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DMSO Physics 2 > SPI review 3 > Flashcards

SPI review 3 Flashcards

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1
Q

a mode

A

amplitude mode

dot moves accross screen and measures distance between probe and reflector

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2
Q

a mode x axis

A

reflector depth, measured by pulses time of flight

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3
Q

a mode y axis

A

ampliude of echo, measured by echo strength

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4
Q

b mode

A

brightness mode, returning echoes are presented as spots on the line of travel of the emitted US pulse. stronger returning echoes the brighter the spot. brightness of dot is proportional to the amplitude of the returning echo

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5
Q

b mode x axis

A

reflector depth, measured by the pulses time of flight

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6
Q

b mode z axis

A

brightness of the dot, measured by reflection of amplitude

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7
Q

there is no __ _____ with b mode

A

y axis

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8
Q

m mode

A

motion mode or t m mode, the only mode that displays the changing position of reflectors with respect to time

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9
Q

m mode x axis

A

time

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10
Q

m mode y axis

A

refelctor depth, measured by pules time of flight

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11
Q

narrow beams provide

A

high quality imaging and good lateral res

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12
Q

2 d images aka

A

b scans b modes cause they are grey scale

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13
Q 
mechanical scanning 
# of crystals and shape
A

scan head contains one disc shaped element

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14
Q

mechanical scanning steering

A

pzt moved by a motor, oscillating crystal or mirror through a pathway, automatically creating a scan plane

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15
Q

mechanical scanning focusing

A

conventional or fixed, curvature (internal) of PZT or an acourstic lent 9External) focuses the beam at a specific depth

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16
Q

mechanical scanning image shape

A

fan or sector shaped, scan lines diverge or separate with depth

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17
Q

mechanical scanning defective srystal

A

destroys entire image

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18
Q

a collection of active elements in a single transducer

A

array

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19
Q

array element

A

a single slab os PZT cut into separrate pieces called elements

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20
Q

array channel

A

a combination of electronic circuitry, the wire and the element

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21
Q

a group of ringed elements (bulls eye) with a common center

A

annular array

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22
Q

a collection of elements in a line

A

linear array

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23
Q

two types of linear array

A

linear switched aka sequential array

linear phased array

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24
Q

elements arranged in an arc

A

convex, curved or cuvilinear array

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25
Q

two types of convex, curved, curvilinear array

A

convex switched aka sequential array

convex phases array

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26
Q

of crystals and shape for linear switched aka sequential arrays

A

large transducers w/ approx 200 rectangular shaped elements arranged in a line

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27
Q

what improves lateral res w/ linear switched aka sequential arrays

A

a few (5-10) of the elemtns are fired at the same time to create a narrow direction beam

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28
Q

linear switched aka sequential arrays steering

A

no steering, pulses sent down parallel lines, the scan lines are parallel and are wqueally spaced

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29
Q

linear switched aka sequential array focusing

A

fixed lens (external) or curved crystal (internal)

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30
Q

linear switched aka sequential array image shape

A

rectangular shape, no wider than the transducer

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31
Q

linear switched aka sequential array defective crystal

A

dropout extending from superficial to deep

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32
Q

adjustable focus or multi focus acheived electronically

A

phases arrays

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33
Q

of crystals for phased arrays

A

approx 200 rectangual shaped elements in a line

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34
Q

phased arrays steering and focusing

A

a collection of electric pulses is delivered to all the elements in various patterns, focusng and steering is electronic

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35
Q

electronic signals excite ___ of the elements and create only ___ _____ _____

A

all

one sound pulse

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36
Q

the phasing patterns

A

focus and steer the sound beam during transmission (nearly simultaneously, 10ns apart)

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37
Q

phases arrays image shape

A

sector or fan shaped

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38
Q

phased array defective crystal

A

if one element malfunctions the steering and focusing become erratic

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39
Q

electronic slope creates

A

beam steering

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40
Q

electronic curvature creates

A

beam transmit focusing

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41
Q

a convex or D shaped firing patter creates a

A

defocused or divergent beam

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42
Q

allows focusing at many depths by delays during reception optimizing image quality

