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SPI REVIEW > Part 2 > Flashcards

Part 2 Flashcards

1
Q

-front t back, parallel to sound beam
-determined by SPL
-same at all depths, does not change
-best with short pulses, less cycles, high frequency
-LAARD
longitudinal, axial,radial,depth

A

axial resolution

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2
Q
  • Side by side, perpendicular to beam
  • Determined by beam width
  • Best with narrowest beams
  • Changes w/ Depth
  • LATA – Lateral, angular, transverse, azimuthal
  • Large Beam diameter , High Frequency – LESS divergence in far field
A

Lateral resolution

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3
Q

Determined by
thickness of PZT
propagation speed of PZT

A

Pulsed transducers

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4
Q

Thinner PZT

A

High frequency

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5
Q

Thick PZT

A

Low frequency

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6
Q

1/2 wavelength thick

A

PZT

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7
Q

1/4 wavelength thick

A

Matching layer

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8
Q

increases efficiency of sound transmission w/ impedance between skin & active element

A

Matching layer

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9
Q

Reduces ringing, shortens pulse duration & SPL

A

Damping material

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10
Q

Maximum Frequency - Minimum frequency equals ?

A

Bandwidth

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11
Q
  • Pulses w/ short duration
  • uses backing material
  • reduced sensitivity
  • wide bandwidth
  • Low Q factor
  • Improved axial resolution
A

Imaging transducer

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12
Q
  • Continous wave
  • no backing material
  • increased sensitive
  • narrow bandwidth
  • high Q factor
  • no image
A

Non - imaging transducer

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13
Q
  • Small diameter
  • lower frequency
  • more divergence
A

Shallow focus

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14
Q
  • large diameter
  • higher frequency
  • less divergence
A

Deep focus ( better lateral resolution in far field)

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15
Q

Determined by frame rate

A

Temporal resolution

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16
Q

Frame is determined by

A 
Image depth 
# of pulses , focus, sector size, line density
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17
Q

Short go return time
Short Tframe
Higher frame rate
superior temporal resolution

A

Shallow imaging

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18
Q

Long go return time
Longer Frame
Low frame rate
Inferior temporal resolution

A

Deep imaging

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19
Q

Single focus
Narrow setor
Low line density
More pulses per frame

A

SUPERIOR TEMP RESOLUTION

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20
Q

High line density improves

A

Spatial resolution

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21
Q 
Uses old data 
post processing
larger pixel size 
same # of pixels as the original ROI
unchanged temporal resolution
A

Read magnification

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22
Q 
Aquires new data 
preprocessing
smaller pixel size 
more pixels than original ROI 
improved spatial resolution
May improve temporal resolution
A

Write magnification

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23
Q

Improves higher signal to noise ration
improved axial, spatial, contrast resolution
-deeper penetration

A

Coded excitation does this

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24
Q

A Mode
X -
Y -

A

X - depth

Y - amplitude

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25
Q

B Mode
X -
Y -

A

x - depth

z - amplitude

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26
Q

M - Mode

A

X - Time

Y - depth

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27
Q

first function of receiver take each signal and make them equally larger
Treats all signals the same

A

Amplification (receiver gain)

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28
Q

Second function of receiver is to correct for attenuation by creating an image uniformly bright from top to bottom. Signals treated differently

A

Compensation (TGC, DGC)

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29
Q

Gray scale mapping
max compression - high contrast , narrow dynamic range (black & white)
min compression - low contrast, wide dyanmic range

A

Compression (log compression, dynamic range)

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30
Q

Fourth function of receiver two part process that changes electrical signals within the receiver into a form for suitable CRT display

A

Demodulation

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31
Q

Two forms or demodulation

A

Rectifaction

Smoothing enveloping

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32
Q

Converting all negative voltage into positive voltages

A

Rectification

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33
Q

Eliminate small bumps in voltage signals

A

Smoothing enveloping

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34
Q

5th function Allow us to choose whether or not to dimply low level signals (gray scale info) strong signals remain unchanged

A

Reject (threshold suppression)

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35
Q
  • Changes brightness of entire image
  • alters signal to nosie ratio
  • alters patient exposure
  • has bio effect concert
A

Output power

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36
Q
  • change brightness of entire image
  • does not affect signal to noise
  • does not change patients exposure
  • no bio effect concerns
A

