Final Review Flashcards
0
Q
Snell’s law describes physics of
A
refraction
1
Q
Name the three components of attenuation
A
Scattering, Absorption, reflection
2
Q
If the power is unchanged and the beam area doubles, what happens to the intensity?
A
it halves
3
Q
If intensity goes up by 25%, what happens to power?
A
it goes up 25%
4
Q
Reflection requires the media to have different
A
Impedance
5
Q
Wavelength has the greatest effect on
A
Axial resolution
6
Q
If the PRF increases, the duty factor
A
increases
7
Q
Longitudinal waves are parallel to the axis of the wave propagation where as transverse waves are perpendicular to the wave propagation. T or F
A
True
8
Q
Spatial pulse length _______ if the frequency is increased.
A
Decreases
9
Q
Propagation speed describes the number of waves in the medium.
T or F
A
False
10
Q
Initially, what determines the amplitude of an ultrasound wave?
A
Ultrasound System
11
Q
The maximum variation of an acoustic variable from its baseline is
A
Amplitude
12
Q
A reduction in intensity of a sound beam to one half its original intensity is a _____ db change
A
-3
13
Q
db is a mathematical representation with a _____ and _____ scale
A
Logarithmic and relative
14
Q
Name the units of attenuation
A
decibels or dB
15
Q
a sound wave strikes a boundary at normal incidence. The impedances of the two media are identical. What percentage of the sound wave is refracted?
A
0%
16
Q
As an ultrasound wave travels through the body, its amplitude usually;
A
Decreases
17
Q
The power of an ultrasound wave can be reported with which of the following?
A
Watts
18
Q
When a sonographer decreases the amplitude of a wave to 1/2 of its original value, how has the power changed?
A
Decreases 25%
19
Q
The intensity of an ultrasound beam is defined as the ____ in the beam ____ by the _____ of the beam
A
Power, divided, cross sectional area
20
Q
What is impedance?
A
The resistance of a medium to the sound traveling through it
21
Q
Reflection requires the media to have different
A
Impedance
22
Q
The two things that are required for refraction to occur are:
A
Oblique incidence, media with different sound speeds
23
Q
With specular reflection, the strength of the received signal depends on the following two factors?
A
Difference in acoustic impedance, angle of incidence
24
For soft tissue, one of the factors responsible for determining acoustic impedance is
Density
25
What interaction of ultrasound and tissue is primarily responsible for imaging the internal structure of organs?
Scattering
26
What sound tissue interaction is necessary to form an ultrasound image?
Reflection
27
Which of the following describes diffuse reflection?
The reflected beam is scattered in various directions
28
If you choose a lower frequency transducer to image a highly attenuating liver, what tradeoff are you making?
Decreased spatial resolution
29
Decreasing the following parameter will improve axial resolution
Spatial pulse length
30
Concentration of force or pound per square inch or pascal's?
Pressure
31
Concentration of mass or mass per unit volume
Density
32
The speed of sound is fastest in solids
| T or F
True
33
Wavelength always _____ as frequencies increase.
Decrease
34
Perpendicular incidence is also known as normal incidence.
| T or F
True
35
Refraction requires the 2 media to have different _______.
Propagation speeds
36
Which of the following will increase the duty factor?
Increasing PRF
37
The amplitude of an echo from a specular reflector depends on all of the following EXCEPT?
angle, attenuation, PRF, distance
PRF
38
What is the approximate coefficient for 1 MHz US in soft tissue?
.5 db/cm
39
You are scanning the liver at an incidence angle of 45 degrees. When the sound hits the interface of a hemangioma and reflects off it, the reflection angle will be______.
45 degrees
40
Pulse repetition frequency is directly related to pulse repetition period.
T or F
False
41
The spatial pulse length
Determines axial resolution
42
An ultrasound wave is a mechanical longitudinal wave.
| T or F
True
43
Compressions are regions of higher pressure. Rarefactions are regions of lower pressure in a sound wave.
T or F
True
44
Constructive interference in a sound wave are also called out-of-phase waves.
T or F
False
45
Destructive interference is also called out-of-phase waves.
| T or F
True
46
By adjusting the imaging depth, the sonographer can change the pulse repetition period, pulse repetition frequency, and the duty factor.
T or F
True
47
Wavelength has the greatest effect on axial resolution.
| T or F
True
48
Beam uniformity is a unitless ratio that describes the distribution of an ultrasound beam in space.
T or F
True
49
Temporal peak and temporal average intensities are the same for pulsed ultrasound
T or F
False
50
A wave's intensity is 2mW/cm2. There is a change of +9 dB. What is the final intensity?
