review Flashcards
1
Q
The effects of the medium upon the sound wave is called?
A
Acoustic propagation properties
2
Q
The effects of the sound wave upon the biologic tissue is called?
A
Biologic effects
3
Q
Name the 3 acoustic variables
A
1) Pressure
2) Density
3) Distance
4
Q
What are the units of density
A
Kg/cm cubed
5
Q
What are regions of higher density and pressure called
A
Compressions
6
Q
What are regions of lower density and pressure called?
A
Rarefractions
7
Q
Name the 7 parameters that describe sound waves
A
1) Period
2) Frequency
3) Amplitude
4) Power
5) Intensity
6) Wavelength
7) Speed
8
Q
The time required to complete a single cycle is called
A
Period
9
Q
What are the units of period and how is it determined. Can period be adjusted by the songrapher
A
Units: seconds (any unit of time)
Determined by: Sound source
CANT be changed
10
Q
The number of cycles that occur in one second is called?
A
Frequency
11
Q
Why is frequency important? and how is it determined
A
Affects penetration and image quality
Determined by sound source
12
Q
How are period and frequency related?
A
Reciprocals and inversely related
13
Q
What is the equation for period and frequency
A
period= 1/ frequency frequency= 1/period
14
Q
The difference between the average value and the max value of an acoustic variable is called
A
Amplitude
15
Q
What are the units of amplitude, how is it determined, and can it be changed?
A
Units: decibels
Determined by: Sound source
CAN be changed
16
Q
Does amplitude increase or decrease as it propagates through the body?
A
Decreases
17
Q
How is power determined and can it be changed?
A
Determined by: Sound source
CAN be changed
18
Q
Does power increase or decrease as sound propagates through the body?
A
Decreases
19
Q
What is the relationship between power and amplitude?
A
Power is proportional to the waves amplitude squared
20
Q
If the amplitude is doubled what is the power increased by a factor of?
A
Power is increased by a factor of 4 (quadrupled)
21
Q
The concentration of energy in a sound beam describes?
A
Intensity
22
Q
What is the equation of intensity
A
Intensity= power/beam area (cm2)
23
Q
How is intensity determined and can it be changed?
A
Determined by: sound source
CAN be changed
24
Q
Does intensity increase or decrease as sound propagates through the body?
A
Decreases
25
How is intensity and power related
Directly
26
True or False
| Intensity is proportional to the amplitude of the wave sqaured
True
27
What is the length or distance of a single cycle?
Wavelength
28
What are the units of wavelength?
How is it determined and can it be changed?
What are the typical values
Units: meters
Determined by: Both source and medium
CANT be changed
Values: 0.1-08 mm
29
What is the equation for wavelength
wavelength= propagation speed/frequency
30
Higher frequency results of what kind of wavelength?
Shorter wavelength
31
What is the equation of wavelength in soft tissue?
wavelength= 1.54 mm/ frequency
32
What is the rate that sound travels through a medium
Propagation speed
33
What are the units of propagation speed? How is it determined and can it be changed?
Units: meters per second
Determined by: Medium
CANT be changed
34
How are wavelength and speed related
Directly
35
What is the equation for speed?
Speed= frequency X wavelength
36
True or False
| Speed only changed if the medium changes
True
37
The time from the start of a pulse to the end of a pulse describes
Pulse duration
38
What is the equation for pulse duration
pulse duration= # of cycles/ frequency
39
What are the units of pulse duration
How is pulse duration determined
Can it be changed
What are the typical values
Units: seconds
Determined by: Sound
CANT be changed
Values: 2-4 cycles
40
The time from the start of one pulse to the start of the next pulse describes
Pulse repetition period
41
What are the units of PRP
How is it determined
Can it be changed
Units: seconds (msec)
Determined by: Sound
CAN be changed
42
What happens to PRP as it increases
The imaging depth increases
43
The number of pulses that occur in one second describes
Pulse repetition frequency
44
What is the importance of PRF
depends solely upon imaging depth and in unrelated to frequency
45
How is PRF determined
Can it be changed
What are the typical values
Determined by sound
CAN be changed
Values: 1,000-10,000 hz or 1-10khz
46
When PRF is high what happens to the image
Image is more shallow
47
The length or distance that a pulse occupies in space is called
Spatial pulse length
48
What are the units of SPL
How is it determined
can be it changed
Units:mm, meters
Determined by: Both
CANT be changed
49
Do shorter pulses create higher or lower quality images
Higher quality images
50
What is the equation for SPL
SPL= # of cycles X wavelength
51
What intensity is the biggest
SPTP
52
Which intensity is most important for thermal bioeffects
SPTA
53
Which intensity is the smallest
SATA
54
What term describes a logarithmic scale
Decibels
55
A decrease in intensity, power, and amplitude of a sound wave as it travels describes
Attenuation
56
What are the units of attenuation
Decibels
57
What 2 things does attenuation of a sound in soft tissue depend on
1) The distance the wave travels
| 2) Frequency
58
What are the 3 components of attenuation
1) Absorption
2) Scattering
3) Reflection
59
This occurs when propagating sound energy strikes a boundary between 2 media and some returns to the transducer
Reflection
60
What type of reflection is smooth and returns in one direction
Specular
61
What type of reflection is rough and when reflected the sound is disorganized and random
Diffuse
62
If the boundary between 2 media have irregularities then the wave redirects in all directions describes
Scattering
63
This type of scattering occurs when a reflector is much smaller than the wavelength and the sound is uniformly distributed in all directions
Rayleigh
64
What are the units of attenuation coefficent
dB/cm
65
As frequency of sound increases what happens to the attenuation coefficient
Increases
66
```
Which of the following is the best estimate for attenuation coefficient of sound traveling in soft tissue?
