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Raad 354 - Physics > SG2 > Flashcards

SG2 Flashcards

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1
Q

what is one misconception about digital radiography

A

digital produce lower dose

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2
Q

what factors remain the same for both digital and film radiography

A
  1. xray imaging system
  2. xray production
  3. xray emission
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3
Q

What is the expectation of digital radiography

A

low dose

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4
Q

what are the differences bw film and digital

A
  1. minimal retakes
  2. consistent image quality
  3. radiation exposure reduced by 20-50% w/o loss of image quality
  4. radiographs can be processed after acquisition
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5
Q

which of the following is a benefit of digital radiographs to produce consistent image quality?
a. narrow exposure latitude
b. wide exposure latitude

A

B

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6
Q

the expectation of lowering patient dose will ___
a. increase the need to increase technical factors
b. increase the need to repeat
c. decrease the need to repeat

A

C

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7
Q

why is there an expectation of lowering pt dose to decrease the need to repeat

A

poor technique

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8
Q

overexpose patient is due to ___

A

repeat

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9
Q

digital radiography reduce motivation towards ___ (4)

A
  1. appropriate technique
  2. patient shielding
  3. proper collimation
  4. correct positioning
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10
Q

how much exposure cannot be recognized as too black
a. eigth fold
b. twenty fold
c. ten fold
d. five fold

A

ten fold exposuure

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11
Q

67% of ____ has no shielding
a. pelvic
b. thyroid
c. abdomen
d. urinary bladder

A

A

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12
Q

___% shield is correctly placed?
a. 10
b. 20
c. 50
d. 80

A

A

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13
Q

82.3% of repeats are due to ___
a. lack of shielding
b. positioning errors
c. inappropriate technique

A

B

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14
Q

what are the variables involves in the production of diagnostic images? (3)

A
  1. anatomy
  2. positioning
  3. physics, principles of exposure
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15
Q

what is the radiographer’s responsibility before the image is sent to the radiologist

A

image analysis

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16
Q

what is used to critically think through the problem and resolve the situation

A

problem-solving process

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17
Q

what are the steps to analytical process

A
  1. recall purpose of exam
  2. check for good balance bw visibility of detail and geometry of image
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18
Q

A good radiograph will have a balance between visibility of ___ & ___

A

detail
geometry of image

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19
Q

what are the 3 steps to effective image critique method

A
  1. classify image
  2. determine cause of problem
  3. recommend corrective actions
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20
Q

what are the 4 critiques to classification of images

A

1.within diagnostic limits?
2. optimal quality?
3. diagnosis –> continued critique
4. repeat –> MANDATORY continued critique

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21
Q

which of the following is mandatory for continued critique before attempting to repeat
a. if the image is submitted for diagnosis
b. if the image needs a repeat

A

B

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22
Q

what are the 3 reasons to determine the cause of unacceptable/suboptimal image?

A
  1. technical
  2. procedural factor
  3. equipment malfunction
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23
Q

which of the following is not procedural factor?
a. proper positioning of body part
b. proper removal of radiopaque object
c. proper record history & communication
d. maintain IR exposure

A

D

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24
Q

which of the following related to visibility of details?
a. resolution
b. sharpness
c. focal spot size
d. kVp/mAs

A

D

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25
Q

A problem that involves patient positioning or patient preparation for the exam is __
a. technical problems
b. procedural problems
c. equipment malfunction

A

B

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26
Q

Proper patient positioning is when ___ (3) aligned with one another

A

part
IR
CR

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27
Q

Proper patient preparation is ___ (3)

A
  1. remove the radiopaque object
  2. proper bowel cleansing
  3. record a thorough history and communication
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28
Q

Which problem can be kept to a minimum through an effective quality control program?
a. technical problem
b. procedural problem
c. equipment malfunction problem

A

C

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29
Q

Problems with density/IR exposure related to ___
a. kvp
b. mAs
c. size
d. IR

A

B

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30
Q

Problems with contrast related to ____
a. kvp
b. mAs
c. size
d. IR

A

A

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31
Q

Problems with recorded detail related to ___
a. kVp
b. mAs
c. IR
d. size

A

C

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32
Q

Problems with distortion related to ___
a. kvp
b. mAs
c. size
d. IR

A

C

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33
Q

what are the demographic info of an optimal image?

