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trisemester 3 TCC > Xray physics WK5 > Flashcards

Xray physics WK5 Flashcards

1
Q

cathode does what with e-?

A

emits them

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2
Q

anode has 2 parts

A

target face & focal spot

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3
Q

smaller focal spot could not be good due to

A

heat energy

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4
Q

as the e- cross from the cathode to the anode what is created?

A

a circuit

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5
Q

the job of the rotor

A

is to distribute heat over larger surface area

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6
Q

due to the target angle on the anode side what happens to the appearance of the focal spot

A

it appears smaller

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7
Q

anode heel effect*

A

anode heel = thins edge of disk

interference of the heel of the anode and the emission of xrays going towards it

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8
Q

when some x-rays are absorbed by the anode heel it is known as what effect?

A

anode heel

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9
Q

reductions of xray photon intensity toward anode side is due to the

A

anode heel absorbing it

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10
Q

as the collimated field increases what happens to the effect of the xray photons?

A

have a greater effect

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11
Q

smaller the focal spots has what affect on the heel effect

A

greater the intensity change

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12
Q

for a upright tube what position is the anode and cathod

A

anode is up and cathode is down

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13
Q

tube failure is due to

A

heat

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14
Q

how is heat generated

A

using higher voltage and amperage

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15
Q

maximum exposures should not be made in what situation when considering the condition of the anode?

A

a cold one

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16
Q

what should we do before taking a large xray of the lumbar

A

pre-heat with small exposure first to avoid anode damage

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17
Q

projectile electrons meaning that the e- are coming from

A

the cathode

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18
Q

in an xray what is kinetic energy changed to and how?

A

xray energy and this is done by the cathode e- striking the tungsten atoms of the anode

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19
Q

what % of the kinetic energy is changed to xray?

A

1

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20
Q

2 different mechanism for xray production

A

characteristic & bremstrahlung

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21
Q

for tungsten how much kVp in order to move e- out of K shell?

A

69

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22
Q

ionization by removal of K shell electrons occurs how

A

BE must be overcome,

the voltage potential between anode and cathode ust be at least 69 kVp in order to deliver projectile e- with 69 kEv

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23
Q

inner shell vacancy is filled by

A

electron from an outer shell

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24
Q

to figure out kEV you substract what of the shells?

A

BE of shells

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25
Q

when e- move –> what is produced?

A

energy as an xray and the energy will be the same and characteristic of tungsten

26
Q

what is the characteristic pattern of tungsten?

A

the movement of a e- from a nearby shell into the vacant one –> generating xray energy

27
Q

photons, where do they go

A

everywhere

28
Q

bremstrahlung means

A 
brems = brakes
strahlung= ray or radiation
29
Q

bremstrahlung is the interaction between what kind of e- and atom?

A

projectile e- which is negatively charged and the the electromagnetic field of the nucleas of the tungsten atom which is positively charged

30
Q

Bremstrahlung:

as the projectile e- changes course and passed by the nucleus what may occur?

A
  • May lose some or all of its kinetic energy

- ->If enough energy is lost, it is expressed as x-ray photon

31
Q

Bremstrahlung:

as the projectile e- changes course what occurs?

A

it released energy

32
Q

Bremstrahlung:

as the projectile e- moves closer to the nucleus what occurs?

A

it will release more energy

33
Q

can 2 projectile e- that are at the same distance have produce different energies?

A

yes

34
Q

At a given tube potential (eg, 70 kVp), every projectile electron does/may not have 70 keV energy
..why?

A

due to voltage ripples

35
Q

Characteristic spectrum characteristics

A

shows discrete bands of photons at specific energy levels

36
Q

Bremstrahlung spectrum characteristics

A

(bottom) shows continuous range of x-ray photon energies

37
Q

the peak of the bremstrahlung peak of spectrum graph is what fraction of the maximal value?

A

1/3

38
Q

average photon energy

A

quality of the xray beam

39
Q

Possible effects on emission spectrum

A

Beam Quality change

Beam Quantity change

40
Q

Beam Quality change =

A

a change in the average photon energy

Recall that it is beam quality that determines the penetrating ability of the beam

41
Q

Beam Quantity change =

A

a change in the number of photons in the beam

This is equivalent to “beam intensity”

42
Q

Variables affecting the x-ray emission spectrum include:

A

Tube voltage (peak voltage = kVp and voltage ripple)
mA
filtration

43
Q

as the voltage is high what happens to quality and quantity ?

A

it is also high

44
Q

Less voltage ripple results in more

A

efficient production of useful x-ray

45
Q

to production of less “soft’ x-ray has what affect on the pt. dose?

A

reduced

46
Q

as the voltage ripple decreases emission spectrum does what?

A

it increases

47
Q

amperage

A

number of e- that are moving in circuit

48
Q

does the quality change when the mA increases?

A

no

49
Q

does the quantity change when the mA increases?

A

yes it increases

50
Q

as kVp changes what else chages?

A

both quality and quantity

51
Q

does bremstrahlung have more energy to lose?

A

yes

52
Q

what do higher energy photons do

A

they go through stuff better = more exposure being high

53
Q

if the quality of photons increase

A

more photons get absorbed

54
Q

kVp rule states that what % is needed to increase the receptor exposure by _____ the amount?

A

15% rule, by 2

55
Q

15% rule states that

A

a 15% increase of kvp will aprox. double image receptor exposure

56
Q

what two thighs have the same effect on the emission spectrum?

A

time & mA

57
Q

mAs is a term to describe

A

a result of mA and time combined

58
Q

as long as the kVp is constant what can you rely on?

A

these exposures make same amount of radiation with same distribution of photon

59
Q

any equal combination of mA and time will have what kind of effect on exposure together?

A

they will have exactly the same emission spectrum

60
Q

Passing an x-ray emission through higher filtration will result in?

A

Beam hardening

61
Q

what occurs at the tube when voltage changes?

A

beam quantity

62
Q

as you increase the mA does the quantity or quality change of the beam?

A

quantity

trisemester 3 TCC (25 decks)

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