Radiation Units of Measurement

Question 1

Define Absorbed Dose and state its unit of measure.

Answer 1

Absorbed Dose (D) is radiation energy absorbed in matter per unit mass. Gray / Gy. 1 Gy = 1 Joule / Kilogram

Question 2

Define Exposure and state its unit of measure.

Answer 2

Exposure measures the number of ionizations in air molecules. Coulombs per Kilogram (c/kg)

Question 3

Define Equivalent Dose and state its unit of measure.

Answer 3

EqD is used to compare biological damage to tissue from different radiation types. Sieverts / sv

Question 4

Define Air Kerma and state its unit of measure.

Answer 4

Air Kerma (Kinetic Energy Released in Mass) measures the total energy of ionizations in air. Gray / Gy

Question 5

What is the formula for Equivalent Dose?

Answer 5

EqD = D x Wr (answer in Sv / Sieverts)

Question 6

What is the formula for Absorbed Dose?

Answer 6

Joules / Kilograms. Absorbed radiation energy in Joules / (divided by) the mass of the tissue in kilograms/kg.

Question 7

What is the formula for Effective Dose?

Answer 7

EfD = D x Wr x Wt (answer in Sv / Sieverts)

Question 8

Review Radiation Weighting Factors

Answer 8

X-Rays: 1
Gamma Rays: 1
Beta Particles: 1
Protons: 2
Slow Neutrons: 5
Fast Neutrons: 10
Alpha Particles: 20

Question 9

Review Tissue Weighting Factors

Answer 9

(From most to least radiosensitive):
Bone Marrow: 0.12
Breasts: 0.12
Lungs: 0.12
Colon: 0.12
Stomach: 0.12
Gonads: 0.8
Liver: 0.4
Thyroid: 0.4
Brain: 0.1
Brain: