - 40dB = 70dB
23
Q
An uncompressed signal has a dynamic range of 85dB. The signal undergoes 30dB of compression. What is the dynamic range of the compressed signal?
A
85dB - 30dB = 55dB
24
Q
After compression, a signal within the ultrasound system has a dynamic range of 70dB. The original signal was compressed by 40dB. What is the dynamic range of the original, uncompressed signal?
A
70dB - 40dB = 110dB
25
A signal within a system’s receiver has a dynamic range of 60dB after compression. The original signal was compressed by 50dB. What is the dynamic range of the original, uncompressed signal?
60dB - 50dB = 110dB
26
Sound with frequency of 4MHz is created by a transducer. What is the fundamental frequency?
A. 4 MHz
B. 8Mhz
C. 2MHz
D. cannot be determined with the information provided
4 MHz
27
Sound with a frequency of 4MHz is created by a transducer. What is the harmonic frequency?
A. 4 MHz
B. 8MHz
C. 2MHz
D. cannot be determined with the information provided
8MHz
28
Which of the following creates harmonics?
A. reflection
B. transmission
C. linear behavior
D. nonlinear behavior
nonlinear behavior
29
Where are harmonics created?
A. in the pulser
B. in the transducer
C. in the tissues
D. in the receiver
in the tissues
30
What nonlinear behavior creates tissue harmonics?
A. microbubbles expand tot a greater extent than they compress
B. sound reflects off of boundaries with different impedances
C. sound travels faster in compressions and slower in rarefactions
D. microbubbles compress to a greater extent than they expand
sound travels faster in compressions and slower in rarefactions
31
What nonlinear behavior creates contrast harmonics?
A. microbubbles expand tot a greater extent than they compress
B. sound reflects off of boundaries with different impedances
C. sound travels faster in compressions and slower in rarefactions
D. microbubbles compress to a greater extent than they expand
microbubbles expand tot a greater extent than they compress
32
Which of the following is associated with the highest mechanical index?
A. low frequency, extreme peak rarefactional pressure
B. high frequency, extreme peak rarefactional pressure
C. low frequency, extreme peak compression pressure
D. high frequency, extreme peak compression pressure
low frequency, extreme peak rarefactional pressure
33
What is the hydrostatic pressure at all locations within the arterial circulation in supine?
all artieries are at the same level as the heart. so the hydrostatic pressure throughout the arterial circulation is 0mmHg
34
What is the hydrostatic pressure at all locations within the arterial circulation?
Depends on locations of the vessel
35
What is the arterial pressure measured in the toe of the upright patient?
240 mmHg
(100mmgh + 140mmgh = 240mmHg)
36
What is the arterial pressure measured at this patient’s knee?
215mmHg
(75mmHg + 140mmHg = 215mmHg)
37
What is the arterial pressure measured at the standing patient’s waist?
190mmHg
(50mmHg + 140mmHg = 190mmHg)
38
What is the arterial pressure measured at the standing patient’s upper arm?
140mmHg
(0mmHg + 140mmHg = 90mmHg)
39
What is the arterial pressure measured at the finger when the patient fully extends an arm toward the sky?
90 mmHg
(-50mmHg + 140mmHg = 90mmHg)
40
Normally, what happens to venous flow in the legs during inspiration?
A. increases
B. decreases
C. no change
decreases
41
All of the following occur during expiration except:
A. venous return tot he heart decreases
B. venous flow in the legs increases
C. abdominal pressure increases
D. the diaphragm rises into the thoracic cavity
abdominal pressure increases
42
Which one of the following is true about color map 1?
A. Red indicates flow toward the transducer
B. red indicates flow away from the transducer
C. Blue indicates turbulent flow
D. Blue indicates laminar flow away from the transducer
E. Red indicates turbulent flow
Red indicates flow toward the transducer
43
Which one of the following is true about color map 1?
A. Blue indicates flow toward the transducer
B. Red indicates flow away from the transducer
C. Blue indicates turbulent flow
D. Blue indicates laminar flow away from the transducer
E. Blue indicates flow away from the transducer
Blue indicates flow away from the transducer
44
Which of the following is true about color map 2?
