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Test 2 Flashcards

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1
Q

what is an artifact?

A

incorrect representation of anatomy or function

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2
Q

what can happen to a structure with an artifact?

A
  • not real
  • missing
  • misplaced
  • incorrect brightness, shape, or size
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3
Q

why may artifacts may be not helpful?

A
  • provide us misinformation (show us structures that are not there)
  • limit our study (hide structures we are trying to see)
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4
Q

why may artifacts be helpful?

A
  • provide us with useful information

- some are characteristic of particular structures/pathologies

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5
Q

what is artifact assumption #1?

A

sound travels in a straight line

-pulse is sent straight out and comes straight back (not always true)

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6
Q

what is artifact assumption #2?

A

echoes originate only from structures along the beam axis

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7
Q

what is artifact assumption #3?

A

amplitude of the returning echo depends only on the interface it strikes
-brightness is only dependant on the reflector boundary (not always true)

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8
Q

what is artifact assumption #4?

A

sound travels at 1.54 mm/us

-constant speed through all tissue=13 us/cm (not always true)

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9
Q

what are groups of artifacts?

A
  • propagation related
  • attenuation related
  • doppler artifacts
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10
Q

what is propagation related artifact relate to?

A

travel of the sound

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11
Q

what is attenuation related artifact related to?

A

relating to change in intensity of the beam

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12
Q

what are some propagation related artifacts?

A
  • slice thickness
  • speckle
  • reverberation
  • mirror image
  • refraction
  • grating lobes
  • speed error
  • range ambiguity
  • resolution artifact
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13
Q

what is slice thickness artifact also known as?

A
  • section thickness artifact
  • partial volume artifact
  • fill-in artifact
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14
Q

what is an assumption for slice thickness artifact?

A

ultrasound beam is razor thin (not true)

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15
Q

with slice thickness artifact, because its a 2D image, thickness collapses into __________

A

zero thickness

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16
Q

echoes picked up from all structures covered by __________

A

thickness

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17
Q

wat may slice thickness artifact happen with?

A

small cystic structures (cysts, carotid, GB)

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18
Q

what better resolution does slice thickness artifact need?

A

better elevational resolution

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19
Q

what is the treatment for section thickness artifacts?

A

THI-narrower and thinner beam

focusing in 3rd dimension

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20
Q

what is speckle?

A

granular appearance of images that is caused by constructive/destructive interference patterns of scattering

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21
Q

what is scattering?

A

echo sound waves take different paths on the way back to the transducer

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22
Q

how may waves come back with scattering?

A

constructively or destructively

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23
Q

constructive interference (in phase)

A

intensity will be much stronger than individual sound waves

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24
Q

destructive interference (out of phase)

A

waves will cancer out

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25
Q

what does speckle result in?

A

-varying intensities (dark and light)

grainy appearance

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26
Q

what is the treatment for speckle?

A
  • newer machines have complicated ‘speckle reuction’
  • persistence
  • increasing fo
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27
Q

when does specular reflection occur?

A

when the object is large and the wavelength is small

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28
Q

when does scattering occur?

A

the object is small and the wavelength is large

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29
Q

what does increasing fo do to wavelength/

A

reduces wavelength

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30
Q

reverberations are multiple reflections between what?

A
  • a structure and the transducer
  • between structures
  • within a structure
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31
Q

what causes reverberations?

A

sound bouncing between 2 strong reflectors

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32
Q

what are reverberation subtypes?

A
  • anterior reverberation
  • comet-tail artifact
  • ring-down artifact
  • twinkling
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33
Q

where does anterior reverberation occur?

A

the transducer face

-sound bouncing between transducer and a strong reflector

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34
Q

what does anterior reverberation trick the machine into thinking?

A

that there are multiple echoes coming back with different travel times

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35
Q

why is each deeper echo weaker in anterior reverberation?

A

the time of flight is longer on each echo, with more attenuation associated with the more time spent in the tissue

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36
Q

what is another name for anterior reverberation?

A

main bang-shows within a cystic structure

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37
Q

when does comet tail artifact occur?

A

between closely spaced structures

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38
Q

what is comet tail artifact caused by?

A

small structures

  • surgical clips
  • adenomyomatosis
  • GB pathology of cholesterol deposition in the wall
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39
Q

how is ring-down artifact different from comet tail artifact?

A

ring down has no attenuation

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40
Q

when may ringdown artifact occur?

