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SPI > Principles & Instruments PT 1 > Flashcards

Principles & Instruments PT 1 Flashcards

1
Q

2D image is composed of

A

pixels

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2
Q

3D image elements

A

voxels

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3
Q

an ellipse can be used to measure

A

area

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4
Q

comet tail and ring down are

A

reverberation artifacts

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5
Q

contrast res =

A

dynamic range / shades

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6
Q

What is the contrast res for a system with a 4 bit memory and 32 dB dynamic range?

A

2 dB/shade

4 bit memory will use 16 shades of gray (2x2x2x2)
contrast res = dynamic range over shades
32 dB / 16 shades = 2 dB/shade

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7
Q

advantage of virtual beam forming (VBF) over traditional pulse echo imaging (PEI)

A

VBF allows for simultaneous real-time gray scale, color, and spectral doppler display

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8
Q

why can VBF display info collected in all 3 modes?

A

it allows for very fast frame rates

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9
Q

in traditional PEI, the gray scale and color image

A

is frozen or refreshes very slowly while doppler tracings are displayed

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10
Q

VBF uses ______ to improve detail resolution across the whole image, ______ is not needed

A

receive focusing

transmit focusing

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11
Q

Pulse-echo systems use strength and _____ of received signals to create the gray scale image. Magnitude and _____ of the received signal are used to create the doppler display

A

time of flight

direction

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12
Q

gain =

A

ratio of amplifier output to the electric power input (measured in dB)

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13
Q

increasing the number of bits per pixel in an image memory will improve the

A

contrast resolution

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14
Q

the ability of a display to distinguish between echoes of different intensities

A

contrast resolution

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15
Q

increased pixel number with higher numbers of bits per pixel will demonstrate

A

the best contrast res on a digital display

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16
Q

bit density and contrast res relationship

A

direct

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17
Q

more bits per pixel = more shades of gray =

A

improved contrast res

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18
Q

spatial compounding can reduce

A

artifacts like enhancement or shadowing

shut this function off to make a stone more evident

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19
Q

reducing rejection or increasing dynamic range will _____ the number of grays on the image

A

increase

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20
Q

pulse duration

A

time it takes for one pulse to occur

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21
Q

System control that simultaneously enhances far field echoes and diminishes near field echoes

A

time gain compensation

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22
Q

increases amplitude of all reflections to create image

A

overall gain

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23
Q

transducer component that reduces sensitivity and efficiency of the US system

A

damping layer by preventing the lowest intensities from forming

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24
Q

circumference =
area =
volume =

A

cm
cm^2
cm^3

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25
Q

8 bit of memory has how many shades of gray?

A

256 shades of gray

8 bit memory has 2^8 = # of shades of gray = 2x2x2x2x2x2x2x2 = 256 shades of gray

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26
Q

removes low amplitude signals and noise from the image

A

increasing rejection

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27
Q

increases the # of shades of gray displayed on the image, including low level echoes and noise

A

increasing compression

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28
Q

amplification of the received signal occurs in the

A

beam former

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29
Q

the beam former generates

A

the voltages applied to the transducer

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30
Q

the beam former determines

A

PRF, frequency, and intensity of the beam

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31
Q

scanning, focusing, and apodization are functions of the

A

beam former

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32
Q

US system component responsible for changing PRF with changes in depth

A

pulser

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33
Q

adjusts timing of voltage applied to crystal to adjust PRF

A

pulser

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34
Q

allows focusing at multiple depths on the image

A

dynamic receive focusing (NOT ADJUSTABLE)

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35
Q

System component responsible for 3D image acquisition and presentation

A

image processor

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36
Q

____ is predominant factor causing attenuation of the US beam and can be counteracted by ____

A

sound absorption

increasing TCG settings in the far field

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37
Q

tissue harmonic imaging

A

reduces grating lobe and side lobe artifacts

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38
Q

cine is

A

postprocessing that allows for review of the stored image data from the last few seconds of real time scanning

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39
Q

M-Mode horizontal axis and vertical axis

A

time (horizontal)

distance (vertical)

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40
Q

2D imaging is best when the US beam strike the specular interface at what angle?

A

90 degrees

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41
Q

perpendicular angle of incidence increases

A

specular reflection

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42
Q

system control to improve anterior aortic wall

A

center beam perpendicular to vessel wall

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43
Q

contrast resolution (dB/shade) =

A

dynamic range / # of shades of gray

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44
Q

converts scan line data into image format for display

A

image processor

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45
Q

period of 5 MHz transducer

A

.2 microseconds

5 MHz = 5,000,000 Hz
period = 1 / frequency = 1/5,000,000 = .0000002 s

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46
Q

graphic representation of the motion of a structure over time

A

M-Mode

47
Q

reducing sector size will reduce # of scan lines produced and increase frame rate, increasing

A

temporal resolution

48
Q

converts received signal from radio frequency form to amplitude (video) form

A

detection or demodulation

49
Q

sector angle and frame rate relationship

A

inverse

50
Q

sector size and # of scan lines relationship

A

direct

51
Q

adjusts # of gray levels to maintain gray scale within range of human vision

A

compression

52
Q

larger dynamic range =

A

improved ability to see subtle differences between tissues

53
Q

smaller dynamic range =

A

more black and white image

54
Q

amount of compensation necessary for different echoes varies with reflector ____

A

depth

55
Q

input power = .05 mW
output power = 500 mW
gain = ?

