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RRE ARRT 2020 practice test

Terms in this set (120)

82. A 5-MHz wave travels through 5 cm of soft transducer is selected instead, what happens to the propagation tissue. If a 3.5-MHz speed of the medium?
no change
What type of wave is sound?
Mechanical, longitudinal wave
The frequency ranges for ultrasound are:
20 kHz
The speed sound in soft tissue is
1540 m/s
Whichofvthe following transducers fires the elements in groups?
Linear sequenced array
The unit for wavelength is
Millimeters
Enchancement is caused by
Weakly attenuating structures
The wavelength in a material having a propagation speed of 1.5 mm/us employing a transducer frequency of 5.0 MHz is:
0.3 mm
8. An ultrasound transducer converts:
mechanical energy into electrical energy and vice versa
9. Arrange the following media in correct order from the lowest attenuation to highest:
Fat, muscle, bone, air
10. Arrange the following media in terms of propagation speed, from lowest to highest:
air, fat, muscle, bone
11. If the frequency doubles, what happens to the wavelength?
Decreases by one half
13. Which of the following would be used to describe the percentage of time that sound is on?
duty factor
12. What happens to intensity if the amplitude of a signal is halved? /
Quartered
14. A 3-dB gain would indicate an increase in intensity by:
2 times
15. Ignoring the effects of attenuation, the intensity of the ultrasound beam is usually greater at the focal zone because of:
The smaller beam diameter
16. Attenuation denotes:
Progressive weakening of the sound beam as it travels
17. Which of the following has the lowest intensity?
SATA
lowest of the intensities
18. What is the definition of the beam uniformity ratio?
The spatial peak intensity divided by the spatial average intensity
19. Continuous-wave Doppler has a duty factor of:
100%
20. The spatial pulse length is defined as product of the and the number of in pulse.
Wavelength, cycles
21. With phased array transducers, the transmitted sound beam is steered by:
Varying the timing of pulses to the individual piezoelectric elements
22. If the gain of an amplifier is 18 dB, what is the new gain if the power is reduced by half?
15 dB
23. Which of the following is true?
SPTP is always equal to or greater than SPTA
24. If the amplitude of a wave is increased threefold, the power will:
Increase ninefold
25. Ultrasound attenuates an average of dB/cm of travel for each megahertz of frequency.
0.7 dB/cm/MHz
26. If the intensity transmission coefficient is 0.74, the intensity reflection coefficient will be:
0.26
27. Acoustic impedance is defined as the product of:
The speed of sound in tissue and density of the tissue
28. Rayleigh scattering is an example of:
A reflector whose size is smaller than the wavelength
29. Assuming normal incidence, if medium 2 impedance is equal to medium 1 impedance:
100% of the intensity will be transmitted
30. What is the total attenuation of a 3.5-MHz pulse after passing through 2 cm of soft tissue?
3.5 dB
31. The thinner the piezoelectric element:
The higher the frequency
33. A sound beam encounters an interface at a 90° angle. If the speed of sound in the first tissue is 1540 m/s and the speed of sound in the second tissue is 1450m/s, which of the following numbers most closely approximates the angle of beam transmission?
90 degrees
32. The unit for impedance is:
Rayls
35. A decibel (dB) describes the:
ratio of two sound intensities
34. ALARA stands for:
As Low As Reasonably Achievable
36. The correct equation for Snell's law is:
sin 6 = (C/C,) x sin 6
37. The attenuation coefficient of sound in soft tissue can be defined by which of the following equations?
Frequency/2
39. The range equation explains:
Distance to reflector
38. The intensity transmission coefficient is equal to:
1 - intensity reflection coefficient
40. The typical value for attenuation coefficient for 6-MHz ultrasound in soft tissue is:
a. 3 dB/cm b. 1 dB/cm/Hz c. 3 dB/cm? d. 2 dB
41. What must be known in order to calculate distance to a reflector?
Attenuation, propagation speed, density
42. Specular reflections:
Occur when the interface is larger than the wavelength
43. What is the reflected intensity from a boundary between two materials if the incident intensity is 1 mW/cm? and the impedances are 25 and 75?
0.25 mW/cm?
44. The layer of material within the transducer which has an intermediate impedance between the transducer element and human tissue is known as the:
. Matching layer
45. Which of the following relates bandwidth to operating frequency?
Quality factor
46. The piezoelectric effect can best be described as:
Mechanical deformation that results from a high voltage applied to the face of the crystal that in turn generates a pressure wave
