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Flashcards in Radiation Deck (21):
0

The maximal annual permissible dose equivalent for occupational radiation exposure is?

5,000 mrem/year (whole body)
15,000 mrem (Eye)
50,000 mrem (Skin)

1000 mrem = 1 rem

1

Recommended annual occupational exposure limit of radiation for pregnant woman is?

< 5 mSv (500 mrem)

Additionally, in any gestational month the occ exposure should not exceed 0.5 mSv

2

The unit of absorbed dose for radiation?

Gy and rad

1 Gy = 100 rad

3

Dose equivalent that measures the biological effect of absorbed radiation taking into account the degree of damage that can be caused by different forms of radiation due to differing linear energy transfer?

Seivert

1 Sv = 100 rem
1 mSv = 100 mrem
1 rem = 1000 mrem
1 Sv = 1000 mSv
For x-Ray and gammer rays, an absorbed dose of one rad results in a dose equivalent of one rem

4

Alpha particles

Can cause extensive ionization in tissues. It represents the greatest internal hazard. They are not normally absorbed by the skin. But rather inhaled.

5

Alpha particle

Can be stopped by paper, skin

6

Beta particles

Penetrates to germinal skin layer.
Can be stopped by heavy clothes

7

Gamma and X-Rays

Can be stopped by lead shielding

8

Occupational limitation for pregnant women

< 500 mrem (5 mSv) / year
< 50 mrem/any pregnant month

9

Public radiation exposure limit

< 2 mrem/ hour
< 100 mrem/ year

10

Radiation dose and Radiation syndromes

0.7-10 Gy: Hematopoietic syndrome
> 10 Gy: GI syndrome, death in 2 wks
> 20-50: CV/CNS syndrome, death in 3 days

11

Wavelength of UV light are of greatest health concern - causes skin cancer, photokeratitis and erythema

280-320 mm

12

Methods of limiting radiation exposure

Time/duration
Distance
Shield

13

Time/ duration and radiation

Less time near radiation, less exposure
- except internal exposure, which is determined by 1/2 life

14

Distance and radiation

Inverse square law:
- double the distance, decrease exposure by 1/4

15

Stochastic effects

No threshold, no minimum exposure needed for effects (cancer)

16

Alpha particle

The nucleus of a helium atom

17

Beta particle

Positive or negative election

18

Neutron

Particle of neutral charge arising from the nucleus

19

Proton

Particle of positive charge emitted from nucleus or produced by recoil from neutron collisions

20

X-ray

Results from changes in the energy levels of the orbiting electron