A
  1. pt & facility name
  2. time & date
  3. CR-cassette & pt barcode scanned
  4. DR exams match w pt info
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34
Q

what do you do if demographic info is incorrect?

A

fix everything before send to PACS

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35
Q

What is the appropriate range of collimation required of the surrounding anatomy?
a. 1-2”
b. 0.5-1”
c. 0.05- 0.5”
d. 0.8-1.3”

A

B

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36
Q

What does good collimation result in

A
  1. proper anatomy showed
  2. decreases patient dose
  3. improve visibility of recorded detail
  4. reduce histogram analysis errors
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37
Q

Good collimation improves ____
a. sharpness
b. spatial resolution
c. contrast
d. patient dose

A

B

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38
Q

what happened if IE # indicates that the IR received less than needed exposure to put in range
a. underexposed
b. overexposed

A

A

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39
Q

what happened if EI# receive more exposure?
a. underexposed
b. overexposed

A

B

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40
Q

quantum noise related to _____
a. underexposed
b. overexposed

A

A

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41
Q

Saturation related to ____
a. underexposed
b. overexposed

A

B

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42
Q

excessive scatter related to _____
a. underexposed
b. overexposed

A

B

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43
Q

When is underexposed projection not repeated?
a. loss of contrast
b. increase in saturation
c. presence of quantum noise
d. additive condition

A

D

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44
Q

when is overexposed projection is not repeated?
a. presence of quantum noise
b. excessive scatter
c. loss of contrast
d. destructive condition

A

D

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45
Q

when is underexposed projection is repeated? (3)

A
  1. IR receive less than needed exposure
  2. loss of contrast
  3. quantum noise that cannot be fixed by postprocessing
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46
Q

when is overexposed projection is repeated?

A
  1. IR receive more exposure
  2. loss of contrast
  3. saturation occur
  4. excessive scatter
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47
Q

Increase in kVp results in ____ projection
a. underexposed
b. overexposed

A

B

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48
Q

Decrease in mAs results in ____ projection:
a. underexposed
b. overexposed

A

A

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49
Q

an underexposed projection will be caused by____ kvp & ____ mAs
a. increase, increase
b. decrease, decrease
c. increase, decrease
d. decrease, increase

A

B

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50
Q

An overexposed projection will be caused by ____ kvp & ____ mAs
a. increase, increase
b. decrease, decrease
c. increase, decrease
d. decrease, increase

A

A

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51
Q

if backup timer of AEC was shorter than exposure time, it will cause ___
a. underexposed
b. overexposed

A

A

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52
Q

If wrong chamber of AEC is activated, it will cause ___
a. underexposed
b. overexposed

A

B

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53
Q

A non-grid technique with a grid will cause ____
a. underexposed
b. overexposed

A

A

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54
Q

a grid technique without a grid will cause ____
a. underexposed
b. overexposed

A

B

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55
Q

an underexposed projection occurs due to ___
a. increase in kVp
b. use grid technique without a grid
c. grid is off level or cut-off
d. increase mAs

A

C

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56
Q

which of the following causes of underexposure do not need a repeat?
a. increase SID w/o decrease mAs
b. increase SID w/o increase mAs
c. destructive condition
d. small field size is used

A

B

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57
Q

which of the following causes of overexposure do not need a repeat?
a. increase SID w/o decrease mAs
b. increase SID w/o increase mAs
c. destructive condition
d. small field size is used

A

A & C

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58
Q

if patient has additive condition, it causes ____
a. underexposed
b. overexposed

A

A

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59
Q

if patient has destructive condition, it causes ___
a. underexposed
b. overexposed

A

B

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60
Q

CAUSES OF OVEREXPOSURE, BUT DON’T REQUIRE A REPEAT is when ___ (2)

A
  1. increase SID w/o decrease mAs
  2. pt has destructive condition
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61
Q

CAUSES OF UNDEREXPOSURE , BUT DON’T REQUIRE A REPEAT is when ___ (3)

A
  1. increase SID w/o increase in mAs
  2. Large field size was used w/o increase in mAs
  3. patient had an additive condition
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62
Q

what are the technical considerations for imaging obese patient (3)

