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Radiologic Technology > Exam 1 > Flashcards

Exam 1 Flashcards

0
Q

+D artifacts appear?

A

black on img

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1
Q

artifact?

A

undesirable OD’s on the img

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2
Q

-D artifacts appear what?

A

white

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3
Q

3 categories of film artifacts?

A

exposure, processing, & handling

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4
Q

pressure type artifacts usually _______________ and appear as ___________

A

sensitize emulsion; appear as higher OD (+D)

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5
Q

artifacts that scrape emulsion appear as

A

lower OD (-D)

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6
Q

guide shoe marks?

A

run II to direction of film travel on leading edge

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7
Q

pi line artifact runs ______ to direction of film travel

A

perp

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8
Q

dichroic stain usually applies to?

A

chemical fog

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9
Q

dichroic stain aka

A

curtain effect

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10
Q

what causes dichroic stain

A

inadequate processing, where chems run down leading edge of film (yellow, purple, or blue)

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11
Q

what causes fog?

A

too high temp or too high humidity (+60%)

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12
Q

fog is what kind of film artifact?

A

handling (storage)

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13
Q

what causes static artifact?

A

low humidity (-40%) & friction

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14
Q

what type of artifact is a static artifact?

A

handling artifact

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15
Q

static artifacts look like?

A

tree, crown, smudge (+D)

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16
Q

half moon marks?

A

from bending/kinking film (+D)

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17
Q

scratch/finger nail marks (as pressure artifact) appear?

A

+D

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18
Q

artifact from moisture on finger?

A

-D, white

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19
Q

dirty screens cause __D artifact?

A

-D

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21
Q

static artifact is +D from what?

A

buildup of e-‘s in emulsion

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22
Q

hypo retention?

A

yellow/brown stains after a long storage T due to hypo retention from the fixer

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23
Q

what type of artifact is hypo retention?

A

handling

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24
Q

hypo retention is caused by what?

A

inadequate washing

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25
Q

processing artifacts are eliminated w what 2 things?

A

a proper processor QC program and frequent cleaning

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26
Q

proper facility design helps reduce?

A

handling/storage artifacts

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27
Q

acceptable QC program has 3 steps:

A

acceptance testing, routine performance monitoring, & maintenance

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28
Q

misalignment must not exceed

A

2% of SID

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29
Q

3 tools used to measure focal spot size:

A

pinhole camera, star pattern, & slit camera

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30
Q

measured kVp should be w/in

A

10% of indicated kVp

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31
Q

exposure timer accuracy should be w/in 5% of indicated time for

A

exposure T’s more than 10 ms

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32
Q

____% acceptable for exposure T’s of 10 ms or less?

A

20%

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33
Q

exposure linearity must be w/in

A

10% for adjacent mA stations

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34
Q

sequential rad exposures should be reproducible to w/in

A

+/- 5%

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35
Q

digi rad IRs have unique artifacts assoc w

A

pixel failure

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36
Q

enviro rad can contrib to

A

ghosting

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37
Q

flatfielding is a software correction that is done to equalize

A

the response of ea pixel to a uniform XR beam

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38
Q

Lossless compression up to ____ generally is considered acceptable and helpful in digi rad img management

A

3:1

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39
Q

histogram?

A

graph of frequency of occurrence v digital value intervals

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40
Q

histogram is a ______ plot

A

discrete

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41
Q

automatic rad field recognition is essential for?

A

artifact-free imgs

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42
Q

what prevents histogram errors that can lead to artifacts? (2)

A

proper coll & centering

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43
Q

partitioning of multiple digi img’s on single IP results in

A

proper separation & coll of ea img

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44
Q

wet pressure sensitization appears as?

A

+D

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45
Q

QA deals w

A

ppl

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46
Q

QC deals w

A

instrumentation & equipment

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47
Q

monitor equipment performance deals w?

A

QC

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48
Q

calibration done by?

A

QC

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49
Q

most equipment performance should be monitored

A

annually or when something is replaced

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50
Q

principally the _________ is responsible for QC

A

medical physicist

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51
Q

5 characteristics focused on by QC:

A

spatial res, contrast res, temporal res, SNR, &

artifacts

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52
Q

QC guidelines developed by:

A

American College of Radiology (ACR)

53
Q

what is the state required filtration?

A

2.5 mm of Al

54
Q

filtration is measured in terms of what?

A

HVL

55
Q

filtration is evaluated how often?

A

annually (or when something is replaced)

56
Q

collimation should not exceed

A

2% of SID

57
Q

coll. is evaluated how often?

A

semi-annually

58
Q

centering indicator must be accurate to

A

1% of SID

59
Q

focal spot size determines

A

spatial res

60
Q

focal spot size is typically measured w?

A

pinhole/slit camera, star pattern

61
Q

focal spot size can alternatively be measured w?

A

line pair test tool

62
Q

line pair test shows what to indicate + spatial frequency –> + spatial res

A

+ line pairs

63
Q

what has most lp’s (& best spatial res)?

A

mammo

64
Q

__% change in kVp —> visible change in OD?

A

4%

65
Q

kVp calibration: measured kVp should be w/in

A

10% of indicated kVp

66
Q

____% accuracy of indicated exposure T for exposures GREATER than 10 ms (exposure timer accuracy)

A

5%

67
Q

___% accuracy for exposure T LESS than 10 ms (exposure timer accuracy)

A

20%

68
Q

exposure timer accuracy is responsible for?

A

pt dose

69
Q

exposure timer accuracy measured on?