A

liquid trapped between gas bubbles produce vibrations

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41
Q

ring down resonance

A

resonance of the bubbles produce vibrations which can be perceived as individual echoes

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42
Q

twinkle artifact appearance

A

focal ‘aliasing’ on calcifications/stones

  • can have prominent comet-tail
  • sometimes called ‘color comet-tail artifact’
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43
Q

how will you know if its twinkling and not aliasing?

A

will not decrease or disappear with increased PRF

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44
Q

what can a strong reflector do to sound?

A

sometimes a strong reflector will create a new path for the sound beam

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45
Q

what does a mirror image involve?

A

a strong reflector (gas/diaphragm)

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46
Q

what does refraction require?

A

oblique incidence through different media

sound beam path may bend going through and on the way back

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47
Q

what may refraction result in?

A

lateral position errors (linea alba)

displaces structures laterally from their correct location

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48
Q

define refraction

A

lateral position error

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49
Q

what is the treatment for refraction?

A

window

spatial compounding

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50
Q

side lobes/grading lobes

A

weak beams that are produced along the edges of elements

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51
Q

what can side lobes/grading lobes mimic?

A
  • amniotic bands on OB

- aortic flap/dissection on abdominal U/S

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52
Q

what is the treatment of side lobes/grading lobes?

A
  • apodization (GL only)
  • subdicing
  • THI
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53
Q

speed error

A

we assume sound travels at 1.54 and all tissue 13 and this is not always true. This is an average velocity

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54
Q

speed of sound in fat

A

1.45 mm/us

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55
Q

speed of sound in muscle

A

1.58 mm/us

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56
Q

is propagation speed (c) is larger than 1.54 the object will be places too ___

A

close

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57
Q

if the propagation speed (c) is smaller than 1.54 the object will be places too __

A

far

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58
Q

what happens with speed error?

A

slower c-posterior structures are placed further

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59
Q

range ambiguity artifact

A

places structures closer to the surface

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60
Q

when does range ambiguity artifact occur?

A

2nd pulse is sent out before all echoes returned from the 1st pulse

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61
Q

detail resolution

A

being unable to separate two distinct objects-cause neighbouring objects to blend/connect

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62
Q

what are attenuation artifacts?

A
  • shadowing
  • enhancement
  • edge shadow
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63
Q

acoustic shadowing

A

increased attenuation

increased % reflection (IRC)

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64
Q

is acoustic shadowing helpful or not?

A

helpful-characterize structures

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65
Q

clean shadowing

A

stones

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66
Q

dirty shadowing

A

gas

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67
Q

what is acoustic enhancement also known as?

A

through transmission

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68
Q

acoustic enhancement

A

decreased attenuation

decreased %reflection (IRC)

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69
Q

what is enhancement?

A

strengthening of echoes distal to a weakly attenuating structure

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70
Q

is acoustic enhancement helpful or not?

A

helpful

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71
Q

focal enhancement or focal banding

A

brightening of echoes can be caused also by the increased intensity in focal region

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72
Q

what does edge shadows involve?

A

curved structures with high c

-multiple refractions at the borders

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73
Q

what does edge shadows cause to the intensity?

A

decrease intensity of beam beyond

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74
Q

what is the treatment for edge shadows?

A
  • new window

- spatial compounding

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75
Q

what are some doppler related artifacts?

A
  • aliasing
  • multiple angle artifact
  • acoustic shadowing
  • mirror image
  • clutter
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76
Q

what does aliasing look like on spectral?

A

doppler spectral info on wrong side of baseline

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77
Q

what does aliasing look like on colour?

A

incorrect colour from the opposite side of baseline on the colour map

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78
Q

PRF needs to be set relativiely ______ in colour doppler?

A

high

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79
Q

NL=

A

1/2 PRF

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80
Q

what is the treatment for aliasing?

A
  • increase PRF
  • Shift baseline
  • increase doppler
  • lower fo
  • use CW
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81
Q

what may increasing doppler and lowering frequency do?

A
  • possibly of error

- loss of resolution

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82
Q

what does CW do to our image?

A

poor range resolution

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83
Q

what is multiple angle artifact?

A

flow is in a single direction but appears as 2 colours

  • 90 to vessel
  • tortuous vessels
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84
Q

acoustic shadowing in doppler

A

a calcified anterior wall can mimic occlusion of an artery

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85
Q

what is acoustic shadowing in doppler treatment?

