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SPI Review > Physics Review > Flashcards

Physics Review Flashcards

1
Q

What’s the maximum number of shades of gray in an 8 bit digital scan convertor?

A

256

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2
Q

What type of resolution is most affected by the mechanical focus on a linear array transducer?

A

Elevational resolution

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3
Q

what three colors a re used on a color monitor to produce the range of available colors\

A

RGB

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4
Q

Which phenomenon is associated with a pattern produced by a sound beam after passing through a small aperture?

A

Diffraction

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5
Q

Reolution When your patient asks you how much longer the ultrasound test, his voice his in the audible frequency range. Which of the following frequencies is in the audible frequency range?

A

10 kHz

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6
Q

What information is present in the A-mode display?

A

Amplitude and reflector distance

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7
Q

Which of the following is NOT a function of the receiver?

A

Not sure Dynamic Aperture???

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8
Q

What term refers to regions of decreased particle density in a sound beam?

A

Attenuation??

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9
Q

Wave length is measured in:

A

Millimeters

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10
Q

Terms used to describe the strength of the sound beam?

A

Intensity and amplitude

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11
Q

What 2D limitation is addressed by 3D ultrasound imaging?

A

3D provides visibility of the coronal plane

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12
Q

Which transducer would provide the longest near-zone length?

A

10 MHz 6mm diameter aperture (hint is biggest diameter).

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13
Q

An interaction of echoes that leads to reinforcement rather than to partial or total cancellation is known as:

A

Constructive interference

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14
Q

You are scanning an interface with a high acoustic impedance mismatch. How will this be displayed on the B-mode image?

A

A bright dot

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15
Q

Sonographic images are usually compressed before sending to PACS in order to:

A

Reduce the time to transmit the image

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16
Q

You are manipulating a volume dataset that was previously obtained on your patient. What is the maximum number of imaging planes that can be obtained from this dataset?

A

There is no limit.

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17
Q

With a standard one-dimensional linear array transducer, what type of resolution is affected most by electronic focusing and dynamic aperture?

A

Lateral resolution

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18
Q

When you switch from a 2.5 MHz to a 5 MHz transducer, the sound wavelength:

A

Halves

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19
Q

What artifact is being described in the previous question?

A

Grading lobes??

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20
Q

These B-mode images of a carotid artery show a graphic overlay indicting the number of lines of sight used to acquire each frame of information. No other system parameter was adjusted., Which statement below is true comparing image A to image B?

A

Image A has better lateral resolution than image B.

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21
Q

Where are images stored in the ultrasound system?

A

The scan converter

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22
Q

The salt and pepper appearance you observe in this ultrasound image is a result of:

A

Acoustic speckle

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23
Q

What interaction of ultrasound and tissue is primarily responsible for imaging the internal structure of organs

A

Scattering

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24
Q

What is the main advantage of using of a 1.5D or multirow array transducer?

A

Narrow slice thickness over large part of the scanned volume.

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25
Q

The spatial resolution of the scan converter is determined by

A

Number of pixels in the scan converter matrix

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26
Q

10 to the -3 equals

A

1/1,000

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27
Q

When you select compound imaging, which artifact is less likely to be observed?

A

Refraction, Shadowing, Enhancement, Acoustic speckle

All of the above

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28
Q

What system component is responsible for transmit focusing?

A

Beam former

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29
Q

Which transducer would have a lower line density in the far field compared to the near field?

A

Curved, tightly curved and phased array (B,C,D)

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30
Q

A method used to improve frame rates with multizone electronic focusing is termed:

A

Parallel processing

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31
Q

Increasing the number of acoustic scan lines in one frame improves which of the following?

A

lateral resolution

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32
Q

What is another name for the hyperechoic artifact distal to a fluid structure

A

Enhancement

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33
Q

The elapsed time between the transmitted pulse and the detected echo is 26 microsecond. How far is the interface from the transducer?

A

2 cm??

