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PHYSICS > Chapter 3 penny > Flashcards

Chapter 3 penny Flashcards

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1
Q

the rules that states that it takes 13 microseconds for sound to travel 1 centimeter in soft tissue

A

13 us rule

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2
Q

the interference pattern caused by scatterers that produces the granular appearance of tissue on a sonographic image

A

acoustic speckle

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3
Q

the height of the spike on the image is related to the strength (amplitude) of the echo generated by the reflector

A

A mode

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4
Q

as low as reasonably achievable; the principle that states one should always use the lowest power and shortest scanning time to reduce potential exposure to the patient

A

ALARA

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5
Q

the part of the receiver that increases or decreases the received echoes equally, regardless of depth

A

amplification

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6
Q

the maximum or minimum deviation of an acoustic variable from the average of that variable; the strength of the receiver

A

amplitude

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7
Q

the part of the digital scan converter that converts the analog signals from the receiver to binary for processing by the computer

A

analog-to-digital converter

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8
Q

without echoes, or black

A

anechoic

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9
Q

the technique that varies the voltage to the individual elements to reduce grating lobes

A

apodization

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10
Q

echoes on the screen that are not representative of actual anatomy, or reflectors in the body that are not displayed on the screen

A

artifacts

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11
Q

a non-Doppler technology that offers real time imaging of blood flow while scanning in grayscale

A

B-flow imaging

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12
Q

the brightness of the dots is proportional to the strength of the echo generated by the reflector

A

B mode

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13
Q

the part of the machine that shapes and steers the beam on the transmit end

A

beam former

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14
Q

the digital language of zeroes and ones

A

binary system

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15
Q

black and white image

A

bistable

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16
Q

the smallest unit of memory in a digital device

A

bit

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17
Q

eight bits of memory

A

byte

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18
Q

display that uses an electron gun to produce a stream of electrons toward a phosphor-coated screen

A

Cathode ray tube

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19
Q

a way of processing the pulse to improve contrast resolution and reduce speckle

A

coded excitation

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20
Q

a type of reverberation artifact caused by small reflectors

A

comet tail

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21
Q

the function of the receiver that changes the brightness of the echo amplitudes to compensate for attenuation with depth

A

compensation

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22
Q

the function of the receiver that decreases the range of signal amplitudes present within the machine’s receiver; opposite of dynamic range

A

compression

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23
Q

the ability to differentiate one shade of gray from another

A

contrast resolution

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24
Q

the function of the receiver that makes the signal easier to process by performing rectification and smoothing

A

demodulation

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25
Q

part of the digital scan converter that converts the binary signals from computer memory to analog for display and storage

A

digital-to-analog converter

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26
Q

the series of echo amplitudes present within the signal

A

dynamic range

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27
Q

refraction artifact caused by the curved surface of the reflecotr

A

edge shadowing

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28
Q

arc-like bands that occur when the machine is too close to an unshielded electrical device

A

electrical interference

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29
Q

an artifact caused by sound passing through an area of lower attenuation

A

enhancement

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30
Q

places grayscale pixels where there is no signal information based on adjacent scan lines; also referred to as pixel interpolation

A

fill-in interpolation

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31
Q

one complete ultrasound image

A

frame

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32
Q

averages the frequencies across the image to improve contrast resolution and reduce speckle

A

frequency compounding

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33
Q

the operating or resonating frequency emitted by the transducer

A

fundamental frequency

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34
Q

an artifact caused by extraneous sound that is not located along primary beam paths; occurs with arrays; reduced or eliminated by apodization, subdicing, and tissue harmonics

A

grating lobes

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35
Q

harmonic signal produced by the patients tissue and that is a multiple of the fundamental frequency; also referred to as native tissue harmonic imaging

A

harmonics

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36
Q

displayed echoes that are relatively brighter than the surrounding tissue; may also be referred to as echogenic

A

hyperechoic

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37
Q

displayed echoes that are relatively darker than the surrounding tissue

A

hypoechoic

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38
Q

display that uses the twisting and untwisting of liquid crystals in front of a light source