16mW/cm2
51
The sonographer does not have the ability to change the power and intensity of the machine.
T or F
False
52
The formula for power is
Power = Intensity x Cross section (beam area)
53
If the power is unchanged and the beam area doubles, what happens to intensity?
It halves
54
3 dB change means the intensity will double in value.
| T or F
True
55
Attenuation decreases when frequency increases or path length increases.
T or F
False
56
What is the actual time that an US machine is creating a pulse?
Pulse duration
57
If the amplitude of a wave is increased to 3 times its original value, what happens to the intensity?
Intensity increases 9 times
58
A linear phased array has a/an _____ footprint?
Small
59
All of the following are TRUE about bandwidth EXCEPT:
Longer pulses have narrower bandwidths and provide better resolution
60
Preprocessing functions can be defined as:
A function that is performed before the echo data are stored in scan converter memory
61
The spatial pulse length
Determines axial resolution
62
To generate an ultrasound image, what is the order of activation for these system components?
P - T - R- M- VD
Pulser, Transducer, receiver, memory, video display
63
Demodulation and rejection are functions of the
Receiver
64
An annular array uses _____ beam steering
Mechanical
65
Spatial pulse length can be improved by
using greatly damped transducers
66
At one near zone length the beam is
Half the transducer diameter
67
The piezoelectric effect, heat energy is converted to mechanical energy.
T or F
False
Mechanical to electric
68
Focal depth is indirectly related to crystal diameter and frequency of US in the crystals
T or F
False
69
Point at which a man made transducer becomes deplarized
Curie point
70
Frequency is inversely related to the speed of sound in the crystals.
T or F
False
71
Which of the following will NOT result in a shorter pulse duration?
Using a lower propagation velocity
72
One way the sonographer can change the axial resolution is by adjusting the maximum imaging depth.
T or F
False
73
With this transducer, a defective crystal will cause a horizontal line dropout across the image.
Annular array
74
Which of the following lists is correct for the impedance from highest to lowest
PZT, matching layer, gel, skin
75
The best lateral resolution can be realized at
The focus
76
The range of frequencies within a pulse
Bandwidth
77
how does bandwidth relate to pulse duration and SPL
SPL and pulse duration = directly related
BOTH inversely related to bandwidth
78
A transducer with a wide bandwidth is likely to have
Good axial resolution
79
Which of the following transducers has the best lateral resolution in far zone
Highest frequency, largest crystal diameter
80
an annular array uses _____ beam steerer
Mechanical
81
Spatial pulse length can be improved by
using greatly damped transducers
82
with these transducers a defected crystal will cause a vertical line dropout in the image.
Linear switched array, convex sequential
83
A curved electrical spike firing pattern yields a?
Focused beam
84
We adjust the "receiving focus" or "dynamic aperture" when we adjust the focal zones on the machine.
T or F
False
85
Which of the following determines the frequency in a pulse wave transducer
thickness and propagation speed
86
States that the wavelength energies combine together to transmit energies along a central axis to give a beam shape of an hour glass.
Huygens
87
Which of the following has the deepest focus
6 MHz, 6mm crystal diameter
88
The beam of an unfocused transducer diverges
Fraunhofer zone
89
Frequency is inversely related to crystal thickness
| T or F
True
90
At 2 near zone length, beam diameter is twice the transducer diameter.
T or F
False
91
With these transducers, a defected crystal will cause poor steering and focusing in the image
Linear phased array, convex phased
92
A defective crystal in this transducer will cause the entire image to be lost
Mechanical transducer
93
Which of the following determines the frequency in a continuous wave transducer
electrical signal from the voltage applied to the PZT
94
Doubling the frequency causes axial resolution to be doubled.
T or F
False
95
Doubling the aperture increases the near zone length.
| T or F
True
96
Axial resolution is
The ability to distinguish two objects parallel to the ultrasound beam
97
Electronic focusing in slice thickness requires 1-2 rows of elements.
T or F
False
98
Which of the following transducers can be electronically steered
sector phased array and linear phased array
99
Axial resolution equals the spatial pulse length divided by 2.
T or F
True
100
Reduces the reflection at the transducer-tissue interphase
Matching layer
101
You decide to narrow your sector size from 90 to 45 degrees. The frame rate is
Doubled
102
All of the following decrease/degrade temporal resolution except...
