finals Flashcards

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1
Q

Unit for effective dose

A

Sv & REM

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2
Q

Unit for absorbed dose

A

Gy & RAD

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3
Q

Becquerel is a unit of

A

radioactivity

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4
Q

Coulombs/kg is a unit of

A

exposure

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5
Q

equation for inverse square law

A

I1/I2 = (D2)^2/ (D1)^2

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6
Q

equation for grid ratio

A

h/d

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7
Q

equation for GCF (nongrid –> grid)

A

mAs (grid)/ mAs (w.o grid)

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8
Q

Higher grid ratio means ___ (2)

A

better scatter clean up
better contrast

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9
Q

equation for GCF (grid –> another)

A

mAs1/mAs2 = GCF1/GCF2

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10
Q

equation for wavelength

A

w = c/f

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11
Q

equation for frequency

A

f = c/ w

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12
Q

ionization radiation = ___ wavelength = _____ frequency

A

short, high

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13
Q

unit for frequency

A

hertz (Hz)

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14
Q

rank longest to shortest wavelength

A

radiowave
microwave
infrared light
visible light
UV light
xray
gamma rays
cosmic rays

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15
Q

5 characteristics of Xray

A
  1. highly penetrating (short wave, high frequency)
  2. cannot be reflected or focused
  3. neutrally charge
  4. no mass
  5. travels in straight line
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16
Q

high penetrating, low ionization is ___

A

gamma

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17
Q

low penetrating, high ionization

A

alpha

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18
Q

which radiation produced at the anode

A

primary

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19
Q

beams with different energy is called ___ (aka ___ radition)

A

heterogenous - primary

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20
Q

What are considered primary radiation

A

Brems & characteristics

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21
Q

Brems produced ____ xray spectrum

A

continuous

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22
Q

Characteristics produced ___ xray spectrum

A

discrete

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23
Q

primary beam photons have keV energy of ___

A

30-40% kVp

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24
Q

What are considered secondary radiation

A

scatter & leakage

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25
Q

what is produced by the energy of primary beam redirected after interacting with matter

A

scatter

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26
Q

scatter radiation does not produce __

A

quantum mottle

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27
Q

scatter radiation effect on images (3)

A

produce noise
reduce contrast resolution
makes image less visible

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28
Q

how do we reduce scatter (4)

A
  1. decrease volume of tissue
  2. decrease kVp
  3. increase collimation
  4. increase atomic #
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29
Q

decrease kVp = ___ scatter

A

reduce

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30
Q

increase atomic # = ___ scatter

A

decrease

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31
Q

what devices are used to reduce scatter (3)

A

collimator
beam-restring devices
grid

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32
Q

which beam-restring devices is the simplest? and which is the most effective in scatter cleanup

A

simplest: aperture diaphragm
effective: cone

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33
Q

which of the following is not beam-restricting devices:
a. aperture diaphragm
b. grid
c. collimator
d. cones
e. all of the above are beam-restring devices

A

B

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34
Q

what is the purpose of grid

A

reduce scatter radiation that reached IR

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35
Q

what is beam restrictors and grid have in common

A

reduce scatter

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36
Q

reduction in total # of xray photons remaining in beam after passing thru given thickness of material is ___
a. HVL
b. attenuation

A

B

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37
Q

thickness of absorbing material required to reduce x-ray intensity to half of its original value is ___
a. HVL
B. attenuation

A

A

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38
Q

what does HVL measures?
a. quantity
b. quality

A

A

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39
Q

2 ways to remove low-energy photons

A

filteration
hardening of beam

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40
Q

remove low-energy photons = ___ patient dose

A

decrease

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41
Q

High-voltage generator is ___ circuit

A

secondary

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42
Q

Components of primary circuit (5)

