# Physics Test Questions

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 Author: dorkfork ID: 288175 Filename: Physics Test Questions Updated: 2014-11-06 18:53:53 Tags: Ultrasound Physics Songraphy Folders: Description: Physics Exams Questions Show Answers:

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1. What type of medium has has the highest absorption coefficient? (air, bone, or soft tissue(water)
Bone
2. The propagation speed is fastest in? (soft tissue, bone or air)?
Soft tissue
3. For soft tissue, if the path length is doubled, total attenuation will:
Double
4. If the attenuation coefficient for muscle is 5.0 dB at 3MHz, what is the attenuation coefficient at 6MHz?
10
5. The portion of sound energy redirected towards the sound source is called:
Reflected
6. If the acoustic output is set at 0 dB, this indicates:
Reference intensity level
7. If the half value layer thickness for muscle is 4cm at 2MHz, the HVL thickness at 4MHz is ___cm.
2
8. If the amplitude is increased by a factor of 2, intensity:
Increases by a factor of 4
9. The maximum pressure variation that occurs in a cycle is termed:
Amplitude
10. An ultrasound field in soft tissue experiences an intensity reduction of 9 dB. This is equivalent to ____ Half Intensity Depth(s).
3
11. The tissue property that determines the amount of refraction at an interface is:
Velocity
12. If the reflection intensity coefficient at an interface is 25%, what is the transmission intensity coefficient?
75
13. Acoustic impedance is equal to:
Density x velocity
14. The propagation speed through the medium is NOT dependent on:
Frequency
15. If the initial intensity is reduced to 25%, this is equivalent to ____ dB.
6
16. Which of the following is an example of a specular reflector?
Diaphragm
17. If the acoustic power is doubled, intensity will:
Double
18. If the wavelength is decreased by 1/4 , the frequency will:
increase by 4
19. What is the typical transmission coefficient at a soft tissue/air interface?
0.1
20. As the temperature decreases, the propagation speed in tissues would:
Decrease
21. If the total attenuation at 2 MHZ = 20 dB, the total attenuation at 4 MHz is ____ dB.
40
22. Which of the following accounts for the greatest portion of the attenuation rate at an air/soft tissue interface?
Reflection
23. Which of the following types of media would have the highest characteristic acoustic impedance value?
soft tissue/air (99.9% reflected back)
24. Decreasing the beam area to 1/6 of the original will result in:
increasing intensity
25. Which of the following conditions is most likely to produce the greatest amount of refraction? (0 degrees = normal incidence)
Muscle/bone interface - 20 degree incidence
26. If the wavelength for a sound field = 2 mm, which of the following interfaces would most likely behave as a specular reflector?
4.0 mm
27. If the wavelength for a sound field is 1 mm, which of the following reflectors would behave as a non-specular reflector?
0.5 mm
28. If the transmission coefficient is 60% at an interface, the reflection coefficient is:
40
29. Which of the following would have the lowest absorption coefficient?
Water
30. Which of the following mediums would have the largest half intensity depth in cm?
soft tissue
31. The sonographic pattern displayed distal to a region with a low attenuation rate is termed:
Enhancement
32. What is the typical per cent reflection at a muscle/bone interface?
50
33. Which of the following factors accounts for the greatest portion of the attenuation rate in soft tissue?
Absorption
34. If the acoustic output is increased by 9 dB, the resulting intensity has increased by a factor of:
8
35. The theory/principle that relates the angle of incidence to the angle of refraction is:
Snell's law
36. A large amplitude pulse (voltage) from the pulser results in:
Increasing transmit intensity
37. Which control changes the intensity of the transmitted pulse?
Acoustic power
38. Increasing the pulse repetition frequency will:
Decrease the maximum imaging depth
39. The primary method that the sonographer uses to control frame rate during real time imaging is:
Imaging depth
40. The initial amplitude is determined by :
Acoustic power control
41. According to the range equation, which of the following are required to calculate the distance to the reflector?
Propagation speed and round trip time
42. The signal processing function that eliminates the negative component of the signal is termed:
Rectification
43. The System Gain function is performed in the:
Beam former
44. Reflector B is twice the distance from the transducer as reflector A. It takes ______ times as long for an echo to arrive from reflector B as from reflector A.
2
45. The sonographer has increased the size of the sector width to image a large mass. What can the sonographer do to maintain the same temporal resolution before this adjustment?
Decrease the number of focal zones.