Narrower sector
103
Which of the following will decrease temporal resolution
Increasing the number of scan lines
104
You decide you need to increase the line density by 4 times to improve your resolution, what also happens
The temporal resolution decreases
105
When you increase scanning depth, which one of these automatically decreases by the system to avoid range ambiguity
PRF
106
You finish your longitudinal kidney image and turn transverse. you decide to narrow your sector size to half the original. If the frame rate remains unchanged, which of the following must happen
the line density was doubled
107
Which of the following will increase duty factor, thereby improving temporal resolution
Increasing the PRF
108
Which of the following is consistent with improved temporal resolution
Higher frame rate
109
The number of images displayed per second in real time imaging is called
Frame rate
110
You decide to change from 5 focal zones to 1 focal zone what is the result
The temporal resolution increases
111
What is the primary advantage of multiple focal zones along each scan line in 2D images
improved lateral resolution
112
Frame rate is limited by the speed of sound in a medium and/or the depth of the view.
T or F
True
113
For each focus on a scan line in each frame a ______ is required
pulse
114
Which of the following will decrease temporal resolution
Increasing the number of scan lines
115
The fraction of the time the sound is transmitting is the
Duty Factor
116
An ultrasound system with shorter pulse duration will generally have better temporal resolution.
T or F
False
117
When penetration is multiplied by the number of foci, the number of scan lines per frame and the frame rate, the result cannot exceed
77,000
118
which of the following does not decrease the frame rate
Increasing the receiver gain
119
If the number of foci increases, the frame rate increases.
| T or F
False
120
In a real time scanner, which of the following choices determines the maximum frame rate.
Depth of View
121
Which of the following exams would require the best temporal resolution
Cardiac
122
Imaging deeper into a structure gives better temporal resolution.
T or F
False
123
The production of deformation from voltage is called
Piezoelectric effect
124
Preprocessing functions may be defined as
A function that is performed before the echo data are stored in memory
125
Use the minimum output power and the highest receiver gain required to produce optimal images describes which principle?
ALARA
126
The master synchronizer functions to
Communicate with all the individual components of the US system
Organize and times their function
Prepares them to operate as a single integrated system
127
What control could you adjust the signal to noise ratio
Power
128
Creates an image of uniform brightness from top to bottom
Compensation
129
Changes the signal form to one more suitable for TV display
Demodulation
130
Every signal is treated identically
Amplification
131
Affects all low level signals everywhere on the image
Rejection
132
Decreases the dynamic range
Compression
133
A-mode scanning represents the depth of the signal in the horizontal dimension.
T or F
True
134
An ultrasound wave is a mechanical longitudinal wave.
| T or F
True
135
The depth of a reflector is 2cm deep. what is the time of flight?
26us
136
The pulse generates the voltages that drive the transducer.
| T or F
True
137
In which case is the temporal resolution least important important
Thyroid
138
While scanning an obese patient for an abdomen, you increase both imaging depth and the scan line density, what also happens
Reduced temporal resolution
139
Increasing the transducer frequency will also have an effect on temporal resolution.
T or F
False
140
A sonographer using a phased array US machine turns off multi-focus feature, what is most likely the consequence of this action
the temporal resolution improves
141
Which operator control allows you to alter frame rate?
Depth
142
You need better spatial resolution to improve your image, which of the following adjustments will improve spatial resolution?
Increasing the frequency
143
Which of the following ultrasound imaging modalities has the poorest temporal resolution
Color flow imaging
144
PRF and frame rate are directly related.
| T or F
True
145
You are scanning a patient and your frame rate is so slow, you decide to do something to increase it, what do you do to have a faster frame rate
Decrease the number of scan lines
146
If you are scanning a left lobe of the liver and are at 8cm depth, then scan the right lobe and switch to 16cm depth, what can you do to keep your frame rate the same.
Narrow your sector
147
If the image depth of a scan is 15cm and there are 100 lines in the image, the number of pulses making up the scan is 100.
T or F
True
148
A-mode scanning represents the depth of the signal in horizontal dimension.
T or F
True
149
The amplitude of the reflection represented on a B-mode image is on the ____ axis
Z axis
150
The elimination of voltages that do not exceed a certain level is
Rejection
151
If the reflector is sitting twice as far away from the transducer, what effect will this have on the time of flight of sound pulse?
Double it.
152
The x axis of M-mode measures what?
Time
153
Rectification is the process of turning positive voltage into negative voltage.
T or F
False
154
When only bright reflecting objects and nothing else is displayed on the ultrasound machine, the sonographer should.
Adjust the reject level
155
The scan converter is part of the ultrasound system that contains the memory bank.
T or F
True.