A
  1. power supply
  2. autotransformer
  3. kVp meter
  4. timer
  5. step-up transformer
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43
Q

what controlled autotransformer?
a. kVp selector
b. mA adjusment

A

A

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44
Q

What operate autotransformer

A

self-induction

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45
Q

what component of the circuit directly determine V

A

autotransformer

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46
Q

AEC timer utilized ____ for exposure control

A

ionization chamber

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47
Q

cons of AEC backup timer

A

too short = underexposed image

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48
Q

AEC measures ___ of radiation reached IR
a. quantity
b. quality

A

A

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49
Q

mA selector controls ___ in the circuit

A

amperage

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50
Q

Rectifiers are located in ___ circuit

A

secondary

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51
Q

which component transform AC to DC

A

rectifiers

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52
Q

Rectifiers is ___ diode

A

solid state semiconductor

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53
Q

half wave have ____ diodies
full wave have __ diodes

A

0,1,2
4

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54
Q

ionization chamber is radio___

A

radiolucent

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55
Q

what does rectifier require to operate

A

voltage rectification

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56
Q

what does high-voltage transformer require to operate

A

AC

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57
Q

Which component increase voltage from autotransformer by a fixed amount

A

step-up transformer

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58
Q

what does filament circuit control

A

degree & saturation the filaments are heated

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59
Q

what activate step-down transformer
a. kVp seelctor
b. mA adjustment

A

B

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60
Q

3 parts of high-voltage generators

A

step-up transformer
filament transformer
rectifiers

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61
Q

increase amperage = increase in __

A

of e- boiled off

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62
Q

the filaments are at which side of the tube

A

cathode

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63
Q

Tube housing can reduce ____

A

leakage radiation

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64
Q

Tube housing can prevent ___

A

electric shock

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65
Q

what is used in the tube housing as an insulator & thermal cushion

A

OIL

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66
Q

why glass is used for tube envelope

A

withstand heat

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67
Q

tube window for useful beam to exit is located in ___

A

glass envelope

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68
Q

TUbe current related to ___

A

mAs

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69
Q

what components are on the cathode side?

A

filament coil
focusing cup

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70
Q

function of filament coil

A

emits electrons when heated

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71
Q

function of focusing cup

A

confines electron beam to a small area of anode

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72
Q

what components are on the anode side

A

target
rotor
stator

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73
Q

functions of anode (3)

A
  1. electrical conductor
  2. mechanical support for target
  3. thermal dissipater
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74
Q

Xray emission source is at __
a. effective focal spot
b. actual focal spot

A

B

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75
Q

why tungsten is chosen as material for target (3)

A
  1. high atomic #
  2. high thermal conductivity
  3. high melting point
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76
Q

____ effective focal spot
____ actual focal spot

A

small
large

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77
Q

a sharper image will have ___ focal spot

A

small effective

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78
Q

pros & cons of small effective focal spot

A

pros: better spatial resolution
cons: more heat concentration

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79
Q

xray emission source is at ___

A

actual focal spot

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80
Q

xray are produced at ___

A

actual focal spot

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81
Q

Bremsstrahlung radiation interacts with

A

The nuclear field

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82
Q

Characteristic radiation interacts with

A

inner shell electrons

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83
Q

Characteristic radiation produced at ___ kVp

A

above 70

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84
Q

The xray primary beam most often consists of

A

Brems radiation

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85
Q

The energy of the beam can be changed through adjustments in
a. kvp
b. mas
c. quantity
d. distance

A

kVp

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86
Q

Off-foused radiation happend at the ___

A

anode

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87
Q

Target is on ___ side

A

anode

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88
Q

off focused radiation produced

A

ghosting effect

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89
Q

what helps reduce the amount of off-focused radiation

A

upper shutter of collimator

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90
Q

rotor is made up of ___

A

copper shaft & soft iron

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91
Q

stator consists of ___

A

electromagnet

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92
Q

Incident e- in photoelectric interacts with

A

inner shell e-

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93
Q

incident e- in compton interacts with

A

outer shell e-

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94
Q

what are ejected from photoelectric

A

photoelectron

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95
Q

what are ejected from compton

A

electron with ionizing capability

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96
Q

what happened when xray strike matter

A
  1. absorbed (photoelectrically)
  2. scatter
  3. direct transmission
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97
Q

reduction in intensity results from ____

A

absorption & scattering

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98
Q

increase kVp = __ PE = ___ Compton

A

decrease / increase

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99
Q

decreased patient dose = ___ PE = ___ Compton

A

decrease/ increase

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100
Q

Which of the following is not required for xray production
a. accelerating of e-
b. slowing of e-
c. rotating target
d. source of free e-

