SPI Review Flashcards
1
Q
What is described as the ability of an object to resist compression and relates to the hardness of a medium?
A
Stiffness
2
Q
An increase in PRF would lead to a _______________ in duty factory
A
An increase in duty factor.
3
Q
Of the following, which has the highest propagation speed?
Air
Bone
soft tissue
water
A
Bone has highest propagation speed
Bone has a propagation speed of 4080m/s
4
Q
Which of the following has the lowest propagation speed?
water
soft tissue
bone
lung tissue
A
Lung tissue. Air has highest attenuation value but lowest propagation speed.
5
Q
As imaging depth increase, the PRF must:
A
Decrease
Depth and PRF are inversely related
6
Q
What describes refraction at an interface?
A
Snell’s law. Snell’s law describes angle of transmission at the interface based on angle of incidence and speed
7
Q
Pressure is typically expressed in:
A
Pascals
May also see kilopascals or megapascals
8
Q
The typical range of frequency for medical diagnostic ultrasound imaging is:
A
2 to 20 MHz
9
Q
The attenuation coefficient in soft tissue is equal to:
A
One half of the operating frequency
10
Q
Micro denotes:
A
One-millionth
11
Q
Centi denotes:
A
One-hundredth
12
Q
Mega denotes:
A
One million
13
Q
Milli deontes:
A
One-thousandth
14
Q
The distance over which one cycle occurs is:
A
wavelength
15
Q
What requires an oblique interface and a propagation speed mismatch?
A
Refraction
16
Q
Areas of high pressure and density are referred to as:
A
compressions
17
Q
SPL can calculated by:
A
multiplying the number of cycles by the wavelength
18
Q
Density is typically measured in :
A
kilograms per centimeter cubed
19
Q
As a sound wave travels through the human body, the intensity of the sound wave decreases as a result of :
A
Attenuation
20
Q
What is the amount of attenuation that occurs if a 6-MHz sound beam travels through 4cm of soft tissue?
A
-12dB
1/2 operating frequency is 3
attenuates 3dB every cm the sound beam travels
3x4cm= -12dB
21
Q
As imaging depth increases, PRP:
A
Increases
depth and PRP are directly related
22
Q
What are the units of duty factor?
A
Duty factor is unitless
23
Q
The percentage of time that the ultrasound system is producing pulses of ultrasound is describes the:
A
Duty factory
24
Q
Density and propagation speed are ______________ related
A
Inversely related
Directly related to stiffness
25
Power is proportional to ___________________
amplitude squared
26
Wavelength is determined by:
Both medium and the sound source
27
Propagation speed is determined by:
Medium only
28
The number of ultrasound pulses emitted in 1 second is:
PRF
29
What is defined as only the time of transmission?
Pulse duration
Time for a pulse to occur only includes on time
30
A doubling of the amplitude results in what change to the intensity of the beam?
The intensity is quadrupled
31
Frequency is determined by:
Sound source only
Thickness of the element and propagation speed of the element determine frequency
32
If the angle of incidence is 40 degrees, what is the angle of transmission at the interface if medium 1 has a propagation speed of 1320 m/s and medium 2 has a propagation speed of 1700 of m/s?
O degrees
>40 degrees
<40 degrees
>40 degrees
Propagation speed 2 is > than one so the angle of incidence would be >
33
The change in the direction of a transmitted sound wave that occurs when sound interacts with two different tissue types that have a different propagation speed is referred to as:
Refraction
34
What would be an appropriate unit of measurement for propagation speed?
millimeters per microsecond (mm/ms)
35
The major component of attenuation is:
absorption
36
In clinical imaging, the wavelength typically measures between:
0.1 -0.8 mm
37
The DF for continuous wave ultrasound is:
100%
38
What relates to the strength of the sound wave?
Amplitude, Intensity and Power
39
Dampening of the sound beam reduces __________________________.
SPL
40
Adding dampening material to the transducer improves which type of resolution?