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34
Q

When increasing the number of transmit focal zones to improve spatial resolution, the tradeoff is

A

Lateral resolution vs temporal resolution

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35
Q

Which of the following interactions of sound and tissue decreases the intensity of the transmitted beam?

A

Absorption, Reflection, Scattering, Conversion of sound to heat (All of the above)

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36
Q

What artifact might you see with an array transducer due to energy that propagates from the transducer in a direction different from the primary beam?

A

Grating lobe

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37
Q

What sound-tissue interaction is necessary to form an ultrasound image?

A

Reflection

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38
Q

Which factor LEAST influences axial resolution

A

Beam width

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39
Q

You have expNDED THe IMAGE SECTOR WIDTH TO IMPROVE VISUALIZATION OF A LARGE MASS. wHAT CAN YOU DO TO maintain the same temporal resolution you had before your adjustment?

A

Decrease the number of focal zones.

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40
Q

Increasing the dynamic range setting affects the ultrasound image by:

A

Decreasing image contrast

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41
Q

The dark area indicated by the arrow in this image is primarily due to

A

Increased attenuation

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42
Q

The range equation describes the relationship between

A

Round-trip pulse travel time and distance to the reflector

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43
Q

Which is an assumption of sonographic imaging that determines how detected echoes are mapped in the image?

A

Echoes originate from the most recently transmitted pulse.

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44
Q

In the scan converter, interpolation is performed to

A

Fill in the empty pixels that occur between acoustic scan lines

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45
Q

During a sonographic exam, you adjusted the following controls. Which one was most likely to have affected the frame rate?

A

TGC??

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46
Q

What best describes the difference between the frequencies for Doppler and for B-mode imaging with a given transducer?

A

The frequency for Doppler is usually lower than B-mode imaging.

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47
Q

What can you do to enhance the visibility of a specular reflector?

A

Scan with perpendicular incidence.

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48
Q

Which technology would be most helpful to obtain accurate anatomic volume measurements?

A

3D imaging

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49
Q

What control could you adjust to improve the signal-to- noise ratio on the image?

A

Frame averaging

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50
Q

Which echo amplitude in the following illustration would produce the brightest dot on a B-mode display?

A

E The highest amplitude

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51
Q

Which control would you adjust to alter the dynamic range of the displayed echoes?

A

Compression

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52
Q

What term describes the ability of an imaging device to separate closely spaced objects?

A

Resolution

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53
Q

What type of transducer will improve the volume averaging demonstrated in this image?

A

1.5D or multi-row array

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54
Q

Axial resolution is improved with

A

Increased bandwidth, Shorter pulse length and shorter wavelength (E-All of the Above)

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55
Q

Which of the following will NOT improve axial resolution?

A

Increased focusing

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56
Q

Resolution of two structures at different depths along the path of the sound beam is termed

A

Axial resolution

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57
Q

What control should you adjust to better compensate for the attenuation of sound as it propagates through tissue.?

A

TGC

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58
Q

You are observing a sonographic artifact based on the interference patterns of scattered echoes. What artifact are you imaging?

A

Acoustic speckle

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59
Q

The speed of sound is defined as the

A

Speed at which the sound wave propagates through the medium.

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60
Q

Which statement is most accurate regarding resolution with a standard one-dimensional linear array transducer?

A

Elevational resolution. It is the worst measure of resolution with type of transducer.

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61
Q

What determines the speed of sound

A

Medium through which sound wave passes

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62
Q

Which of the following is most likely to decrease beam intensity?

A

Increasing a beam area

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63
Q

While performing an ultrasound exam, you decide to adjust the system settings to improve the image. Which of the following is not user adjustable?

A

Echo arrival time

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64
Q

What system function is limited by the speech of sound in tissue?

A

PRP

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65
Q

What type of imaging results in selective reception of frequencies that are 2 times that of the transmitted frequency?

A

Tissue harmonic imaging

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66
Q

What best describes the method used to created the triangular-shaped image format in the image below?

A

Electronic steering with most elements fired for echo pulse-echo sequence. Small time differences steer the beam.