46. Increasing the number of scan lines per frame improves:
Detail resolution
47. If the gain is increased by 9 dB, the power has been increased by a factor of:
8
48. Adjusting the TGC controls affects the settings in the:
Beam former
49. Which of the following transducer arrays utilizes electronic beam steering?
Sector
50. On an A-Mode display, the height of the spike represents:
The echo intensity
51. The computer parameter that limits the number of gray levels available to display on the image matrix is:
Number of bits in computer word
52. Which of the following system components generates the signals to focus and steer the sound field?
Beam former
53. The pulse repetition period is the reciprocal of:
Pulse repetition frequency
54. In cardiac imaging, reducing the size of the sector angle will:
Increase the frame rate
55. The ability to distinguish between adjacent structures producing echo amplitudes of similar amplitude is termed:
Contrast resolution
56. The typical dynamic range in the amplifier is:
60-100
57. What is the maximum number of displayed shades of gray in a 7-bit processor?
128
58. Which of the following digital scan converters would display the best contrast resolution?
8 bit
59. In which of the following modes is time the unit of measurement on one axis?
M-mode
60. How many levels of information can a single bit represent?
2
61. Preprocessing programs are performed in the:
Image processor
62. Postprocessing programs are performed in the:
Display
63. The use of cine loop will primarily improve _________ resolution
Temporal
64. During real time imaging, if the scan line density is reduced to 1/4, the maximum frame rate is:
Increased by a factor of 4
65. In clinical applications, maximum reflection amplitude occurs with:
Normal incidence
66. At a muscle/fat boundary, the percentage of sound energy reflected will be:
60 %
67. As sound propagates through the medium, amplitude:
Decreases
68. As frequency increases, half intensity depth:
Decreases
69. Propagation speed is determined by the:
Medium
70. By altering the imaging depth, the period of the wave:
Remains unchanged
71. At a soft tissue/air interface, the percentage of sound transmitted will be:
0.1%
72. Determine the power if the amplitude of the wave is 4.
• 16 = 42
• Power = amplitude2
73. The _______ is a unit of measurement used to express the difference or ratio between two variables.
decibel
74. The sonographer can change the sound field intensity by manipulating:
Transmit power
75. For soft tissue, which of the following would most likely be used to represent a 50% reduction in intensity?
-3 dB
76. The total attenuation for a 10 MHz sound field in soft tissue at 2 cm is _____ dB.
10dB
77. Increasing intensity increases
Propagation speed
78. At soft tissue interfaces, the percentage of ultrasound energy transmitted is approximately _____ %,
99
79. Which of the following has an average propagation speed of 1.54 mm/µs?
Muscle, soft tissue
80. As sound propagates through the medium, intensity:
Decreases
81. Frequency is determined by the:
Piezoelectric element
82. The best example of a Rayleigh scatterer is:
Red blood cell
83. The initial amplitude is determined by :
Acoustic power control
84. As propagation speed and density values increase, acoustic impedance:
Increases
85. Determine the attenuation coefficient in dB/cm for a 10 MHz sound field in soft tissue.
10dB/cm
86. The attenuation rate will increase if there is an increase in:
frequency
87. A region of high pressure, high density is:
Compression
88. Wavelength is determined by the:
• Frequency
• (increase frequency to decrease wavelength)
89. To maximize reflection from a specular reflector, the sonographer should strike the interface at ______ degrees.
90
90. This artifact cannot occur at perpendicular incidence
Refraction
91. As sound propagates through a medium, power:
Decreases
92. A sound beam's wavelength is 0.5 mm. Which of the following would be an example of a nonspecular reflector?
0.4 mm
93. Impedance is equal to:
c x p
94. For an unfocused circular soundfield, the crystal diameter is 30 mm. What is the beam diameter in mm at a depth equal to twice the near field length?
30
95. Elevational resolution is related to:
Beam width
96. The intensity of a focused beam is generally:
Highest in the focal zone
97. The product of the period and the number of cycles in the pulse is:
Pulse duration
98. Axial resolution can be improved by using:
Higher frequency transducers
99. The type of real-time transducer that employs a combination of electronic focusing and mechanical steering is:
Vector array
100. The reverse piezoelectric effect is best described as:
Mechanical deformation resulting from high voltage applied on crystal faces, generating ultrasound
101. Which of the following transducers would be most useful for imaging superficial structures?
5 MHz, superficial focus
102. Lateral resolution is equal to:
Beam area
103. The unit of measurement for the duty factor is:
Percent
104. Increasing the pulse repetition period:
Increases the maximum imaging depth that can be imaged
105. For an unfocused sound field utilizing a 10 mm crystal diameter, the sound field diameter at the end of the near field will be ____ mm.