A) 1.8 dB/cm/MHz
B) 0.77 dB/cm/MHz
C) 0.45 dB/cm/MHz
D) 1.0 dB/cm/MHz
```
C) because it is closest to 0.5
67
How is impedance determined
| What are the units
Determined: Medium
Units: Rayls or "Z"
68
What are 4 other names for normal incidence
Perpendicular
Orthogonal
Right angle
90 degrees
69
What incidence is anything other than 90 degrees or not at right angles?
Oblique incidence
70
What intensity is the sound wave at the instant prior to striking a boundary?
Incident intensity
71
What intensity is after striking a boundary it changes direction and returns back from where it came
Reflected intensity
72
What intensity occurs after striking a boundary and continues on in the same general direction that it was originally traveling?
Transmitted intensity
73
What is the unit for all intensites
W/cm2
74
What is the equation for incident intensity
Incident intensity= reflected intensity+ transmitted intensity
75
What intensity coefficient occurs when the percentage of the US intensity bounces back when the sound strikes the boundary
Intensity Reflection coefficient (IRC)
76
What intensity coefficient occurs when the percentage of the US intensity that is allowed to pass through when the beam reaches a boundary between 2 media
Intensity Transmission coefficient (ITC)
77
True or False
| Coefficients are reported in without units and are reported in percentages
True
78
In soft tissue what percentage of intensity is reflected back at an air tissue interface
99%
79
In soft tissue what percentage of intensity is reflected at a bone tissue interface
50%
80
With normal incidence what occurs only if the 2 media at the boundary have different acoustic impedances
Reflection
81
Transmission with a bend is called
Refraction
82
Refraction occurs when what 2 conditions are met
1) oblique incidence
| 2) Different propagation speeds
83
What law describes the physics of refraction
Snell's law
84
```
Which of these media have the greatest attenuation and the slowest speed?
A) bone
B) Tendon
C) Fat
D) Air
```
D) air
85
```
Which of these media have the greatest attenuation and the fastest speed?
A) Bone
B) Tendon
C) Lung
D) Fat
E) Air
```
A)Bone
86
The time needed for a pulse to travel to and from the transducer and reflector is called
Time of flight
87
True or false
| In soft tissue every 13 seconds of go return time means the reflector is 1 cm deeper in the body>
True
88
What is the equation for time of flight
Depth (mm)= 1.54 mm X go return time/ 2
89
Any device that converts one form of energy into another is
Transducer
90
What is a property of certain materials to create a voltage when pressure is applied or when they are mechanically deformed called
Piezoelectric effect
91
What is anther name for the piezoelectric effect
Ferroelectric material
92
What material is the piezoelectric made out of
Lead zirconate titanate
93
What is the complete destruction of all living microorganisms by means of exposure to heat, chemical agents, or radiation
Sterilization
94
This refers to the application of a chemical agent to reduce or eliminate infectious organisms on an object such as a transducer
Disinfection
95
How thick if the active element
1/2 wavelength thick
96
This part of the transducer protects the internal components from damage and insulates the patient from electric shock
Case
97
This part of the transducer has an impedance between those of the skin and the active element to increase the percentage of transmitted US between the active element and the skin
Matching layer
98
How thick is the matching layer
one quarter wavelength thick
99
True or false
| Short pules create better images
True
100
This part of the transducer is bonded to the active element to reduce its ringing and is commonly made of epoxy resin impregnated with tungsten
Damping element
101
What is another name for the damping element
Backing material
102
The range of frequencies between the highest and the lowest frequency emitted from the transducer describes
Bandwidth
103
When compared to therapeutic transducers, do imaging transducers use a wide or narrow bandwith
Wide
104
This represents the extent of damping and is a unitless number
Quality factor
105
When compared to therapeutic transducers do imaging transducers use a low or high Q
Low
106
This describes the sound waves frequency equal to the frequency of the voltage applied to the PZT by the machines electronics
Continuous wave transducer
107
The main frequency of the US for a pulsed transducer is determined by what 2 characteristics of the crystal
1) The thickness
| 2) The propagation speed of the piezoelectric material
108
For pulsed ultrasound when the frequency is higher is the crystal thick or thin? Is the PZT fast or slow
```
Crystal= thin
PZT= fast
```
109
For pulsed ultrasound when the frequency is low is the crystal thick or thin? Is the PZT fast or slow
```