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67
Q

How can you optimize your system to demonstrate a shadow distal to the calcification?

A

Increase the transducer frequency

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68
Q

The propagation speed for sound is lowest in which of the following biological tissues?

A

Fat. Bone has a high propagation speed which will cause attenuation.

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69
Q

If you wish to use an array transducer that allows you to control transmit focal depth. What type would you select.

A

All of the above.

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70
Q

:Which of the following best describes M-Mode?

A

dEPTH OF REFLECTORS ALONG A SINGLE LINE OF SIGHT vs. time.

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71
Q

During the performance of a sonogram you would be most likely to encounter refraction in this view?

A

Curved interface. Refraction of the sound beam requires sound reflection from a curved interface

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72
Q

The conversion of an incident pressure wave to an electrical signal is the

A

Piezoelectric effect

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73
Q

While performing a sonographic exam, you increase both imaging depth and scan line density. These adjustments produce the following result

A

Reduced temporal resolution

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74
Q

You have chosen to enlarge an ultrasound image with a read magnification. Which of the following is NOT related to read magnification?

A

Preprocessing

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75
Q

If you increase the PRF and leave all other controls unchanged what will happen?

A

Frame rate will increase

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76
Q

When you adjust the pulse repetition frequency, you are changing

A

The number of pulses per second

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77
Q

Without interpolation, which of the following would best describe the resultant B-mode image?

A

A series of scan lines with blank data between the line

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78
Q

Transducer for cardiac imaging

A

Phased array

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79
Q

Spatial pulse length is equal to

A

The wavelength times the number of cycle in the pulse.

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80
Q

Bandwidth refers to

A

The range of frequencies in a pulse

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81
Q

What term refers to regions of decreased particle density in a sound beam?

A

Rarefaction

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82
Q

How is reflector depth determined with pulse-echo ultrasound

A

Echo arrival time

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83
Q

Increasing the frequency on a multifrequency transducer from 3.5 MHz to 5.0 MHz will

A

Decrease the wavelength

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84
Q

You have been requested to image a superficial mass and to adjust your equipment to optimize spatial resolution. Spatial resolution consists of

A

Lateral and axial

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85
Q

The regions of low pressure and density that are formed during sound propagation are termed

A

Rarefactions

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86
Q

If you wish to perform a sonogram with the largest possible field of view in both the near field and at depth, what type of array transducer would be most preferable?

A

Curved array

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87
Q

Increasing which of the following will result in improved axial resolution?

A

Frequency

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88
Q

Which of the following helps to improve the lATERAL RESOLUTION IN A b-MODE image?

A

Increased aperture

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89
Q

What transducer component is designed to control ringing of the piezoelectric element?

A

backing material

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90
Q

While preforming an obstetrical sonogram, you wish to increase the frame rate ot evaluate the fetal heart. What should you do?

A

Decrease the sector width

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91
Q

Which of the following describes sound propagation through a vacuum?

A

Sound can not travel through a vacuum.

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92
Q

Which adjustments increase the duty factor?

A

Increasing PRF

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93
Q

Which of the following frequencies is considered to be ultrasound?

A

2 MHz

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94
Q

What component of the ultrasound system convers the electric energy provided by the pulser into acoustic pulses transmitted into the patient?

A

Transducer

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95
Q

When you change the transmit frequency, which of the following is altered?

A

Number of cycles per second

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96
Q

What is the disadvantage of a water-path scanner

A

Bubbles in the fluid can inhibit sound transmission into the body.

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97
Q

When the sound beam is refracted during a sonographic examination, which of the following might you detect on the ultrasound image?

A

Lateral misregistration

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98
Q

Snell’s law describes

A

The angle of sound transmission at an interface between media having different propagation speeds
The relative speed in two media is the angel of transmission as related to the incident beam angle

99
Q

Requirements of magnetic field tracking for 3D reconstruction include

A

Minimization of electromagnetic interference
Transmitter must be in close proximity to the receiver
Ferrous metals must not be within the field
All of the above

100
Q

What is the purpose of curving the transducer elements or applying a lens over the elements?