156
An ultrasound system is operating on the harmonics mode, the harmonic frequency is on 8MHz, what is the transmitted frequency?
4 MHz
157
The ultrasound machine transmits a pulse with a fundamental frequency of 4MHz. when the sonographer switches to harmonic mode, what will the harmonic frequency be?
8MHz
158
The distance to a reflector is doubled, the time of flight for the pulse to travel to the reflector and back is
2 times
159
The range equation represents the relationship of the distance of the reflector to ____ and _____
Time of flight, distance
160
Post processing of the image occurs
after the A/D converter and storage but before display
161
Harmonics frequency characteristics occur due to non linear behavior.
T or F
True
162
When the sonographer is operating the ultrasound machine in continuous wave, the electrical frequency equals the ultrasound frequency.
T or F
True
163
What function of the receiver converts electronic signals from radiofrequency form to video form?
Demodulation
164
Which operator control adjusts the dynamic range of the displayed echoes
Compression
165
What are the two steps of demodulation?
Rectification and smoothing
166
What effect will you detect in the image if you increase the threshold control?
Decreased appearance of weak echo signals
167
List the order of operation of the instrumentation in the imaging process of ultrasound: Storage, Master synchronizer, receiver, display, transducer, pulser and beam former
```
Trandsucer
pulser and beam former
receiver
display
storage
master synchronizer
```
168
When you adjust the TGC what component of the ultrasound system implements the changes?
Receiver
169
A pulse is emitted by a transducer and is traveling in soft tissue. The go-return time, or time of flight, of a sound pulse is 52 microseconds. what is the reflector depth?
4cm
170
A lower frequency probe requires greater compensation than a higher frequency probe.
T or F
False
171
A-mode X and Y axis
```
X = depth
Y = amplitude
```
172
B-mode Z and X axis
```
Z = echo intensity or amplitude
X = depth
```
173
Velocity mode color doppler, and variance mode color doppler will produce identical images when blood flow patterns are laminar.
T or F
True
174
Aliasing is a disadvantage of power Doppler.
| T or F
False
175
Color Doppler instruments use
Pulsed Doppler
176
Which of the following on a color doppler display is/are presented in real time
Gray scale anatomy, flow direction
177
Which of the following reduce the frame rate of a color Doppler image
Wider color window
| increased ensemble length
178
Spectral analysis of color flow Doppler is most commonly performed by which of the following techniques
Autocorrelation
179
Compared with doppler shift imaging, Doppler power imaging is
More sensitive
angle independent
aliasing independant
speed independent
180
The two most common color maps used in color flow imaging is
Variance and Velocity
181
Lack of color in a vessel containing blood flow may be attributed to...
Low color gain
high wall filter setting
low priority setting
182
Auto correlation produces
Mean value of the Doppler shift and the variance
183
an annular array uses _____ beam steerer
Mechanical
184
Spatial pulse length can be improved by
using greatly damped transducers
185
with these transducers a defected crystal will cause a vertical line dropout in the image.
Linear switched array, convex sequential
186
A curved electrical spike firing pattern yields a?
Focused beam
187
We adjust the "receiving focus" or "dynamic aperture" when we adjust the focal zones on the machine.
T or F
False
188
Which of the following determines the frequency in a pulse wave transducer
thickness and propagation speed
189
States that the wavelength energies combine together to transmit energies along a central axis to give a beam shape of an hour glass.
Huygens
190
Which of the following has the deepest focus
6 MHz, 6mm crystal diameter
191
The beam of an unfocused transducer diverges
Fraunhofer zone
192
Frequency is inversely related to crystal thickness
| T or F
True
193
At 2 near zone length, beam diameter is twice the transducer diameter.
T or F
False
194
With these transducers, a defected crystal will cause poor steering and focusing in the image
Linear phased array, convex phased
195
A defective crystal in this transducer will cause the entire image to be lost
Mechanical transducer
196
Which of the following determines the frequency in a continuous wave transducer
electrical signal from the voltage applied to the PZT
197
Doubling the frequency causes axial resolution to be doubled.
T or F
False
198
Doubling the aperture increases the near zone length.
| T or F
True
199
Axial resolution is
The ability to distinguish two objects parallel to the ultrasound beam
200
Electronic focusing in slice thickness requires 1-2 rows of elements.
T or F
False
201
Which of the following transducers can be electronically steered
sector phased array and linear phased array
202
Axial resolution equals the spatial pulse length divided by 2.