A

irradiation T of ion chamber or photodiode

70
Q

[automatic exposure control (AEC)] back up timer should terminate exposure at…(2)

A

6 s or 600 mAs, whichever occurs first

or, at 1.5 x’s the original exposure

71
Q

what is exposure linearity?

A

many combo’s of the mA and exposure T must produce same mAs value

72
Q

exposure linearity must be w/in

A

10% of adjacent mA stations

73
Q

(other than exposure linearity) ___________ must be w/in 10% btw adjacent mA stations

A

mR/mAs values

74
Q

exposure linearity measured w

A

radiation dosimeter

75
Q

(exposure reproducibility) rad exposure should be reproducible to w/in

A

5%

76
Q

(exposure reproducibility) output rad intensity should not vary more than

A

5%

77
Q

what should be cleaned w soft, lint-free cloth & anti-static sol.

A

intensifying screen

78
Q

intensifying screens should be cleaned how often?

A

at least every other mo.

79
Q

screen film contact is measured how?

A

w wire mesh test

80
Q

screen film contact should be evaluated how often?

A

semi-annually

81
Q

protective apparel should be checked?

A

annually

82
Q

used to measure light intensity for film illuminator?

A

photometer

83
Q

film illuminator light intensity should not vary more than

A

10%

84
Q

if you change 1 bulb, you have to?

A

change ALL bulbs (even in adjacent view boxes in the room)

85
Q

development temp?

A

95º F (37º C)

86
Q

3 types of digi rad artifacts?

A

IR artifacts, software artifacts, object artifacts

87
Q

IR artifacts? (5)

A

rough handling, scratches, dust, residual glue, ghost img

88
Q

ghost img from?

A

incomplete erasure

89
Q

if CR IP has not been used for_____, it should be erased again before use

A

24 hrs

90
Q

software artifacts: (2)

A

dead pixels, failure of electronic processing

91
Q

interpolation?

A

(software) mathematical process of assigning a digi value to a dead pixel based on recorded value of adjacent pixels
(correctional algorithm)

92
Q

flatfielding can minimize effect of

A

irregular patterns

93
Q

software correction that is performed to equalize the response of ea pixel to a uniform XR beam

A

flatfielding

94
Q

ensures a uniform response on the pixels

A

flatfielding

95
Q

compression when fine detail not required

A

Lossy

96
Q

object artifacts: (4)

A

tech error in pt positioning, coll., histogram selection, & backscatter

97
Q

what can you do to avoid backscatter?

A

put a shield behind the IR

98
Q

a plot of the frequency of appearance of a given object characteristics

A

histogram

99
Q

histogram is ____________ v. _____________

A

frequency of occurrence v. digi value intervals

100
Q

shape varies w ea anatomical projection in a what?

A

histogram

101
Q

what occurs if the XR exposure field is not properly collimated, sized, & positioned

A

exposure field recognition errors

102
Q

exposure field recognition errors can lead to ________________ bc of signal outside of exposure field being included in the histogram

A

histogram anal. errors

103
Q

proper coll. & centering prevent what kind of errors that can lead to artifacts?

A

histogram errors

104
Q

allows 2+ img’s to be projected onto single IP

A

partitioning

105
Q

img field must be oriented w the size & dimension of the IP to avoid img artifacts

A

alignment

106
Q

any undesirable densities on the processed img (other than those caused by scatter rad or fog)

A

artifacts

107
Q

how do you reduce backscatter?

A

coll.

108
Q

4 IP artifacts & how they appear on img?

A

cracks —> lucent —> -D
tape residue —> -D
hair —> -D
backscatter —> +D

109
Q

intermittent appearance of extraneous line patterns

A

plate reader artifacts

110
Q

dirt on light guide appears as? (late reader artifact)

A

horizontal white lines

111
Q

plate reader loading multiple IP’s in a single cassette appear as (plate reader artifact)

A

ghost

112
Q

moiré pattern error (2 causes)

A

when grid lines are II to plate reader’s laser scan lines &

when grid frequency matches scanning frequency (frequency harmonics)

113
Q

debris on mirror in laser printer appear as

A

fine white lines

114
Q

what operational error causes unattenuated rad striking IP —> histogram will be changed so it is outside normal exposure indicator range for selected body part?

A

insufficient coll.

115
Q

should use smallest IP possible & proper coll.

to avoid what kind of error?

A

operational error

116
Q

upside down IP appears as?

A

white grid-type pattern & white areas that correspond to hinges

117
Q

underexposure produces

A

quantum mottle

118
Q

how do you fix quantum mottle?

A

+ mAs

119
Q

overexposure affects what? how?

A

contrast (decreases contrast)

120
Q

what causes overexposure?

A

insufficient kVp

121
Q

what acquisition error causes inaccurate pixel values?

A

incomplete charge transfer

122
Q

if exposures taken in too rapid sequences it could cause what?

A

electronic memory artifact

123
Q

it is acceptable to perform a _________ instead of measuring focal spot size (for spatial res)?

A

line pair test

124
Q

comparing the mR output at 50 mA @ .2 s, 100 mA @ .1s is part of a test for

A

linearity

125
Q

most common processing artifacts (film) are?

A

pressure artifacts

126
Q

most pressure artifacts are caused by what?

A

transport system of processor

127
Q

guide shoe marks appear as?

A

-D (II to film travel)

128
Q

pi line marks appear as?

A

+D (perp to film’s direction)

129
Q

artifact that looks like pi lines but are not spaced 3.14” apart?

A

scratch artifact

Radiologic Technology (5 decks)

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