Axial
Damping shortens the pulse increasing axial resolution
41
What time is defined as the beginning of one pulse to the beginning of the next pulse, and therefore, includes "on" time and "off" time.
Pulse repetition period (PRP)
42
What are the units for pressure?
Pascals or pounds per square inch
43
What term is defined as "the power of a wave divided by the area over which the power is distributed?"
Intensity
44
Transducers have material within them that when electronically stimulated produces ultrasound waves. This is most likely some form of:
Lead zirconate titanate
45
The amplitude of a wave is doubled. What effect does this have on the power of the beam?
It quadruples.
Power is proportional to amplitude squared
46
The portion of the sound beam where the molecules in the medium are farther apart describes an area of:
Rarefaction
47
If only the density of a medium is increased, then the propagation speed will:
Decrease
Density and propagation speed are inversely related
48
Sound is technically a:
Mechanical and longitudinal wave
49
The maximum or minimum value of an acoustic variable from the baseline to the peak describes the:
Amplitude
50
What is considered ultrasonic?
Greater than 20,000 Hz
51
What is the speed of sound in soft tissue?
1540 m/s or
1.54 mm/ms
52
What would be considered the narrowest part of a sound beam?
Focal Zone
53
What is the part of the transducer that shortens the vibration of the element?
Damping material
54
Along with imaging depth, what else determines the frame rate?
Number of lines per frame/line density
Number of focal zones
55
Which type of resolution is necessary for providing an accurate representation of moving structures?
Temporal resolution
56
If the depth is increased and the frame rate is unchanged, what else must have decreased?
The number of scan lines per frame.
57
Which transducer can be described as having the scan lines originate from a common point of origin?
Sector phased array
58
You are using a 6 MHz broadband transducer that offers the lowest frequency at 4.5 MHz and the highest frequency at 7.5 MHz. What is the bandwidth of this transducer?
3 MHz
59
Along with crystal diameter, the divergence in the far field is also determined by:
Frequency.
Aperture and frequency determine divergence in the far field
60
What would cause a decrease in temporal resolution?
Increased line density
61
What would increase temporal resolution?
Decreased sector size
Single transmit focal zone
Increased PRF
62
What would cause an increase in frame rate?
Increased PRF(same as decreasing depth)
63
What happens to the diameter of the sound beam in the fresnel zone?
It decreases with distance from the transducer
64
Which resolution typically has the lowest numerical value in clinical imaging?
Longitudinal
65
What is likely to increase the near zone length?
A large crystal diameter and high frequency
Large crystal diameter and high frequency does not image deep so there is less divergence
66
Imaging transducers typically have ________________ quality factors and ___________________ bandwidths
low quality factor, wide bandwidth
67
Damping material produces:
Decreased sensitivity
Wide bandwidth
low quality factor
decreased SPL
68
What electrical patterns produces electronic focusing of the ultrasound beam?
curved
69
In an unfocused, single element transducer, the width at the focal point of the sound beam measures how much compared to the beam width at the face of the transducer?
One half
Measures one half of the beam width at the face of the transducer
70
What facilitates the transmission of sound from the element into the patients skin?
Matching layer
71
What describes the range of frequencies present within the beam?
Bandwidth
72
What type of interference results in a higher amplitude sound wave?
Constructive interference
73
What does not affect temporal resolution?
SPL
74
What best describes the components of the damping material?
Epoxy resin loaded with tungsten
75
Describe the characteristics of the linear sequenced array transducer?
Rectangular shape
Firing is sequential
Electronically focused
76
Lateral resolution varies with ____________________
depth
77
Damping material improves __________________--- resolution.
Axial
78
Which transducer has a trapezoidal image shape and is from a phased array transducer
Vector
79
Temporal resolution relates to
frame rate
80
What may also be referred to a the far zone?
Fraunhofer zone
81
What states that waves are the result of the interference of many wavelets produced at the face of the transducer?
Huygens principle
82
What resolution is in the third dimension of the beam?