Crystal= thick
PZT= slow
```
110
What is another name for the focus
Focal point
111
the location where the beam is the narrowest is called
The focus
112
What are 2 other names for the near zone
1) Near field
| 2) Fresnel zone
113
What zone is the region from the transducer to the focus called
Near zone
114
What are 2 other names for the focal length
1) Focal depth
| 2) Near zone length
115
What zone is the distance from the transducer to the focus
Focal Length
116
What are 2 other names for the far zone
1) Far field
| 2) Fraunhofer zone
117
What is the region around the focus where the beam is relatively narrow
Focal zone
118
Adjustable focus systems are called
Phased array
119
With a fixed focus transducer what are 2 factors that determine the focal depth
1) Transducer diameter
| 2) Frequency of sound
120
How are transducer diameter and focal depth related
Directly
121
How are frequency and focal depth related
Directly
122
```
Which of the following probes creates a beam with the shallowest focus
A) Small diameter, high frequency
B) Large diameter, high frequency
C) Small diameter, low frequency,
D) Large diameter, low frequency
```
C because shorter focal lengths are associated with small diameter low frequency probes
123
What describes the gradual spread of the ultrasound bream in the far field
Beam divergence
124
What 2 factors combine to determine beam divergence
1) Transducer diameter
| 2) Frequency of the sound
125
How are crystal diameter and beam divergence related
Inversely
126
True or false
| Smaller diameter crystals produce beams that spread out more in the far field
True
127
Do small or large diameter crystals improve lateral resolution in the far field
Large because the crystals create sound beams that diverge less in the far field
128
V-shaped waves are known as what 3 things
1) spherical waves
2) diffraction patterns
3) huygens' wavelets
129
What shape does large PZT crystals create
Hour glass figure
130
Do narrow beams create better or worse images
Better
131
Do sound beams diverge or converge in the near zone
Converge
132
Do sound beams diverge or converge in the far zone
Diverge
133
```
Which of the following transducers has the best lateral resolution in the far field
A) 4 HMz, 4 mm crystal diamter
B) 6 MHz, 4 mm crystal diamter
C) 4 MHz, 6 mm crystal diameter
D) 6 MHz, 6 mm crystal diamter
```
D)
134
The ability to distinguish two structures that are close to eachother front to back parallel to or along t he beams main axis is called
Axial resolution
135
What are 4 other names for axial resolution
Longitudinal
Axial
Range or radial
Depth
136
Do shorter pulses provide better or worse images
Better
137
What are the units for axial resolution
mm
138
With axial resolution what type of frequency and wavelength are needed for the best images
High frequency short wavelength
139
The minimum distance that 2 structures are separated by side to side or perpendicular to the sound beam that produces 2 distinct echoes is called
Lateral resolution
140
What are 4 other names for lateral resolution
Lateral
Angular
Transverse
Azimuthal
141
Which resolution is better axial or lateral
Axial
142
Lateral resolution is best at what point of the transducer
Best at the focus or near zone because the sound beam is narrowest at that point
143
True or false
| Since the beam diameter varies with depth, the lateral resolution also varies with depth
True
144
Focusing alters the beam in what 3 ways
1) narrower in the US beam
2) Shallower focus
3) Smaller focal zone
145
Where in the transducer is focusing mainly effective
In the near field and the focal zone
146
What are the 3 specific types of foucisng
1) Lens
2) Curved
3) Electronic
147
This type of focusing is external
Lens
148
This type of focusing is internal
Curved
149
What type of transducers have the poorest lateral resolution
Fixed focus since the focal depth is fixed and cant be adjusted
150
What type of transducers have the best lateral resolution
Phased array because the focal depth can be adjusted
151
This type of mode a dot moves across the display at a constant speed and when the echo returns an deflection proportional to the amplitude of the returning echo is observed
A- mode (amplitude)
152
In A mode which axis represents depth
X axis
153
In A mode which axis represents amplitue
Y axis
154
This type of mode the returning echoes are presented as spots on the line of travel of the emitted US pulse
B-mode (brightness)
155
In B mode which axis is represents depth
X axis
156
In B mode which axis represents the brightness of the dot
Z axis
157
Which mode is the only mode that displays the changing position of reflectors with respect to time
M-mode
158
In M mode which axis represents time
X axis
159
In M mode which axis represents depth
Y axis
160
For mechanical scanning how many active elements do the crystals contain?