5
106. Grating lobes in electronic array systems:
Are controlled with a process called subdicing
107. As frequency increases, the beam width will:
Decrease
108. The principle that states that all points on a wavefront can be considered as point sources for the production of spherical secondary wavelets was postulated by:
Huygen
109. The ____ relates the bandwidth to operating frequency
Quality factor
110. For an unfocused circular sound field, the crystal diameter is 40 mm. What is the beam diameter 1cm from the crystal surface in mm?
40
111. The piezoelectric properties of the transducer will be lost if the crystal is heated above the:
Curie point
112. What is the most commonly used material for ultrasound transducer crystal elements?
113. A decreased pulse duration produces:
Better axial resolution
114. The beam of an unfocused transducer diverges where?
• In the Fraunhofer zone
• Far Field
115. The amount of divergence in the far field can be decreased by:
Increasing the frequency or a larger crystal diameter
116. The near field length of an unfocused transducer depends on:
Frequency and diameter
117. Extraneous sound energy emitted from a linear sequenced array are called:
• Grating Lobes
• Corrected by subdicing
118. The spatial pulse length:
Decreases with increasing frequency
119. Transmit delay focusing in a linear array transducer will improve:
Lateral resolution
120. Axial resolution depends on the ______
wavelength/frequency (higher frequency/shorter wavelength)
121. The damping material will improve
Increase damping material>>shorter pulse>>wider bandwidth>>better axial resolution
122. A long near zone can be obtained by:
Increase frequency (decrease λ)
123. Higher the ____ the shorter the SPL
Frequency
124. Shorter the SPL the better the ____ resolution
axial
125. SPL=
• SPL= λ x # of cycles in pulse
• Shorter the SPL the better the axial resolution
• Higher the frequency the shorter the SPL
126. Longitudinal or axial resolution is directly dependent on:
• Spatial pulse length
• SPL= λ x # of cycles in pulse
• Shorter the SPL the better the axial resolution
• Higher the frequency the shorter the SPL
127. Generally, ultrasound transducers have better _____ resolution than ________ resolution.
Better axial resolution than lateral resolution
128. Which equipment assumption is violated when refracted echo information is processed?
All echoes come from straight ahead
129. To reduce the Mechanical Index (MI), the sonographer would:
Decrease acoustic power, increase the number of focal zones
130. Mechanism through which ultrasound energy can produce a biological effect
Stable caviatation, transient cavitation, increase in temperature
131. The artifact indicated by " A" is indicates:
Large acoustic impedance missmatch
132. If the focal zone is decreased to 1/5 of its original area, the intensity will:
Increase by 5
133. Which rod groups scanned from side C would evaluate lateral resolution?
Rod group C
134. Side lobe artifact produces which of the following sonographic characteristics?
• Energy distribution outside main beam profile
• Horizontal linear extensions from specular reflector (i.e. septa)