47. Which of the following are most commonly used in ultrasound transducers?
Lead zirconate titanate
49. The preferred method for sterilizing ultrasound transducers is:
. Cold sterilization
50. A transducer with which frequency would have the thickest element(s)?
MHz
48. Diffraction refers to:,
Spreading out of the ultrasound beam
51. Which of the following is best defined as the ability to discriminate between two closely spaced reflectors?
Spatial resolution
52. Which of the following is an effect of focusing?
Improved lateral resolution
53. Bandwidth is:
The range of frequencies produced by the transducer
54. What is the technique that permits "virtual palpation" of a lesion to determine the hardness or softness of tissue?
Elastography
55. The acoustic impedance of the transducer's matching layer:
Is chosen to improve transmission into the body
56. If the amount of damping decreases, the bandwidth:
decreases
58. The near-zone length is determined by:
Transducer frequency
57. The region where the sound beam diameter is the smallest is referred to as the:
the beam is smallest at the focal zone or focus
59. A two-element continuous-wave transducer:
Is only used for spectral Doppler
60. A wave's initial intensity is 2 mW/cm?. There is an increase of 10 dB. What is the final intensity?
20 mW/cm2
61. Which of the following is described best as a transducer that has multiple elements in a curved shape?
Curvilinear
62. What is the name of the control that compensates for attenuation related to path length?
Time-gain compensation
63. The echoes are stored before final display by the:
Computer memory
64. What portion of the ultrasound system drives the transducer?
Pulser
65. What Doppler mode uses the amplitude of the Doppler shift in order to produce an image demonstrating flow in a vessel?
Power Doppler
66. How many different shades of gray can the human eye discern at one time?
100
67. Most current ultrasound systems have shades of gray available,
256
68. How many bits per pixel can be displayed with 4 bits of memory?
16
69. The spatial resolution capabilities of the system are primarily functions of the:
Transducer
70. The echo intensity on a grayscale of 32 shades is represented by the binary number:
100000
71. Preprocessing of the information that is fed to the scan converter:
Determines the assignment of echoes to predetermined gray levels
72. Which of the following do grayscale systems typically use as a means of signal dynamic range reduction?
Compression
73. Area is expressed by which of the following units?
cm2
74. If the frequency of a transducer is increased, which of the following will decrease?
Wavelength
75. With tissue harmonic imaging,
There are decreased artifacts in the near field
76. Which of the following is in the range of infrasound?
15 Hz
77. Which of the following is in the range of audible sound?
a. 15 Hz b. 18 kHz c. 25,000 Hz d. 2 Hz
78. Which of the following can be changed by the operator?
Wavelength
79. Which of the following is the time it takes for one cycle to occur?
Period
80. The length of the pulse is the:
Spatial pulse length
81. Assuming oblique angle of incidence, if the propagation speed of medium 1 is great than the propogatio speed of medium 2, what will the angle of transmission be?
Less than the angle of incidence
83. The slowest propagation speed is found in which medium?
Air
84. Which of the following represents the strength of the beam?
Intensity
85. Which of the following is the unit of pressure amplitude?
Pascal, (Pa) is the unit for pressure amplitude
86. Which of the following is the unit of intensity?
W/cm2
87. What else changes with a change in amplitude?
Output power
88. Which of the following will increase the acoustic exposure to the patient?
Increased output gain
89. Which operator control adjusts the intensity of the transmitted pulse?
Power
90. What happens to the power if the intensity is doubled?
It doubles
91. The number of pulses that occur in 1 s is the:
Pulse repetition frequency
92. What is along the x-axis on a spectral Doppler waveform?
Time
96. When using tissue harmonic imaging, the frequency used is
Double the fundamental frequency
97. In B-mode imaging, amplitude is located on the _______________ -axis of the image
z
98. Which of the following determines the radial resolution of a system?
Spatial pulse length
99. The axial resolution can be improved by decreasing the or increasing the
Number of cycles in a pulse, frequency
100. Two reflectors are 1.3 mm apart in a plane that is parallel to the beam. The spatial pulse length of the transducer is 2.6 mm. These two reflectors:
Will not show up on the image at all
101. In what zone does beam divergence occur?
Fraunhofer zone
102. The larger the aperture,
The longer the near zone
103. The ability to resolve two reflectors that lie parallel to the beam is the resolution of a system
Axial
104. The more focal zones used,
The worse the temporal resolution
105. In the most common type of transducers, the slice-thickness plane is focused:
Using a lens
106. If sound travels through a large quantity of water and then encounters a reflector, the reflector will appear to be:
Too far away
107, What is the maximum temperature increase below which there should be no thermally induced biologic effects?
10°C
108. Two sound beams with different frequencies are traveling through soft tissue. Which beam will travel faster?
Both will travel at the same speed
109. A video display that is limited to only black and white, with noother shades of gray, is called:
Bistable
110. What is the name for the smallest amount of digital storage?
The bit
112. Information that travels to the scan converter from the receiver is initially in what format?
Analog
111. In the Fresnel zone,
The beam area decreases with distance the transducer
113. Which of the following is true about color Doppler?
Each pixel can either be grayscale or color
114. Which of the following preserves the pixel density when enlarging the image?
Write magnification
115. What is the relationship between amplitude and frequency?
No relation
116. What is the relationship between spatial pulse length and pulse duration?
Directly related
117. Which of the following is true about axial resolution?
It does not vary with depth
118. If the is increased, the flow increases.
Pressure differential
119. Which law describes the relationship between flow and the pressure differential, viscosity, and length?
Poiseuille's law
120. The most common type of flow found in the body is:
Laminar
93. What is a unit of spatial pulse length? '
m
94. What testing device is used to measure acoustic output (intensity) level?
Hydrophone
95. What is the principle that states sound waves are the result of the interference of many wavelets produced at the face of the transducer?
Huygen's principle
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