A
  1. increase attenuation
  2. increase mAs & kVp
  3. greater SNR
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63
Q

For every ___cm of added tissue thickness, the mAs should be doubled

A

4cm

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64
Q

doubled mAs to maintain IR exposure will demonstrate ____
a. low contrast
b. high contrast
c. high resolution
d. low resolution

A

A

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65
Q

For every cm of added tissue thickness, the kVp should be increased by ____

A

2

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66
Q

which of the following will increase scatter and decrease contrast
a. doubled mAs
b. increased kVp by 2

A

B

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67
Q

____ should be set as high as possible to reduce dose but not so high that it creates scatter
a. mAs
b. kVp
c. mA
d. seconds

A

B

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68
Q

what will be increased if kVp is increased by 2?
a. scatter
b. contrast
c. resolution
d. dose

A

A & D

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69
Q

what will be decreased if kVP is increased by 2?
a. scatter
b. contrast
c. resolution
d. dose

A

B

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70
Q

if kVP increased by 2, ___? (3)

A
  1. increase dose
  2. increase scatter
  3. decrease contrast
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71
Q

technical adjustments for S-M plaster cast?
a. +5-7Kvp, 50%-60% mAs
b. +8-10kVp, 100% mAs
c. no adjustment

A

A

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72
Q

technical adjustments for L plaster cast?
a. +5-7Kvp, 50%-60% mAs
b. +8-10kVp, 100% mAs
c. no adjustment

A

B

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73
Q

technical adjustments for fiberglass cast?
a. +5-7Kvp, 50%-60% mAs
b. +8-10kVp, 100% mAs
c. no adjustment

A

C

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74
Q

To demonstrate long bones with the least amount of distortion, the CR should be _____ & IR should be ____
a. perpendicular, parallel with bones long axis
b.. parallel, perpendicular to bones long axis

A

A

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75
Q

the relationship bw CR, IR and bone will determine ____

A

degree and type of distortion

76
Q

What is the Law of Isometry

A

the CR should be set at ½ of the angle formed between the object and IR to minimize foreshortening​

77
Q

A ___ CR best demonstrates the anatomic relationships at the joints
a. parallel
b. perpendicular

A

B

78
Q

What are the main 4 components of CT unit

A
  1. gantry
  2. xray tubes
  3. table
  4. collimator
79
Q

which component of CT unit is a movable frame and the most visibile part?
a. gantry
b. xray tubes
c. table
d. collimator

A

A

80
Q

Which component of CT unit produce excessive heat?
a. gantry
b. xray tubes
c. table
d. collimator

A

B

81
Q

Which component of CT unit determine the voxel length or section thickness?
a. gantry
b. xray tubes
c. table
d. collimator

A

D

82
Q

which component of CT unit decrease beam attenuation?
a. gantry
b. xray tubes
c. table
d. collimator

A

C

83
Q

xray tubes can produce _____ exposure per examinations?
a. 30
b. 20
c. 40
d. 50

A

A

84
Q

Accurate centering will avoid ___

A

degrade edge image

85
Q

what does Gantry include?

A

Xray tubes & detectors

86
Q

what material is made of the table of CT unit

A

carbon graphite fiber

87
Q

carbon graphite fiber can ____ beam attenuation

A

decrease

88
Q

collimators of CT unit varies from ____
a. 1-5mm
b. 1-10mm
c. 1-13mm
d. 1-15mm

A

C

89
Q

what controlled the collimators of CT unit?

A

software program

90
Q

collimation width determines _____ or ___

A

voxel length or section thickness

91
Q

what does doubled collimated mean?