A

liquid crystal display

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39
Q

used to display motion of the reflectors

A

M mode

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40
Q

the timing component of the ultrasound machine that notes how long it takes for signals to return from reflectors

A

master synchronizer

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41
Q

an artifact caused by sound bouncing off strong reflectors and causing a structure to appear on both sides of the reflector

A

mirror image artifact

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42
Q

an artifact caused by the beam bouncing off several reflectors before returning to the transducer

A

multipath

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43
Q

low-level echoes on the display that do not contribute to useful diagnostic information

A

noise

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44
Q

strength of the sound entering the patient

A

output

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45
Q

receiver function that increases or decreases all of the echo amplitudes equally

A

overall gain

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46
Q

a type of display and storage device commonly used in sonography and other imaging modalities

A

picture archiving and communications system

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47
Q

the smallest component of a two-dimensional digital image

A

pixel

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48
Q

occurs at the receiver to the relatively weak signal coming from the transducer; ultimately, the signal has to be increased so the rest of the receiver can analyze it

A

preamplification

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49
Q

occurs in the A-to-D converter; the image must be live

A

preprocessing

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50
Q

artifact that occurs because the actual propagation speed of the tissue is greater than or less than 1540 m/s, the machine places the reflector at the wrong location on the display

A

propagation speed errors

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51
Q

occurs in the D-to-A converter; the image must be frozen

A

postprocessing

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52
Q

harmonic technology in which the fundamental frequency is flipped 180 degrees and transmitted, which cancels out the fundamental frequency via destructive interference, leaving only the harmonic signal

A

pulse inversion technology

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53
Q

part of the beam former that controls the amount of energy in the pulse

A

pulser

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54
Q

equation used to calculate the distance to the reflector; in soft tissue d=0.77t where “d” is the depth of the reflector and “t” is the round trip time of the pulse

A

range equation

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55
Q

the type of magnification performed in the D-to-A converter (postprocessing) that magnifies the image by enlarging the pixels

A

read zoom

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56
Q

the component of the machine that processes the signals coming back from the patient

A

receiver

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57
Q

the part of the receiver that inverts the negative voltages to positives

A

rectification

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58
Q

function of the receiver that is used to reduce image noise, sets a threshold below which the signal will not be displayed

A

rejection

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59
Q

an artifact caused by the beam bouncing between two strong reflectors

A

reverberation

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60
Q

an artifact caused by vibration of air bubbles

A

ring-down

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61
Q

the part of the ultrasound machine that processes the signals from the receiver; consists of the A-to-D converter, computer memory, and D-to-A converter

A

scan converter

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62
Q

created when one or more pulses of sound return from the tissue containing information related to the depth and amplitude of the reflectors

A

scan line

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63
Q

an artifact caused by the failure of sound to pass through a strong attenuator

A

shadowing

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64
Q

an artifact caused by extraneous sound that is not found along the primary beam path; occurs with single element transducers

A

side lobes

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65
Q

another name for the receiver

A

signal processor

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66
Q

artifact that occurs as a result of the beam not being razor thin; thus, unintended echoes may appear in the image as the beam slices through structures adjacent to intended reflectors; also known as elevational plane artifact

A

slice thickness artifact

67
Q

part of the demodulation component of the receiver; an “envelope” is wrapped around the signal to eliminate the “humps”

A

smoothing

68
Q

technique that eliminates edge shadowing because the object is imaged at different angles

A

spatial compounding

69
Q

algorithm used in signal processing to reduce the amount of acoustic speckle

A

speckle reduction

70
Q

large, flat, smooth boundaries that cause reflections

A

specular reflectors

71
Q

dividing the piezoelectric elements into very small pieces to reduce grating lobes

A

subdicing

72
Q

TGC

A

time-gain compensation

73
Q

ensures the electrical signals travel in the correct direction

A

transmit/receive switch

74
Q

the smallest component of a 3D image

A

voxel

75
Q

volume element

A

voxel

76
Q

picture element

A

pixel

77
Q

the type of magnification performed in the A-to-D converter (preprocessing) that magnifies the image by redrawing it before it is stored in the memory