A
  • window
  • power doppler to assess for true stenosis
  • use upstream/downstream clues
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86
Q

what causes mirror image in doppler?

A

same as grey scale-strong reflector

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87
Q

what is the treatment for mirror image in doppler?

A

change window

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88
Q

what is mirror image in spectral also known as?

A

cross-talk

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89
Q

what are reasons for mirror image in spectral doppler?

A
  1. gain is too high-causes cross talk

2. near 90 degrees will show flow on both sides of baseline

90
Q

how do we fix spectral doppler mirror image?

A

proper gain and angle

91
Q

why may 90 degree interrogation experience 2 direction flow?

A

because beams are focused and not cylindrical portions of the beam

92
Q

clutter/flash artifact

A

anything that is moving may cause doppler shift (valves/tissue motion)

93
Q

what is the treatment for clutter/flash artifact?

A
  • increase wall filter

- turn down gains

94
Q

what happens in the pulser?

A

voltage pulse in created, delayed, and sent out

95
Q

what happens at the transducer?

A

voltage is converted to a sound pulse

96
Q

what happens after striking multiple reflectors through multiple layers of tissue?

A

the corresponding echoes return to the transducer

97
Q

what happens to echoes upon returning to the transducer?

A

echoes converted back into an analog voltage signal

98
Q

what happens in the beam former?

A
  • the signal is amplified to compensate for attenuation
  • echoes from various depths are built into scan lines
  • this info is digitized for processing
99
Q

what happens in the signal processor?

A

unnecessary frequencies and amplitudes are removed

100
Q

what happens in the image processor?

A

scan lines are built into frames

  • each pixel within a frame will be assigned a # based on
  • intensity
  • depth
  • direction
101
Q

where are frames stored?

A

image memory

102
Q

what happens to frames after being retrieved from the image memory?

A

retrieved from image memory and processed again before being converted to analog voltage signals
THESE ARE SENT TO THE DISPLAY

103
Q

CRT

A

cathode ray tubes

104
Q

what does CRT contain?

A
  • phosphor-coated florescent screen (matrix of pixels)
  • electron beam generator
  • magnetic deflection coils
105
Q

Electrons which strike the inside of the screen will cause the pixels at that spot to temporarily ________

A

light up

106
Q

The brightness of the dot on the screen = ___________________

A

the strength of the electron beam

107
Q

where does the strength in the screen come from?

A

strength of returning echo

108
Q

what do magnetic deflection coils do?

A

can deflect the electron beam one way or another

109
Q

raster scanning

A

the CRT will generate electron beams that will ‘sweep’ the inner surface of the screen and cause lines to appear on the screen

110
Q

how many lines does raster scanning involve?

A

525 horizontal lines

111
Q

what are horizontal lines in raster scanning grouped into?

A

odd and even fields (262.5 lines/field)

112
Q

twin interlacing

A

in a given moment, one field is constructed, in the next moment, the other is contructed

113
Q

how many fields are shown per second in raster scanning?

A

60 fields per second
BUT each field is only half an image
therefore 30 images/second (30 Hz)

114
Q

refresh rate

A

raster scanning on a CRT displays 30 images per second

115
Q

RR (refresh rate)=

A

how many images are shown on the screen per second

116
Q

what does RR involve?

A

this involves retrieval from our image memory, digital to analog conversion, and then voltages to the display

117
Q

frame rate (Hz)

A 
how quickly frames are built 
# of images entered into the image memory per second
118
Q

what does refresh rate limit?

A

frame rate (we see RR)

119
Q

frame rate-

A

frame rate-image memory-refresh rate

120
Q

there are more frames built that we can see live canning, where are they?

A

we can see them in cineloop

121
Q

how many cathode ray tubes involve colour displays?

A

3

-1 per colour (RGB)

122
Q

what will provide a desired mix of colour?

A

CRT will fire electrons into appropriate groupings to provide desired mix of color

123
Q

what is flat panel display also known as?

A

liquid crystal display (LCD)

124
Q

what is Flat Panel Display (LCD)?

A

matrix of ‘photo-electric elements’

125
Q

what is a common matric of ‘photo-electric elements’?

A

1024x768

126
Q

what will decide luminance (brightness of element)?

A

amplitude of voltage

127
Q

is there raster scanning in flat panel display?

