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Flashcards in SPI review 3 Deck (123):
1

a mode

amplitude mode
dot moves accross screen and measures distance between probe and reflector

2

a mode x axis

reflector depth, measured by pulses time of flight

3

a mode y axis

ampliude of echo, measured by echo strength

4

b mode

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

5

b mode x axis

reflector depth, measured by the pulses time of flight

6

b mode z axis

brightness of the dot, measured by reflection of amplitude

7

there is no __ _____ with b mode

y axis

8

m mode

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

9

m mode x axis

time

10

m mode y axis

refelctor depth, measured by pules time of flight

11

narrow beams provide

high quality imaging and good lateral res

12

2 d images aka

b scans b modes cause they are grey scale

13

mechanical scanning
# of crystals and shape

scan head contains one disc shaped element

14

mechanical scanning steering

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

15

mechanical scanning focusing

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

16

mechanical scanning image shape

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

17

mechanical scanning defective srystal

destroys entire image

18

a collection of active elements in a single transducer

array

19

array element

a single slab os PZT cut into separrate pieces called elements

20

array channel

a combination of electronic circuitry, the wire and the element

21

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

annular array

22

a collection of elements in a line

linear array

23

two types of linear array

linear switched aka sequential array

linear phased array

24

elements arranged in an arc

convex, curved or cuvilinear array

25

two types of convex, curved, curvilinear array

convex switched aka sequential array

convex phases array

26

# of crystals and shape for linear switched aka sequential arrays

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

27

what improves lateral res w/ linear switched aka sequential arrays

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

28

linear switched aka sequential arrays steering

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

29

linear switched aka sequential array focusing

fixed lens (external) or curved crystal (internal)

30

linear switched aka sequential array image shape

rectangular shape, no wider than the transducer

31

linear switched aka sequential array defective crystal

dropout extending from superficial to deep

32

adjustable focus or multi focus acheived electronically

phases arrays

33

# of crystals for phased arrays

approx 200 rectangual shaped elements in a line

34

phased arrays steering and focusing

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

35

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

all

one sound pulse

36

the phasing patterns

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

37

phases arrays image shape

sector or fan shaped

38

phased array defective crystal

if one element malfunctions the steering and focusing become erratic

39

electronic slope creates

beam steering

40

electronic curvature creates

beam transmit focusing

41

a convex or D shaped firing patter creates a

defocused or divergent beam

42

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

dynamic receive focusing

43

annular phased arrays # of crystals

small number of ring shaped elements

44

annular phased arrays use inner crystals for

shallow regions and outer crystals for deep regions

45

annular phased arrays have small diameter rings which have

a shallow focus but diverge rapidly

46

annular phased arrays have large diameter rings which

have a deep focal length

47

annulary phased array image shape

sector or fan shaped

48

annular phased arrays steering

mechanically, unlike other phased array transducers

49

annular phased array focusing

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

50

annular phased array defective crystal

horizontal band dropout

51

pzt arranged in a curve to provide natural sector image

convex aka curved arrays

52

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

sequential or phased

53

# of crystals for convex aka curved arrays

approx 200 rectangular shaped crystals

54

convex aka curved arrays shape

blunted sector, fan shaped image

55

a for of electronic receive, electronic focusing

dynamic aperture

56

how does dynamic apeture work

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

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

as narrow as possible\

lateral

58

2 d arrays create

3 d images

59

# of elements in 2 d arrays

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

60

allow focusing in the plane of the beam width

1 1/2 dimensional arrays

61

improves ______ res by making __ _______ ______

elevational

a thinner slice

62

combine linear sequental and linear phased array technologies

vector arrays

63

vector arrays image shape

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

64

what is an advantage of 1 1/2 dimensional arrays

reduced slice thickness

65

seeing diff ray shades in an image

contrast resolution

66

seeing detail in an aimage

spatial aka detail resolution

67

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

temporal res

68

temporal res is determined by

frame rate, higher the better

69

units for frame rate

hertz (per sec)

70

frame rate determined by

imaging depth

number of pulses per frame

71

frame rate and imaging depth are _____ related

inversley, shallower depth higher frame rate

72

frame rate and number of pulses are _____ related

inversly, fewer pulses higher frame rate

73

frame rate is limited by

speed of sound in a medium and depth of view

74

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

fundimental limitation to frame rate

75

4 factors under sonographer control that affect temporal res

max imaging depth

# of pulses per scan line (multi focus systems)

sector size

line density (lines per angle of sector)

76

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

temporal

spatial (detail)

77

multi focusing degrades _____ res but improves ______ res

temporal

lateral

78

temporal res and image quality are ______ related

inversly

79

FR

frame rate

80

Tf

time to create a frame

81

FR and Tf are

recipricals

82

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

the line density was doubled

83

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

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

84

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

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

85

US system components

master synchronizer

transducer

pulser

receiver

display

storage

86

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

master synchronizer

87

converts electrical into acoustic energy and vise versa

transducer

88

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

pulser

89

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

receiver

90

associated with the presentation of processed data for interpretation

display

91

archive the US data

storage

92

pulser function

recvs timing signal from synchronizer

creates electrical signal that excites pzt

produces electrical voltage 10-500 volts that excites pzt

93

continous wave pulser mode

electrical freq=usfreq

94

the pulser is not called the beam former for what

phased arrays

95

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

excitation voltage from the pulser

96

pzt vibrates with a magnitude related to

pulser voltage

97

weak signals returning are boosted by what

receiver

98

receiver functions in order

amplification
compensation
compression
demodulation
rejection

99

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

amplification
aka
recaiver gain

100

amplification changes the

brightness of the entire image

101

signal to noise ratio is _____ when amplification levels change

unchanged

102

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

compensation

103

compensation aka

time gain compensation
depth compensation
swept gain

104

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

TGC

105

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

compression

106

compression decreases the ____ ______ of the signals

dynamic range

107

compressions effect on image

changes the gray scale mapping

108

how to calculate changes in dynamic range and its units

dB

add or subtract, from begining range

109

is compression adjustable by sonographer

yes

110

changes the signals form to one more suitable for display

demodulization

111

is demodulization adjustable by sonographer

no

112

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

rectification

113

putting an envelope around the bumps to even them out

smoothing

114

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

rejection aka suppression and threshold

115

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

lateral and longitudinal res

116

harmonics are

multiples of the freq

117

harmonics are created in

the tissues, not in the trans or receiver

118

__ ______ behavior creaste hamonics

non linear

119

what creates harmonics

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

positive and negative pulses are transmitted down each scan line

form of harmonic imaging called pulse inversion

121

disadvantage of pulse inversion imaging is

frame rate if 1/2 that of fundamental imaging

122

pulse inversion degrades ___ while improving ______

temporal
spatial

123

pulse inversion harmonics uses

wide bandwidth or broadbaned transducers