A. blue indicates flow toward the transducer
B. Blue indicates flow away from the transducer
C. Light blue indicates turbulent flow
D. Dark blue indicates laminar flow away from the transducer
E. Red indicates turbulent flow
Blue indicates flow away from the transducer
45
Which of the following is true about color map 2?
A. Green indicates higher velocity flow toward the transducer
B. Red indicates flow away from the transducer
C. Green indicates higher volume flow toward the transducer
D. Blue indicates laminar flow away from the transducer
E. Red indicates turbulent flow
Green indicates higher velocity flow toward the transducer
46
Which statement is true about color map 1?
A. Red and yellow indicates flow toward the transducer
B. Red indicates flow away from the transducer
C. Blue indicates turbulent flow
D. Green indicates laminar flow away from the transducer
E, Red indicates turbulent flow
Red and yellow indicates flow toward the transducer
47
Which statement is true about color map 1?
A. Red and yellow indicates flow away from the transducer
B. Red indicates flow away from the transducer
C. Blue indicates turbulent flow
D. Green indicates turbulent flow away from the transducer
E. Red indicates turbulent flow.
Green indicates turbulent flow away from the transducer
48
Which statement is the best reason why color map 1 is a variance mode map?
A. Red indicates flow toward the transducer
B. Blue indicates flow away from the transducer
C. Blue and green indicate flow away from the transducer
D. Yellow indicates flow away from the transducer
E. Red indicates turbulent flow
Blue and green indicate flow away from the transducer
49
Which statement is true about color map 2?
A. Light blue indicates flow toward the transducer
B. Red indicates flow away from the transducer
C. Dark blue indicates turbulent flow
D. Dark blue indicates laminar flow away from the transducer
E. Red indicates turbulent flow
Dark blue indicates laminar flow away from the transducer
50
Which statement is true about color map 2?
A. Red indicates turbulent flow toward the transducer
B. Red indicates flow away from the transducer
C. light blue indicates turbulent flow
D. Light blue indicates laminar flow toward the transducer
E. Red indicates turbulent flow
light blue indicates turbulent flow
51
A video display that is limited to black and white only, with no shades of gray, is called ______.
A. binary
B. bistable
C. monochrome
D. inchworm
bistable
52
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
30
53
What was the original purpose for the ultrasound system’s analog scan converter?
A. to increase the dynamic range of ultrasound systems
B. To make real- time imaging possible
C. to increase the sensitivity of ultrasound systems
D. to allow for gray scale imaging
to allow for gray scale imaging
54
Which of the following is best described as an analog number?
A. the weight of a person
B. the number of people in a room
C. the number of stars in the sky
D. the number of tires on a car
the weight of a person
55
True or False?
A digital representation of a number can be achieved only specific fixed values.
True
56
True or False?
Digital scan converters do not use computer technology to process electronic data into images.
False
they use computer technology to process data
57
Two 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. System B has 250,000 pixels, with 12 bits assigned to each. Which system is more likely to have the capability to display very small details in an image?
A. System A
B. System B
C. Both are the same
D. cannot be determined
system A
58
What happens to a digital image when the pixel density increases?
A. spatial detail improves
B. temporal resolution increases
C. the field of view expands
D. There are more shades of gray
spatial detail improves
59
Two digital scan converters are undergoing evaluation. System A has 1,000,000 pixels and the picture size is 100 square inches. System B has an image size of 10 square inches composed of 250,000 pixels. Which image is more likely to display very small details?
A. system A
B. system B
C. Both are the same
D. Cannot be determined
system B
60
What is the smallest part of a digital picture called?
A. bit
B. byte
C. pixel
D. fractel
pixel
61
True or False?
The greater the number of bits assigned to each pixel of a digital image, the greater the number of shades of gray the image has.
true
62
What is the smallest amount of digital storage called?
A. bit
B. byte
C. pixel
D. fractel
bit
63
Which of these is a binary number?
A. 1221 1221
B. 10000000
C. 98765432
D. 01010102
10000000
64
Two digital scan converters are undergoing evaluation. System A has 1,000,0000 pixels, with 4 bits assigned to each. System B has 250,000 pixels, with 12 bits assigned to each. Which system is more likely to display images with very subtle differences in grayscale?