T or F
True
203
Reduces the reflection at the transducer-tissue interphase
Matching layer
204
You decide to narrow your sector size from 90 to 45 degrees. The frame rate is
Doubled
205
All of the following decrease/degrade temporal resolution except...
Narrower sector
206
Which of the following will decrease temporal resolution
Increasing the number of scan lines
207
You decide you need to increase the line density by 4 times to improve your resolution, what also happens
The temporal resolution decreases
208
When you increase scanning depth, which one of these automatically decreases by the system to avoid range ambiguity
PRF
209
You finish your longitudinal kidney image and turn transverse. you decide to narrow your sector size to half the original. If the frame rate remains unchanged, which of the following must happen
the line density was doubled
210
Which of the following will increase duty factor, thereby improving temporal resolution
Increasing the PRF
211
Which of the following is consistent with improved temporal resolution
Higher frame rate
212
The number of images displayed per second in real time imaging is called
Frame rate
213
You decide to change from 5 focal zones to 1 focal zone what is the result
The temporal resolution increases
214
What is the primary advantage of multiple focal zones along each scan line in 2D images
improved lateral resolution
215
Frame rate is limited by the speed of sound in a medium and/or the depth of the view.
T or F
True
216
For each focus on a scan line in each frame a ______ is required
pulse
217
Which of the following will decrease temporal resolution
Increasing the number of scan lines
218
The fraction of the time the sound is transmitting is the
Duty Factor
219
An ultrasound system with shorter pulse duration will generally have better temporal resolution.
T or F
False
220
When penetration is multiplied by the number of foci, the number of scan lines per frame and the frame rate, the result cannot exceed
77,000
221
which of the following does not decrease the frame rate
Increasing the receiver gain
222
If the number of foci increases, the frame rate increases.
| T or F
False
223
In a real time scanner, which of the following choices determines the maximum frame rate.
Depth of View
224
Which of the following exams would require the best temporal resolution
Cardiac
225
Imaging deeper into a structure gives better temporal resolution.
T or F
False
226
The production of deformation from voltage is called
Piezoelectric effect
227
Preprocessing functions may be defined as
A function that is performed before the echo data are stored in memory
228
Use the minimum output power and the highest receiver gain required to produce optimal images describes which principle?
ALARA
229
The master synchronizer functions to
Communicate with all the individual components of the US system
Organize and times their function
Prepares them to operate as a single integrated system
230
What control could you adjust the signal to noise ratio
Power
231
Creates an image of uniform brightness from top to bottom
Compensation
232
Changes the signal form to one more suitable for TV display
Demodulation
233
Every signal is treated identically
Amplification
234
Affects all low level signals everywhere on the image
Rejection
235
Decreases the dynamic range
Compression
236
A-mode scanning represents the depth of the signal in the horizontal dimension.
T or F
True
237
An ultrasound wave is a mechanical longitudinal wave.
| T or F
True
238
The depth of a reflector is 2cm deep. what is the time of flight?
26us
239
The pulse generates the voltages that drive the transducer.
| T or F
True
240
In which case is the temporal resolution least important important
Thyroid
241
While scanning an obese patient for an abdomen, you increase both imaging depth and the scan line density, what also happens
Reduced temporal resolution
242
Increasing the transducer frequency will also have an effect on temporal resolution.
T or F
False
243
A sonographer using a phased array US machine turns off multi-focus feature, what is most likely the consequence of this action
the temporal resolution improves
244
Which operator control allows you to alter frame rate?
Depth
245
You need better spatial resolution to improve your image, which of the following adjustments will improve spatial resolution?
Increasing the frequency
246
Which of the following ultrasound imaging modalities has the poorest temporal resolution
Color flow imaging
247
PRF and frame rate are directly related.
| T or F
True
248
You are scanning a patient and your frame rate is so slow, you decide to do something to increase it, what do you do to have a faster frame rate
Decrease the number of scan lines
249
If you are scanning a left lobe of the liver and are at 8cm depth, then scan the right lobe and switch to 16cm depth, what can you do to keep your frame rate the same.
Narrow your sector
250
If the image depth of a scan is 15cm and there are 100 lines in the image, the number of pulses making up the scan is 100.
T or F
True
251
A-mode scanning represents the depth of the signal in horizontal dimension.
T or F
True
252
The amplitude of the reflection represented on a B-mode image is on the ____ axis
Z axis
253
The elimination of voltages that do not exceed a certain level is
Rejection
254
If the reflector is sitting twice as far away from the transducer, what effect will this have on the time of flight of sound pulse?
Double it.
255
The x axis of M-mode measures what?