A

c. rotating target

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101
Q

Compton scatter most likely occurs with
a. An xray interacting with an outer shell electron
b. projectile electron interacting with outer shell e-

A

A

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102
Q

The anode heel effect causes
a. An x ray field with lower intensity on the anode side
b. xray with lower contrast
c. xray with higher quality on anode side

A

An x ray field with lower intensity on the anode side

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103
Q

thicker body part is placed on which side of xray tube

A

cathode

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104
Q

increase anode heel effect = ____ angle

A

small

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105
Q

increased anode heel effect = ___ SID

A

decreased

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106
Q

The line focus principle explains the relationship between:____
a. The actual focal spot and the effective focal spot
b. The large focal spot and small focal spot
c. The large focal spot and actual focal spot

A

A. The actual focal spot and the effective focal spot

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107
Q

Line focus principle results in greater ____ & ____

A

heat capacity
image sharpness

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108
Q

For line focus principle, what needed to be angled for heating while maintaining small focal spot

A

TARGET

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109
Q

Quantity aka ____ (3)

A

xray output
intensity
exposure

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110
Q

quantity is affected by ____ (4)

A

kvp
mas
distance
filtration

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111
Q

quantity is measured by _____

A

milliroentgens

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112
Q

Quantity is also known as all of the following except :____
a. xray output
b. exposure
c. energy
d. intensity

A

C

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113
Q

IR exposure is measured by ___

A

numeric exposure value

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114
Q

Quality aka ___

A

penetrability

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115
Q

HIGH penetration in material of ____ atomic #

A

LOW

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116
Q

quality is affected by ____ (2)

A

kvp
filtration

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117
Q

increase mAs = ____ quantity

A

increase

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118
Q

increase kVp = ____ quantity

A

increased 4x

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119
Q

increase distance = ___ quantity

A

decrease

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120
Q

increase filtration = ____ quantity

A

decrease

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121
Q

intensity is _____
a. quantity
b. quality

A

A

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122
Q

increase kVp = ____ speed + energy of photons

A

increase

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123
Q

what can remove low-energy photons

A

increase filtration

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124
Q

increase filtration = ___ resolution

A

increase

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125
Q

Beam quality is a measurement of
a. Half-value layer
b. beam divergence
c. amount of radioactivity
d. amount of xray in primary beam

A

A

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126
Q

What are the prime factors

A

kvp
mas
distance

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127
Q

what material is used for filtration

A

aluminum

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128
Q

thicker filters = ___ atomic # = ____ reduction of output

A

high
high

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129
Q

purpose of filtration

A

remove low-energy xray photons

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130
Q

filtration ____ intensity of beam AND ____ photon energy

A

decrease
increase

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131
Q

total filtration is combination of ____
a. inherent & added
b. inherent & compensating
c. added & compensating

A

A

132
Q

purpose of grid

A

improve contrast by absorbing scatter

133
Q

when to use grid

A

body thickness over 13cm or 10 for film

kvp > 70

134
Q

grid is made up of ____ strips & ____ interspace

A

radiopaque
radiolucent

135
Q

Grid lines could be visible in all of the following except ___
a. when using stationary grid
b. when the bucky oscillates
c. when CR is not perpendicular to IR

A

B

136
Q

which type of grid has the tube angled with length of grid without cut-off

A

parallel

137
Q

which type of grid has focal range

A

focused

138
Q

grid with wide focal range = ____

A

low grid ratio

139
Q

better scatter cleanup = ____ grid raatio

A

high

140
Q

narrow focal range = ____ grid ratio

A

high

141
Q

which type of grid has 2 linear grids perpendicular to one another

A

crosshatch

142
Q

which type of grid is best at scatter cleanup

A

crosshatch

143
Q

if primary beam is angled into lead and leads to decrease in density along periphery of film, what error occured?