1 active element
161
For mechanical scanning the crystal element is shaped like what?
Disc shaped
162
In mechanical scanning what is the image shaped like
Fan or sector shape
163
What type of transducer is a collection of active elements in a single transducer
Array
164
This type of transducer is a collection of elements in a line
Linear array
165
This type of transducer is a group of ringed elements (bull's eye) with a common center
Annular array
166
This type of transducer the elements are arranged in an arc
Convex or curved array
167
Approx how many elements are arranged in a line for a linear array
200
168
What element shape does a linear array have
Rectangle
169
This type of array fires at exactly the same time to create a narrow directional beam. What type of resolution does it improve
Linear. Improves lateral resolution
170
This type of array the scan lines are parallel and are equally spaced
Linear
171
In mechanical scanning what happens to the image when a crystal is defective
The entire image is destroyed
172
What is another name for swithched array
Sequential
173
In linear arrays when a crystal is defective what happens to the image
There is dropout extending from superficial to deep
174
This type of array can be adjusted or multi focus and is achieved electronically
Phased
175
Approx how many crystals are in a phased array
100-500
176
What type of image shape does a phased array make
A fan or sector shape
177
In this type of array the elements are fired nearly simultaneoulsy
Phased
178
In a phased array when there is no steering what happens to the focus
there is no transmit focus
179
In a phased array when there is upward steering what happens to the focus
There is not transmit focusing
180
In a phased array when there is a defective crystal what happens to the image
If one element malfunctions the steering and focusing becomes erratic
181
This system creates electronic patterns and delays are approx 10 nanoseconds
Beam former
182
This type of array the crystals are concentric rings cut from the same circular slab of PZT and the array looks like a bull's eye target
Annular phased array
183
In annular phased arrays what happens to the image when a crystal is defective
There is a horizontal (side-to side) band of drop out
184
A form of electronic receive electronic focusing is called
Dynamic aperature
185
This type of array creates a 3D US image and can measure volume more accurately than 2D.
Multidimensional array
186
This type of array is trapezodial and has a flat top that does not come to a point
Vector array
187
The ability to accurately locate moving structures at any particular instant in time is called
Temporal resolution
188
What does temporal resolution depend on
Frame rate
189
What is the fundamental limitation of temporal resolution
Speed
190
What are the typical values for frame rate
20-100 hz
191
Period multiplied by the number of cycles in a pulse equals
- Amplitude
- Wavelength
- Pulse duration
- Sound velocity
-Pulse duration
192
As wavelength increases:
- resolution improves
- frequency decreases
- depth of penetration increases
- attenuation decreases
-frequency decreases
193
How are period and wavelength related
Directly
194
What is the average speed of sound in soft tissue
1,540 m/s
195
All of the following are possible units for amplitude except:
- degrees
- decibels
- pascal
- watts
Watts
196
What machine controls affects amplitude
Output power
197
What effect will an increase in area have on intensity if power remains unchanged
Decrease
198
What is the acoustic characteristic of a medium
Impedance
199
Ultrasound transducers utilize which effect upon transmission
Reverse piezoelectric
200
The fundamental frequency for pulsed wave transducers is determined primarily by the elements
Thickness
201
The impedance value for the damping block is
Equal to the active element
202
Which of the following increases with damping:
- Output intensity
- Sensitivity
- Quality factor
- Bandwidth
-Bandwidth
203
Damping improves
Radial resolution
204
Methods for reducing the overall beam width in the near field includes all of the following except increase:
- focus
- transducer diameter
- frequency
- damping
-damping
205
A receive focus method utilizing delay lines is called
Dynamic
206
Changing pulse duration will affect all of the following except
- axial resolution
- lateral resolution
- spatial pulse length
- duty factor
-Lateral resolution
207
The resolution most affected by spatial pulse length is
Longitudinal
208
By increasing the image depth, duty factor
increases
209
What instrument control directly affects amplification
Overall gain
210
Which of the following has the narrowest dynamic range:
- transducer
- amplifier
- memory
- display
-display
211
The mode that displays returning echoes only from a pre-selected tissue depth is
C
212
A 1-bit digital system is considered
Bistable
213
A cosine of zero degrees is
1
214
A cosine of ninety degrees is
0
215
The major advantage of PW Doppler is:
- range discrimination