A

40 dB

56
Q

gain =

A

ratio of amplifier output to electric power input

57
Q

can change the image data displayed on an archived exam on the US system

A

change the gray map

58
Q

reduces appearance of posterior shadowing and enhancement

A

spatial compounding

59
Q

each returning reflection is made stronger/larger for additional processing and storage

A

amplifier

60
Q

overall gain adjustment does not improve

A

SNR

61
Q

amplification is adjusted by

A

overall gain control

62
Q

harmonic frequencies are generated

A

as sound travels through the medium

63
Q

sound moves slightly faster in areas of ____ and slightly slower in areas of ____

A

compression

rarefaction

64
Q

edge enhancement, pixel interpolation, persistence, and 3D image acquisition are all types of

A

preprocessing

65
Q

process performed in beam former where the output voltage is varied to decrease the formation of lobe artifacts

A

apodization

66
Q

doubling sector width BUT halving line density will cause ____ for temporal res

A

no change

67
Q

beam former parts (in order) to produce and receive sound waves

A

pulser–>pulse delays–>transmit/receive switch–>amplifier–>analog to digital convertor–>echo delays–>summer

68
Q

low frequency, high amplitude sound waves will cause

A

an increase in MI and risk for cavitation

69
Q

activation of B-color improves

A

contrast resolution

70
Q

focusing of the transmitted and received beam occurs in the

A

beam former

71
Q

when evaluative heavily calcified arteries, what system setting should be increased to improve to demonstration of flow in the vessels

A

persistence and sensitivity

72
Q

instrument control the sonographer uses to adjust amplitude of a reflected sound wave

A

receiver gain

73
Q

POSTprocessing assignment of color instead of gray

A

B color

74
Q

harmonic imaging primarily improves

A

spatial resolution with the greatest affect (improvement) on lateral resolution

75
Q

M-mode vertical axis

A

depth

76
Q

changes element back and forth from transmit to receive

A

beam former

77
Q

system control that reduces noise and smooths the image using frame averaging

A

persistence

78
Q

when using virtual beam forming the US beam is

A

laser thin

79
Q

beam former component that protests the sensitive circuitry of the amplifier

A

transmit receive switch

80
Q

of pulses in a scan line will affect

A

of focal zones

81
Q

console setting that can be changed to adjust the propagation speed of the transmitted wave

A

there is no way to adjust this; propagation speed is determined by properties of the media it travels through

82
Q

in order to improve spatial res and SNR, ____ uses frequency modulation to manipulate the transmitted beam

A

coded excitation

83
Q

3D images displayed in real time

A

4D imaging

84
Q

RIS (radiology information system)

A

refers to a software program that stores medical records and patient info

85
Q

increased frequency improves

A

axial res, lateral res, and beam width

86
Q

spatial high pass filter used to emphasize changes in brightness across the image to make boundaries of vessels more prominent

A

edge enhancment

87
Q

increasing edge enhancment

A

increases image contrast and decreases contrast res

88
Q

filter and compression are functions of the ______

A

signal processor

89
Q

type of receive focusing; uses more crystals to receive deeper reflections than to receive shallow reflections; reduces appearance of lobe artifact

A

dynamic aperture

90
Q

necessary machine setting when performing contrast eval of the heart

A

MI set below 0.3

High MI will cause premature bursting of microbubbles

91
Q

coded excitation improves

A

contrast res

92
Q

leads to misregistration of data and incorrectly placed pixels deeper than the normal location

A

US system is calibrated to 1450 m/s as speed of sound in ST;

reflected info will appear to take longer causing pixel placement deeper than normal location

93
Q

part of beam former that creates a digital echo signal that is sent to the signal processor

A

analog to digital convertor

94
Q

distance to reflector = velocity x 1/2 (time of flight)

A

range equation

95
Q

13 microsecond rule

A

distance in cm = time of flight / 13 microseconds

96
Q

PRF of pulser is ____ PRF of US system

A

equal to

97
Q

control that adjusts the image contrast

A

dynamic range

98
Q

control that affects power of the beam

A

transmit gain

99
Q

If you are scanning an abd but accidentally select carotid preset

A

depth setting will be very superficial causing potential nonvisualiztion of the abdominal structures

100
Q

disadvantage to increased edge enhancement

A

amplifies noise and speckle = reduced SNR

101
Q

what region of the TCG curve is the deepest region attenuation compensation can occur

A

the knee

102
Q

the strength of a received echo determines the ___ on the display

A

brightness of the pixel

103
Q

performs bandpass filtering, amplitude detection/demodulation and compression

A

signal processor

104
Q

field of view size and frame rate relationship

A

indirect

105
Q

Frequency compounding effect on image

A

improves SNR, spatial res, and image quality, reduces speckle and clutter artifact

106
Q

PACS

A

picture archiving communication system

107
Q

even and odd harmonic frequencies are created by

A

nonlinear behavior sound beams

108
Q

created by tissue boundaries during transmission of fundamental frequency through the tissue; result of nonlinear behavior

A

harmonic frequencies

109
Q

resulting harmonic beam is

A

narrower, smaller side lobes, better lateral res, and less clutter with improved contrast resolution

110
Q

second harmonic frequency =

A

2 x fundamental frequency

111
Q

demodulation is only necessary when

A

TV monitor is used

112
Q

removes carrier signals and reconstructs the signal envelope

A

demodulation

113
Q

to increase amplitude of the US pulse produced by the transducer

A

voltage amplitude form the pulser must increase

SPI (3 decks)

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