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Physics > Ch. 1 & 11 > Flashcards

Ch. 1 & 11 Flashcards

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1
Q

electromagnetic energy is also known as what

A

radiation

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2
Q

output of radiographic unit’s radiation measurement in air

A

coulomb/kilogram (c/kg)

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3
Q

we use these instead of parallel grids to prevent grid cutoff due to beam divergence

A

focused grids

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4
Q

grid that can be used on both 40” and 72” SID

A

dual focused grid

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5
Q

what do filters do

A

filter out low energy photons which decreases patient dose

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6
Q

x-ray tubes operated above 70 kVp are required a filtration of what

A

at least 2.5 mm aluminum

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7
Q

particulate matter capable of ionizing an atom

A

alpha and beta particles

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8
Q

radiation that is capable of removing an orbital electron from one of the subjects atom

A

ionizing radiation

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9
Q

what are all the names for kVp

A

strength, penetration, quality, potential difference, electric potential

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10
Q

who initially brought to light the dangers of x-ray and who else was the first casualty

A

Thomas Edison; Clarence Dally

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11
Q

what does CT stand for

A

computed tomography

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12
Q

what is penumbra

A

blurring of the edges (unsharpness)

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13
Q

direct square law is also called

A

maintenance law

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14
Q

what is the speed of light

A

3x10^8 m/s

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15
Q

how is the magnification factor (MF) calculated

A

SID/SOD=MF

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16
Q

to maintain optimal exposure while changing the SID you use

A

direct square law/maintenance law

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17
Q

increasing kVp does what to patient dose

A

decreases patient dose by increasing transmission and decreasing absoption

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18
Q

decreasing collimation does what to scatter and contrast

A

increases scatter and lowers contrast

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19
Q

using a grid does what to contrast

A

increases contrast by eliminating scatter

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20
Q

the head and neck of the anode are made of what

A

molybdenum

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21
Q

what do you do if your image is under exposed and under penetrated

A

increase kVp by 15%

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22
Q

what is the negative side of the tube head called

A

cathode

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23
Q

insufficient mAs will result in what

A

increased quantum noise (grainy image)

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24
Q

what does a grainy image indicate

A

not enough mAs

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25
Q

40” is equivalent to how many cm

A

100cm

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26
Q

72” is equivalent to how many cm

A

180cm

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27
Q

as SID increases what happens to spatial resolution and magnification

A

spatial resolution increases and magnification decreases

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28
Q

tube head assembly includes what

A

x-ray tube, collimator, stand/overhead

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29
Q

a minimum of how much change in kVp is needed in order to see it with your human eyes

A

10% change

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30
Q

the higher the SNR

A

the better the image/spatial resolution

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31
Q

when do we use a grid

A

body part is over 10 cm thick

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32
Q

what does scatter do to an image

A

fogs the image, decreases subject contrast

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33
Q

a minimum of how much change in mAs is needed in order to see it with your eyes

A

30% change

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34
Q

kVp is the main controller of what in production of the x-ray

A

subject contrast

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35
Q

what does radiopaque mean

A

stops/absorbs x-rays

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36
Q

as SID decreases what happens to spatial resolution and magnification

A

spatial resolution decreases and magnification increases

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37
Q

as OID increases what happens to spatial resolution, magnification, and contrast

A

spatial resolution decreases, magnification increases, and contrast increases

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38
Q

only way to get rid of scatter

A

use a grid

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39
Q

mAs controls what

A

number of photons - receptor exposure

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40
Q

what is a “noisy image” called/known as

A

quantum mottle

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41
Q

the only way to fix a grainy image

A

retake with more mAs

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42
Q

increasing kVp will do what to scatter and contrast

A

increase scatter, decrease subject contrast

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43
Q

what is it called when you can alter the factors kVp, mA and exposure time (s) to get the same image/dose

A

reciprocity law

44
Q

we get an approximate dose of how much natural occurring radiation

A

3 mSv/yearly

45
Q

largest natural source of radiation; radioactive gas produced by the decay of uranium; all earth based materials have it within them

A

radon

46
Q

who discovered x-rays and when

A

Wilhelm Roentgen, November 8, 1895

47
Q

measures radioactive material

A

Becquerel (Bq)

48
Q

what side is usually on the patients head side, or our left side

A

anode (positive side)