- aliasing
- Nyquist limit
- range ambiguity
-range discrimination
216
The color flow Doppler artifact associated with the superimposition of color on moving tissue is
Ghosting
217
The type of bioeffects mechanism caused by the movement of a mediums particles is
Direct mechanical
218
Experimental studies performed in the living body of a plant or animal is called
In vivo
219
Experimental studies performed outside the living body in an artificial environment is called
In vitro
220
What ultrasound component converts electrical into acoustic energy during transmission
Transducer
221
What ultrasound component creates the firing pattern for phased array systems
Pulser
222
The function of this component receives timing signal from synchronizer and creates an electrical signal that excites the PZT crystal
Pulser
223
True or false
| Greater electrical voltage the greater acoustic intensity
True
224
This ultrasound component is determined by the excitation voltage from the pulser and piezoelectric crystal vibrates with a magnitude related to pulser voltage
Transducer output
225
Changes in transducer output have what affect on the entire image
Brightnesss
226
Would you increase or decrease transducer output to improve signal-to-noise ratio
Increase
227
What are the 5 receiver operations
1) Amplification
2) Compensation
3) Compression
4) Demodulation
5) Rejection
228
This receivers purpose is to increase the strength of all electrical signals in the receiver prior to further processing
Amplification
229
This receiver purpose is used to create images of uniform brightness from top to bottom
Compensation
230
What will you adjust if you cannot see reflectors in the near or far field on your image
Adjust the TGC
231
This receivers purpose is to allow us to see all gray shades and decreases the dynamic range of the signals
Compression
232
If a signal with an initial dynamic range of 120 dB is compressed by 35 dB what is he dynamic range
120-35= 85 dB
233
This receivers purpose is to change the signal form to one more suitable for TV display.
Demodulation
234
What are the 2 steps of demodulation
1) Rectification
| 2) Smoothing
235
This receivers purpose is to display low level echoes only when clinically meaningful and is used to eliminate low level noise in our images
Rejection
236
When the image is too bright due to high output power, what happens to lateral and longitudinal resolution
Degrades
237
Which choice is best when the image on your ultrasound system displays reflectors only in a region far from the transducer but no reflectors in a region close to the transducer
a) Adjust the systems compensation
b) Use a higher frequency transducer
c) Decrease the output power
d) Adjust the reject level
a) Adjust the systems compensatino
238
Which choice is best when the image on your ultrasound system is saturated (too bright everywhere)
a) Decrease the overall amplification or gain
b) Use a higher frequency transducer
c) Decrease the output power
d) Adjust the reject level
c) Decrease the output power
239
Which choice is best when the image on your ultrasound system displays only bright reflectors but no weak reflectors throughout the image
a) Increase the systems overall gain
b) Use a higher frequency transducer
c) Increase the output power
d) Adjust the reject level
d) Adjust the reject level
240
Which choice is best when the image on your ultrasound system displays only reflectors in a region close to the transducer but not deep
a) Adjust the systems compensation
b) Use a higher frequency transducer
c) Increase the output power
d) Adjust the reject level
a) Adjust the systems compensation
241
In what area of a stenotic blood vessel does the max velocity of blood occur
a) within the stenosis
b) before the stenosis
c) before and after the stenosis
d) one cm after the stenosis
a) within the stenosis
242
If the frequency doubles, what happens to the wavelength
Decreases two fold
243
The type of artifact that produces a reduction in echoes distal to a highly reflective or highly attenuating structure is
Shadowing
244
Multipath artifacts result from
a) echoes that return directly to the transducer
b) shot gun pellets
c) echoes that take an indirect path back to the transducer
d) sound wave propagates through a medium at a speed other than soft tissue
e) small amplitude echoes resulting from electrical interference
c) echoes that take an indirect path back to the transducer
245
Viscosity is measured in units of
Poise
246
When an ultrasound beam passes obliquely across the boundary between two materials, what will occur if there is a difference in acoustic impedance in the two materials
a) reflection, impedance
b) reflection, density
c) refraction, propagation speed
d) refraction, impedance
c) refraction, propagation speed
247
What ultrasound method requires 2 active elements mounted side by side
Continuous wave doppler
248
The axial resolution of a transducer can be improved with____ but at the expense of _____
a) increased damping, sensitivity