Time
256
Rectification is the process of turning positive voltage into negative voltage.
T or F
False
257
When only bright reflecting objects and nothing else is displayed on the ultrasound machine, the sonographer should.
Adjust the reject level
258
The scan converter is part of the ultrasound system that contains the memory bank.
T or F
True.
259
An ultrasound system is operating on the harmonics mode, the harmonic frequency is on 8MHz, what is the transmitted frequency?
4 MHz
260
The ultrasound machine transmits a pulse with a fundamental frequency of 4MHz. when the sonographer switches to harmonic mode, what will the harmonic frequency be?
8MHz
261
The distance to a reflector is doubled, the time of flight for the pulse to travel to the reflector and back is
2 times
262
The range equation represents the relationship of the distance of the reflector to ____ and _____
Time of flight, distance
263
Post processing of the image occurs
after the A/D converter and storage but before display
264
Harmonics frequency characteristics occur due to non linear behavior.
T or F
True
265
When the sonographer is operating the ultrasound machine in continuous wave, the electrical frequency equals the ultrasound frequency.
T or F
True
266
What function of the receiver converts electronic signals from radiofrequency form to video form?
Demodulation
267
Which operator control adjusts the dynamic range of the displayed echoes
Compression
268
What are the two steps of demodulation?
Rectification and smoothing
269
What effect will you detect in the image if you increase the threshold control?
Decreased appearance of weak echo signals
270
List the order of operation of the instrumentation in the imaging process of ultrasound: Storage, Master synchronizer, receiver, display, transducer, pulser and beam former
```
Trandsucer
pulser and beam former
receiver
display
storage
master synchronizer
```
271
When you adjust the TGC what component of the ultrasound system implements the changes?
Receiver
272
A pulse is emitted by a transducer and is traveling in soft tissue. The go-return time, or time of flight, of a sound pulse is 52 microseconds. what is the reflector depth?
4cm
273
A lower frequency probe requires greater compensation than a higher frequency probe.
T or F
False
274
A-mode X and Y axis
```
X = depth
Y = amplitude
```
275
B-mode Z and X axis
```
Z = echo intensity or amplitude
X = depth
```
276
Velocity mode color doppler, and variance mode color doppler will produce identical images when blood flow patterns are laminar.
T or F
True
277
Aliasing is a disadvantage of power Doppler.
| T or F
False
278
Color Doppler instruments use
Pulsed Doppler
279
Which of the following on a color doppler display is/are presented in real time
Gray scale anatomy, flow direction
280
Which of the following reduce the frame rate of a color Doppler image
Wider color window
| increased ensemble length
281
Spectral analysis of color flow Doppler is most commonly performed by which of the following techniques
Autocorrelation
282
Compared with doppler shift imaging, Doppler power imaging is
More sensitive
angle independent
aliasing independant
speed independent
283
The two most common color maps used in color flow imaging is
Variance and Velocity
284
Lack of color in a vessel containing blood flow may be attributed to...
Low color gain
high wall filter setting
low priority setting
285
Auto correlation produces
Mean value of the Doppler shift and the variance
286
Tube length, radius and viscosity all effect ______?
Resistance
287
A smaller vessel lumen (from stenosis for instance) result in?
More resistance
288
Which of the following will help to eliminate aliasing?
Change over to continuous wave Doppler
289
A larger vessel has ____ Flow
increased
290
Speed of flow is consistant across the entire tube. This is known as ____ Flow
plug flow
291
Speed of flow is slowest at the outer edges because of the friction with the walls. this is known as _____ flow
laminar
292
The person at the sound sourse hears?
No shift
293
The observer distant from the sound source hears a
Doppler effect
294
When we hear more cycles per second we hear a
Higher frequency
295
recieved frequeny minus the source frequency =
Doppler shift
296
The sound that we send into the body
Inaudible
297
The Doppler shifted frequency is
audible
298
Negative shifts are demonstrated?
Below the baseline
299
Positive shifts are demonstrated?
Above the baseline
300
The measured velocity is the true velocity at______ degrees
0 degrees
301
No Doppler shift will be appreciated at _______ degrees
90 degrees
302
The measured velocity is underestimated about 30% at _____ degrees
45 Degrees
303
When nothing is moving we get
No doppler shift
304
The nyquist limit appears at
half the PRF
305
If a vessel has a stenosis that narrows the vessel by half, the average speed through the stenosis is?
Doubled
306
Two important charectoristics of fluid that affect flow are?
Density and Velocity
307
Mass is an objects resistance to acceleration or flow. This resistance is called?