49
Q

visibility of detail

A

contrast resolution

50
Q

what controls contrast resolution

A

use of grids

51
Q

used to measure occupational dose (dose equivalent), also measures effective dose - exam based area (eyes)

A

sievert (Sv)

52
Q

if you want tokVp see more bone what do you do

A

increase contrast by decreasing kVp

53
Q

unit of absorbed dose, allover dose, dose in patient

A

gray (Gy)

54
Q

using < 100 mA; small filament; small focal spot, will result in

A

small penumbra/good spatial resolution

55
Q

what the body takes in and absorbs inside the body

A

dose

56
Q

what is the positive side of the x-ray tube head called

A

anode

57
Q

what do you do if you have an over penetrated and over exposed image

A

lower kVp by 15%

58
Q

describes photons losing intensity as they travel through matter

A

attentuation

59
Q

what mA is used for larger body parts - chest, hips, abdomen

A

300 mA and above

60
Q

the chicken scratches on bone are called what

A

trabecular patterns

61
Q

what do you do to maintain exposure while decreasing dose

A

increase kVp by 15% while decreasing mAs by half

62
Q

where are x-rays made

A

actual focal spot on the anode

63
Q

main controller for spatial resolution

A

focal spot size (FSS)

64
Q

what does radiolucent mean

A

x-rays travel through it

65
Q

what do you do for an underexposed image

A

double mAs

66
Q

what do you do for an overexposed image

A

half the mAs

67
Q

using >300 mA; large filament; large focal spot, will result in what

A

large penumbra, bad spatial resolution

68
Q

the anode consists of what

A

anode target and induction motor

69
Q

if you want more grays on your image you will want

A

low subject contrast, high kVp

70
Q

detail and making of detail

A

spatial resolution

71
Q

main controller for spatial resolution

A

focal spot size (FSS); OID and SID influence it

72
Q

mA comes from what transformer

A

step-down transformer

73
Q

what does ALARA stand for

A

As Low As Reasonably Achievable

74
Q

the filament in the cathode is made of what

A

thoriated tungsten

75
Q

kVp is secondary controller of what

A

receptor exposure (RE)

76
Q

what material is sometimes added to tungsten on the target plate to increase thermal capacity and tensile strength

A

Rhenium

77
Q

what does increasing the collimation do

A

decreases the light field

78
Q

what does decreasing collimation do

A

increases the light field

79
Q

influences of spatial resolution

A

OID and SID

80
Q

the relationship between distance and x-ray beam intensity is best described by what

A

inverse square law

81
Q

what mA is used for extremeties

A

100 and below

82
Q

where are x-rays made

A

actual focal spot on the anode

83
Q

describes photons being totally stopped in the body

A

absorption

84
Q

50% of the population has this type of body habitus

A

sthenic (average)

85
Q

the intensity a photon loses in the body as it travels through the body; energy given off

A

kerma

86
Q

to maintain exposure when shooting a thicker part what must you do

A

increase mAs

87
Q

increasing collimation will do what to scatter and contrast

A

decrease scatter; increase contrast, but require more mAs

88
Q

describes the boiling off of electrons at the filament

A

thermionic emission

89
Q

spatial resolution is also what

A

detail

90
Q

how many more electrons are boiled off the large filament

A

4x

91
Q

what does SNR stand for

A

signal to noise ratio

92
Q

what is the range of kVp we use

A

60-120 kVp

93
Q

how far can you be off with a grid before it effects your image

A

3-5 degrees

94
Q

for every change of what in part thickness must the radiographer alter mAs by factor of 2

A

every 4-5 cm

95
Q

particulate and electromagnetic radiation emitted by sun and stars

A

cosmic radiation

96
Q

radiation naturally within us as metabolites, mainly potassium-40

A

internally deposited radionuclides

97
Q

relationship between matter and energy

A

E=MC^2

98
Q

glass envelope is usually made of what

A

borosilicate glass

99
Q

photon losing intensity as it travels through air

A

air kerma

100
Q

already on the Earth, deposits uranium, thorium, and other radionuclides on the planet

A

terrestrial

101
Q

very slender body habitus

A

asthenic

102
Q

what percent of population is asthenic

A

10%

103
Q

a more slender, taller build is known as

A

hyposthenic

104
Q

what percent of the population is hyposthenic

A

35%

105
Q

a larger, stocky build

A

hypersthenic

106
Q

what percent of the population is hypersthenic

A

5%

Physics (9 decks)

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