135. The risk of cavitation is considered low when the MI value is ____ or lower.
0.5
136. The area of the sound field characterized by violent intensity changes is:
Near field
137. Transient cavitation refers to :
• AKA collapse cavitation or normal cavitation
• Bubble oscillation so large that the bubble collapses
138. No thermal effects have been documented when the temperature elevation is below ___ degrees.
2
139. A Thermal Index (TI) value of one (1) indicates:
Potential to increase tissue temperature by 1 degree
140. The artifact indicated by the white line can be eliminated by:
Aliasing
141. Which mode has the potential for the highest thermal production?
Color doppler
142. A device commonly used to measure the output of diagnostic ultrasound systems is:
Hydrophone
143. A tumor has a slower propagation speed than the soft tissue average propagation speed. This will result in:
144. For a given sound field, which of the following would demonstrate the lowest intensity value?
SATA
145. What type of tissue is most susceptible to the effects of cavitation?
• Aerated lung tissue
• Air in GI tract
146. With all other parameters constant, increasing the acoustic output by a factor of eight (8) will:
147. Which artifact is associated with reverberation and resonance in a small gas bubble or surgical staple?
Comet tail
148. Which of the following parameters directly relates to heating of tissues?
• Increase thermal index
• Increased frequency or output power
149. Which of the following rod groups scanned from side A would evaluate axial resolution?
Rod group B
150. What factors would produce the greatest TI values?
• High frequency
• Narrow focal zone
• Stationary color doppler
151. What factors would produce the greatest MI values?
Low frequency, high intensity
152. The artifact indicated by the arrow is due to:
• Reverberation/ comet tail
• Large acoustic impedance missmatch
153. Which system control manipulations would best limit patient exposure to ultrasound energy?
• Decrease scan time
• M-mode vs. color doppler or pulsed wave
• Decrease frequency
154. A transducer has a very wide slice thickness. This may produce:
• Filling defect of a cystic/anechoic structure
• Filling in of vessels / small cyts
155. Which of the following produces the split image artifact?
• fat/muscle interface near the surface
• i.e. linea alba
156. Which of the following types of tissue will demonstrate the greatest temperature elevation?
• embryo <8 weeks conception
• head, brain, and spine of any fetus or neonate
• eye in any patient
157. Which of the following digital scan converters would display the best contrast resolution?
• 8 bit
• 8 is the current standard
• 2= shades of gray, where n = bits in a computer word
158. Bioeffects have been observed in experimental animals with focused intensities greater than:
1 W/cm2
159. On an A-Mode display, the height of the spike represents:
The echo intensity
160. The System Gain function is performed in the:
Beam former
161. What is the maximum number of displayed shades of gray in a 6-bit processor?
2= 64
162. What determines the power of the ultrasound field?
Voltage applied to the transducer
163. The typical pulse repetition frequency range for clinical imaging applications is:
• Low range
• 10-20kHz
164. The term signal to noise ratio is:
The ratio of signal amplitude to the variation in noise
165. In cardiac imaging, reducing the size of the sector angle will:
Increase the frame rate
166. If the imaging depth is quartered, the frame rate will be:
167. The signal processing function that eliminates the negative component of the signal is termed:
Rectification
168. Adjusting the TGC controls affects the settings in the:
Beam former
169. The ability to distinguish between adjacent structures producing similar echo amplitudes is termed:
Contrast resolution
170. When the pulse repetition period is increased:
Imaging depth is decreased
171. If the gain is increased by 6 dB, the power has been increased by a factor of:
4
172. Which control changes the intensity of the transmitted pulse?
Acoustic power
173. Increasing the number of scan lines per frame improves:
Detail resolution
174. The use of cine loop will primarily improve _________ resolution
Temporal
175. What system component generates the signals to focus and steer the sound field?
Beam former
176. When comparing Write magnification with Read magnification, Write magnification:
Improves spatial resolution compared to read magnification
177. During real time imaging, if the scan line density is reduced to 1/2, the maximum frame rate is:
Doubled
178. Preprocessing programs are performed in the:
Image processor
179. If the original acoustic power is 100 mW and the power control is increased by 3 dB, the new power is _____ mW.
200
180. In real time systems, the range equation is used to determine reflector:
Depth
181. The typical dynamic range in the amplifier is:
60-100
182. The sonographer has increased the size of the sector width to image a large mass. What can the sonographer do to maintain the same temporal resolution before this adjustment?
Decrease the number of focal zones.
183. Increasing the pulse repetition frequency will:
Decrease the maximum imaging depth
184. Reflector B is twice the distance from the transducer as reflector A. It takes ______ times as long for an echo to arrive from reflector B as from reflector A.
2
185. The computer parameter that limits the number of brightness levels available to display on the image matrix is:
Number of bits in computer word
186. The primary method that the sonographer uses to control frame rate during real time imaging is:
Imaging depth
187. Which mode has time the unit of measurement on one axis?
M-mode
188. Flow through a blood vessel is determined by:
• 1. Pressure difference
• 2. Vascular resistance
189. Vessel diameter increase as _____ increases.
Pressure
190. Veins or arteries, which are more distensible?
Veins are 6-10 x as distensible as arteries
191. Arteries
• Transport blood to tissues
• High pressure
192. Arterioles
• Last, smallest branches of the arterial system
• Act as "control valves" for blood flow into capillaries
193. Capillaries
Exchange between blood and interstital spaces
194. Vasodilitation occurs when?
• During exercise
• After a meal
195. Vasoconstriction occurs when?
• In a resting state
• With fasting
196. Venules
Collect blood from capillaries and connect to larger veins
197. Veins
• Blood returned to heart
• Body contians many more veins than all other parts of the vascular system
198. AO/ICV
Have the smallest cross-section area and therefore the highest velocity
199. Relationship of velocity to area
Velocity is inverse to area
200. Energy derived from the cardiac pump
Potential/pressure energy
201. Potential energy
• Pressure/stored energy
• Derived from the cardiac pump
• Distends vessels and stores energy
202. Kinetic energy
• Energy of motion
• KE < PE due to distensibility of vessels
203. Kinetic energy can increase due to:
• Increase in flow>> i.e. exercise
• Stenosis (increased velocity)
