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Radt. 3000 > Exam 2- Factors selected at control panel > Flashcards

Exam 2- Factors selected at control panel Flashcards

1
Q

mA-

A

quantity of electrical current flowing in a circuit

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2
Q

cathode contains-

A

filament

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3
Q

when current is applied to the filament circuit-

A

-flow through filament
-heat up filament circuit
-electrons will be boiled off

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4
Q

filament-

A

coil of wire where electrons are going to be boiled off

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5
Q

Thermionic emission-

A

boiling off of electrons at filament

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6
Q

focusing cup-

A

place on cathode where electrons are boiled off of filament & held in place

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7
Q

space charge/electron cloud-

A

collection of electrons boiled off filament in focusing cup

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8
Q

the lower the mA-

A

the lower quantity/amount of electrons boiling off the filament

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9
Q

as more circuit is applied to the filament, the circuit-

A

gets hotter

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10
Q

intensity/quantity of the x-ray beam is directly proportional to-

A

mA

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11
Q

exposure time-

A

amount of time in which beam is activated & exposure occurs

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12
Q

when using a breathing technique, use a _____ exposure time-

A

longer

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13
Q

want exposure time as short as possible to-

A

eliminate motion

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14
Q

2 types of motion-

A

voluntary & involuntary

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15
Q

eliminate voluntary motion-

A

good patient instructions

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16
Q

eliminate involuntary motion-

A

-short exposure time
-immobilization devices

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17
Q

mAs-

A

total quantity of x-rays produced at exposure

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18
Q

penumbra-

A

blur

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19
Q

mA directly proportional to-

A

beam intensity & exposure

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20
Q

time/exposure time directly proportional to-

A

quantity/intensity/exposure of x-rays produced bec it is directly proportional to electrons

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21
Q

mAs directly proportional to-

A

receptor exposure

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22
Q

quantum model referred to as-

A

mottle

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23
Q

causes mottle to appear on radiograph-

A

insufficient exposure/mA, s, or mAs

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24
Q

mottle-

A

grainy appearance in image

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25
Q

low exposure (low mA & short exposure time) results in-

A

mottle

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26
Q

exposure index-

A

when you make an exposure & a # pops up it represents the amt. of exposure to IR

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27
Q

exposure index ranges-

A

1500-1700

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28
Q

law of reciprocity-

A

states as long as product remains the same, mA & time can be altered & still produce same total exposure (mAs)

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29
Q

mA, s, or mAs increases-

A

receptor exposure (they’re directly proportional

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30
Q

kVp-

A

measure of force behind a current of electricity that causes it to flow

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31
Q

direction of electron flow-

A

when potential diff. in x-ray tube, electrons flow from C(-)–A (+) side

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32
Q

kVp determines-

A

how fast electrons will travel from cathode side to anode side

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33
Q

kV-

A

measures quality of x-rays produced at exposure

34
Q

higher energy electrons result in-

A

higher energy x-ray photons that will be more penetrating

35
Q

kVp affects-

A

quantity of x-ray beam bec higher energy electrons have more interactions at anode & produce more x-ray photons

36
Q

higher energy electrons have-

A

more energy @ anode & produce more x-ray photons

37
Q

2 types of x-rays produced-

A

Brimstrung & Characteristic

38
Q

high kVp is used for-

A

thicker parts (chest)

39
Q

w: low energy you’re going to have-

A

higher contrast between adjacent structures

40
Q

scale of contrast refers to-

A

the entire image

41
Q

interactions w: matter-

A

1.) Compton Scattering/Effect
2.) Coherent Scattering
3.) Photoelectric Effect
4.) Pairproduction
5.) Photodisintegration
6.) X-ray photon

42
Q

interactions w: matter that occur in diagnostic range (3)-

A

1.) Compton Scattering/Effect
2.) Coherent Scattering
3.) Photoelectric Effect

43
Q

compton scatter/effect-

A

interactions account for 99% of scatter that reaches IR

44
Q

photoelectric effect-

A

-x-ray photon is completely absorbed & doesn’t reach IR
-results in subj. contrast in img

