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X Ray Physics > final > Flashcards

final Flashcards

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1
Q

what controls x ray energy?

A

KVP

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2
Q

what are INTENSIFYING screens used for?

A

to reduce patient exposure

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3
Q

difference between voltage ripple and x-ray energy?

A

inverse - as voltage ripple increases x ray energy decreases

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4
Q

lead screen on the back of the casette does what?

A

reduces compton scatter

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5
Q

for a compensating filter in a lateral lumbar spine radiograph?

A

filter up

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6
Q

xray production is slowed down due to an electromagnetic force field called

A

bremsstrahlung

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7
Q

at what point are xrays produced in the tube?

A

when electrons strike the anode (focal spot, target)

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8
Q

electron transition in tungsten that produces the highest energy xray?

A

P to K - characteristic 69.5 kEv

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9
Q

in lateral spine thoracic radiograph where is the anode?

A

down

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10
Q

what exposure factor controls the QUANTITY of xrays in the beam?

A

mAs

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11
Q

what factor is selected to select filament size (large vs small)

A

mA

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12
Q

which side of the radiograph exhibits the most blur?

A

cathode side

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13
Q

which has the greatest specific ionization alpha or beta?

A

alpha

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14
Q

define isotropic

A

360 degree emission

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15
Q

which is most likely to occur in human tissue direct or indirect effect?

A

indirect effect

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16
Q

what is the only similarity between particulate radiation and xray?

A

they can ionize

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17
Q

define the term ionize

A

when an electron is totally removed from an atom

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18
Q

xray tubes target is made of what?

A

tungsten

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19
Q

if a tube overload occurs what must be done to fix it?

A

decrease mA and increase time

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20
Q

how often must lead walls be replaced

A

NEVER

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21
Q

what does a rectifier do?

A

converts AC to DC current

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22
Q

what does an electromagnetic induction motor do

A

spins the rotor/anode target

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23
Q

what type of radiation can be stopped by a piece of paper

A

alpha

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24
Q

what is the charge on the focusing cup?

A

very negative

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25
Q

what is the difference between x ray and gamma ray

A

the origin gamma comes from nucleus - otherwise it is identical

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26
Q

where should anode for an AP thoracic spine film be

A

UP

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27
Q

primary parts of cathode

A

filaments large and small and focusing cup

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28
Q

ALARA

A

as low as reasonably achievable

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29
Q

which rectifier will provide the least radiation exposure to patient

A

high frequency (30% less)

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30
Q

compare the mass of an xray to an alpha particle

A

an xray has no mass - alpha particles have 4 AMU of mass

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31
Q

compare wavelengths of xrays to radio waves

A

xrays have shorter wavelengths

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32
Q

electrons travel from where to where

A

cathode to anode to make xrays

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33
Q

to double radiographic density you must

A

also double mAs

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34
Q

to double radiographic density using kVP

A

increase kVp by 15%

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35
Q

what is the controlling factor of radiographic density?

A

mAs

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36
Q

define linearity

A

the ability to manipulate mA and time and get the same mAs

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37
Q

define reproducibility

A

doing the exact same exposure over and over and getting the exact same results

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38
Q

relationship between frequency and wavelength

A

inverse

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39
Q

formula for heat units

A

kVP x mAs

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40
Q

what produces the majority of xrays in the xray beam

A

bremsstrahlung

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41
Q

optimum kvp for extremities under 10 cm

A

50-60

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42
Q

optimum kvp for spine imaging

A

70-90

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43
Q

two akas for SID

A

FFD and TFD

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44
Q

wave equation

A

speed of light = wavelength x freq

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45
Q

define LD 50/30

A

means lethal dose where 50% of exposed pop dies within 30 days

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46
Q

does a nonstochastic effect have a threshold?

A

YES (stochastic means random)

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47
Q

stochastic effect

A

does NOT have a threshold

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48
Q

males receiving radiation for ankylosing spondylitis experience increases in

A

leukemia

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49
Q

2 devices used to reduce compton scatter

A

collimation
bucky and compression band
lead lining in back of casette

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50
Q

hormesis

A

the notion that some radiation may actually be good for you

51
Q

mutation that is unique to radiation exposure

A

none

52
Q

relationship between SID and magnification

A

inversely related

53
Q

two radiation induced malignancies

A

leukemia

thryoid, skin, bone, lung cancers

54
Q

interaction with matter that results in inner shell ionization

A

photoelectric absorption

55
Q

differential absorption of xrays by tissues results in this photographic property

A

contrast on xray film

56
Q

one disadvantage to use of radiographic grids

A

increases patient exposure dramatically

57
Q

improper or wrong SID used on focus grid, pattern of grid cutoff looks like

A

both sides are cutoff so the film is underexposed on both lateral edges

58
Q

personnel dosimeter should be worn

A

on the collar or outside apron

59
Q

annual whole body MPD for occupational exposure is

A

5 REM

60
Q

MPD for pregnant occupational worker

A

0.5 REM over the gestation period

61
Q

how are kvp and compton scatter related

A

directly, as kvp goes up compton scatter goes up

62
Q

the shortest latent period of all cancers is

A

leukemia

63
Q

dust on an intensifying screen results in

A

little white specks on the processed film

64
Q

color safe light required to be used with rare earth film screen combos

A

RED

65
Q

a red safe light is considered universal - state the name of the safelight

A

GBX

66
Q

degree and direction of central ray angle used with a crosshatch grid

A

none

67
Q

5 mAs required at 40 SID what is necessary at 80 SID to maintain density

A

20 mAs (distance doubled so multiply by 4x)

68
Q

radiation that comes from the tube housing in areas other than the port

A

leakage radiation

69
Q

level of fetal exposure below which no abortion is recommended

A

10 RAD (bushong 10-25 rule)

70
Q

what is film latitude?