204. Movement of fluid between 2 points requires:
• Difference in energy
• Difference in pressure
205. Example of low resistance
• Organs
• Low resistance = greater energy difference = greater flow
206. Example of high resistance
• Resting muscle
• High resistance = less flow
207. Pouseuille's law
Defines relationship between pressure, volume flow, and resistance
208. The longer the vessel the _____ the resistance.
• Higher
• High pressure is required to maintain flow
209. The shorter the vessel the ____ the flow volume.
Higher
210. What has the most significant impact on flow rate?
• Smaller the radius, the higher the resistance
211. Smaller the radius, the _____ the resistance.
Higher (and higher pressure)
212. Plug flow
• Flat profile
• Seen in stenotic area
• Same velocity throughout vessel (slower flow at wall)
213. Laminar flow
• Most common flow pattern
• Seen during systole in smaller arteries
• Flow in center is highest and gradually tapers as it reaches the wall of the vessel
214. Disturbed flow is signified by?
215. Mathematical number to determine when flow turbulence will occur?
Reynold's number
216. Reynolds number for when turbulance will occur
2000 Re or higher
217. Harmonic resonance produced by flow turbulence transmitted into vessel walls is known as
audible bruit
218. Where is normal disturbed flow visualized throughout the cardiac cycle?
• Bifurcations
• Curves
219. Significant stenosis
70% blockage
220. Tardus parvus
Dampened wave forn distal to a stenosis
221. Monophasic flow
• Low resistance, continuous and steady throughout S and D
• Seen in normal arteries that supply low resistance vascular beds -liver, spleen, brain, kidneys
222. Triphasic flow
• Highest resistance to flow
• Seen in distal AO/iliac arteries
223. Cosine of the doppler angle is ______ly related to the doppler angle.
• Inversely related
• Angle of 0 = cosine 1.00
• Angle of 90 = cosine 0
224. Increase transmit frequency and _____ the size of the Doppler shift
Increase
225. Decrease velocity of flow and _____ the size of the Doppler shift.
Decrease
226. Increase the Doppler angle and _____ the size of the Doppler shift.
Decrease
227. Decrease the Doppler angle and ______ the size of the Doppler shift.
Increase
228. Cosine = 0
• 90 degree angle
• No Doppler shift
229. Cosine = 1.00
• 0 degree angle
• Largest Doppler shift
230. With spectral analysis the frequency is displayed on which axis?
Vertical y axis
231. What is displayed on the X axis of spectral analysis?
Time
232. Amplitude or power is displayed as what on spectral analysis?
Brightness
233. FFT
• Fast fourier time
• Current computer program for analyzing and displaying spectral representation
234. How can aliasing be eliminated?
• Increase PRF (increased nyquist limit)
• Shift baseline
• Increase size of angle
• Decrease transmit frequency
235. Main disadvantage of pulsed Doppler is?
Aliasing
236. Nyquist Limit
• 1/2 the PRF
• Exceeding this produces aliasing
237. PRF control
Changed the number of pulsed emitted per second
238. Primary advantage of CW Doppler
No velocity limit/ no aliasing
239. Main disadvantage of CW Doppler
• Large fixed sample volume
• POOR RANGE RESOLUTION
240. Color Doppler
• Qualitative, NOT quantitative information
• Will produce aliasing
• Good range resolution
• BART
241. How to eliminate color aliasing
• Increase PRF (scale setting)
• Decrease sample volume depth
• Use larger Doppler angle
• Lower transmit frequency
• Go from triplex(color, image, spectra) to duplex (color, image)
242. Power Doppler
• Encodes amplitude of blood cells
• Provides no info on direction of flow
• NO aliasing and less angle dependant
243. Components of pulsed Doppler instrumentation:
• Pulser
• Gated detector
• Spectral analysis
• Memory
• Display
• Speakers
244. Length of pulses produced by pulser
5-30 cycles
245. The time period for acquisition of Doppler signal is determined by the _____.
Size of the gate
246. Phase shift means
Motion is present
247. Rhythmic cycles or beats produced when waves of different frequencies produce interference are added together and termed
Beat frequency
248. Minimum number of cycles per pulse is?
4
249. Number of cycles required for fast flow
6-10
250. Number of cycles needed for gray scale
2-3 cycles
251. Number of cycles needed for slow flow
20-30
252. Typical sampling rate
25,600 times per second
253. High pass filter
• Rejects all frequencies below the threshold vaule
• Usually 100Hz
• Removes wall thump but not slow flow
254. Low pass filter
• Eliminates high frequency noise
• Improper adjustment can eliminate high frequency (fast) flow
255. One speed estimate has a _____  pulse minimum.
Three
256. More than 3 pulses are required in order to:
• Improve accuracy of the estimate
• Determine the variance
• Improve detection of slow flow
257. Typical ensemble length range
10-20 pulse
258. Increasing ensemble length will ___ frame rate.
Decrease
259. Ensemble length
• AKA pulse packet size
• The number of pulses required to produce one color scan line

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