A

no raster scanning

128
Q

what does RR= on a typical LCD

A

60 Hz

129
Q

what are LCD advantages over CRT?

A
  • The display is much lighter and much, much thinner
  • Excellent image quality: brighter image and higher contrast
  • Significantly reduced eyestrain
  • Perform very well in a wide range of ambient light environments
  • Lower power consumptions and energy emissions
130
Q

flat panel display (plasma)

A
  • electrical charge ionizes gas producing UV light
  • UV light hits a phosphor coated screen which will glow
  • 85Hz
131
Q

flat panel display (organic LED)

A
  • latest greatest, even thinner

- involves Light Emitting Diode

132
Q

what are some display modes?

A

B-mode
M-mode
A-mode

133
Q

B-mode

A

brightness mode (grayscale, 2D)

134
Q

what does B-mode do?

A

suggests the brightness of each reflector at each anatomical position

135
Q

M-mode

A

motion mode (cardiac structures)

136
Q

what does M-mode display?

A

information from a single scan line

-beam is stationary

137
Q

M-mode and amplitude

A

amplitude at each depth represents of reflector like B-mode

138
Q

M-mode y axis

A

depth

139
Q

M-mode x axis

A

time

140
Q

A-mode

A

amplitude mode

141
Q

what does A-mode display?

A

information from a single scan line

-bean is stationary

142
Q

A-mode y axis

A

amplitude (brightness)

143
Q

A-mode x axis

A

depth

144
Q

in A mode what are brighter areas represented by?

A

higher peaks

145
Q

when is A mode used?

A

ophthalmic imaging

146
Q

What are types of image storage?

A
  • RAM
  • ROM
  • PROM
147
Q

what does RAM stand for?

A

random access memory

148
Q

RAM

A

information storage
temporary, very quick to access
very volatile, memory is dumped often

149
Q

what may happen with RAM?

A

information is lost when the machine is turned off

150
Q

what uses RAM inside the machine?

A

image memory

-information is lost once un-frozen

151
Q

what does ROM stand for?

A

read-only memory

152
Q

ROM

A

permanent info in storage
can still be accessed
not to be changes

153
Q

how is ROM different from RAM?

A

information will remain even if the machine is turned off

154
Q

what does PROM stand for?

A

programmable ROM

155
Q

PROM

A

permanent info in storage

can still be accessed, adjusted, erased

156
Q

will the info remain when machine is turned off in PROM?

A

yes

157
Q

where might the images we take and store fall under?

A

PROM

158
Q

what are extensions of image storage?

A

recording and archiving

159
Q

mass storage

A

large amounts of information stored

160
Q

floppy disks

A

magnetic medium

161
Q

what are the advantages of floppy disks?

A

archiving capability

were very colorful

162
Q

what are disadvantages of floppy disks?

A

poor access

small memory 1.44 Mb

163
Q

what are advantages of video tapes?

A

record motion

164
Q

what are disadvantages of video tapes?

A

poor resolution

poor access

165
Q

what are advantages of thermal paper?

A
  • printer itself is small
  • relatively inexpensive
  • no wet chemical is required
166
Q

what are the disadvantages of thermal paper?

A
  • fair image quality

- archival properties were poor

167
Q

digital image recording

A

hard disk drive
optical disks (CD/DVD)
magnetic optical disks
flash memory (USB/memory cards)

168
Q

hard disk drive

A

standard component on computers

uses rotating platters with magnetic surfaces

169
Q

what are the advantages to hard disk drive?

A
  • can read and write to these surfaces quickly

- large storage capacity

170
Q

what are the disadvantages to hard disk drive?

A

requires power

can crash-require backups

171
Q

optical disks

A

CD/DVD

written and read by lasers

172
Q

what are advantages to optical disks

A
  • can read and write to/from these surfaces quickly
  • medium storage capacity
  • no power required
173
Q

what are the disadvantages to optical disks?

A

can break

lose it

174
Q

what are different types of optical disks?

A
  • read only
  • write once, read many
  • rewritable
175
Q

magneto-optical disks

A

combination magnetic/optical

rewritable

176
Q

what are advantages to flash drives?

A
  • can read and write to/from these surfaces quickly
  • larger storage capacity than CD’s now
  • no power required
177
Q

what are the disadvantages to flash drives?

A

can lose them

178
Q

what does HIS stand for?

A

hospital information system

179
Q

HIS

A

integrated info system designed to manage the administrative financial and clinical aspects of a hospital

180
Q

what does RIS stand for?