A

write zoom

78
Q

the plane that is perpendicular to the beam path

A

x-axis

79
Q

the plane that is parallel to the beam path

A

y-axis

80
Q

the brightness, or amplitude, of the dots on the display

A

z-axis

81
Q

no image generated, only a set of spikes representing the amplitude of reflectors and their dpeth

A

A mode

82
Q

depth along y-axis
time along x-axis

A

M mode

83
Q

“ice-pick” imaging

A

M mode

84
Q

determines the sequence of the voltage pulses sent to the individual elements in an array transducer

A

beam former

85
Q

controls apodization

A

beam former

86
Q

works by decreasing the strength of the voltage pulse sent to the outermost elements

A

apodization

87
Q

part of the beam former

A

pulser

88
Q

the stronger the output power, ______ the beam of sound entering the medium

A

stronger

89
Q

controls the amount of power entering the patient

A

pulser

90
Q

the higher the output power, the _______ the return echo

A

stronger

91
Q

more complicated way of driving the energy pulse

A

coded excitation

92
Q

sends a series of encodes pulses to form one scan line instead of the one-pulse-per-scan-line method

A

coded excitation

93
Q

allows for multiple focal zones, improved penetration, speckle reduction, B-flow imaging, and improved contrast resolution

A

coded excitation

94
Q

controls the timing of the elements to shape the beam for focusing
controls the timing of the elements to steer the beam
controls apodization

A

beam former

95
Q

part of the beam former
generates the voltage that drives the transducer
directly controls the amount of power entering the patient

A

pulser

96
Q

processes the return echo coming back in this order:
amplification
compensation
compression
demodulation
rejection

A

receiver

97
Q

converts analog information from the transducer to digital (binary) form required by scan converter and computer

A

analog-to-digital converter

98
Q

ensures the electrical signals travel in the correct direction
ensures that the pulser voltages go to the transducer, and the received voltages from the transducer go to the signal processor

A

transmit/receive switch

99
Q

part of the image processor
digital memory

A

scan converter/ image memory

100
Q

electron gun shoots a stream of electrons to phosphor coated screen. Beam is steered using magnetic fields. Only seen on older equipment.

A

Cathode Ray Tube

101
Q

also called flat panel display
display two polarized filters in front of a light source
sandwiched between the filters are liquid crystals that twist and untwist with the application of electricity to determine if the backlighting gets through or not

A

liquid crystal display

102
Q

uses a computer to store images and videos. can transmit images to remote locations. Backed up by RAID array

A

PACS

103
Q

high amplitude voltage pulse equals _____ amplitude signal strength

A

high

104
Q

tells the pulser to send out a pulse and pays attention to when the echoes come back to determine their range

A

master synchronizer

105
Q

ensures that a new pulse is not sent out until the previous pulse has returned

A

master synchronizer

106
Q

the deeper a wave travels, the more ______ the wave becomes

A

deformed

107
Q

harmonic signal is very narrow, thereby offering improved _________.

A

lateral resolution

108
Q

Signals travel from the ______ to the _________ and then to ________ and then to ________.

A

receiver
analog-to-digital converter
scan converter/image memory
digital-to-analog converter

109
Q

Number of ______ determines number of shades of grey possible.

A

bits

110
Q

The more pixels, the better ________.

A

spatial resolution

111
Q

two displays used as ultrasound monitors

A

cathode ray tube
liquid crystal display

112
Q

What assumptions does the ultrasound machine make that can result in artifacts?

A

sound beams travel in a straight line and go directly from the transducer and back
the only propagation speed in the body is 1540 m/s
any reflection that comes back to the transducer must have been along the path of the beam
the slice-thickness beam is razor thin

113
Q

produces a “step-ladder” appearance of parallel echoes that are equally spaced and decrease in brightness (amplitude) with depth

A

reverberation

114
Q

Two types of reverberation

A

comet-tail
ring-down

115
Q

caused by small structures like surgical clips or adenomyomatosis within the gallbladder wall

A

comet tail

116
Q

caused by sound interacting with small air bubbles, causing the bubbles to vibrate

A

ring down artifact

117
Q

occurs when the sound is aimed toward a large specular reflector that acts like a mirror and directs some of the sound in a direction other than back to the transducer

A

mirror image artifact

118
Q

causes artifacts as the beam is directed away from the path in which it was originally intended to go

A

refraction

119
Q

eliminates edge shadowing because object is imaged from different angles

A

spatial compounding

120
Q

improves margin delineation

A

spatial compounding

121
Q

reduces speckle artifact and reverberation

A

spatial compounding

122
Q

techniques used to reduce or eliminate grating lobes

A

tissue harmonics
apodization
subdicing

123
Q

if actual propagation speed through which sound is traveling is less than 1540 m/s, reflectors will be displayed on screen _______.