A

range of error

71
Q

a long latitude film will respond to a wide range of useful _____

A

density

72
Q

relationship of film contrast to film latitude

A

inverse

73
Q

the writing on the safelight filter is placed where

A

away from bulb so it wont melt - 4 ft

74
Q

what is film base made of

A

mylar

75
Q

what is the film emulsion made of

A

silver halide crystals in gelatin

76
Q

what are intensifying screens made of

A

rare earth crystals

77
Q

minimum speed for spine imaging

A

400

78
Q

film speed for detailed extremities

A

100

79
Q

safelight bulbs should be this watts

A

15 or less

80
Q

black tree branch artifact caused by

A

static

81
Q

humidity to store films

A

40-60%

82
Q

latent image

A

invisible image on the film before processing

83
Q

manifest image

A

the visible image on film after processing

84
Q

an occupationally exposed person’s own personal exposure if included in REM unit T/F

A

False

85
Q

which is most likely to cause fog in an image

A

use of high kvp - creates longer range higher kvp goes further into range of compton scatter

86
Q

grid that is designed so that strips coincide with the divergence of the xray beam

A

focused

87
Q

image density can be DOUBLED by

A

inc kvp 15% and inc mAs by 100%

88
Q

short scale of contrast wanted (high contrast)

A

decr kvp and incr mAs 2x

89
Q

when OID is long it is more what kind of xrays produce image

A

divergent xrays produced

90
Q

stochastic effect

A

requires no threshold of radiation exposure for effect to occur

91
Q

linear non threshold

A

dose response relationship

92
Q

non stoachastic threshold

A

requires a threshold to reach first

93
Q

maximum permissible dose

A

max radiation dose would not be expected to produce significant radiation effect

94
Q

what is the annual whole body MPD for occupationally exposed persons

A

5 REM

95
Q

cumulative MPD old formula

A

5(n-18) n = age

96
Q

new formula MPD

A

1X Age = 55 REM/year

97
Q

on dosimeter report what does m mean

A

exposure received was so minimal it did not record

98
Q

cardinal principles of radiation protection

A

time
distance
shielding

99
Q

what allows a greater amount of weekly radiation exposure

A

controlled area - entire x ray room

100
Q

max exposure rate of controlled area

A

less than 100 mR per week

101
Q

max exposure rate of uncontrolled area

A

less than 10 mR per week

102
Q

protective tube housing

A

must reduce leakage radiation to less than 100 mR/hour at one meter

103
Q

SID indicator

A

must be accurate withing 2% of indicated SID

104
Q

filtration

A

total 2.5 mm Al equivalent

105
Q

PBL positive beam limitation

A

automatic collimation - must be accurate to within 2%

106
Q

how often must film badges be sent in for processing

A

once every month

107
Q

non-stochastic effects

A

erythema, cataracts, sterility

108
Q

what factors influence the amount of effect produced by radiation

A

dose rate and area of body exposed

109
Q

cells most sensitive to radiation

A

lymphocytes

110
Q

law of bergonie and tribondeau

A

cells that are undifferentiated and rapidly dividing are more likely to be effected by xrays

111
Q

major cell types at risk

A

embryonic
lymphocytes
erthyrocytes
sperm

112
Q

women are more x ray resistant than men are T/F

A

true

113
Q

acute radiation syndrome is relevant in diagnostic xray T/F

A

false

114
Q

hematopoietic syndrome

A

200-1000 RAD whole body

115
Q

GI syndrome

A

1000-5000 RAD whole body

116
Q

CNS syndrome

A

over 5000 RAD

117
Q

there is no UNIQUE radiation induced disease T/F

A

true

118
Q

long term effects DO NOT occur in most irradiated individuals T/F

A

true

119
Q

some ways to reduce exposure to patients

A
  1. aim beam at a primary wall that is not facing a waiting room
  2. collimate well each time
  3. gonadal shields
  4. set up patient correctly - high mA short time
  5. use high freq rectifier for xray
  6. use a high speed system
  7. only use the bucky when appropriate (>10 cm or >60 kvp)
  8. use compensating filters to assist
  9. long SID
  10. maintain equipment
  11. proper record keeping
120
Q

as speed increase detail/sharpness

A

decreases

121
Q

slow speed has little ___ and is more

A

divergence and blurrier bigger

122
Q

black crescent moon shapes artifact are from

A

bending film

123
Q

what is not a cardinal principle of radiation protection

A

kvp

124
Q

radiation does not add up T/F

A

true - damage does

X Ray Physics (1 decks)

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