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Part 2 Boards > Xray Physics > Flashcards

Xray Physics Flashcards

1
Q

a unit of ionizing radiation that is 99% heat and 1% diagnostic

A

roentgen ( xray photon)

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2
Q

REM

A

roentgen equivalent in man (tech dose)

5 REMs is safe dose per year

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3
Q

MPD

A

maximal permissable dose (badges)

number of REMs a person can get in a lifetime without getting radiation poisoning

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4
Q

RAD

A

roentgen absorbed dose (in anything)

used to identify radiation in patients
measures radiation being absorbed

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5
Q

what are the different forms of primary radiation

A

bremsstrahlung
and
characteristic

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6
Q

which primary radiation comprises the most photons and interacts with the NUCLEUS of the cell

A

bremsstrahlung

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7
Q

which primary radiation contains the most energy and interacts with the INNER SHELL of the cell and an outer shell electron fills its spot

A

characteristic

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8
Q

what are the different forms of secondary radiation

A

Compton
and
thompson

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9
Q

which secondary radiation interacts with the OUTER SHELL and LOSES energy

A

Compton

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10
Q

which secondary radiation has EQUAL energy exchange within the cell

A

Thompson

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11
Q

which form of radiation is also called classical

A

Thompson

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12
Q

filters are made up of what

A

aluminum

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13
Q

grids are made up of what

A

lead strips

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14
Q

what supports the emulsion with silver bromide and halide crystals

A

film base

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15
Q

what light is considered safe for X-ray use

A

red light

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16
Q

what is the X-ray process

A

develop
fix
wash
dry

(DFWD)
don’t forget wash/dry

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17
Q

what tissues are most radiosensitive (mutate)

A

blood (WBC) , sperm

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18
Q

what tissues are least sensitive (death)

A

nerve, thyroid, ovaries

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19
Q

what does the developer do

A

brings out the latent image by developing the exposed silver halide crystals to metallic silver

reduces the amount of exposed silver crystals

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20
Q

what does the fixer do

A

neutralizes developer
removes unexposed crystals
hardens the image

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21
Q

brown or greasy discoloration to film is caused by what

A

poor washing

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22
Q

brown or yellow film is caused by what

A

old developer

“old yeller”

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23
Q

if film is unexposed and developed it will be __

A

translucent

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24
Q

if film is exposed and developed it will be __

A

black

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25
Q

spider appearance on the film is caused by what

A

static

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26
Q

small dots on the film are caused by what

A

water droplets

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27
Q

corner clipped off on the film is caused by what

A

copy of film

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28
Q

vertical lines on the film are caused by what

A

dirty rollers or static grid

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29
Q

scratchy border around the film is caused by what

A

old screen

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30
Q

contrast = ?

A

kvp

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31
Q

density = ?

A

mas

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32
Q

quality of X-rays is

A

kvp

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33
Q

quantity of X-rays is

A

mas

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34
Q

darkness of the film is controlled by

A

mas

35
Q

if you change 15% of kvp, you must change mas by

A

30-50%

36
Q

what is the inverse square law

A

the dose is proportional to the inverse of the square of the radius. Thus if you double the distance you reduce the dose by a factor of four

FFD to mas

37
Q

shades of the film are controlled by

A

kvp

38
Q

what is the total amount of filtration

A

2.5 mm

39
Q

what does SID, FFD and OFD mean

A

source image distance

film focal distance

object film distance

40
Q

increased detail on film is noted with what

A 
increase FFD 
decrease OFD 
umbra 
small crystals 
small focal spot
41
Q

decreased detail on film is noted with what

A 
decreased FFD 
increase OFD 
penumbra 
large crystals 
large focal spot
42
Q

what is in the emulsion in the film

A

silver bromide and halide crystals

43
Q

the protective housing of the xray tube is made of what

A

lead

44
Q

cathode is positive or negative charge

anode is positive or negative charge

A

cathode - neg

anode - pos

45
Q

what does the cathode consist of

A

large filament
small filament
focusing cup

46
Q

what serves as the source of electrons in the production of X-rays

A

filament

47
Q

filaments are made of what

A

tungesten

48
Q

what occurs when a current is applied to the filament

A

thermionic emission

49
Q

what is part of the cathode that encases the two filaments

A

focusing cup

50
Q

where does thermionic emission occur

A

focusing cup

51
Q

electrons move from __ to __ in the xray tube

A

cathode to anode

52
Q

why does the anode rotate

A

dissipate heat

53
Q

the focal spot on the anode is determined by what

A

size of filament

54
Q

what is the line focus principle

A

makes the focal spot size appear smaller

decreases the target angle which decreases the spot

55
Q

what heats the filament causing a boiling off of electrons

A

mA

56
Q

it takes a minimum change of mas by ___% to see minimum change in density on the film

A

30%

57
Q

if mas is doubled then the density is ___

A

doubled

58
Q

what is the force applied to accelerate electrons from cathode to anode

A

KVP

59
Q

low kVP means __ energy and __ penetration

A

low energy

weak penetration

60
Q

what is the difference in density between to structures

A

contrast

61
Q

what controls contrast

A

KVP

62
Q

increase in KVP causes a __ in contrast

A

decrease

63
Q

low KVP produces __ scatter and __ radiation to the patient

A

decreased scatter

increased radiation

64
Q

what is another term for low contrast

A

long scale

65
Q

to lower contrast, (__ scale of contrast)(more shades of __) you must do what

A

long scale
more shades of grey

increase KVP by 15% and decrease MAS by 50%

66
Q

to raise contrast, (__ scale of contrast)(more shades of __) you must do what

A

short scale
more shade of black and white

decrease KVP by 15% and increase MAS by 100%

67
Q

what is the 15% rule

A

increase in KVP by 15% doubles the density

decrease in KVP by 15% will cut density in half

68
Q

what mainly controls density

A

MAS

69
Q

what is the anode heel effect

A

rotating anode is angled that produces varying intensity of x-rays

intensity and density decreases on anode side of film

place thinner portion of what is being xray toward this end

(example: you would place the anode end of the xray tube towards the toes and cathode end towards the ankles)

70
Q

what is the inverse square law

A

intensity is inversely related to square of FFD

40 inch FFD is doubled to 80 in FFD, so intensity is 1/4
this means we must increase MAS by 4 times

80 inch FFD is reduced to 40 in FFD, so intensity is 4x
this means we must reduce MAS by 1/4

71
Q

what makes up the intensifying screens?

why is this important

what is the intensifying screens job

A

fluorescent crystals

small crystals - less light - lower contrast
large crystals - more light - more contrast

increases density by intensifying xray photons

converts xray photons to visible light

72
Q

what is the picture made by the useful beam

A

umbra

73
Q

what are the blurry halo parts of the image

A

penumbra

74
Q

how do we decrease penumbra

A

increase FFD
decrease OFD
small filament
small focal spot

75
Q

scatter can be reduced by what 4 things

A

grids
air gap technique
collimators
filters

76
Q

what is the proper grid ratio

A

12:1

77
Q

what is the best way to reduce scatter

A

collimation

78
Q

1 RAD =

A

1 REM

79
Q

which primary radiation is majority of useful beam

A

bremstralung

80
Q

low energy photon is absorbed by the subject creating a latent image

A

photoelectric effect

81
Q

what chemicals are used in the developer

A

hydroquinone and phenidione

82
Q

what converts one form of energy to another

A

transducer

83
Q

what steps up or steps down the power

A

transformer

84
Q

what term is used when a beam of radiation loses energy as it passes through matter

A

attenuation

Part 2 Boards (34 decks)

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