b) frequency, lateral resolution
c) focusing, sensitivity
d) focusing, lateral resolution
e) beam width, lateral resolution
a) increased damping, sensitivity
249
Which of the following is NOT an acoustic variable
a) density
b) pressure
c) temperature
d) force
d) force
250
Improper location of an echo may be attributable to
propagation speed error
251
What is the most common result of high intensity ultrasound
Heat
252
Normal incidence is the term used when the ultrasound beam strikes a boundary between 2 media at what angle
Orthogonal
253
An artifact that is produced from interaction to the incident beam with a curved surface and that results in an acoustic shadow is referred to as
Edge artifact
254
When the piezoelectric crystal continues to vibrate after the initial voltage pulse, this is referred to as
Ring down time
255
The range equation relates
a) frequency, velocity, wavelength
b) frequency, velocity, time
c) distance, velocity, time
d) distance, frequency, time
e) incidence, reflection, refraction
c) distance, velocity, and time
256
The development of an electrical charge across the crystal thickness following deformation describes
Piezoelectric effect
257
Real time ultrasound transducers can be classified as
Phased, linear, annular, and vector
258
Which of the following ultrasound beams has a characteristic that is most likely to cause temp elevation in soft tissue
a) strongly focused
b) medium focused
c) unfocused
c) unfocused
259
One reason focused ultrasound beams with low intensities are less likely to cause bioeffects is that a focused beam is less efficient in heating a large mass of tissue to critical temp
True
260
The diameter of a disc shaped, unfocused piezoelectric crystal is 1 cm. What is the best estimate for the minimum lateral resolution of the ultrasound system
a) 1 mm
b) 5 mm
c) 1 cm
b) 5 mm
261
Acoustic impedance is a property of the____ and has units of___
Medium, Rayls
262
What causes enhancement artifact
a) sound beams bending
b) linear array transducer architecture
c) unexpectedly low acoustic attenuation
d) acoustic energy radiating in a direction other than the beams main axis
c) unexpectedly low acoustic attenuation
263
Where are shadowing artifacts commonly seen on an acoustic scan
a) deeper than a structure with a high impedance
b) shallower than a structure with a low propagation speed
c) deeper than a structure with a high attenuation
d) alongside of a structure with a low elastance
c) deeper than a structure with a high attenuation
264
Acoustic focusing of an ultrasound beam may create which artifact
Enhancement
265
What is a comet tail artifact fundamental mechanism of formation
Reflection
266
Unexpectedly low attenuation results in what artifact
Enhancement
267
The damping material helps to decrease the PRP achieved at a given imaging depth
False
268
What is the best estimate of the propagation speed of the ferroelectric element of a transducer used in a typical diagnostic imaging laboratory
a) 1.2 mm/microseconds
b) 4.0 m/sec
c) 4.0 mm/microseconds
d) 1.0 km/sec
c) 4.0 mm/microseconds
269
These transducer systems typically produce an image that throughout its entire depth, is approx as wide as the ultrasound transducer itsself
- linear switched array
- linear phased
- mechanical
- annular phased array
- convex or curvilinear array
- vector array
- linear switched array
- convex or curvilinear array
- vector array
270
Withh these transducers a sector image is produced At the top, the sector is very narrow and tapers to a point
- Linear switched array
- linear phased
- Mechanical
- Annular phased array
- Convex or curvilinear array
- vector array
- linear phased
- mechanical
- convex or curvilinear phased
- vector
271
What is the use of a greater number of channels to receive echoes from ever increasing depth called
Dynamic aperature
272
The pulse duration is increased as a result of the presence of backing material
False
273
What is the advantage of using a 1 1/2 dimensional array transducer
Improved elevational resolution
274
The backing material helps to decrease the duty cycle at a particular PRF
True
275
A bit is bistable having a value of what
0 or 1
276
What reduces speckle and minimizes shadowing artifacts
Compound imaging
277
Define the smallest amount of digital storage
Binary digit
278
Define the smallest element of a digital picture
Pixel
279
A group of 8 bits is called
a byte
280
Manipulating data before storage is in the scan converter is called
Preprocessing
281
Manipulating data after it has been stored in the scan converter is called
-This can also only be performed on frozen images
Postprocessing
282
An uncompressed signal within a systems receiver has a dynamic range of 135 dB. The receiver compresses the signal by 45 dB what is the dynamic range of the compressed signal
a) 135 dB
b) 45 dB
c) 90 dB
d) 100 dB
c) 90 dB
283
A signal in a receiver after compression has a dynamic range of 125 dB. The receiver compressed the signal by 25 dB. what was the initial dynamic range of the signal