A. System A
B. System B
C. both are the same
D. cannot be determined
system B
65
A byte is composed of _____ bits. A word is composed of _____ bytes.
A. 2,2
B. 8,2
C. 16, 16
D. 8, 16
8, 2
66
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 assigned to each pixel pf fa digital image does not directly affect the spatial resolution of the image.
67
What happens to an image when the number of bits allocated to each pixel increases?
A. spatial detail improves
B. frame rate increases
C. field of view expands
D. more shades of gray
More shades of gray
68
What is the maximum number of shades of gray that are represented with 4 bits?
A. 4
B. 8
C. 12
D. 16
16
69
With 6 bits, what is the largest number of different gray shades that can be stored?
A. 8
B. 16
C. 64
D. 256
64
70
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
4 bits, 4 bits, 4 bits
71
What is the number of binary digits required to store 29 levels of gray?
A. 4
B. 5
C. 6
D. 29
5
72
True or False?
For digital image information to be displayed on a conventional television screen, the data must be processed by a digital-to-analog converter.
true
73
True or False?
Preprocessing of image data occurs after the data has been stored in the scan converter.
False.
this is achieved before image storage in the scan converter. TGC and write magnification are examples of preprocessing.
74
True or False?
Postprocessing of image data occurs after the data has been stored in the scan converter.
True
75
All of the following are true of read zoom except:
A. Preprocessing function of a receiver
B. same number 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 number of ultrasound pulses are used to create the original ROI and the zoomed image
preprocessing function of a receiver
76
All of the following are true of write zoom except:
A. preprocessing 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 used to create the original ROI
the same number of pixels are in the original ROI and the zoomed image
77
True or False?
The assignment of different shades of gray to the digital numbers stored in the san converter acts to improve the diagnostic value of an ultrasound exam.
True
78
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/cm^2
C. dynamic range, dB
D. Proportionality, dB
dynamic range, dB
79
Which of these components typically has the greatest dynamic range?
A. Display
B. Pulser
C. Amplifier
D. Demodulator
amplifier
80
Which of the following components typically has the lowest dynamic range?
A. display
B. pulser
C. amplifier
D. demodulator
display
81
Why is it necessary for the receiver to perform compression on the electrical signals that it processes?
A. The dynamic range of the system's electronics is less than the dynamic range of the received sound reflection
B. the display's dynamic range exceeds the transducer's dynamic range
C. the dynamic range of the receiver is less than the dynamic range of the image processor
D. the dynamic range of the display exceeds the dynamic range of all other components of the ultrasound system.
The dynamic range of the system's electronics is less than the dynamic range of the received sound reflection
82
A signal with a 120dB dynamic range is compressed by 40dB. What is the dynamic range of the compressed signal?
A. 40 dB
B. 120 dB
C. 3 dB
D. 80 dB
80 dB
120dB - 40dB= 80dB
83
A signal with a 120dB dynamic range was previously compressed by 40dB. What is the dynamic range of the original uncompressed signal?
A. 160 dB
B. 120 dB
C. 3 dB
D. 80 dB
160dB
120dB + 40dB= 160dB
84
Which display is limited to a single pair of brightness or display levels?
A. CRT
B. binary
C. bistable
D. grayscale
Bistable
85
All of the following are consistent with an image containing black and white only with no shades of gray except:
A. Bistable
B. high contrast
C. wide dynamic range
wide dynamic range
86
Which of the following terms is not associated with a wide dynamic range image?
A. low contrast
B. many shades of gray
C. bistable
bistable
87
Which of the following flow patterns is associated with cardiac contraction?
A. phasic
B. spontaneous
C. Steady
D. Pulsatile
E. continuous
pulsatile
88
Which of the following terms does not belong with the others?
A. phasic
B. spontaneous
C. pulsatile
D. venous
pulsatile
89
Which of the following is not associated with laminar flow?
A. layered
B. normal
C. aligned
D. smooth
E. Chaotic
chaotic
90
Which of the following is not associated with turbulent flow?
A. parabolic
B. eddy
C. vortex
D. swirling
E. spectral broadening
parabolic
91
What is the primary reason blood moves from one location to another?