A

grid cut-off

144
Q

how to fix off-level grid

A

grid perpendicular to CR

145
Q

when does off-focused error occur

A

when used at SID out of focal rang

146
Q

which type of error is describes:
“ focused grid not aligned with labeled tube side facing ray tube”

A

upside down

147
Q

what is the effect caused by upside-down grid error

A

uneven exposure

148
Q

What caused moire effect

A

grid lines captured & parallel to scan lines

149
Q

moire effects occured in ____ grid

A

stationary

150
Q

HVL is a measurement of beam ____
a. quantity
b. quality

A

A

151
Q

5 image characteristics

A

brightness
contrast
noise
distortion
spatial resolution

152
Q

brightness is measured by ____

A

candela

153
Q

brightness is controlled by ____
a. postprocessing
b. preprocessing

A

a

154
Q

window level adjusts ___
a. brightness
b. contrast

A

A

155
Q

increase window level = ___ brightness

A

decrease

156
Q

why we dont adjust window width for brightness

A

data from original histogram is lost
narrow dynamic range –> misdiagnosed

157
Q

contrast is ____ of pixel

A

bit depth

158
Q

contrast describes:
a. visibility
b. sharpness

A

A

159
Q

distortion describes:
a. visibility
b. sharpness

A

B

160
Q

brightness & contrast corresponds to :
a. visibility
b. sharpness

A

A

161
Q

distortion & spatial resolution corresponds to :
a. visibility
b. sharpness

A

B

162
Q

sharpness is determined by ____ (3)

A

matrix size
pixel size
bit depth

163
Q

sharpness is measured by ___ (4)

A

PSF
LSF
MTF
system noise

164
Q

increased kVP = ___ scale

A

short

165
Q

decreased kVp = ____ scale

A

long

166
Q

short scale is for which structure

A

skin
bone

167
Q

long scale is for which structure

A

soft tissue

168
Q

Window width adjusts ____
a. brighness
b. contrast

A

B

169
Q

What is the amount of mAs that can compensate for kVp

A

NONE

170
Q

subject contrast depends on ____

A

kvp & irradiated material

171
Q

subjected contrast resulted from ____

A

differential absorption

172
Q

increased subject contrast = ___ kVp

A

decrease

173
Q

spatial resolution aka ____ (3)

A

definition, sharpness, recorded detail

174
Q

short wavelength = __ frequeny & resolution

A

increase

175
Q

short wavelength is for ___ objecct

A

small

176
Q

problems with spatial resolution (4)

A

no motion
decreased OID
decreased focal spot size
increase SID

177
Q

if SNR increased = ____ image quality

A

increased

178
Q

how do you optimize SNR

A

noise intolerance
set exposure value
monitor

179
Q

noise intolerance = ____

A

exposure creep

180
Q

lack of attention to wide dynamic range = ____

A

dose creep

181
Q

decreased noise will ___

A

increase pt dose

182
Q

difference bw optimal image and best image

A

optimal: balance of noise & pt dose

best: no noise & high pt dose

183
Q

what caused size distortion

A

magnification

184
Q

decreased magnification = ___ spatial resolution

A

increase

185
Q

increase visualization = increased in ___ while maintaining____

A

OID
SID

186
Q

minimize OID = ____ distortion

A

decrease

187
Q

maximize SID = ____ distortion

A

increase

188
Q

why shape distortion happen

A

object plane & image plane not parallel

189
Q

shape distortion depends on what factors (3)

