Flashcards in Radiation Deck (21)
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
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
The unit of absorbed dose for radiation?
Gy and rad
1 Gy = 100 rad
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?
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
Can cause extensive ionization in tissues. It represents the greatest internal hazard. They are not normally absorbed by the skin. But rather inhaled.
Can be stopped by paper, skin
Penetrates to germinal skin layer.
Can be stopped by heavy clothes
Gamma and X-Rays
Can be stopped by lead shielding
Occupational limitation for pregnant women
< 500 mrem (5 mSv) / year
< 50 mrem/any pregnant month
Public radiation exposure limit
< 2 mrem/ hour
< 100 mrem/ year
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
Wavelength of UV light are of greatest health concern - causes skin cancer, photokeratitis and erythema
Methods of limiting radiation exposure
Time/ duration and radiation
Less time near radiation, less exposure
- except internal exposure, which is determined by 1/2 life
Distance and radiation
Inverse square law:
- double the distance, decrease exposure by 1/4
No threshold, no minimum exposure needed for effects (cancer)
The nucleus of a helium atom
Positive or negative election
Particle of neutral charge arising from the nucleus
Particle of positive charge emitted from nucleus or produced by recoil from neutron collisions