Elevational resolution
(Slice thickness plane)
83
The higher the frequency, the _________________ the near zone length
longer
84
What is defined as shocking the piezoelectric elements one at a time or more than one at a time with very small time differences in between in order to shape and steer the beam?
Phasing
85
Spatial resolution consist of
Contrast resolution
Axial resolution
Elevational resolution
Lateral resolution
Elevational resolution
86
Which transducer has no range resolution?
Continuous wave transducer
87
Which transducer is not used for imaging?
Continuous wave transducer
88
What transducer is also referred to as a sector or vector transducer?
Phased array
89
What shortens the length of the pulse by decreasing the number of cycles in the pulse?
Backing material
90
Which transducer produces a pie shaped image?
Phase array
91
What portion of the transducer is closest to the patient?
Matching layer
92
What does heat sterilization do to an ultrasound transducer?
Kills pathogens and destroys the transducer
93
What is defined as the minimum distance two reflectors can be, parallel to the beam, and still appear on the screen as two dots?
Range or Axial resolution
94
What describes the result of destructive interference?
The resulting wave is smaller than the original wave
95
To produce a transducer with a higher frequency one should:
Use a thinner piezoelectric element
96
A transducer is being used to image two reflectors parallel to the beam that are 0.2mm apart. The spatial pulse length of the transducer is 0.3 mm. What is seen on the display, one reflector or two?
Two.
SPL is 0.3. Axial resolution is 1/2 SPL so axial resolution is 1.5 so you would see two dots
97
What would be best utilized for imaging of deep structures in the abdomen?
Curved sequenced array transducer
98
What best describes the frame rate?
The frame rate is equal to the pulse repetition frequency divided by the lines per frame
99
What is defined as time or the ability to display structures in real time?
Temporal resolution
100
When high level disinfection is needed, how are ultrasound transducers commonly disinfected?
With cold disinfection methods
101
The output of the pulser determines the __________________ of the acoustic pulse
Intensity
102
What is the function of the receiver that changes the brightness of the echo amplitude to adjust for attenuation with depth?
Compensation
103
What tasks is incorporated in the process of demodulation?
Rectification
Rectification and smoothing are part of the demodulation component of the receiver
104
What is the smallest element in a digital picture?
pixel
105
The part of the transducer called a transmit channel consists of a transducer element and a____________________
pulse delay
Pulser sends to pulse delay which sends the signal at the appropriate time to the PZ element
106
The part of the machine that ensures that the signal from the pulser goes to the transducer and the signal from the patient goes to the amplifier is:
T/R switch
107
A video display that is limited to only black and white with no other shades of gray is called a_______________
Bistable
108
What type of display uses a backlight with two polarized filters to produce an image?
LCD
109
In tissue harmonics imaging, what frequency is used to produce the image?
Double the fundamental frequency
110
What backup system is used to protect the stored data on a PACS?
Raid array
or Redundent backup system
111
With 6 bits, what is the largest number of different shades of gray that can be stored?
64
2n n=#of bits
2 to the 6th power
2x2x2x2x2x2= 64
112
In B-Mode imaging, the stronger the return echo, the _____________________ the dot
brighter
113
What happens to a digital image when the pixel density is increased?
There is more spatial detail
114
You are using a transducer that produces a beam with a very wide elevational plane. Which of the following problems are most likely to encounter as a result?
Slice thickness artifact
115
The potentially useful artifact that one might see behind a weakly attenuating structure is:
enhancement
116
When you adjust the output power control, you affect the following system component:
Pulser
117
The part of the receiver that reduces low level system noise is:
Rejection
Removes unwanted noise
118
What receiver function is responsible for decreasing the difference between the largest and smallest received signal amplitudes?
Compression
Higher compression has few shades of gray
119
Sound bouncing off a strong reflector and producing an image on the opposite site of the strong reflector is:
Mirror image artifact
120
What must be known to calculate the distance from a transducer to a reflector?