A

radiology information system

181
Q

RIS

A

electronic system built to manage the workflow in the radiology department

182
Q

what does PACS stand for?

A

picture archiving and communication system

183
Q

PACS

A

storage, retrieval and distribution of images

184
Q

what are some examples of PACS?

A
  • When you store images for the radiologist, it goes into PACS
  • When you review images on your workstation, you access PACS
185
Q

What are the benefits to quality assurance?

A
  • promote properly working equipment
  • detect declining performance
  • prevent equipment malfunction and downtime
  • optimize operator and patient safety
186
Q

who does good quality typically involve?

A
  1. physicians/radiologists
  2. the sonographer/manager
  3. service personnel
187
Q

physicians /radiologists and QA

A

to assess image quality and direct protocol

188
Q

sonographers/managers in QA

A
  • assess image quality
  • preform some routine testing and record keeping
  • perform routine basic maintenance
189
Q

service personnel

A
  • assess image quality
  • preform diagnostic testing
  • preform maintenance
  • repair malfunctioning equipment
  • maintain service records
190
Q

preventative measures?

A

DAY to DAY tasks

  • clearing hard drive
  • cleaning the machine
  • cleaning the dust out of the filters
  • checking the wires for damage
191
Q

how often is QA testing done?

A

semi annual (6 months) to annual

192
Q

what does QA testing involve?

A
  • record keeping

- can involve service personnel

193
Q

what are the 2 main types of testing?

A
  1. operational QA

2. acoustic output

194
Q

operational QA

A
  • anatomical imaging/measurements

- doppler evaluation

195
Q

acoustic output

A
  • beam former

- related to bioeffects

196
Q

TEP

A

tissue equivalent phantoms

197
Q

what is TEP also known as?

A

tissue mimicking phantom (TIM)

198
Q

what is TEP?

A
  • mimics soft tissue characteristics

- we scan along the top

199
Q

what is TEP filled with?

A
  • graphite-filled aqueous gels
    (1. 54 mm/us)
  • urethane rubber
    (1. 45 mm/us)
200
Q

what is the propagation speed in TEP?

A

about 1.54 mm/us

201
Q

what is the attenuation coefficient in TEP?

A

about 0.5 dB/cm/MHz

202
Q

what is used to demarcate echogenic points?

A

nylon strings

203
Q

what does TEP come with?

A

blueprints

204
Q

what resolution do we check with blueprint and TEP?

A
  • axial resolution

- lateral resolution

205
Q

what can TEP mimic?

A

cysts

solids

206
Q

when looking at solids what did we check for?

A

contrast resolution

207
Q

what is contrast resolution associated with in TEP with contrast resolution?

A

lesion detection

208
Q

what are operational QA parameters?

A
  • detail/contrast resolution
  • sensitivity (lesion detection)
  • uniformity
  • TGC
  • accuracy of depth and distance (caliper accuracy)
  • maximum penetration
209
Q

TO=

A

test objects

210
Q

what is TO?

A

thin scattering wires provide outlines/interfaces

check measurements, resolution, accuracy e.t.c

211
Q

doppler TEP

A

contains tubular areas with pumps

-flow mimicking fluid (check flow direction)

212
Q

doppler TO description

A
  • cheaper
  • less accurate
  • moving solid object
  • can do pulsatile and reverse motions
213
Q

what can doppler TO be programmed to mimic?

A

normal waveforms

214
Q

what is acoustic output related to?

A

bioeffects

215
Q

what is a hydrophone?

A

small transducer element on a long hollow needle ( less than 1mm diameter)

216
Q

point transducer at hydrophone, hydrophone picks up pressure wave and converts to ____________

A

voltage

217
Q

Polyvinylidene Fluoride Membrane (PVDF)

A

converts pressure wave to voltage

218
Q

what can be connected to a oscilloscope?

A

both a microprobe/PVDF membrane

219
Q

what can we figure out from a oscilloscope chart?

A
  • T
  • PD
  • PRP
  • DF
  • f
  • wavelength
  • SPL
220
Q

spectrum analyzer

A

connected to oscilloscope: able to break down incoming bandwidth to individual frequencies

221
Q

most importantly, the oscilloscope readings can calculate what?

A

amplitude-based on the peaks of the signal

222
Q

what does amplitude relate to?

A

intensity

Physics 2 (4 decks)

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