A

thickness
position
shape

190
Q

how to decrease shape distortion

A

body // IR and perpendicular to CR
minimize OID

191
Q

elongation is a type of ___ distortion

A

shape

192
Q

elongation is caused by ____
a. tube angle
b. body part

A

tube angle

193
Q

foreshortening is a type of ___ distortion

A

shape

194
Q

foreshortening is cause by ____
a. tube angle
b. body part

A

body apart

195
Q

Attenuation varies depend on ____ (2)

A

pt thickness & composition

196
Q

differential absorption & attenuation depend on ____ (3)

A
  1. atomic #
  2. mass density
  3. xray energy
197
Q

increase atomic # = ____ attenuation

A

increase

198
Q

pathology will cause changes in _____ (3)

A

thickness
effective atmoic #
density

199
Q

Additive is a condition in which ___

A

there is an increase in thickness, effective atmoic #, and/or density

200
Q

additive conditions ____ attenuation

A

increase

201
Q

as additive disease worsens, IR exposure ____

A

decreases

202
Q

Destructive is a condition in which ____

A

there is an decrease in thickness, effective atmoic #, and/or density

203
Q

destructive conditions ____ attenuation

A

decrease

204
Q

as destructive disease worsens, IR exposure ____

A

increase

205
Q

Which of these pathologies result in the increased attenuation of the beam
a. osteoporosis
b. emphysema
c. pneumothorax
d. congestive heart failure

A

D

206
Q

Which of these pathologies result in the decreased attenuation of the beam
a. tuberculosis
b. pneumonia
c. cardiomegaly
d. emphysema

A

D

207
Q

tuberculosis

A

additive

208
Q

pneumothorax

A

destructive

209
Q

atelectasis

A

additive

210
Q

pagets disease

A

additive

211
Q

emphysema

A

destructive

212
Q

bowel obstruction

A

destructive

213
Q

osteoporosis

A

destructive

214
Q

What is being described:

highest actual atomic #
low effective #
low density

A

AIR

215
Q

What is being described:

lowest effective #
low density
similar tissue to water

A

FAT

216
Q

What is being described:

high actual atomic #
high effective #
higher density than FAT

A

MUSCLE

217
Q

highest attenuator is ___

A

BONE

218
Q

fat has tissue similar to ___

A

water

219
Q

which one has higher density
a. muscle
b. fat

A

A

220
Q

How can a technologist tell if an image is overexposed
a. the exposure indicator number will be out of range
b. loss of contrast
c. image show quantum mottle
d. image show saturation

A

A

221
Q

what is dexel

A

Rounds average attenuation coefficient to nearest preset value in dynamic range

222
Q

3 components of dexel

A

A-Se
TFT
Capacitor

223
Q

A pixel corresponds to ___

A

area of pt’s tissue

224
Q

pixel size depends on ____

A

matrix size

225
Q

___ pixel size = more details

A

small

226
Q

what is subset of bit depth

A

dynamic range

227
Q

what is subset of dynamic range

A

grayscale

228
Q

how to calculate # shade of grays

A

2^bit depth

229
Q

large matrix size = ____ quality

A

high

230
Q

voxel is collected by ___

A

dexel

231
Q

The main image capture component of all dr detectors is the
a. Active matrix array
b. pixel
c. voxel
d. flat panel IR

A

A

232
Q

AMA is main image capture of ____
a. DR
B. CR

A

DR

233
Q

What made up of AMA (2)

A

flat panel & dexel

234
Q

function of AMA

A

convert remnant xray to electrical signal

235
Q

A cassette-based is used in ___
a. CR
b. DR

A

CR

236
Q

IR type for DR & CR

A

DR: TFT
CR: PSP

237
Q

function of PSP

A

stores xray energy as latent image

238
Q

PSP is sensitive to ___

A

BG radiation

239
Q

CR imaging plates use which of the following?
a. barium fluorohalide
b. amorphous silicon
c. amorphous selenium
d. barium sulfate

A

A

240
Q

dexel material for direct capture

A

amorphous selenium

241
Q

dexel material for indirect capture

A

amorphous silicon

242
Q

xray strikes the scintillator in ___
a. direct capture
b. indirect capture
c. CR

A

B

243
Q

which IR type has 7 layers
a. PSP
b. TFT

A

PSP

244
Q

what is quantization

A

3rd step of digitizing images

level out brightness level for pixel to nearest gray available in preset dynamic range

245
Q

Histogram shows ___
a. brightness value
b. grayscale.