a) 125 dB
b) 100 dB
c) 25 dB
d) 150 dB
d) 150 dB
284
An ultrasound system is operating in the harmonic mode. The fundamental frequency is 4MHz. What is the transmitted frequency
a) 8 MHz
b) 3 MHz
c) -3 dB
d) 4 MHz
d) 4 MHz
285
An ultrasound system is operating in the harmonic mode. The harmonic frequency is 8 MHz. What is the transmitted frequency
a) 8 MHz
b) 3 MHz
c) -3 dB
d) 4 MHz
d) 4 MHz
286
All of the following are characteristics of contrast agents except
a) high reflectivity
b) cost effective
c) metabolically inert
d) small enough to flow thru capillaries
b) cost effective
287
Which of the following is associated with pulse inversion imaging
a) improved temporal resolution
b) reduced frame rates
c) high frequency phase multipliers
d) amplitude modulation
b) reduced frame rates
288
What form of behavior creates harmonics
non linear
289
True or False
| Pulse inversion harmonics uses narrow bandwidth
False
290
The study of blood moving through the circulatory system describes
Hemodynamics
291
Name the 3 basic forms of blood flow
1) pulsatile
2) Phasic
3) Steady
292
This type of blood flow occurs as a result of cardiac contraction
Pulsatile flow
293
This type of flow is a result of respiration
Phasic
294
What are the 2 forms of laminar flow
1) plug flow
| 2) parabolic
295
This type of flow occurs when all of the layers and blood cells travel at the same velocity
Plug flow
296
What flow is commonly found in a normal physiologic state
Laminar flow
297
This type of blood flow is characterized by chaotic flow patterns in many different directions and at many speeds
Turbulent
298
What is the Reynolds number for turbulent flow
greater than 2,000
299
What is the Reynolds number for laminar flow
less than 1,500
300
Name the 3 forms of energy associated with blood
1) kinetic
2) pressure
3) gravitational
301
What form of energy is associated with a moving object
Kinetic
302
What form of energy is stored or has potential energy
Pressure
303
As blood flows through circulation energy it is lost in what 3 ways
1) viscous
2) frictional
3) inertial
304
This type of energy loss describes the thickness of a fluid.
- What are the units is measured in?
- How is it determined
Describes viscous energy
- Units are poise
- determined by hematocrit
305
This type of energy loss occurs when flow energy is converted to heat as one object rubs against another
Frictional
306
This energy loss relates to the tendency of a fluid to resist changes in its velocity
Inertia
307
Narrowing in the lumen of a vessel describes
Stenosis
308
The velocity of a stenosis is highest at what portion of a vessel
Narrowest part of the lumen
309
This describes the relationship between velocity and pressure in a moving fluid
Bernoulli's principle
310
What is the hydrostatic pressure at all locations within the arterial circulation
0 mmHg
311
What is the arterial pressure at the knee of the supine patient
140 mmHg
312
What is the arterial pressure in the carotid artery of the neck of the supine patient
140 mmHg
313
What is the arterial pressure measured in the toe of the upright patient
240 mmHg
314
What is the arterial pressure measured at a patients knee
215 mmHg
315
During inspiration does venous flow from the head, arms and IVC increase or decrease
Increase
316
During inspiration does venous return to the heart increase or decrease
Increase
317
During inspiration does venous flow in the legs increase or decrease
decrease
318
During expiration does venous flow from the head, arms, and IVC increase or decrease
Decrease
319
During expiration does venous flow in the legs increase or decrease
Increase
320
True or False
One reason focused ultrasound beams with low intensities are less likely to cause bioeffects is that a focused beam is less efficient in heating a large mass of tissue to a critical temperature
True
321
True or False
| It is generlaly believed that the effects of diagnostic ultrasound on biologic media are minimal
True
322
Which sound wave is least likely to create cavitation
a) 5 MHz, 2 MPa
b) 2 MHz, 4 MPa
c) 6 MHz, 2 MPa
d) 2 MHz, 2 MPa
c) 6 MHz, 2 MPa
323
True or False
The AIUM suggests that in vitro research confirming bioeffects is valuable and valid. Their results are significant and should be direclty applied to the clincial area
False
324
What type of artifact causes a reflection to be placed at an incorrect depth
a) lateral incertitude
b) shadowing
c) range ambiguity
d) indeterminate relaxation
c) range ambiguity
325
All of the following occur with focusing except
a) lower intensity at the focus
b) shorter near zone length
c) more compact focal zone
d) smaller diameter beam diameter at the end of the near zone
a) lower intensity at the focus
326
Which artifact results in improper side by side positioning of reflectors
a) multipath
b) comet tail
c) refraction
d) reverberation
c) refraction
327
Side lobe artifact usually results in all of the following except
a) hollow structures appearing filled in on the image
b) reflectors not appearing on an image