Round trip time and propagation speed
121
Contrast resolution is:
The ability to see differences in shades of gray
122
Which of the following occurs after the image has been stored in memory?
Postprocessing
123
In which mode is the strength of the reflector represented by the brightness of the dot?
B-mode
124
Which mode displays the movement of the reflectors along a single scan line?
M-mode
125
In M-mode imaging, what is represented by the x-axis?
Time
Depth is along the Y axis
126
The harmonic signal is produced by:
the patients tissue
127
When imaging in tissue harmonic imaging the __________________ __________________ is filtered out.
fundamental frequency
128
A sound wave travels 26 ms to a reflector. How far away is the reflector assuming the medium is soft tissue?
4 cm
d=0.77(speed)
d=0.77(52)
=40mm or 4.0 cm
129
What is a technique used to reduce the presence of grating lobes?
Apodization
Used by the beam former to reduce grading lobes by minimizing voltage strength
130
The strength of the voltages sent to each element is determined by the:
Beamformer
131
An advantage of coded excitement is improved:
signal to noise ratio
132
If the far field of the image is too dark, the preferred technique is to:
Optimize TGC
133
Read zoom is a _____________________ function
Postprocessing function
Write zoom is preprocessing
134
Which type of zoom offers a high quality zoom but must be selected while the image is live?
Write zoom
135
As the sound beam propagates deeper, the strength of the beam is attenuated. This explains the need to have which receiver function?
Compensation
136
The smallest component of a 3D image is the:
voxel
137
The technique that uses made-up pixel information to replace areas between the scan lines where there is no actual signal information is:
Fill in interpolation
138
What is the standard for data exchange among imaging systems?
DICOM
139
An artifact that occurs when a sound beam bounces back an forth between two strong reflectors, creating a series of repeating lines is:
Reverberation
140
Additional reflectors on the screen (with an array transducer) that are from extraneous sound waves off the primary axis of the beam are:
Grating lobes
141
Sound travels through a large quantity of muscle tissue. The reflector will be displayed:
Too close to the transducer
142
A shadow occurs when sound:
propagates through an area of increased attenuation
143
The digital echo information is taken from the memory and sent to the ____________________ so that it can be shown on an analog display.
D to A converter
144
Which older mode may still be used today in ophthalmology?
A-Mode
145
Which part of the US machine does not affect the amount of energy entering the patient?
Receiver
146
An image with 1 bit of memory can display ________________ shades of gray
Two
2 to the 1st power
Bistable(Black and white)
147
Sound that strikes air and creates a streak-like artifact is called:
Ring down artifact
148
A technique that averages out the frequencies present within the beam to improve contrast resolution and reduce speckle is:
Frequency compounding
Reduces speckle
149
Artifacts related to propagation speed occur because:
The machine assumes 1540m/s for all tissue
150
What provides the potential energy in the cardiovascular system?
Beating heart
In the form of blood pressure
151
A "color" (red, blue, green) is called a
hue
152
What is the name of the blunted flow profile that is seen at the entrance of a large vessel?
Plug flow
153
What does increasing the PRF/scale setting on a spectral doppler do?
Decreases the potential of aliasing by increasing the nyquist limit
154
In CW instrumentation transducer frequency matches that of the
oscillator
155
When is doppler shift the highest?
When the beam is parallel to the direction of flow
(at a 0 degree angle)
156
What will eliminate alaising?
Decreasing the PRF
157
When a reflector moves toward the transducer, what will happen to the reflected frequency?
It will increase
158
From a hemodynamics standpoint, what has to be increased in order to see an increase in flow volume?
Pressure difference
The higher the pressure difference the greater the amount of flow. This is described by Pouisouillies law
159
Adjusting ____________________ has no effect on the measured frequency shift.
Amplitude
(not part of the doppler equation)
160
What is the formula for Ohm's law
V=IR
161
What is the point at which Reynolds number predicts turbulance?
>2000
162
In order to maintain volume flow as a constant, if the area of the vessel increases what must happen to the velocity?