A

To provide focusing in the out of plane (elevational) direction

101
Q

What is an advantage of single-crystal or pure-wave crystal transducers?

A

Wide bandwidth

102
Q

The intensity transmission coefficient at the interface between two structures equals 1/100. What is the intensity reflection coefficient?

A

99/100

103
Q

Which statement is NOT true regarding lateral resolution?

A

It remains constant throughout scanning depth.

104
Q

Testicular

A

Electronic

105
Q

Another name for axial resolution

A

Range resolution

106
Q

You are imaging a structure containing two media having the same acoustic impedance. What will occur at the boundary of the two structures?

A

All of the sound will be transmitted.

107
Q

What is a typical frame rate for B-mode real time imaging?

A

10-50 Hz

108
Q

What is the main advantage you will have by choosing a transducer that produces a thin slice over the image plane?

A

Decreased volume averaging

109
Q

Which of the following statements regarding the effect of frequency on Rayleigh scattering is TRUE?

A

Scattering intensity is proportional to frequency raised to the fourth power.
Rayleigh scatter=red blood cell

110
Q

What is the purpose of subdicing?

A

To reduce grating lobes

111
Q

Electronic noise is reduced in the ultrasound system by this method

A

Rejection

112
Q

What is a side lobe

A

Sound beam emitted from the transducer that travels in a different directions from the main beam

113
Q

For a single transducer to offer multiple frequency selections for scanning, it must have

A

wide bandwidth

114
Q

If you increase pulse repetition frequency to a level too great for the depth of field, the result will be

A

Range ambiguity. (Misplaced axially)

115
Q

What artifact will you see in the color Doppler image if you cannot increase the PRF to a level greater than 2 times that of the Doppler frequency shift?

A

Aliasing

116
Q

Which prefix equals 10 to the third

A

Milli is -3
Micro is -6,
Mega is +6
Centi is -2

117
Q

Which of the following describes diffuse reflection?

A

The reflected beam is scattered in various directions.

118
Q

You are imaging a 3D dataset that has anisotropic resolution. What does this mean?

A

Unequal resolution is present between imaging planes.

Isotropic resolution means the spatial resolution is equal.

119
Q

Where is the point of maximum intensity in a sound beam?

A

Focal Point. The beam is the narrowest.

120
Q

What can you improve by changing the gray-scale map?

A

Contrast resolution

121
Q

The sound beam can be focused by all of the following except:

A

the matching layer

122
Q

You may observe a mirror image articfact with whi8ch imaging mode

A 
B-mode
Spectral Doppler
Color Doppler
Power Doppler
All of the above
123
Q

During a sonographic exam, which one was most likely to have affected the frame rate?

A

Scan depth

124
Q

The term signal to noise ration denotes

A

The relative amplitude of the signal compared to the amplitude of the noise.

125
Q

What is an advantage of using a 3D/4D transducer with an automated sweep compared to a traditional transducer with a freehand sweep?

A

Measurement accuracy

126
Q

An echo from which one of the following sound reflectors is most dependent on the angle of incidence?

A

Specular reflector

127
Q

The shadow depicted in this image of a renal stone is primarily a result of the following sound-tissue interaction

A

Reflection

128
Q

You are imaging with a 5 MHz linear array transducer. What sound parameter stays constant as the beam propagates through the tissue?

A

None of the above

129
Q

When you increase the scanning depth, which of the following is automatically decreased by the system to avoid range ambiguity

A

PRF

130
Q

A type of sonographic imaging that transmits two pulses of opposite phrase in rapid succession so they can be cancelled out upon reception is termed

A

Pulse inversion harmonics

131
Q

Wavelength depends on

A

Frequency and propagation speed

132
Q

What advantage will you obtain when using tissue harmonics operating mode?

A

Improved contrast resolution

133
Q

A digital scan converter is another name for what system component?