c) reflectors appearing in improper locations on the image
d) reflectors appearing in multiple locations on the image
b) reflectors not appearing on an image
328
The excitation of array elements with dissimilar voltagesis called____ and is used to___
a) dynamic aperture, reduce refraction
b) subdicing, eliminates lobes
c) apodization, remove flash artifact
d) apodization, reduce lobe artifact
d) apodization, reduce lobe artifact
329
With regard to the backing material of a pulsed ultrasound transducer True or False
The damping material helps to decrease the pulse repitition period achieved at a given imaging depth
False
330
What helps to determine the frequency of the sound produced by the transducer of a continuous wave ultrasound system
a) piezoelectric crystal diamter
b) piezoelectric crystal thickness
c) damping material density
d) ultrasound system electronics
d) ultrasound sysem electronics
331
With regard to the backing material of a pulsed ultrasound transducer True or False
The pulse duration is increased as a result of the presence of backing material
False
332
An ultrasonic pulse is traveling in soft tissue. Which of the following is most important in the determination of the frequency of the sound
a) the propagation speed of the ultrasound transducer matching layer
b) the thickness of the transducers backing material
c) the impedance of the transducers matching layer
d) the propagation speed of the transducers active element
d) the propagation speed of the transducers active element
333
What component of an ultrasound system is made of lead zirconate titanate (PZT)
Transducers active element
334
You are asked to fabricate a pulsed ultrasound transducer with the highest possible frequency. Which piezoelectric crystal would you select
a) 6 mm thick, 4 cm diameter, 4.0 mm/ms
b) 8 mm thick, 2 cm diameter, 6.0 mm/ms
c) 4 mm thick, 9 cm diameter, 5.0 mm/ms
d) 2 mm thick, 6 cm diameter, 6.0 mm/ms
d) 2 mm thick, 6 cm diameter, 6.0 mm/ms
335
The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. True or False
The frequency is increased
False
336
Typically as an ultrasound wave travels through soft tissue the power of the wave
Decreases
337
How many nanoseconds are in 7 seconds
a) 7,000,000
b) 7,000,000,000
c) 7 million
d) 0.00000007
b) 7,000,000,000
338
Three sound waves with identical frequencies of 3 MHz have powers of 2 mW, 5 mW, and 15 mW. They all travel through the three media wood, brick, and fat with identical thicknesses of 5 cm. True or False
The waves travel through all 3 media at the same speed since they have identical frequencies
False
339
True or False
| A sonographer can adjust the duration of an acoustic pulse since it depends upon the pulses propagation speed
False
340
An ultrasound pulse propagates from soft tissue through a mass. Sound's propagation speed in the mass is 1,575 m/s. True or False
The period of the sound wave decreases as it travels through the mass
False
341
A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The beam is unfocused. True or False
The near zone is the only region where the diameter of the sound beam is smaller than the transducer
False
342
The maximum imaging depth during an exam is unchanged. A new transducer with a longer pulse duration is used. True or False
The duty factor is increased
TRue
343
What happens to the PRP if the sonographer decreases the max imaging depth achieved in an ultrasound scan
Decrease
344
True or False
the period of an ultrasound wave is related to the frequency and is the same, regardless of whether the wave is pulsed or continuous
TRue
345
Which of these functions are performed by the receiver of an ultrasound system
a) amplification
b) threshold
c) compensation
d) demodulation
e) all the above
e) all the above
346
2 ultrasound transducers are used to perform doppler exams on the same patient These exams are identical except that the transducer frequencies are 5 and 2.5 MHz. Which exam will measure the highest doppler shift
a) 2.5 MHz exam
b) 5 MHz
c) neither
d) cannot be determined
b) 5
347
True or False
Velocity mode color doppler and variance mode color doppler will produce identical images when blood flow patterns are turbulent
False
348
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
a) attenuation
349
True or False
| Color flow doppler relies on pulsed doppler principles and is immune to aliasing artifact
False
350
True or False
On a color doppler image, red always represents flow toward the transducer, whereas blue indicates the flow away from the transducer
False
351
All of the following are related to a dedicated CW doppler transducer except
a) wide bandwidth
b) high quality factor
c) higher sensitivity
d) range ambiguity
a) wide bandwidth
352
True or False
Velocity mode color doppler and variance mode color doppler will produce identical images when blood flow patterns are laminar
True
353
True or False
The appearance of negative velocites in a pulsed doppler display always indicates that red blood cells are moving away from the transducer
False