A

radiation beam - tube exit
detector entrance

92
Q

what is the aperture for Gantry of CT unit?
a. 10-20”
b. 30-40”
c. 20-34”
d. 25-35”

A

C

93
Q

What does detectors of CT respond to

A

extreme speed without lag

94
Q

what is CT detector high capture efficiency
a. how well detectors receive photon from patients
b. how well detectors receive photons from xray tube
c. how well detectors convert incoming xray photons
d. how well detectors converts absorbed photon info to digital signal for computer

A

A

95
Q

what is CT detector high absorption efficiency
a. how well detectors receive photon from patients
b. how well detectors receive photons from xray tube
c. how well detectors convert incoming xray photons
d. how well detectors converts absorbed photon info to digital signal for computer

A

C

96
Q

what is CT detector high conversion efficiency
a. how well detectors receive photon from patients
b. how well detectors receive photons from xray tube
c. how well detectors convert incoming xray photons
d. how well detectors converts absorbed photon info to digital signal for computer

A

D

97
Q

CT detectors receive photons from ____
a. xray tube
b. collimator
c. patient

A

C

98
Q

which of the following control CT detector high capture efficiency?
a. distance bw detector
b. thickness of detector
c. material used for detector
d. size of detector

A

A & D

99
Q

which of the following control CT detector high absorption efficiency?
a. distance bw detector
b. thickness of detector
c. material used for detector
d. size of detector

A

B, C , D

100
Q

how to increase the sensitivity of the solid state detector

A

allow incoming xray beam to be a diverging fan shape

101
Q

which of the following cause concentric ring artifact?
a. tight collimation
b. wide collimation
c. misalignment

A

C

102
Q

which of the following cause star pattern artifact?
a. misalignment
b. object of greatly different contrast
c. tight collimation

A

B

103
Q

CT image quality is controlled by _____

A

resolution & noise

104
Q

Resolution depends on ____ (3)

A

pixel, voxel, matrix size

105
Q

Noise on CT image related to amount of data collected by ___

A

detectors

106
Q

Most noise is a result of ____

A

statistical fluctuation in the info recorded by detectors

107
Q

___ is used in fluoroscopy to reduce patient dose and should be used whenever possible

A

pulse progressive fluoroscopy

108
Q

Table top exposure rate should not exceed ___
a. 5R/min
b. 7R/min
c. 10R/min
d. 12R/min

A

C

109
Q

which audible timer is served as a reminder of how much time has been used in fluoro?
a. 4min
b. 5min
c.7min
d. 8min

A

B

110
Q

which part of fluoro cause increased in patient dose?

A

magnification image intensifier

111
Q

magnification image intensifier caused an increased in ____
a. dose
b. contrast.
c. resolution

A

A

112
Q

Lead apron and gloves must be at least _____
a. 0.2mm Pb/eq
b. 0.5mm Pb/eq
c. 0.15mm Pb/eq
d. 0.05mm Pb/eq

A

B

113
Q

the highest source of exposure is _____

A

scatter from patient

114
Q

A ____ mm Pb/eq lead shield should cover bucky tray
a. 0.2mm Pb/eq
b. 0.5mm Pb/eq
c. 0.25mm Pb/eq
d. 0.05mm Pb/eq

A

C

115
Q

what is photoemission

A

emit e- when illuminated by input phosphor
(electron emission after light stimulation)

116
Q

the # of e- emitted = ____

A

light intensity

117
Q

increased in strength of e- emitted = ___ light

A

increase

118
Q

less intense light is
___ wavelength
___ frequency

A

long
short

119
Q

photoemission happened at____
a. anode
b. cathode

A

B

120
Q

what is the material for input phosphors?
a. cesium iodine
b. zinc cadmium sulfide
c. Cs
d. Aluminum

A

A

121
Q

what is the material for output phosphors?
a. cesium iodine
b. zinc cadmium sulfide
c. Cs
d. Aluminum

A

B

122
Q

input phosphors located at ___
a. anode
b. cathode

A

B

123
Q

output phosphors located at ___
a. anode
b. cathode

A

A

124
Q

_____ bond to input phosphors

A

photocathode

125
Q

convert energy into visible light is____
a. input phosphors
b. output phosphors

A

A

126
Q

convert electrons into light is____
a. input phosphors
b. output phosphors

A

B

127
Q

____ is the site where accelerated electrons interact and produce light
a. anode
b. cathode

A

A

128
Q

Photoelectron at output phosphor produces ____ more light photons
a. 50-75 times
b. 40-50 times
c. 60-70 times

A

A

129
Q

what is last image hold

A

maintain last image until it is replaced

130
Q

what is pulse fluoro

A

high-power generator that is combined with a detector comprised of a TFT in contact with image intensifier output anode screen

131
Q

what are the post processing advantages of digital fluoro (3)