A

Image memory

134
Q

Wideband width improves

A

Axial resolution

135
Q

Dynamic apodization is a method employed to

A

Reduces side lobes

136
Q

Imaging frame rate decreases when you

A

Increase sector width

137
Q

Acoustic impedance increases with which of the following

A

Increased tissue density

Increased prop speed

138
Q

What term descrivbes the rate at which the transmitter applies electronic voltage pulses to the transducer

A

PRF

139
Q

What technique would be most likely to produce grating lobes in your image?

A

Beam steering

140
Q

The technique of frame averaging during real-time acquisition is designed to

A

reduce random noise

141
Q

What effect will you detect in the image if you increase the threshold control?

A

Decreased appearance of weak echo signals

142
Q

What is the advantage of a water-path scanner?

A

Near-field reverberations are reduced.

143
Q

You are performing a 3D sonogram and notice the volume rate is 8 Hz. What does this represent?

A

Number of volumes displayed per second.

144
Q

Which describes constructive interference?

A

Sound waves are in phase an resulting amplitude is increased.

145
Q

What type of focusing is performed by delay circuitry upon reception?

A

Dynamic receive focusing

146
Q

What system control convers the numbers stored in memory to proportional voltages that control the brightness io a CRT monitor?

A

Digital to analog converter

147
Q

The ultrasound in your lab has a transducer with a small footprint. This kind of transducer has the following disadvantage.

A

Resolution is degraded at large distances

148
Q

Black image

A

A Lateral
B Elevation
C-Axial

149
Q

Electronic focusing in the transmit mode is accomplished using

A

time delays to excite transducer elements

150
Q

Which of the following is NOT a limitation of M-Mode scanning?

A

With M mode, motion lkateral to the transducer is not displayed but motion axial to the transducer is

151
Q

Varying the excitation voltage to each element in the group used to form the ultrasound pulse is called

A

Apodization

152
Q

What is the advantage of using Write zoom instead of Read zoom magnification?

A

Write zoom provides better spatial resolution than read zoom.

153
Q

If the number of cycles in a pulse is increase but the wavelength remains the same, which of the following is true?

A

Pulse duration increases

154
Q

Increasing the dynamic range setting affects the ultrasound image by

A

Decreasing image contrast

155
Q

The matching layer between the piezoelectric element and the tissue is designed to

A

Reduce the acoustic impedance mismatch between the element and the tissue.

156
Q

What can you do to improve contrast resolution in the ultrasound image?

A

Use a 2D or matrix array transducer

157
Q

Choose two benefits of harmonic imaging

A

Grating lobe artifacts are reduced and lateral resolution is improved.

158
Q

What type of resolution is determined by the number of pixels in the scan converter?

A

Spatial

159
Q

With absorption, acoustic energy is converted to

A

Heat

160
Q

Which one will not cause a redirection of part of the ultrasound energy?

A

Absorption

161
Q

Which travels faster sound thru air or soft tissue?

A

Sound travels must slower through air than soft tissue. 330 m/s, 1540 m/s

162
Q

What occurs when you image a structure with oblique incidence?

A

The angle of reflection will be oriented away from the transducer resulting in decreased visualization of the structure.

163
Q

For pulsed ultrasound, which of the following factors determine the frequency of the sound wave?

A

Transmitter frequency.

164
Q

You are using a transducer that produces a beam with a very wide slice thickness. Which of the following problems are you most likely to encounter as a result?

A

Partial volume artifact

165
Q

In order to focus a sound beam relatively far away from the transducer, it is advantageous to

A

Increase the diameter of the element

166
Q

What can you do to improve the temporal resolution while scanning?>

A

Decrease the acoustic scan line density

167
Q

Preprocessing functions are

A

a function that is performed before the echo data are stored in memory

168
Q

When you image a structure that is a specular reflector, the strength depends on the following two factors

A

Difference in acoustic impedance

Angle of incidence

169
Q

What two conditions must be present to cause refraction of a sound wave

A

Oblique incidence and different media propagation speeds

170
Q

Doppler pulses used for diagnostic purposes are typically ____ cycles long.

