Xray physics WK5

Question 1

cathode does what with e-?

Answer 1

emits them

Question 2

anode has 2 parts

Answer 2

target face & focal spot

Question 3

smaller focal spot could not be good due to

Answer 3

heat energy

Question 4

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

Answer 4

a circuit

Question 5

the job of the rotor

Answer 5

is to distribute heat over larger surface area

Question 6

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

Answer 6

it appears smaller

Question 7

anode heel effect*

Answer 7

anode heel = thins edge of disk

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

Question 8

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

Answer 8

anode heel

Question 9

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

Answer 9

anode heel absorbing it

Question 10

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

Answer 10

have a greater effect

Question 11

smaller the focal spots has what affect on the heel effect

Answer 11

greater the intensity change

Question 12

for a upright tube what position is the anode and cathod

Answer 12

anode is up and cathode is down

Question 13

tube failure is due to

Answer 13

heat

Question 14

how is heat generated

Answer 14

using higher voltage and amperage

Question 15

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

Answer 15

a cold one

Question 16

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

Answer 16

pre-heat with small exposure first to avoid anode damage

Question 17

projectile electrons meaning that the e- are coming from

Answer 17

the cathode

Question 18

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

Answer 18

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

Question 19

what % of the kinetic energy is changed to xray?

Answer 19

1

Question 20

2 different mechanism for xray production

Answer 20

characteristic & bremstrahlung

Question 21

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

Answer 21

69

Question 22

ionization by removal of K shell electrons occurs how

Answer 22

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

Question 23

inner shell vacancy is filled by

Answer 23

electron from an outer shell

Question 24

to figure out kEV you substract what of the shells?

Answer 24

BE of shells

Question 25

when e- move --> what is produced?

Answer 25

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

Question 26

what is the characteristic pattern of tungsten?

Answer 26

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

Question 27

photons, where do they go

Answer 27

everywhere

Question 28

bremstrahlung means

Answer 28

``` brems = brakes strahlung= ray or radiation ```

Question 29

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

Answer 29

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

Question 30

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

Answer 30

- May lose some or all of its kinetic energy | - ->If enough energy is lost, it is expressed as x-ray photon

Question 31

Bremstrahlung: | as the projectile e- changes course what occurs?

Answer 31

it released energy

Question 32

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

Answer 32

it will release more energy

Question 33

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

Answer 33

yes

Question 34

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

Answer 34

due to voltage ripples

Question 35

Characteristic spectrum characteristics

Answer 35

shows discrete bands of photons at specific energy levels

Question 36

Bremstrahlung spectrum characteristics

Answer 36

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

Question 37

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

Answer 37

1/3

Question 38

average photon energy

Answer 38

quality of the xray beam

Question 39

Possible effects on emission spectrum

Answer 39

Beam Quality change | Beam Quantity change

Question 40

Beam Quality change =

Answer 40

a change in the average photon energy | Recall that it is beam quality that determines the penetrating ability of the beam

Question 41

Beam Quantity change =

Answer 41

a change in the number of photons in the beam | This is equivalent to “beam intensity”

Question 42

Variables affecting the x-ray emission spectrum include:

Answer 42

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

Question 43

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

Answer 43

it is also high

Question 44

Less voltage ripple results in more

Answer 44

efficient production of useful x-ray

Question 45

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

Answer 45

reduced

Question 46

as the voltage ripple decreases emission spectrum does what?

Answer 46

it increases

Question 47

amperage

Answer 47

number of e- that are moving in circuit

Question 48

does the quality change when the mA increases?

Answer 48

no

Question 49

does the quantity change when the mA increases?

Answer 49

yes it increases

Question 50

as kVp changes what else chages?

Answer 50

both quality and quantity

Question 51

does bremstrahlung have more energy to lose?

Answer 51

yes

Question 52

what do higher energy photons do

Answer 52

they go through stuff better = more exposure being high

Question 53

if the quality of photons increase

Answer 53

more photons get absorbed

Question 54

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

Answer 54

15% rule, by 2

Question 55

15% rule states that

Answer 55

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

Question 56

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

Answer 56

time & mA

Question 57

mAs is a term to describe

Answer 57

a result of mA and time combined

Question 58

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

Answer 58

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

Question 59

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

Answer 59

they will have exactly the same emission spectrum

Question 60

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

Answer 60

Beam hardening

Question 61

what occurs at the tube when voltage changes?

Answer 61

beam quantity

Question 62

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

Answer 62

quantity