Receiver gain

37
Q

If image is to dark

A

Increase receiver gain

38
Q

If image is to bright

A

reduce output power

39
Q

Image element
Image detail
Spatial resolution

A

All pertain to pixels

40
Q

Computer memory
Gray shades
Contrast resolution

A

All pertain to bits

41
Q

Maintains & organizes system timing

A

Master synchronizer

42
Q

Converts electrical sdingals

A

Transducer

43
Q

determines PRP, PRF & amplitude along with firing patterns

A

Pulser

44
Q

Produces pictures to display

A

Receiver

45
Q

CRT/ Television

A

Display

46
Q

Archive

A

Storage

47
Q

Created in tissue from non-linear behavior

A

Harmonics

48
Q

Created during reflection

A

contrast harmonics

49
Q

Created during transmission

A

Tissue harmonics

50
Q

Fills in missin data, imrpoves spatial resolution

A

Fill-interpolation

51
Q

For phases transducers only, frames are averages & improves signal to noise ratio, reduces artifact , improves station resolution, reduces temporal resolution

A

Spatial compounding

52
Q

Advanced tecnquie that reduces speckle & noise , reflect signal is divided into subabnds of limited frequencies & an image is created from each sub band. Image from sub band combines into a single image

A

Frequency compounding

53
Q

Image processing technique the continues to display information from older images then a smoother image with reduced noise, higher signal to noise ratio & improved image quality is produced

A

Temporal compounding (persistence)

54
Q

Venous flow

A

Phasic flow

55
Q

Cardiac contraction

A

Pulsatile

56
Q

Constant speed, venous circulation

A

Steady flow

57
Q

2 x velocity x transducer frequency x cos 0 / propagation speed

A

Doppler shift equation

58
Q

0 or 180

A

Most accurate doppler shift

59
Q

Clinically best

A

60

60
Q

90

A

no measurement

61
Q

Advantage - measure high velocities

Disadvantage - range ambiguity , lack of TGC

A

CW (non imaging) - no damping)

62
Q

advantage - range resolution
disadvantage - inaccurate measurement of high velocities
aliasing can occur

A

Pulsed wave (uses damping)

63
Q
  1. adjust scale
  2. low frequency
  3. shallow sample volume
  4. use cw transducer
  5. adjust baseline
A

Eliminate aliasing

64
Q

Greater accuracy sensitive to low flow

disadvantage - more time to get imp, frame rate, and tamp resolution reduced

A

Packet/ ensemle length

65
Q

multiple equally spaced, parraell to sound beam, deeper & along straight line

A

reverberation

66
Q

single, solid hyper echoic line

A

comet tail/ ring down

67
Q

structure above has high attenuation, shadow color same as background color, absence of true anatomy below

A

shadowing

68
Q

refraction @ edge of circular structure, hypo due to refraction and beam spreading

A

edge shadowing

69
Q

opposite of shadow, structure below has low attenuation, hyperechoic, parallel to sound beam

A

enhancement

70
Q

ide by side form of enhancement, hyperechoic, high intensity in focal zone

A

Focal enhancement/ banding

71
Q

– 2nd copy of reflector, artifact is DEEPER then real & equal distance from mirror

A

Mirror image

72
Q

correct number of reflectors at improper depth, faster than soft tissue – shallow reflector, slower than soft tissue – deeper

A

Prop speed

73
Q

obliquely 2nd copy of true reflector & media have different propagation speeds, appear side by side cannot tell which one is real & degrades lateral resolution

A

Refraction

74
Q
  • ONLY with mechincal single crystal transducer, 2nd copy of true reflector placed side by side
A

Side lobes

75
Q

only with array transducers, 2nd copy of true reflector , side by side

A

Grating lobes

76
Q

elevational resolution, beam has greater width than reflector, fill in anechoic structures also called partial volume artifact/ curried with a 1 ½ dimensional array transducer. Linear array = poor

A

slice thickness

77
Q

Grainy appearance from interference effects of scattered sound

A

Speckle

78
Q

late reflections appear to shallow on image, cured by a LOWER PRF. (incorrect depth)

A

Range ambiguity

79
Q

reflector place incorrectly on display

A

Multipath

80
Q

strategic pins located @ speed of soft tissue. Tests lateral & axial resolution. Cannot evaluate gray scale (no attenuation)

A

AIUM 100 mm test object

81
Q

– pins mimic cysts & solid masses, has attenuation can evaluate gray scale

A

Tissue equivalent phantom

82
Q

100 W/cm ^2

A

unfocused

83
Q

1 w/cm^2

A

focused

84
Q

measures acoustic output of transducer

A

Hydrophone

85
Q

measures beam profiles from interactions of sound waves and light

A

Acoustic optics

86
Q

– transducer turns acoustic energy into heat calculating total power

A

calorimeter

87
Q

measures specific points in space and change in temp

A

Thermocouple

88
Q

science to identify & measure characteristics of US relevant to potential bioeffects

A

Dosimetery

89
Q

dynamic technique that produces images from sound reflections based on differing stiffness

A

Elastography

SPI REVIEW (3 decks)

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