A

5-30

171
Q

If you are using a transducer with poor elevation resolution, which of the following problems are you most likely to encounter?

A

Inability to clearly demonstrate small cystic structures

172
Q

Which of the following minimizes the degree to which beam width varies with depth?

A

Dynamic aperture

173
Q

As a general observation about media in diagnostic sonography, sound propagates faster I materials with greater

A

Stiffness

174
Q

Which of the following would increase the spatial pulse length

A

Increased number of cycles per pulse

175
Q

What is the relationship of frequency to absorption

A

If frequency is doubled then absorption is doubled.

176
Q

In sound wave propagation, a region of elevated pressure is termed

A

Compression

177
Q

What transducer component reduces reflection at the transducer/skin surface?

A

Matching layer

178
Q

The number of images displayed per second in real time is termed

A

frame rate

179
Q

You are using a linear array transducer to evaluate the thyroid gland. For standard B-mode imaging, this transducer most likely produces pulses of how many cycles?

A

One to three

180
Q

You have increased the output power by 10 dB. The signal intensity has

A

increased by a factor of 10.

181
Q

In this image of an artery there is a calcification with a dark vertical band extending beyond it. Which explanation best describes the etiology of the dark band?

A

Reduction in signal amplitude in tissue distal to a highly attenuating or reflecting object.

182
Q

You are scanning a large mass that is primarily fat. Which of the following are you most likely to encounter?

A

Axial misregistration of objects distal to the mass on the screen due to the slower propagation speed through fat.

183
Q

Which of the following artifacts commonly results in echoes filling in the lumen of small vessels

A

Partial volume

184
Q

Which of the following best describes the f-number?

A

Focal length divided by the aperture

185
Q

With a standard one-dimensional linear array transducer, what type of resolution is affetcted most by electronic focusing and dynamic aperture?

A

Lateral resolution

186
Q

Pulse repetition period is the inverse of

A

PRF

Pulse repetition period is the time between pulses.

187
Q

What effect will you see in the image if you increase the reject level?

A

Decreased low level echoes

188
Q

Ultrasound propagation velocity depends on

A

density and compressibility

189
Q

What interaction of ultrasound and tissue is primarily responsible for imaging for the internal structure of organs

A

Scattering

190
Q

Disadvantage of a tightly curved array transducer..

A

Lateral resolution degrades with depth

191
Q

Axial resolution is determined by

A

Pulse duration

192
Q

For a linear array transducer consisting of a single row of elements, what method is most used to focus the beam in the elevational direction?

A

Mechanical focusing

193
Q

Which of the following describes an analog signal

A

Continuous variation of the signal is possible

194
Q

The transducer you are using transmits wide-bandwidth pulses whose frequency content is 2-5 MHz. Which of the following most correctly describes the reflected echo after they have traversed the tissue.

A

The echo signals will be shifted down in frequency due to the increased attenuation of higher frequencies.

195
Q

What represents the best measure of resolution for modern day ultrasound scanners?

A

axial

196
Q

Which of the following artifacts may result in both an axial and lateral displacement of a reflector on the ultrasound image?

A

Multipath artifact

197
Q

With A-mode, the strength of the echo signal is represented by

A

The height of the spike

198
Q

What type of transducer has the same measurement for elevational and lateral resolution

A

Annular array

199
Q

You have obtained an ultrasound image that demonstrates refraction of the sound beam. This artifact may be manifested as

A

Lateral displacement of the displayed position of a reflector

200
Q

What happens when pressure is applied to a piezoelectcal crystal?

A

It emits an electrical signal

201
Q

Which of the following increases as frequency increases

A

All of the above

202
Q

Acoustic impedance

A

Equals density times the propagation speed

203
Q

What is the purpose of the preamplification of the incoming signal that occurs in the transducer assembly?

