Chapter 6

Question 1

What does mA control?

Answer 1

Size of the filament, focal spot size, size of the beam, and the resistance

Question 2

How does mA effect resistance?

Answer 2

The higher the mA, the bigger the electron beam, the less the resistance

Question 3

What is saturation current?

Answer 3

Filament is heated with mA and there is no more electrons to boil off

Question 4

What is Thermionic Emission?

Answer 4

Electrons boil off

Question 5

Where do electrons hang out after boiling off the filament?

Answer 5

Space charge

Question 6

What charge does the focusing cup have?

Answer 6

Negative

Question 7

What causes the electrons to move from the cathode to anode?

Answer 7

kVp
Electric potential
Potential difference

Question 8

What charge does the Anode have?

Answer 8

Positive

Question 9

Where are Xrays and heat made?

Answer 9

The focal spot

Question 10

What are the 2 interactions within the tube?

Answer 10

Characteristic
Brems

Question 11

When does a Charactertistic interaction happen?

Answer 11

When incoming electron is at least 69.5 keV

Question 12

If kVp is less than 70, then all photons will be:

Answer 12

Brems

Question 13

What happens during a Brem’s interaction

Answer 13

Filament electron misses tungsten electrons and gets attracted to the nucleus

The stronger the attraction, the more energy the filament loses when it breaks and the stronger the brems photon

Question 14

What is the average energy of Brems?

Answer 14

1/3 of the kVp selected

Question 15

What is the beam before filtration?

Answer 15

Heterogenous

Question 16

What is the beam after filtration?

Answer 16

Homongenous

Question 17

What does total filtration need to be a minimum off?

Answer 17

2.5mm of Al

Question 18

Why do we use filtration?

Answer 18

To take out any weak photon that would only contribue to patient dose, they are undiagnostic

Question 19

How much Al is inherent filtration?

Answer 19

.5mm

Question 20

What is total filtration?

Answer 20

Inherent + added

Question 20

What is Beam hardening?

Answer 20

Filtration takes away weak photons and increases the overall average energy of the beam

Question 21

What are compensation filters?

Answer 21

Used to compensate for vatiations in patient thickness and will create a more uniform exposure

Question 22

How should a wedge filter be used?

Answer 22

Thick part of wedge over thin part of patient

Question 23

What is HVL?

Answer 23

Amount of Al necessary to reduce the beam to 1/2 its intensity

Question 24

What is the normal HVL?

Answer 24

3-5mm Al

Question 25

How does HVL effect beam quality and quantity?

Answer 25

Increases quality Decreases quantity

Question 26

What is beam quantity?

Answer 26

The number of x-rays in a beam

Question 27

What is beam quantity affected by?

Answer 27

mAs kVp Distance Filtration Grid

Question 28

How does beam quantity affect radiation dose to the patient?

Answer 28

An increase in quantity, increases the radiation dose

Question 29

What type of relationship does mAs have with beam quantity?

Answer 29

Direct

Question 30

How does a 15% change in kVp affect quantity of Xrays?

Answer 30

Halving or doubling the quantity of xrays reaching the IR

Question 31

What is the main control to change quantity?

Answer 31

mAs

Question 32

How does beam quantity vary with distance?

Answer 32

Intensity of the beam gets less over large distances (inverse square law)

Question 33

How does distance affect divergence?

Answer 33

As distance increase, beam divergence decreases

Question 34

What is beam quality?

Answer 34

Strength or penetrating ability of the photons transmitted through the body

Question 35

What color is created when then photons reach the IR?

Answer 35

Black

Question 36

What color is created when the photons don't reach the IR?

Answer 36

White

Question 37

What is the relationship between kVp and quality?

Answer 37

The higher the kVp, the higher the quality of the beam

Question 38

Other names for beam quantity?

Answer 38

Patient dose Rate Amount Number Quantity

Question 39

How does SID affect beam divergence?

Answer 39

The greater the SID, the less the beam divergence

Question 40

How does FSS affect beam divergence?

Answer 40

The greater the FSS, the greater the beam divergence

Question 41

How does collimation affect beam divergence?

Answer 41

The greater the collimation, the less the beam divergence