A

too far away

124
Q

If actual propagation speed through which sound is traveling is more than 1540 m/s, reflectors will be displayed on screen _____.

A

too close

125
Q

Two potentially useful artifacts

A

shadowing
acoustic enhancement

126
Q

also known as elevational plane

A

slice thickness plane

127
Q

solution for slice thickness artifact

A

better focusing in elevational plane

128
Q

storage in memory corresponding to each pixel on the display

A

image matrix

129
Q

if the actual propagation speed of the tissue is greater than or less than 1540 m/s, the machine places the reflector at the wrong location on the display.

A

propagation speed errors

130
Q

if the image is too dark, the _________ should always be increased before output power

A

receiver gain

131
Q

Present day scan converters are ______ devices.

A

digital

132
Q

incoming signals are assigned shades of gray based on their amplitudesw

A

preprocessing

133
Q

one-to-one correspondence
physical beam forming is directly coupled with displayed scan lines

A

Operating principle 1

134
Q

virtual beam forming does not rely on one-to-one relationship
uses weakly focused or nonfocused transmit beams and computed reception “beams”
images are in focus throughout, improved quality

A

Operating principle 2

135
Q

Operating principle 1 is composed of:

A

beam former
signal processor
image processor
display

136
Q

where the action originates

A

beam former

137
Q

the beam former consists of:

A

pulser
pulse delays
transmit/receive switch
amplifiers
analong-to-digital converters
echo delays
summer

138
Q

to avoid _________, all echoes from one pulse must be received before the next pulse is emitted.

A

echo misplacement

139
Q

The pulser and pulse delays carry out the following tasks:

A

sequencing
phase delays
variations in pulse amplitudes

140
Q

an independent signal path consisting of a transducer element, delay, and possibly other electronic components

A

channel

141
Q

an increased number of ______ allow more precise control of beam characteristics

A

channels

142
Q

modern sonography systems typically consist of ____, _____, and _____ channels

A

64, 128, 192

143
Q

protects the sensitive input components of the amplifiers from the large driving voltages from the pulser

A

transmit/receive switch

144
Q

Amplifiers _______ voltage amplitudes

A

increase

145
Q

The beam former has _____ amplifier(s) for each channel

A

one

146
Q

3dB

A

x2

147
Q

10 dB

A

x10

148
Q

attenuation and maximum amplifier gain determine the _________.

A

maximum imaging depth

149
Q

maximum amplifier gain is determined by ________.

A

noise

150
Q

maximum amplifier gain is determined by ________.

A

noise`

151
Q

recieves digital signals from the beam former

A

signal processor

152
Q

signal processor functions performed in order

A

bandpass filtering
amplitude detection
compression

153
Q

sharpens boundaries to make them more detectable and measurements more precise

A

edge enhancement

154
Q

reduces noise and smooths image by frame averaging

A

persistence

155
Q

acquiring several 2D scans for 3D volume of information in the image memory

A

3D acquisition

156
Q

holding and displaying one frame out of a sequence

A

freeze

157
Q

storing the last several frames acquired before freezing

A

cine loop

158
Q

_______ divides the image into pixels

A

image memory

159
Q

Brightness is ________ to echo strength

A

proportional

160
Q

if the frame rate increases, temporal resolution _____.

A

improves

161
Q

if PRF increass, frame rate ______ increases

A

increases

162
Q

presents information regarding contraction and relaxation strain and strain rate information for the myocardium of the beating heart

A

cardiac strain imagain

163
Q

a combined presentation of a sonographic anatomic image with another imaging form

A

fusion imaging

PHYSICS (26 decks)

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