A. energy gradient
B. anemia
C. pressure gradient
D, systole
E. friction
energy gradient
92
All of the following decrease the flow energy of a fluid except:
A. Frictional loss
B. viscous loss
C. inertial loss
D. velocity loss
velocity loss
93
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
flow through a stenosis
94
The arterial blood pressure of a supine individual is 120mmHg. 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
0 mmHg
95
The arterial blood pressure of a supine individual is 120mmHg. What is the hydrostatic pressure at the subject’s hips?
A. 100 mmHg
B. 0 mmHg
C. 40 mmHg
D. 120 mmHg
E. -120 mmHg
0 mmHg
96
he arterial blood pressure of a standing individual is 120mmHg. What is the hydrostatic pressure at the subject’s ankle?
A. 100 mmHg
B. 0 mmHg
C. 40 mmHg
D. -100 mmHg
E. -120 mmHg
100 mmHg
97
The arterial blood pressure of a standing individual is 120mmHg at the level of the heart. What is the measured blood pressure at the subject’s ankle?
A. 100 mmHg
B. 0 mmHg
C. 40 mmHg
D. -100 mmHg
E. 220 mmHg
220 mmHg
98
What happens to the diaphragm when an individual breathes in?
A. it ascends into the thorax
B. it descends into the abdomen
it descends into the abdomen
99
What happens to venous return to the heart when an individual inhales?
A. increases
B. decreases
C. remains the same
increases
100
What happens to venous flow in the legs when an individual inhales?
A. increases
B. decreases
C. remains the same
decreases
101
What happens to the diaphragm when an individual breathes out?
A. it ascends into the thorax
B. it descends into the abdomen
it ascends into the thorax
102
What happens to venous return to the heart when an individual exhales?
A. increases
B. decreases
C. remains the same
decreases
103
What happens to venous flow in the legs when an individual exhales?
A. increases
B. decreases
C. remains the same
increases
104
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, millimeters
frequency, per second
105
In clinical imaging, which reflectors produce most relevant Doppler shifts?
A. blood vessels
B. blood plasma
C. platelets
D. red blood cells
red blood cells
106
If red blood cells are traveling toward a transducer, the frequency emitted by the transducer is _____ the frequency reflected from the red blood cells.
A. greater than
B. equal to
C. less than
less than
107
In standard Doppler, what is true about the reflected frequency produced by blood cells traveling 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
it is ultrasonic
108
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. -0.02 MHz to 0.02 MHz
D. none of the above
-0.02 MHz to 0.02 MHz
109
When red blood cells 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
less than
110
What information does the Doppler shift furnish concerning the blood cells that produce it?
frequency
speed
velocity
density
velocity
111
Blood moving at a velocity of 2 m/s creates a Doppler frequency of 3,000Hz. What will the Doppler shift be if the velocity increases to 4m/s?
A. 3,000 Hz
B. 2 Hz
C. 1,500 Hz
D. 6,000 Hz
6,000
when the velocity doubles, Doppler shift doubles
112
Two ultrasound transducers are used to perform Doppler exams on the same patient. The exams are identical except that the transducer frequencies are 5 and 2.5MHz. Which exam will measure the highest velocities?
A. the 2.5 MHz exam
B. the 5 MHz exam
C. neither
D. cannot be determined
neither
velocities measured by Doppler exams are the same, regardless of the frequency of the transducers.
113
Two ultrasound transducers are used to perform Doppler exams on the same patient. The exams are identical except that the transducer frequencies are 5 and 2.5MHz. Which exam will measure the highest Doppler shift?
A. the 2.5 MHz exam
B. the 5 MHz exam
C. neither
D. cannot be determined
the 5 MHz exam
114
When using a 4MHz 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
1,500 Hz
115
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
cosine
116
Two otherwise identical Doppler studies are performed, except that the angle between flow and the sound beam is 0 degrees in the first study and 60 degrees in the second. The velocity measure in the first study is 2m/s. What velocity will be measured in the second study?
A. 2 m/s
B. 4m/s
C. 1m/s
D. cannot be determined
1m/s
Maximum velocities are measured at a zero degree angle only one-half of the true velocity is measured when the angle is 60 degrees.
117
What is true of the Doppler shift when the sound beam is normally incident to the velocity of the red blood cells?