It must decrease
163
Venous blood returns to the heart from the lower extremities through:
Calf muscle pump
Expiration
Venous valves
(Flow stops with inspiration)
164
In a standing patient, where is the hydrostatic pressure highest?
In the feet
165
A stenosis of 75% in area is equal to what percent of stenosis is diameter?
50%
166
An arterial waveform that has flow above and below the zero flow baseline is properly referred to as:
Multiphasic
167
What will be seen with a stationary reflector?
The incident frequency is equal to the reflected frequency. (No reflector motion)
168
What happens as the frequency of the transducer increases?
The amount of scatter is increased
169
What happens as the doppler angle in increased?
It decreases the frequency shift
170
What component of the ultrasound machine is used to detect positive versus negative frequency shifts?
Phase quadrature
171
CW Doppler devices must have at least _______________ piezoelectric elements
two
172
Undersampling of the blood flow will result in:
aliasing
(alaising results when the sample is not sampled often enough)
173
What mathematical processing technique is used to analyze the data and produce a spectral waveform?
Fast Fourier transform
174
What represents the resistive index?
Peak systolic velocity minus the end diastolic velocity divided by the peak systolic velocity
175
What does the brightness of the dots that makeup the spectral display represent?
The number of red blood cells present
176
What describes the principle that an object at rest will stay at rest unless acted on by an outside force?
Inertia
177
In order to add more spectral doppler waveform to the display, what setting on the machine should be adjusted?
Sweep speed
178
What may result if the spectral doppler gain is too high?
Overmeasurement of the velocities
179
The doppler angle is lowest at what angle to flow?
90 degrees
( This is a normal incidence, No shift)
180
What signal processing technique used for color doppler is not as accurate as, but is faster than the technique used for spectral doppler?
Autocorrelation
181
A low pass filter is used for what doppler imaging technology?
Tissue doppler imaging
182
What type of doppler does not rely on the frequency shift but instead relies on the amplitude (strength) of the sift?
Power doppler
(amplitude is equal to # of RBC's present)
183
What is it called when the 2D image, color doppler image and spectral doppler are displayed simultaneously?
Triplex mode
184
What is the duty factor for CW?
100%
185
With CW doppler there is a large _____________ __________ that obtains signal strengths from all vessels within
sample volume
186
When comparing 2D(grayscale) imaging, and color doppler imaging there is worse ____________________ resolution
temporal resolution with color doppler
(poor temporal resolution and slow frame rate)
187
Aliasing occurs with color doppler
True or False
True
188
What frequency shifts would exhibit aliasing if the PRF is 5000 Hz?
3.0 kHz
(aliasing occurs at a shift greater than 1/2 the PRF)
189
Frequency shift is within the _________________ range of sound
audible
190
The ensemble length of color doppler is about ________________ _________________ pulses per scan line
10 to 20
(May also be know as packet size)
191
What happens if blood flow is sample in the center of laminar flow?
There will be a higher velocity than if sampled toward the edges
192
Color doppler imaging only measures
mean velocity
193
Power doppler signal is obtained by
detecting amplitude of shift.
(Power doppler cannot measure velocity or direction of flow)
194
Assuming flow is constant, what happens in a region of blood vessel narrowing?
There is an increase in the velocity along with a corresponding increase in pressure
(This is according to Bernoullies principle)
195
Spectral doppler envelope is thickened in the presence of _______________________
Turbulance
196
What is the term for the pressure difference between the inside of a vein and the tissue outside?
Transmural pressure
197
What will a proximal stenosis look like on the spectral waveform?
There will be a delay in systolic upstroke
(Dampened tardus parvus waveform, more indicative of a more proximal stenosis)
198
The low velocity component is missing on a spectral waveform. What should be adjusted to fix it?
High pass filter
( wall filter control eliminates the low frequency shift on spectral waveforms)
199
In the exercising patient, the distal arteriols are dilated. What type of flow pattern would most likely be demonstrated on spectral doppler within the proximal vessels?
Monophasic
