Radiation Exposure Flashcards
alpha particles
most dangerous if exposed internally
BUT stopped by even a piece of paper
Ci
- Curie
- measure of how much radiation one fram of a radium isotope emits
Bq
- Becquerel
- number of particles or photons (in the case of wave radiation) that are emitted per sec
absorbed dose
the amount of ionizing radiation or ;dose; received by a person or object is expressed as energy absorbed er unit of ass
dose = E/mass (Gy or Joules/kg)
1 Gy = 100 rad
effective dose
represents the amount of E deposited to the body, taking into account the tissue being irradiated and the type of incident radiation
effective dose usually expressed in milliSieverts or microSieverts
1 Sv = 1/kg equivalent
1 Sv = 100 rem
amount of annual natural background radiation received per person in Canad
2-4 mSv
occupational limit set by Canadian Nuclear Safety Commission
50 mSv in a single year and 100 mSv over 5 yrs (20 mSv per year avg)
natural radioactivity in food
banana = 15 Bq of potassium 40
radioactivity of a few banas is sufficient to trigger radiation sensors used to detect possible smuggling of nuclear materials
acute radiation sickness occur through…
nuclear weapons
accidental nuclear release
industrial exposure
medical exposure
limit for a pregnant worker
once pregnancy declared = 4 mSv for remainder of pregnancy
radiation-induced cancer
Level & type of exposure
- nuclear weapons
- accidental nuclear release
- industrial exposure
- medical exposure
- environmental exposure
Genetic factors
- DNA damage and repair
radon as carcinogen
- gas, inhaled
- decays to release alpha particles
radon
inert gas
doesn’t react easily w anything; can get through certain barriers including house basement
how many alpha particles are emitted per atom of decaying radon
4
0.05-0.5 Gy
no clinical symptoms
minor lymph reductions
potential chromosomal damage
1 Gy
nausea and vomiting within 48 hrs of exposure (10% of patients)
2 Gy
nausea and vomiting within 24 hrs of exposure (50% of patients)
prominent decreases in lymphs and granulocytes
4 Gy
nausea and vomiting within 12 hrs of exposure (90% of patients),
mortality of 50% without medical support
6 Gy
mortality of 100% within 30 d without medical support
10 Gy
maximum survivable dose with aggressive medical support
50 - 100 Gy
CNS and C collapse within 24-48 hrs, mortality 100%
The radioactive isotopes from nuclear disasters include
iodine-31
cesium-134/137
strontium-90
plutonium-241
americium-241
the total worldwide average effective dose from natural background radiation is around _____ mSv per year
2.4
what is the dose of a medical CT scan?
10 mSv
__% of lung cancer deaths are related to being exposed to radon in the home
16
this is the leading cause of lung cancer in non-smokers
radon exposure
types of DNA damage
base modification
single and double strand breaks
ataxia telangiectasia (AT)
- individuals with this condition extremely radiosensitive and are at an elevated risk of cancer
- caused by genetically inherited mutations in the ATM gene
- rare! 1 in 40 000 live births
- 1 in 100 ppl carry a mutation in the ATM
genetic risk scores
recognition of multi-genic nature of radiation response
intended initially for younger cancer pts receiving radiotherapy to avoid radiation-induced secondary cancers later in life
GRS should improve as genomic sequencing becomes more commonplace
