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BOARDS Part 1 > x ray physics > Flashcards

x ray physics Flashcards

1
Q

(3) parts of the cathode

A

lg filament
sm filament
focusing cup

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2
Q

what controls the quantity of electrons (mA) emitted from the filament

A

the temp of the filament

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3
Q

__ is the source of electrons in an X-ray machine

what is it made of?

A

filament, tungsten

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4
Q

the focusing cup is a part of the __

A

cathode

anode is positive electrons

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5
Q

the reason that an X-ray has a rotating target ?

A

dissipate the heat generated

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6
Q

the focal spot will be determined by the ___ of the filament

A

size

smaller filament = better detail

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7
Q

increase (mAs) will cause the image to look ___

A

darker (greater radiographic density)

more electrons produced = darker image

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8
Q

___: the overall blackening of the film

A

density

mAs and density are directly proportional

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9
Q

what is the primary method to control the blackening of the film?

A

changing mAs

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10
Q

___:the force applied to accelerate the electrons from the cathode to the anode at the time of exposure

A

kilovoltage (kVp)

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11
Q

Low kVp= __ penetration

high kVp= __ penetration

A

low kVp= weak penetration (black and white film)

high kVp= strong penetration = greater ability to penetrate the body = greater scatter

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12
Q

__ controls contrast

A

kVp

mAs controls density

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13
Q

to lower contrast: __ kVp and ___ mAs

A

lower contrast: (more grey)
incr kVp
dec mAs

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14
Q

to raise contrast: ___ kVp and __ mAs

A

to raise contrast:
decr kVp
incr mAs

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15
Q

15% Rule: a ___ in kVp by 15% will double the overall density. A 15% __ in kVp will cut the density by 1/2

A

an increase in kVp by 15% will double the overall density

A 15% decrease in kVp will cut the density by 1/2

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16
Q

Anode heel effect: the intensity of the X-ray is greater at the __ side

A

cathode

intensity and density on the anode side of the film decrease

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17
Q

What type of body part should be placed not eh anode side of the film? (anode heel effect)

A

anode: toes, thin body areas
cathode: heel, thicker body areas

18
Q

give 4 differences between the anode and cathode side of the X-ray machine

A

anode:
1. less X-rays
2. smaller focal spot
3. more detail
4. thinner body part

cathode: 
1 more X-rays
2. lg focal spot 
3. less detail 
4. thicker body part
19
Q

__: the length of space from the focal spot (tube) to the recording medium (film)

A

focal film distance (FFD)/ source image distance (SID)

20
Q

intensifying screens are made of __

A

fluorescent crystals

fluorescent salts change xray photons into visible light photons

21
Q

___: the blurry halo parts of the image

A

penumbra

22
Q

4 causes of penumbra

A
  1. tube to close to the film (short FFD)
  2. pt to far fro the film (long OFD)
  3. to big of a filament on the cathode
  4. focal spot to big
23
Q

name the 2 types of distortion

A

size and magnification

24
Q

name 4 methods to decrease scatter radiation

A
  1. grids
  2. air gap technique
  3. collimator
  4. filter
25
Q

fun of the grid?

A

improve in exposure factors to maintain density

26
Q

grid ratio is the ___ of the lead strips to the ___

A

height of the strips to the distance between them

grid ratio is 12: 1

27
Q

___: limits the size of the beam to the size of the body part needed to be captured on the film

A

collimation

28
Q

what is the best way to reduce scatter radiation to the pt

A

collimate

29
Q

___: removal of low NRG photons

what is it made of?

A

filtration

made of aluminum

30
Q

___ REMs/ RADs is the safe limit per year

A

5 REMs

31
Q

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

A

Maximum Permissible Dose (MPD = 5)

32
Q

___: is a type of radiation. It is the majority of useful beams. Interacts with eh target nucleus

A

Bremsstrahlung aka Braking Radiation

33
Q

___: moderate NRG Xray knocks out n outer shell e- . This causes loss of NRG (primary source of scatter)

A

compton scatter (incr patient radiation)

34
Q

__: Low NRG X-ray that changes direction with no NRG loss. Contributes to film fog

A

classical scatter (aka: Thompson Scatter, coherent scatter)

35
Q

___: caused by fluctuation of the number of photons absorbed by the intensifying screen to form the image on the film

A

quantum mottle (aka: radiographic noise)

faster screen = more mottle

36
Q

developer exposes the ___ crystals to bring out the image

A

silver halide

37
Q

look at pg 6 X-ray physics in Irene gold for see the types of developers

A

.

38
Q

__: changes AC to DC

A

rectifier

39
Q

__: changes the NRG from one form to another

A

transducer

40
Q

___: beam of radiation loses NRG as it passes thru matter

A

attenuation

BOARDS Part 1 (33 decks)

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