x ray physics

Question 1

(3) parts of the cathode

Answer 1

lg filament
sm filament
focusing cup

Question 2

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

Answer 2

the temp of the filament

Question 3

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

what is it made of?

Answer 3

filament, tungsten

Question 4

the focusing cup is a part of the __

Answer 4

cathode

anode is positive electrons

Question 5

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

Answer 5

dissipate the heat generated

Question 6

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

Answer 6

size

smaller filament = better detail

Question 7

increase (mAs) will cause the image to look ___

Answer 7

darker (greater radiographic density)

more electrons produced = darker image

Question 8

___: the overall blackening of the film

Answer 8

density

mAs and density are directly proportional

Question 9

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

Answer 9

changing mAs

Question 10

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

Answer 10

kilovoltage (kVp)

Question 11

Low kVp= __ penetration

high kVp= __ penetration

Answer 11

low kVp= weak penetration (black and white film)

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

Question 12

__ controls contrast

Answer 12

kVp

mAs controls density

Question 13

to lower contrast: __ kVp and ___ mAs

Answer 13

lower contrast: (more grey)
incr kVp
dec mAs

Question 14

to raise contrast: ___ kVp and __ mAs

Answer 14

to raise contrast:
decr kVp
incr mAs

Question 15

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

Answer 15

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

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

Question 16

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

Answer 16

cathode

intensity and density on the anode side of the film decrease

Question 17

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

Answer 17

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

Question 18

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

Answer 18

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

Question 19

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

Answer 19

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

Question 20

intensifying screens are made of __

Answer 20

fluorescent crystals

fluorescent salts change xray photons into visible light photons

Question 21

___: the blurry halo parts of the image

Answer 21

penumbra

Question 22

4 causes of penumbra

Answer 22

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

Question 23

name the 2 types of distortion

Answer 23

size and magnification

Question 24

name 4 methods to decrease scatter radiation

Answer 24

1. grids
2. air gap technique
3. collimator
4. filter

Question 25

fun of the grid?

Answer 25

improve in exposure factors to maintain density

Question 26

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

Answer 26

height of the strips to the distance between them grid ratio is 12: 1

Question 27

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

Answer 27

collimation

Question 28

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

Answer 28

collimate

Question 29

___: removal of low NRG photons what is it made of?

Answer 29

filtration | made of aluminum

Question 30

___ REMs/ RADs is the safe limit per year

Answer 30

5 REMs

Question 31

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

Answer 31

Maximum Permissible Dose (MPD = 5)

Question 32

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

Answer 32

Bremsstrahlung aka Braking Radiation

Question 33

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

Answer 33

compton scatter (incr patient radiation)

Question 34

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

Answer 34

classical scatter (aka: Thompson Scatter, coherent scatter)

Question 35

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

Answer 35

quantum mottle (aka: radiographic noise) faster screen = more mottle

Question 36

developer exposes the ___ crystals to bring out the image

Answer 36

silver halide

Question 37

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

Answer 37

.

Question 38

__: changes AC to DC

Answer 38

rectifier

Question 39

__: changes the NRG from one form to another

Answer 39

transducer

Question 40

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

Answer 40

attenuation