Inertia
308
Mass per unit volume describes?
Density
309
Resistance to flow offered by fluid in motion is called?
Viscosity
310
Blood flows from _____ side to the _____ side in our circulation
arterial to venous
311
artieries are the ______ pressure side in the circulation
High
312
Veins are the _____ pressure side in our circulation
low
313
In order for blood to flow we need a _____ differance
Pressure
314
Increased radius causes _____ resistance
decreased
315
increased tube length causes _____ resistance
increased
316
Increased resistance causes _____ velocity
faster
317
Increased viscosity causes ____ resistance
higher
318
As blood flows along the circulatory path, some energy is lost in the form of ______
Heat
319
This states that the radius of the stenosis has a dramatic effect on the stenosis because it is raised to the fourth power
Poisuille's law
320
The body tries to keep flow constant proximal to, in, and distal to a stenosis, this is called
Continuity rule
321
Another word for the brightness of a hue and saturation presented is?
Luminance
322
Aliasing is a disadvantage of power Doppler.
| T or F
False
323
The sound beam is traveling East to West, The blood flow is traveling North to south, which statement is true
No Doppler shift is created
324
Velocity mode color Doppler and variance mode color Doppler will produce identical images when blood flow is laminar.
T or F
True
325
You are scanning a pediatric patients liver, performing Doppler of the hepatic artery using a transducer with a frequency of 8 MHz. Aliasing is occuring and you would like to eliminate it. You can change transducers and scan with a 2.5 MHz transducer in order to succussfully eliminate aliasing.
T or F
True
326
Spectral analysis of color flow Doppler is most commonly performed by which of the following techniques
Autocorrelation
327
No aliasing, no angle dependance and increased sensitivity are all features of color Doppler.
T or F
False
328
Which of the following will help to eliminate aliasing?
increase your angle so it is closer to 90 degrees
329
One of the disadvantages of having more pulses in color packet is?
More time is required to aquire the information
330
Which of the following reduce the frame rate of a color Doppler image?
Wider color window
| Increased ensamble length
331
All of the following are true about the nyquist limit except
It cannot be changed by the operator
332
The two most common color maps used in color flow images are?
Variance and velocity
333
One thing autocorrelation does not determine is
Perfusion
334
Autocorrelation is used with color Doppler because of the enormous amount of Doppler information that requires processing. Autocorrelation is much more accurate and much faster than Fast fourier transformation.
T or F
False
335
If you are scanning a liver, performing duplex Doppler on the hepatic artery at the depth of 11cm and aliasing is occuring, you can reposition your probe to scan at a depth of 13cm and the aliasing will be eliminated.
T or F
False
336
This type of flow occurs at the bifurcation area
Disturbed
337
When there is no pressure difference, there will be no flow. but according to Bernoulli's principle, when there is pressure difference fluid will flow from the area of low pressure to the area of high pressure.
T or F
True
338
The resistance to flow offered by a fluid in motion is
Viscosity
339
the top and bottom end of the color map represents?
the nyquist limit
340
Bernoulli's effect is an increase in pressure associated with high flow speed at or through a stenosis.
T or F
False
341
This flow happens past a stenosis and has a random and chaotic flow pattern.
Turbulent
342
Which of the following on a color Doppler display are presented in real time
Gray scale anatomy and flow direction
343
Grating lobes occur with mechanical transducers.
| T or F
False
344
This artifact produces equally spaced echoes parallel with the sound beam
reverberation
345
The most likely cause for a beam thickness of artifact
Partial volume effect
346
Propagation speed describes the number of waves in the medium.
T or F
False
347
A highly attenuating structure causes what to occur?
Shadowing
348
Enhancement occurs due to abnormally low attenuation resulting in bright echoes.
T or F
True
349
When reducing an ultrasound image all of the following assumptions are made except.
All structures create reflections of equal magnitude
350
Mechanical or single crystal transducers create side lobes.
| T or F
True
351
The know that artifacts are not the true anatomical structure. Artifacts do not help in making a diagnosis.
T or F
False
352
Mirror image artifact can appear along side of the true anatomy.
T or F
False
353
Absorption coefficients are highest in bone.
| T or F
True
354
Of the following choices, which is considered most important to the sonographer with regards to bioeffects?
Duration of study
355
Which testing device is used to measure acoustic output power?
Hydrophone
356
It is generally beleived that the ultrasound bioeffects are minimal at intensity levels typical of those produced by diagnostic imaging equiptment
True
357
Maximal heating is related to temporal peak intensity.
| T or F
False
358
Which of the following is NOT a potential mechanism for production of bioeffects from ultrasound exposure of the body?