A

dynamic receive focusing

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43
Q

annular phased arrays # of crystals

A

small number of ring shaped elements

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44
Q

annular phased arrays use inner crystals for

A

shallow regions and outer crystals for deep regions

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45
Q

annular phased arrays have small diameter rings which have

A

a shallow focus but diverge rapidly

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46
Q

annular phased arrays have large diameter rings which

A

have a deep focal length

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47
Q

annulary phased array image shape

A

sector or fan shaped

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48
Q

annular phased arrays steering

A

mechanically, unlike other phased array transducers

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49
Q

annular phased array focusing

A

multi focusing provides electroinic focusing in all planes at all depths, a core sample, this provides optimal lateral res at all depths throught the image

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50
Q

annular phased array defective crystal

A

horizontal band dropout

51
Q

pzt arranged in a curve to provide natural sector image

A

convex aka curved arrays

52
Q

convex aka curved arrays may be ____ or ______ just line linear array

A

sequential or phased

53
Q

of crystals for convex aka curved arrays

A

approx 200 rectangular shaped crystals

54
Q

convex aka curved arrays shape

A

blunted sector, fan shaped image

55
Q

a for of electronic receive, electronic focusing

A

dynamic aperture

56
Q

how does dynamic apeture work

A

as returning echoes hit trans, the size of the trans surface listening for echoes is varied by varying the numver of elements used to receive the reflected signal

57
Q

dynamic apeture allows the receive beam to be __________ at all depths, and optimized ______ res at all depths

A

as narrow as possible\

lateral

58
Q

2 d arrays create

A

3 d images

59
Q

of elements in 2 d arrays

A

can have thousands in up and down and side to side directions

60
Q

allow focusing in the plane of the beam width

A

1 1/2 dimensional arrays

61
Q

improves ______ res by making __ _______ ______

A

elevational

a thinner slice

62
Q

combine linear sequental and linear phased array technologies

A

vector arrays

63
Q

vector arrays image shape

A

trapezoidal, a sector with a flat top that does not come to a point

64
Q

what is an advantage of 1 1/2 dimensional arrays

A

reduced slice thickness

65
Q

seeing diff ray shades in an image

A

contrast resolution

66
Q

seeing detail in an aimage

A

spatial aka detail resolution

67
Q

the ability to accurately locate moving structures at any particular instant in time

A

temporal res

68
Q

temporal res is determined by

A

frame rate, higher the better

69
Q

units for frame rate

A

hertz (per sec)

70
Q

frame rate determined by

A

imaging depth

number of pulses per frame

71
Q

frame rate and imaging depth are _____ related

A

inversley, shallower depth higher frame rate

72
Q

frame rate and number of pulses are _____ related

A

inversly, fewer pulses higher frame rate

73
Q

frame rate is limited by

A

speed of sound in a medium and depth of view

74
Q

since the sonographer can adjust the depth of view but not the speed of sound in the medium, the speed of sound is a

A

fundimental limitation to frame rate

75
Q

4 factors under sonographer control that affect temporal res

A

max imaging depth

of pulses per scan line (multi focus systems)

sector size

line density (lines per angle of sector)

76
Q

when line density is low ______ res improves but ______ res degrades

A

temporal

spatial (detail)

77
Q

multi focusing degrades _____ res but improves ______ res

A

temporal

lateral

78
Q

temporal res and image quality are ______ related

A

inversly

79
Q

FR

A

frame rate

80
Q

Tf

A

time to create a frame

81
Q

FR and Tf are

A

recipricals

82
Q

the sector size changes from 90 to 45 but the frame rate ramains the same, what else happened

A

the line density was doubled

83
Q

what is the frame rate is each image of ultrasound system is created in 0.02 seconds?