A

window level and width
filtering techniques
digital substraction

132
Q

Xray generator must switch on and off to accommodate for ____ (2)

A

interrogation time
extinction time

133
Q

time required to turn on generator is ___
a. interrogation time
b. extinction time

A

A

134
Q

time required to turn off generator is ___
a. interrogation time
b. extinction time

A

B

135
Q

interrogation time ___
a. achieve necessary kVp & mAs
b. prepare for next pulse

A

A

136
Q

extinction time ___
a. achieve necessary kVp & mAs
b. prepare for next pulse

A

B

137
Q

how last image hold reduce patient dose

A

a single frame image is displayed continuously until next exposure is required

138
Q

how pulse fluoro reduce patient dose

A

short burst of radiation produce individual frames

139
Q

function of magnification tube

A

magnify image electronically by changing voltage on electrostatic lens

140
Q

increase voltage = ___ focus e- at closer to input screen

A

increase

141
Q

image is magnified when reach ____ screen

A

output

142
Q

function of photocathode

A

emit e- when stimulated by input phosphor

143
Q

electrons accelerate from ____ to ___ and ___

A

cathode
anode
output screen

144
Q

primary brightness gain occurs from _____ (2)

A

acceleration
focusing of electron beam

145
Q

function of output screen

A

converts electrons into light which are available for viewing

146
Q

the ratio of the number of light photons at the output phoshor to the number of xrays at the input phosphor is ___
a. brightness gain
b. flux gain
c. magnification gain

A

B

147
Q

The ratio of the square of the diameter of the input phosphor to the square of the diameter of the output phosphor​ is____
a. brightness gain
b. flux gain
c. minification gain

A

C

148
Q

The product of the minification gain and the flux gain is ___
a. brightness gain
b. flux gain
c. minification gain

A

A

149
Q

flux gain equation

A

output light photons/ input xray photons

150
Q

[flux gain] - number of input xray photons should be ____ than output light photons

A

less

151
Q

minification gain happened due to ___

A

the same number of electrons that were produced at the LARGE input screen being compressed into the area of the SMALL output screen

152
Q

output phosphor is ____
a. 2.5-5cm
b. 10-40cm

A

A

153
Q

input phosphor is ___
a. 2.5-5cm
b. 10-40cm

A

B

154
Q

minification gain equation

A

(di/do)^2

155
Q

minification gain is an increase in ____
a. brightness/ intensity
b. density
c. # of photons
d. quality

A

A

156
Q

brightness gain of image intensifiers ____ with tube age and use

A

decrease

157
Q

fluoro xray tubes are designed for ___ operation times at ___ mA
a. shorter, higher
b. longer, lower

A

B

158
Q

tube target of fluoro xray tube is set to _____

A

prevent SOD of less than 15”

159
Q

diameter of output phosphor is ___
a. 2.5-5cm
b. 10-40cm

A

A

160
Q

diameter of input phosphor is ___
a. 2.5-5cm
b. 10-40cm

A

B

161
Q

inverse square law formula

A

I1/I2 = (d2)^2/ (d1)^2

162
Q

15% rule

A

decrease kVp by 15% and double mAs

163
Q

which radiation-induced response is directly related to dose?
a. deterministic
b. probabilistic

A

A

164
Q

which radiation-induced response is proportional to dose?
a. deterministic
b. probabilistic

A

B

165
Q

SSD for mobile radiography
a. > 12”
b. < 12”
c. > 15”
d. < 15”

A

A

166
Q

what are 2 goals for Radiation protecion

A
  1. prevent occurrence of serious radiation-induced
  2. reduce stochastic effects to acceptable degree
167
Q

effective dose limit for occupational worker
a. 50 mSv/y
b. 50 mSv/ mo
c. 30 mSv/y
d.30 mSv/ mon

A

A

168
Q

Which of the following is a specialized procedure that produces a series of 3-D images to better visualize abnormal tissue superimposed by normal tissue?
a. Digital Subtraction
b. Panorex
c. Mini C-Arm
d. Digital Breast Tomosynthesis

A

D

169
Q

During linear tomography, the amount of blur created in the image is directly related to the:
a. Tomographic Angle
b. Object Plane
c. Pivot point
d. Length of exposure time