45
Q

____ & ____ primarily affect img. quality-

A

compton & PE

46
Q

kVp increases, what decreases-

A

photoelectric effect decreases & produces more Compton scattering

47
Q

scatter-

A

-unwanted exposure
-should use a grid to reduce it
-also called fog sometimes

48
Q

kVp increases, any scatter produced x-ray photons will have-

A

higher energy produced

49
Q

if scattered photons have a higher energy-

A

it is more likely to penetrate patient & go straight to IR

50
Q

3 ways increasing the kVp can increase receptor exposure-

A

1.) quantity of x-rays will also increase because of interactions at anode
2.) x-ray photons with higher energy are more likely to penetrate through patient & get to IR
3.) energy of Compton Scattering is more likely to increase/have higher energy & penetrate patient & strike IR

51
Q

minimum kVp required to-

A

-penetrate anatomy of interest adequately
-produce desired scale of contrast

52
Q

kVp that is too low will not-

A

penetrate anatomy & increase patient dose

53
Q

higher kVp reduces-

A

patient dose because as kVp increases, mAs can decrease

54
Q

optimal kVp-

A

setting will be similar, but vary among manufacturer’s processing systems

55
Q

If kVp doesn’t penetrate part (too low), what will result for that?

A

Insufficient exposure to IR (MOTTLE IN IMAGE)

56
Q

If you use a kVp that is too hot/high, what will happen to image?

A

Darker because it’s over-penetrating part

57
Q

wide exposure latitude-

A

-increased kVp, wider exposure latitude
-Optimal kVp for proj. may be 100, w: range of 95-105

58
Q

Narrow Exposure Latitude-

A

-decreased kVp, narrow exposure latitude
-Optimal kVp for proj. may be 52, w; range of 50-54

59
Q

if the kVp is too penetrating-

A

more of the beam will penetrate the anatomy than it should, thus increasing receptor exposure

60
Q

too much receptor exposure from excessive kVp-

A

negatively affects image quality

61
Q

increasing kVp by 15% change will-

A

double receptor exposure

62
Q

increase kVp by 15% to maintain-

A

RE, cut your mAs in half

63
Q

kVp increases-

A

receptor exposure

64
Q

kVp decreases-

A

contrast

65
Q

no practical amount of mAs can compensate-

A

for insufficient kVp

66
Q

purpose of AEC-

A

produce more consistent exposure & reduce repeats

67
Q

optimum mA-

A

maximum mA setting for a given focal spot size, which doesn’t overload anodes capacity

68
Q

AEC acts as-

A

back up timer when exposure is made

69
Q

AEC location-

A

after the patient, but before the IR

70
Q

density control setting-

A

-each setting represents 25% change in beam intensity
-N- means normal, could be from 1-8 & -1 to -8

71
Q

mAs readout-

A

when mA is set & use AEC, the AEC will multiply mA by AEC time & get mAs readout

72
Q

limitations of AEC (4)-

A

1.) anatomy must completely cover detector
2.) detector must be covered with anatomy of interest
3.) failure to collimate will result in more scatter production
4.) AEC shouldn’t be used if prosthetic/surgical device over detector

73
Q

APR-

A

preset technical factors

74
Q

APR allows tech. to-

A

choose exam & utilizes electronically stored technical factors

75
Q

2 types of technique charts-

A

-fixed kVp
-variable kVp

76
Q

fixed kVp-

A

uses optimal kVp for that body part & mAs varies depending on part thickness

77
Q

variable kVp-

A

kVp changes with part thickness & mAs remains constant

78
Q

if you change the kVp, kVp varies by-

A

2 for every cm of part thickness

79
Q

exposure standardization-

A

elimination of variation as much as possible in as many as possible factors which affect optimum exposure time

80
Q

exposure standardization reduces-

A

patient exposure

Radt. 3000 (6 decks)

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