A. it is at maximum
B. it is half of maximum
C. it is absent
D. it is at minimum
it is absent
118
A maximum Doppler shift is obtained when the angle between the direction of blood flow and the direction of the sound beam is _______.
A. 10 degrees
B. 90 degrees
C. 180 degrees
D. 270 degrees
180 degrees
119
True or False?
The appearance of negative velocities on the spectral display of a continuous wave Doppler exam always indicates that red blood cells are moving away from the transducer.
True
120
With regard to CW Doppler, is the following true or false?
A minimum of two distinct piezoelectric crystals are in the transducer.
True
121
With regard to CW Doppler, is the following true or false?
Problems with aliasing significantly limit its clinic utility.
False
Aliasing is an artifact where high doppler shifts are misidentified as flow in the opposite direction
122
With regard to CW Doppler, is the following true or false?
Frequencies measured at the transducer are produced from many different locations along the ultrasonic beam.
true
123
With regard to CW Doppler, is the following true or false?
The duty cycle of the continuous wave is 100%
true
124
All of the following are related to dedicated continuous wave Doppler transducers except:
A. wide bandwidth
B. high quality factor
C. higher sensitivity
D. range ambiguity
wide bandwidth
125
A duplex ultrasound system displays ______ information.
A. M-mode, two dimensional image, and A-mode
B. A-mode and B- mode
C. two dimensional image and Doppler
D. two dimensional image and M-mode
two dimensional image and Doppler
126
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
Backing material
127
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
Attenuation
128
True or False?
The appearance of negative velocities in a pulsed Doppler display always indicates that red blood cells are moving away from the transducer.
False
Negative velocities on the spectral display of a pulse Doppler exam may indeed indicate that RBC are traveling away, however aliasing may also cause negative velocity in the spectrum.
129
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
Aliasing
130
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. pulse repetition frequency, the pulse repetition frequency
C. Nyquist limit, half of the emitted frequency
D. Nyqyist limit, half of the emitted PRF
Nyquist limit, half of the emitted PRF
131
True or False?
In a pulsed Doppler exam, the use of a higher transducer frequency increases the likelihood that aliasing will appear.
True
132
True or False?
The higher the pulse repetition frequency of a Doppler exam, the more likely aliasing is to occur.
False
Aliasing is less likely to occur with high PRF
133
A system has three transducers with frequencies of 7.5MHz, 5MHz, and 3.25MHz. Aliasing appears while using the 5.0MHz transducer during a pulsed Doppler exam. What should the sonographer do?
A. use the 3.25 MHz transducer
B. use the 7.5 MHz transducer
C. nothing; the other transducers do not provide solutions to the problem
Use the 3.25 MHz transducer
134
The frequency of a pulsed Doppler wave is 6MHz, and the PRF is 5kHz. 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
2.5 kHz
135
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 pulse repetition period
D. use of a continuous wave system
selection of another imaging view that provides a greater pulse repetition period
136
True or False?
TGC cannot be used with continuous wave Doppler.
True
137
Which of the following determines the gray scale in a Doppler spectrum?
A. number of reflectors
B. velocity
C. frequency shift
D. laminar flow
Number of reflections
138
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
amplitude of the echo
139
True or False?
Color flow Doppler exams tend to have lower temporal resolution than traditional two-dimensional, real-time imaging.
True
140
True or False?
Color flow Doppler imaging incorporates pulsed Doppler principles and procides range resolution.
True
141
True or False?
Color flow Doppler relies on pulsed Doppler principles and is immune to aliasing artifact.
False
it's CW Doppler
142
True or False?
Color flow Doppler systems display anatomical data in gray scale while simultaneously displaying flow information in color.
True
143
True or False?
On a color Doppler image, red always represents flow toward the transducer, whereas blue indicates flow away from the transducer.
False
144
True or False?
Absence of color on a color Doppler image always indicates a region of no blood flow.
False
145
The two most common color maps used in color flow imaging are:
A. Variance and direct
B. variance and velocity
C. turbulence and variance
D. power and velocity
Variance and velocity
146
True or False?
Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are laminar.
True
147
True or False?
Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent.
True
148
True or False?
Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow patterns are turbulent.
