SPI review 3 Flashcards
(123 cards)
1
Q
a mode
A
amplitude mode
dot moves accross screen and measures distance between probe and reflector
2
Q
a mode x axis
A
reflector depth, measured by pulses time of flight
3
Q
a mode y axis
A
ampliude of echo, measured by echo strength
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
5
Q
b mode x axis
A
reflector depth, measured by the pulses time of flight
6
Q
b mode z axis
A
brightness of the dot, measured by reflection of amplitude
7
Q
there is no __ _____ with b mode
A
y axis
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
9
Q
m mode x axis
A
time
10
Q
m mode y axis
A
refelctor depth, measured by pules time of flight
11
Q
narrow beams provide
A
high quality imaging and good lateral res
12
Q
2 d images aka
A
b scans b modes cause they are grey scale
13
Q
mechanical scanning # of crystals and shape
A
scan head contains one disc shaped element
14
Q
mechanical scanning steering
A
pzt moved by a motor, oscillating crystal or mirror through a pathway, automatically creating a scan plane
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
16
Q
mechanical scanning image shape
A
fan or sector shaped, scan lines diverge or separate with depth
17
Q
mechanical scanning defective srystal
A
destroys entire image
18
Q
a collection of active elements in a single transducer
A
array
19
Q
array element
A
a single slab os PZT cut into separrate pieces called elements
20
Q
array channel
A
a combination of electronic circuitry, the wire and the element
21
Q
a group of ringed elements (bulls eye) with a common center
A
annular array
22
Q
a collection of elements in a line
A
linear array
23
Q
two types of linear array
A
linear switched aka sequential array
linear phased array
24
Q
elements arranged in an arc
A
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
