3. Prime Factors

Question 1

What factors are directly proportional to mAs, s, and mA?

Answer 1

The intensity
Radiation reaching the IR
Patient dose

Question 2

What are the 3 units that intensity is measured in?

Answer 2

○ Roentgens (R)
○ milliRoentgens (mR)
○ Coulombs/kg (C/kg)

Question 3

In which way is intensity measured?

Answer 3

With a dosimeter

Question 4

What is a focus cup?

Answer 4

Keeps electrons in a stream so that they hit the target

Question 5

Define EI value:

Answer 5

Measure of how much radiation the IR saw

Question 6

What is the mass and charge of a photon?

Answer 6

No charge or mass

Question 7

What are the 3 advantages of reciprocity?

Answer 7

1. Control motion
2. Control of focal Spot Size
3. Control of breathing techniques

Question 8

What are two ways that you control motion for a patient that can’t hold still?

Answer 8

1. Immobilization device (pigg o stat for infants)
2. Shorten exposure time

Question 9

What is the focal spot limited by?

Answer 9

The mA

Question 10

With a further SID, what happens to intensity?

Answer 10

Decreases due to beam geometry

Question 11

To have the same intensity with a further SID, what do you have to increase?

Answer 11

mAs

Question 12

For the same body part, which distance will require a higher technique to get the same amount of radiation to the IR, 100cm or 180cm?

Answer 12

180 cm