A

A

170
Q

A typical effective dose of a barium enema is approximately 8 mSv. Using the BERT method this could be compared to ________________ of natural background radiation.
a. 1.0 year
b. 2.4 days
c. 2.7 years
d. 182 days

A

C

171
Q

During portable radiographic exams the SSD should never be less than:
a. 56 inches
b. 24 inches
c. 12 inches
d. 40 inches

A

C

172
Q

The effective dose limit for the lens of the eye for occupationally exposed individuals is:
a. 5 Sv
b. 500 mSv
c. 150 mSv
d. 50 mSv

A

C

173
Q

The effective dose limit for skin, hand, feet for occupationally exposed individuals is:
a. 5 Sv
b. 500 mSv
c. 150 mSv
d. 50 mSv

A

B

174
Q

which of the following creates images of an anatomic area within a plane while blurring structures above and below
a. DXA
b. C-arm FLuoro
c. Linear TOmography
d. Panorex

A

C

175
Q

when performing mobile imaging, the minimum distance a radiographer should stand away from primary beam is ___
a. 2 feet
b. 2m
c. 10 feet
d. 10m

A

B

176
Q

BERT stands for___
a. beneficial exposure radiation time
b. barium enema radiation tomography
c. background equivalent radiation time
d. below equivalent reduction time

A

C

177
Q

What is an advantage of C-arm fluoroscopy compared with
traditional image-intensified fluoroscopy in a standard x-ray
room?
a. the x-ray tube can be positioned under the patient
b. provides dynamic imaging
c. monitors total fluoroscopy time
d. allows imaging in a variety of planes

A

D

178
Q

In mammography, because the breast has _____ subject
contrast, it is necessary to use a _____ kilovoltage exposure
technique.
a. high, high
b. low, high
c. high, low
d. low, low

A

D

179
Q

During DXA scanning, the T-score indicates the number of
standard deviations the individual measurement is from the
data mean for a population sample of _____.
a. similarly aged individuals
b. a wide range of age groups
c. young, healthy adults
d. older, healthy adults

A

C

180
Q

During linear tomography, a smaller tomographic angle will
create:
a. increased amount of blur.
b. decreased focal plane thickness.
c. increased focal plane thickness.

A

C

181
Q

The circular structure that the patient and table travel
through during the CT scanning process that encompasses
the x-ray unit, data acquisition system, and the
detector/detectors is the:
a. donut.
b. couch.
c. magnet.
d. gantry

A

D

182
Q

In a major improvement from single-slice CT acquisition,
spiral (helical) CT allowed:
a. continuous movement of the table and the patient
through the gantry.
b. the entire volume of tissue to be scanned in one
acquisition.
c. scan time to be reduced.
d. all of the above.

A

D

183
Q

The ____ controls how much of the detector is exposed
during CT imaging, and severely limits the amount of scatter
reaching the detectors.
a. prepatient collimator
b. postpatient collimator
c. bowtie filter
d. detector array

A

B

184
Q

The amount of CT numbers that are visible in the image is
known as the:
a. window level (WL).
b. window width (WW).
c. raw data.
d. histogram

A

B

185
Q

The ability of the image to differentiate between structures
with very different attenuation characteristics (CT numbers)
when they are very close together is known as the:
a. patient dose.
b. contrast resolution.
c. edge enhancement filter.
d. spatial resolution.

A

D

186
Q

The ability to discriminate between structures with very
similar attenuation characteristics (CT numbers) is known as
the:
a. patient dose.
b. contrast resolution.
c. edge enhancement filter.
d. spatial resolution.

A

B

187
Q

Which of the following statements is true regarding the use
of lead shielding during CT?
1. The AAPM recommends against using lead
shielding in lieu of other methods of radiation
protection.
2. Lead shielding of radiosensitive tissues can be
effective in limiting radiation dose when the
shields are placed appropriately outside the SFOV
(out-of-plane).
3. The lead shielding must completely surround the
patient, because the tube(s) travel in a circular
motion.
4. The lead shielding must lie on the couch, because
the radiation comes from the area around the
table.
a. 1 only
b. 2 and 3 only
c. 2 and 4 only
d. All of the above

A

B

Raad 354 - Physics (2 decks)

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