Radiation biology

Question 1

What units is exposure measured in?

Answer 1

Roentgens (R)

Question 2

What unit is absorbed dose in?

Answer 2

Gray or Rads (1 Gy = 100 rads) Energy absorbed - a physical quantity

Question 3

How is Equivalent dose calculated and what unit is it in?

Answer 3

Absorbed dose x weighting factor (x-rays = 1, alpha particles = 20) Sievert (Biologic effect - corrected for type of radiation)

Question 4

How is Effective dose calculated and what unit is it in?

Answer 4

Effective dose = Eq dose x tissue weighting factor Sievert Biologic effect on tissue type (if whole body then equal to equivalent dose)

Question 5

Most sensitive phase of cell cycle

Answer 5

M-phase > G2 > G1 > S

Question 6

Law of Bergonie and Tribondeau

Answer 6

Cell sensitivity is directly related to reproductive activity and inversely related to differentiation

Question 7

Acut Radiation Syndromes

(1) Organ systems
(2) Doses
(3) Latent Period

Answer 7

Some perspective mGy is a diagnostic dose (30 mGy for CT AP)

Gy is a dose that makes you sick

Question 8

What symptom is a marker for severity and prognosis in cases of possible acute radiation syndrome?

Answer 8

Vomiting

Question 9

LD 50/30 for a person

Answer 9

3-4 Gy without treatment

Up to 8.5 Gy with treatment

Question 10

Dose and onset of: Early Transient Erythema

Answer 10

2 Gy skin dose; hours

Question 11

Dose and onset of: Severe “Robust” Erythema

Answer 11

6 Gy skin dose; 1 week

Question 12

Dose and onset of: Telangiectasia

Answer 12

10 Gy skin dose; 52 weeks

Question 13

Dose and onset of: Dry desquamation

Answer 13

13 Gy skin dose; 4 weeks

Question 14

Dose and onset of: Moist desquamation / ulceration

Answer 14

18 Gy skin dose; 4 weeks

Question 15

Dose and onset of: Secondary ulceration

Answer 15

24 Gy skin dose; > 6 weeks

Question 16

Dose and onset of: Temporary epilation

Answer 16

3 Gy; 21 days

Question 17

Dose and onset of: Permanent epilation

Answer 17

7 Gy; 21 days

Question 18

Acute exposrure threshold to cause cataract

Answer 18

0.5 - 2.5 Gy

Question 19

Annual Dose Rate Limit for cataracts

Answer 19

150 m Sv

Senile cataracts affect the anterior lens; radiation induced cataracts tend to involve the posterior lens

Question 20

Temporary and Permanent Sterility/Infertility

Answer 20

• Male Temporary: 0.15 - 2.5 Gy
• Male Permanent: 5 Gy
• Female at age 12: 10 Gy
• Female at age 45: 2 Gy
• Female of unknown age: 6 Gy

Question 21

Dose to cause symptom: Nausea (30% of people)

Answer 21

0.75 - 1.25 Gy WB

Question 22

Dose to cause symptom: Depress circulating lymphocytes

Answer 22

0.25 Gy WB

Question 23

Dose to cause symptom: LD 50/60 (Marrow)

Answer 23

3-4 Gy WB

Question 24

Dose to cause symptom: LD 50/4 (GI)

Answer 24

8-10 Gy WB

Question 25

Dose to cause symptom: LD for CNS

Answer 25

>20 Gy (20 -100) WB

Question 26

Dose to cause symptom: Double the natural or spontaneous mutation rate

Answer 26

1 Gy

Question 27

Dose to cause symptom: Effective dose from background radiation in the US

Answer 27

3 mSV per year

Question 28

Sentinal event dose

Answer 28

15 Gy

Question 29

Occupation exposure limits to lens, radiation worker and extremity (mSv/year)

Answer 29

150, 50, 500

Question 30

Public exposure limit

Answer 30

1 mSv/year (continuous)

5 mSv/year (infrequent)

Question 31

Public exposure limit: Embryo/fetus via mother

Answer 31

5 mSv/year (1mSv to fetus directly)

Question 32

Public exposure limit: Embryo fetus (post declared pregnancy)

Answer 32

0.5 mSv/month

Question 33

Public exposure limit: Controlled Areas

Answer 33

50 mSv/month

Question 34

Public exposure limit: Uncontrolled areas

Answer 34

5 mSv/year

Question 35

Genetically significant dose

Answer 35

0.25 mSv

Question 36

Effective dose from background radiation in the US

Answer 36

3 mSv per year