Fractionation
359
What is the highest SPTA intensity of an unfocused ultrasound wave where there have been no observed bioeffects
100 mW/cm2
360
Some ultrasonic bioeffects studies are performed in vivo. what is the meaning of the term in vivo?
Observable in a living body
361
what kind of resolution cannot be assessed on a test phantom?
Contrast
362
Cavitation is related to temporal peak intensity.
| T or F
True
363
A mirror image artifact is a result of the machines assumption that?
Sound travels directly to the reflector and than back to the transducer
364
A quality assurance program is?
Needed by all labs
365
Which of the following sets of properties of a test phantom is most relevent when assessing depth calibration accuracy?
reflector spacing and propagation speed
366
Sometimes this can be interpretted as an editional vessel which has a spectrum similar to that of the real vessel
Doppler mirror image
367
When you increase the PRF in attempt to solve the problem of aliasing, you can encounter
Range Ambiguity
368
An artifact that gives rise to a double or duplicate image
Split image or refraction
369
The most likely cause for beam thickness artifact is
Volume averaging
370
With this artifact, the correct number of echoes appear on the image: there is less than average attenuation on a structure: and the artifact is parallel to the sound beam.
Enhancement
371
This artifact causes a sound beam to bounce off a reflector and be redirected, it places the artifact deeper than the true reflector
Mirror image
372
This artifact places structures much closer to the surface than they should be
Propagation speed error
373
With this artifact there is high attenuation, absence of true anatomy on the scan, and structures that lie deeper than the original structure are not imaged
Shadowing
374
The most common type of artifact in patients with a shotgun wound is
Comet tail artifact
375
At this point aliasing begins
nyquist limit
376
With this color representation, low velocity red is seperated from low velocity blue by a black line
flow reversal
377
With this color representation, high velocity red and high velocity blue are shown directly next to one another with no black line inbetween
Aliasing
378
An artifact produced from interaction of the incidence beam with a curved surface and results in an acoustic shadow is
a refractive edge shadow artifact
379
Two things that can help reduce grating lobes are harmonics and apodization.
T or F
False
380
Which of the following bests describes and epidemiologic bioeffect study?
Randomized and Prospective
381
Mirror image artifacts is often seen around the pancreas.
| T or F
False
382
Which artifact has a grainy appearance and is caused by interference effect of scattered sound
Speckle
383
You are performing a QA test on US system using a tissue equivilant phantom. you make an adjustment using a knob on the system council that changes the appearance of reflector brightness from fully bright to barely visible. you are evaluating what?
Sensitivity
384
With transiate cavatation, the bubbles burst.
| T or F
True
385
The force excerted on a sound beam on an absorber or a reflector is called radiation force.
T or F
True
386
You are most likely to experience the range ambiguity artifact on Doppler under which of the following conditions?
Pulsed wave Doppler, PRF 22kHz, 3 MHz Doppler frequency
387
All of the following statements regarding in-vitro bioeffects are true except?
In_vitro bioeffects conclusions are clinically relevent
388
Attenuation in tissue primarily due to absorption that is conversion of sound energy to heat energy. Thus ultrasound increases the temperature of tissue as it travels through it. The extent to which the temperature rises relies on the following four factors. T or F
Implied intensity or power, frequency, impedance, age of patient
False
389
When producing an ultrasound image all assumptions are made except?
All structures create reflection of equal magnitude
390
From a safety standpoint. Which of the following methods is the best?
Low transmit output and high receiver gain
391
At what location in a sound beam is SPTA intensity the highest
The focal point
392
If the output of an US machine is calibrated in dB and the output is increased by 20 dB, the beam intensity is increased by
100 times
393
How is range ambiguity artifact eliminated
lower the PRF
394
Under which circumstance is cavitation most likely to occur
High pressure, low frequency
395
Side lobes are caused by the use of single crystal transducers
Grating lobes are caused by the use of arrays
T or F
True
396
The propogation speed of US in an AIUM test object is
1.54 mm/microsec
397
Generally linear ray tansducers have excellent elevational resolution.
T or F
Fales
398
If sound is traveling faster than the machine expects, it places the structure shallower than it should be
T or F
True
399
Which type of artifact occurs most commonly with highly reflective objects
Shadowing
400
A shadowing artifact occurs behind an artifact because of
Higher than usual attenuation
401
If the wires in an AIUM test object do not appear in the same place as on the display, what is the issue?
Registration accuracy