A

brightness value

246
Q

histogram has ____ that can recognize false densitities

A

light field recognition

247
Q

Histogram analysis do 2 things: _____

A

compare histograms
eliminate data that skew with rescaling

248
Q

5 histograms selection errors

A

▫Segmentation
▫Matching
▫Prosthetic & lead apron in collimated area
▫Pre-fogging of IR from BG radiation
▫Extreme scatter radiation

249
Q

An image with appropriate spatial resolution could be said to have:___
a. sharpness
b. visibility
c. distortion
d. noise
e. quantum mottle

A

a. sharpness

250
Q

The total number of pixel values that can be produced by the digital system is the ____
a. bit depth
b. dexel
c. exposure latitude
d. dynamic range

A

a. bit depth

251
Q

The range of exposures that can be captured by a detector is the ____
a. dynamic range
b. grayscale
c. contrast
d. window level

A

a. dynamic range

252
Q

The ability to produced quality images within a range of acceptable techniques is _____
a. exposure latitude
b. dynamic range
c. rescaling
d. DQE

A

a. exposure latitude

253
Q

A graphic representation of the recorded signals received by the IR is known as
a. DR
b. histogram
c. rescaling
d. image sampling

A

Histogram

254
Q

Spatial resolution is controlled by ___
a. bit size
b. mas
c. kvp
d. pixel size

A

a. bit size

255
Q

Interpolation can fix ___
a. dead pixels
b. image ghosting
c. effects of scatter
d. segmentation errors

A

a. dead pixels

256
Q

LUT gives _____

A

just right amount of brightness & contrast

257
Q

adjustments to LUT

A

output pixels adjusted to same output Q values

258
Q

LUT adjustments happened during____

A

image rescaling

259
Q

4 steps to preprocessing?

A
  1. Field uniformity
  2. Dexel & noise correction
    3.Histogram & analysis
    4.Rescaling
260
Q

field uniformity has this computer software called ____ that compensate areas out of range of uniformity

A

electronic amplification

261
Q

Anode heel effect is partially compensated by ____

A

field uniformity

262
Q

purpose of field uniformity

A

correct uneven distribution of BG density

263
Q

What is segmentation failure

A

When individual exposure cant be separated

264
Q

when will segmentation failure happen

A

CR

265
Q

interpolation is ___
a. postprocessing
b. preprocessing

A

B

266
Q

how does interpolation reduce noise

A

through software KERNEL

267
Q

purpose of interpolation

A

give dead pixels the gray surrounding it

268
Q

DQE stands for ___

A

detective quantum efficiency

269
Q

purpose of DQE

A

measure the efficiency of IR in converting xray into radiographic image

270
Q

DQE =1 means ___

A

100% of information is converted

271
Q

increase DQE = ___ IR exposure AND ____

A

decrease
pt dose

272
Q

which of the following provide ideal brightness & balanced grayscale regardless of technique
a. rescaling
b. field uniformity
c. LUT adjustment

A

RESCALING

273
Q

process of rescaling

A

S –> Q –> placed in permanent LUT

274
Q

amorphous selenium absorbs _____
a. xray
b. light

A

a. xray

275
Q

amorphous silicon absorbs _____
a. xray
b. light

A

b. light

276
Q

which phosphor is in scintillator layer for indirect capture

A

cesium iodide

277
Q

what is the phosphorescent screen of indirect capture DR

A

scintillation layer

278
Q

immediate light emission by some types of stimulation is ____

A

Fluorescence

279
Q

delayed emission of light is ____

A

Phosphorescence

280
Q

what is the second stimulation to phosphorescence

A

laser beam

281
Q

latent image becomes ___ after exposure

A

manifest image

282
Q

underexposure cause ____

A

quantum mottle

283
Q

overexposure caused ____

A

saturation

284
Q

windowing affects ___ of images

A

visibility

285
Q

3 functions of PSP

A
  1. Ionize phosphors
  2. Trap e- & convert to electric signals
  3. Stores xray energy as latent image
286
Q

