Week 1 Radiation Protection Flashcards
Ionization
Process by which a neutral atom acquires a positive or a negative charge
Ionizing Radiation
Produces positively and negatively charged particles as it passes through matter
International Commission on Radiological Protection (ICRP)
set the first rad protection standards
National Council on Radiation Protection and Measurement (NCRP)
was established in the US and is the primary standard setter
Nuclear Regulatory Commission (NRC)
US agency that regulates the safe use of reactor-produced radioactive materials in medical and nonmedical practices and naturally occurring radioactive material such as radium and radon
Agreement States
Agreement in which the federal government could relinquish authority to the states portions of its regulatory authority (agreement between the governor and the commission). These programs are reviewed by the NRC.
States
regulates x-ray machines (including Linacs)
Dose equivalent
Biological effects depend on dose & type of radiation
Same dose of radiation can have different effect based on the type of radiation
𝐻=𝐷 ∙ Q
H = dose equivalent D = absorbed dose Q = quality factor
Quality Factor (Q)
Takes into account the biologic effectiveness
of the radiation type.
X-ray, Gamma Ray Quality Factor
1
Neutrons <10KeV Quality Factor/Thermal Neutrons
5
Protons >2Mev QF.
2
Alpha particles, fast neutrons QF
20
SI Unit of Dose Equivalent
Sievert! SV
1Sv=1J/kg
1Sv=1Gy
1rem=10^-2 Sv
Effective Dose Equivalent
Definition: sum of the weighted dose equivalents for irradiation tissues or organs
Effective dose
quantity that account for the differences
Associated with the same probability of cancer and genetic effects for a non-uniform irradiation as a uniform irradiation.
Total effective equivalent from background
3.0 mSv/yr (300 mrem/yr)
<10 cGy
Can produce: genetic effects (gene mutations), neoplastic diseases (leukemia), effect on growth and development, effect on life span, cataracts.
Stochastic effects
the probability of occurrence increases with absorbed dose, but severity does not depend on dose
Ex: cancer or genetic effects
No threshold dose
All or none effect
Nonstochastic effects
Increases in severity with increasing dose
Ex: organ atrophy, fibrosis, cataracts, blood changes, decreases in sperm count
Has threshold dose
Annual occupational exposure limit:
50mSV (5 rem) per year
General Public limit: Infrequent exposure
5mSv (0.5rem) per year
General Public limit Frequent exposure
1mSV (0.1 rem) per year (also students <18yo)
Embryo Fetus Exposure limit:
total is 5 mSv (0.5rem) and per month 0.5 mSv (0.05 rem)
Lifetime total effective dose
< 10 times x age (years)
Maximum permissible dose–Controlled
0.1 mSv/wk (5 mSv/yr
Maximum permissible dose–Noncontrolled
0.02 mSv/wk (1 mSv/yr