A

50Hz, cause 0.02 is 1/50th sec, Ft is reciprical of FR

84
Q

what is the time needed to make a single image if the frame rate of US is 20Hz

A

0.05sec, cause reciprical of 20Hz is 1/20 which is also 0.05

85
Q

US system components

A

master synchronizer

transducer

pulser

receiver

display

storage

86
Q

communicates with all of the individual components of the US system. organized and times their functions so as to operate as a single integrated system

A

master synchronizer

87
Q

converts electrical into acoustic energy and vise versa

A

transducer

88
Q

controls electrical signals sent to the trans for sound pulse generation. deterines the PRF, pulse amplitude, and pulse repetition period. creates the firing pattern for phased array systems which is called the beam former

A

pulser

89
Q

the electronics associated with processing the electroinc signal produced by trans during reception and creating image for display

A

receiver

90
Q

associated with the presentation of processed data for interpretation

A

display

91
Q

archive the US data

A

storage

92
Q

pulser function

A

recvs timing signal from synchronizer

creates electrical signal that excites pzt

produces electrical voltage 10-500 volts that excites pzt

93
Q

continous wave pulser mode

A

electrical freq=usfreq

94
Q

the pulser is not called the beam former for what

A

phased arrays

95
Q 
transducer output aka
output gain
acoutic power
pulser power
energy output
transmitter output
is determined by what
A

excitation voltage from the pulser

96
Q

pzt vibrates with a magnitude related to

A

pulser voltage

97
Q

weak signals returning are boosted by what

A

receiver

98
Q

receiver functions in order

A 
amplification
compensation
compression
demodulation
rejection
99
Q

purpose is to increase strength of signals in receiver prior to further processing

A

amplification
aka
recaiver gain

100
Q

amplification changes the

A

brightness of the entire image

101
Q

signal to noise ratio is _____ when amplification levels change

A

unchanged

102
Q

used to create image of uniform brightness from top to bottom, makes all echoes same regardless of depth

A

compensation

103
Q

compensation aka

A

time gain compensation
depth compensation
swept gain

104
Q

what will you adjust is you cannot see reflectors in the near or far field on the image?

A

TGC

105
Q

reducing the total range, the smallest to the largest signal and allows us to see all gray shades is

A

compression

106
Q

compression decreases the ____ ______ of the signals

A

dynamic range

107
Q

compressions effect on image

A

changes the gray scale mapping

108
Q

how to calculate changes in dynamic range and its units

A

dB

add or subtract, from begining range

109
Q

is compression adjustable by sonographer

A

yes

110
Q

changes the signals form to one more suitable for display

A

demodulization

111
Q

is demodulization adjustable by sonographer

A

no

112
Q

turning all negative voltages into positive ones, corrects for or eliminates negative voltages

A

rectification

113
Q

putting an envelope around the bumps to even them out

A

smoothing

114
Q

displays low level echoes only when clinically meaningful, used to eliminate low level noise in out images, but does not affect bright echoes

A

rejection aka suppression and threshold

115
Q

what degrades due to the image being too bright due to output power

A

lateral and longitudinal res

116
Q

harmonics are

A

multiples of the freq

117
Q

harmonics are created in

A

the tissues, not in the trans or receiver

118
Q

__ ______ behavior creaste hamonics

A

non linear

119
Q

what creates harmonics

A

sound moving slower in rarefactions and faster in compressions, this small difference in speeds is known as non linear and distorts the sound wave to create harmonics

120
Q

positive and negative pulses are transmitted down each scan line

A

form of harmonic imaging called pulse inversion

121
Q

disadvantage of pulse inversion imaging is

A

frame rate if 1/2 that of fundamental imaging

122
Q

pulse inversion degrades ___ while improving ______

A

temporal

spatial

123
Q

pulse inversion harmonics uses

A

wide bandwidth or broadbaned transducers

DMSO Physics 2 (26 decks)

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