exposure latitude controls ____

A

brightness & contrast

287
Q

wide exposure latitude = ____

A

low contrast

288
Q

narrow exposure latitude = ____

A

high contrast

289
Q

what is exposure indicator number

A

indicate level of radiation exposure to IR

290
Q

if out of exposure indicator range it will cause ____

A

NOISE

291
Q

what is dynamic range

A

range of exposure intensities to IR

292
Q

what is dynamic range compression

A

remove darkest to lightest pixel values from grayscale

293
Q

DRC allows __

A

windowing

294
Q

spatial domain operation is __
a. preprocessing
b. postprocessing

A

POSTPROCESSING

295
Q

what is point processing

A

performs specific pixels in sequence

296
Q

image substraction is an example of ___
a. point processing
b. area processing
c. global operations

A

A

297
Q

what is area processing

A

Execute mathematical function on a subsection of image

298
Q

magnification is an example of ___.
a. point processing
b. area processing
c. global operations

A

b. area processing

299
Q

image orientation is an example of ____
a. point processing
b. area processing
c. global operations

A

c. global operations

300
Q

with global operations, middle column is being ____ while corresponding columns are ____

A

translated
inverted

301
Q

detail processing is in which domain operation

A

frequency

302
Q

windowing is in which domain operation

A

intensity

303
Q

high frequency = ____ pixel size

A

increase

304
Q

high wavelength = ____ pixel size

A

decrease

305
Q

what is submatrix

A

spatial detail processing with kernels

306
Q

what allows frequency processing to separate structure

A

fourier transformation

307
Q

4 postprocessing features of detail processing

A
  1. smoothing
  2. BG suppression
  3. local contrast of fine details
  4. edge enhancement
308
Q

mid-size structures suppressed by contrast reduction & move into BG happened in ____

A

detail processing

309
Q

pro and con of edge enhancement

A

Pro: increase local contrast for small pathology changes
Cons: increase image noise

310
Q

if over enhance local contrast = ___

A

loss of details

311
Q

BG suppression reduce contrast of ____ structures

A

larger mid-frequency and low-frequency

312
Q

pro & con of BG suppression

A

Pros: effective in tissues like fat pads
Cons: Result is similar to edge enhancement

313
Q

Smoothing removes ___ structures

A

highest-frequency

314
Q

which 2 postprocessing features give the same result

A

BG suppression & edge enhancement

315
Q

soft edge is due to ___

A

decrease in local contrast

316
Q

noise is reduced by ___

A

interpolation

317
Q

purpose of smoothing

A

corrects for dead pixels in IR + amount of mottle

318
Q

severe mottle = ___

A

gross underexposure

319
Q

Cons of smoothing

A

lose small details that contribute to diagnostic information

320
Q

decoupling local contrast is ____

A

fine details visible
whole image has same contrast

321
Q

if we eliminate noise, we need to accept the fact that

A

some fine details are gonna be lost

322
Q

soft tissue technique can be stimulated by ___

A

DRC

323
Q

adjust pixel values to fit average histogram & small exposure error is _____

A

rescaling

324
Q

segmentation doesnt occur in ___
a. CR
b. DR

A

B.

325
Q

what can correct quantum mottle
a. kernel
b. frequency filtering algorithm
c. none

A

kernel

326
Q

what can correct electric mottle
a. kernel
b. frequency filtering algorithm
c. none

A

frequency filtering algorithm

327
Q

What is imaging cycle in order

A

exposure –> histogram –> permanent LUT (rescaling) –> anatomical LUT (gradation) –> default detail processing –> displayed image