10/03

Question 1

What is the effective dose for posterior BW PSPP - rectangular collimation?

Answer 1

5 uSv

Question 2

What is the effective dose for FMX - round collimation?

Answer 2

388 uSv

Question 3

1 Gy = ____ rad
1 Sv = ____ rem
which doses use which units

Answer 3

100 rad = 1 Gy : Absorbed
100 rem = 1 Sv : Effective and Equivalent

Question 4

What are the 4 kinds of interactions of X-rays with matter and their percentage of occurrence

Answer 4

No interaction: 9%
Coherent (no biologic change): 7%
Photoelectric absorption: 27%
Compton scattering: 57%

Question 5

Examples of Deterministic effects from injury from x-ray interaction?

Answer 5

Xerostomia
Osteoradionecrosis
Cataracts
Poor fetal development
Fertility
Alopecia
Erythema

Question 6

Examples of Stochastic effects from injury from x-ray interaction?

Answer 6

Leukemia
Thyroid cancer
Salivary gland tumors
Heritable disorders

Question 7

What portion of biologic injury is due to direct vs indirect biologic injury?

Answer 7

Direct (directly ionizing macromolecule) = 33%
Indirect (hydrolysis of H20–> free radicals–> damage from hydrogen peroxide) = 67% (PRIMARY)

Question 8

FITB: To somatic cells - genetic mutations cause ________
To germ line cells - genetic mutations cause ________

Answer 8

Malignancy (affect parent, not kids)
Heritable effects (no effect on parent)

Question 9

What is the sequence of radiation injury

Answer 9

Latent period
Period of injury
Recovery period

Question 10

What are the factors modifying effects of x-radiation (6)

Answer 10

1. Total dose (^ damage)
2. Dose rate (^ damage)
3. Oxygen (^ damage)
4. Area exposed
5. Cell type and function
6. Age