RadMath Boot Camp

Question 1

Measurement of exposure

Answer 1

Coulombs/kilogram

Question 2

Unit of measurement for Air Kerma

Answer 2

Gy (Gy = 1 Joule/Kg)

Question 3

Absorbed dose (D)
Unit of measurement

Answer 3

Gy (D = 1 Joule/Kg)

Question 4

Equivalent dose (EqD)
unit of measurement

Answer 4

Sv

Question 5

Equivalent dose (EqD)
formula

Answer 5

EqD = D x Wr

Question 6

Effective Dose (Dose)
unit of measurement

Answer 6

Sv

Question 7

Effective dose (Dose)
formula

Answer 7

EfD = D x Wr X Wt

Question 8

Exposure

Answer 8

measurement of ionizations in the air

Question 9

Air Kerma

Answer 9

energy of ionizations in air

Question 10

Equivalent Dose measures…

Answer 10

the biological damage of radiation in matter

Question 11

Effective dose measures…

Answer 11

biological damage and is used to measure stochastic effects

Question 12

Mass maintenance formula

mass-distance formula

Answer 12

mA1 D1^2
——— = ———-
mA2 D2^2

Question 13

Inverse Square Law

Answer 13

I1 D2^2
—– = ———–
I2 D1^2

Question 14

Image factors that affect image contrast

Answer 14

• kVp
• grids
• patient size
• scatter
• to a lesser extent, OID (e.g., air gap technique)

Question 15

Image factors that affect spatial resolution

Answer 15

• SID
• OID
• Focal spot size

Question 16

Image factors that affect distortion

Answer 16

• SID
• OID
• tube angle
• receptor angle

Question 17

distortion

Answer 17

misrepresentation of size or shape of object being imaged

Question 18

15% rule

Answer 18

if kVp goes up by 15%, mAs will decrease by half;

if kVp goes down by 15%, mAs will double

Question 19

magnification

Answer 19

due to beam divergence, the image of an object is larger than the object itself

Question 20

magnification factor equation

Answer 20

SID
MF = -------
          SOD
OR
           Image size
MF = --------------------- 
           Object size

Question 21

Image size equation related to magnification

Answer 21

Image size = Object size x MF

Question 22

Object size equation related to magnification

Answer 22

Image
size
Object size = ————
MF

Question 23

Factors that affect penumbra (focal spot blur)

Answer 23

• up = increase in blur
• Focal spot size
• OID
• up = decrease blur
• SOD
• SID

Question 24

penumbra formula

Answer 24

OID
P = FSS x ——-
SOD

Question 25

mm to in conversion

Answer 25

in = mm / 25.4

Question 26

grid conversion chart

Answer 26

no grid 1

5: 1 2
6: 1 3
8: 1 4
10: 1 5 (or 4.5)
12: 1 5
16: 1 6

Question 27

heat units formula

Answer 27

HU = kVp x mAs x MF

Question 28

Modification factors for calculating HU

Answer 28

• single phase = 1
• 3-phase, 6P = 1.35
• 3-phase, 12P = 1.41
• HF = 1.45