A

To increase echo voltages before noise is induced through the cable

204
Q

The ability to distinguish between adjacent structures that produce echoes of similar amplitude is termed

A

contrast resolution

205
Q

If the number of cycles in the transmitted pulsed wave is increased

A

Axial resolution is degraded

206
Q

Which of the following helps to improve axial resolution in a B-mode image

A

Increase bandwidth

207
Q

Diagnostic ultrasound is limited in its diagnostic application to the adult brain because

A

The great acoustic impedance mismatch between the cranium and soft tissue causes most of the sound to be reflected at that interface

208
Q

Interference patterns of reflected waves causes

A

Acoustic speckle

209
Q

system performance order

A

Pulser, beam former, receiver, memory, display

210
Q

A-mode lines of sight=

A

1

211
Q

What benefits would you obtain by choosing a transducer having a large diameter c9mpared to one having a small diameter

A

It can focus at greater depths.

212
Q

Electronic steering is most commonly applied to which of the following real time transducers

A

Phased array

213
Q

To alter dynamic range, which control would you use

A

Compression

214
Q

Which of the following helps to improve the elevation resolution in B-mode image.

A

Focusing with an acoustic lens

215
Q

What control should you adjust to modify the image if the attenuation coefficient of the tissue is very high

A

Compensation

216
Q

When you adjust the TGC, what component of the ultrasound system implements the changes?

A

The receiver

217
Q

When an electrical signal is applied to a piezoelectric element, what happens

A

It expands and contracts

218
Q

What defines the best axial resolution that can be obtained with a given transducer?

A

SPL/ 2

219
Q

What is the disadvantage of using multiple transmit focal zones

A

Decreased temporal resolution

220
Q

The algebraic summation of waves leading to patterns of minima and maxima is called

A

Interference

221
Q

You are using a 45 MHz , 40 mm linear array transducer to image a structure. What is the width of the image

A

40 mm

222
Q

Artifact associated with resonance of a gas bubble

A

Ring down

223
Q

For soft tissue, one of the factors responsible for determining acoustic impedance is

A

Density

224
Q

The maximum cyclical change in a quantity is known as

A

Amplitude

225
Q

Purpose of radiofrequency shield around the crystal and backing material of the ultrasound probe

A

It reduces electromagnetic interference

226
Q

Another term for nonspecular reflection is

A

Scattering

227
Q

Dynamic receive focusing uses

A

Time delays

228
Q

What is required for sound reflection at the interface of two structures

A

A difference in the acoustic impedance of the media

229
Q

What does not affect impedance

A

Frequency

230
Q

What scanning mode does not rely on the principle of echo ranging to determine interface location

A

Transmission

231
Q

A standard for handling and transferring images and medical information between computers

A

DICOM

232
Q

Which phenomenon is associated with a pattern produced by a sound beam after passing through a small aperture

A

Diffraction

233
Q

You have decreased the acoustic power by -3 dB. Which of the following most accurately describes this adjustment?

A

The intensity has been halved.

234
Q

Relationship between Doppler and B-mode

A

Doppler frequency is usually lower than for imaging.

235
Q

If you choose a lower frequency traqnsducer to image a highly attenuating structure, what tradeoff are you making?

A

Decreased spatial resolution for improved penetration.

236
Q

Which is the best choice to help you demonstrate tissue boundaries that are not perpendicular to the sound beam

A

Spatial componding

237
Q

What type of transducer could you choose to produce a beam that is symmetrical about the beam axis.

A

Annular array

238
Q

Shadowing at the lateral edges o a structure. Is caused by

A

Different media propagation speeds

239
Q

Phantom is evaluated by what type of resolution

A

Elevational

240
Q

Purpose of applying multiple matching layers to the transducer face

A

Multiple matching layers result in increased transducer bandwidth

241
Q

A-mode display contents of cyst will appear as

A

an area with no spikes

242
Q

What artifact is related to Beam attenuation

A

enhancement

243
Q

A commonly used material in modern transducer elements is

A

Lead zirconate titanate

244
Q

Which of the following is not associated with a Low-Q transducer

A

Long pulse length

SPI Review (1 decks)

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