180quiz2typed

• previously mentioned
• agents produce indirect effects because the damage is not caused by the
• radiation but the indirect effect of the radiation.

•Single strand break

• –Point mutation, commonly occur
• with low LET

indirect bc low LET

•Easy type of damage to repair

• •Basically, the DNA molecule is the most
• important molecule

• •Therefore, if the DNA molecule is hit and
• inactivated the cell will most likely die

water 80% DNA 1%

•Instant death

–1000 Gy in a few seconds

• •Reproductive death at the cellular level
• –10 Gy

• •Apoptosis
• –Cells die without attempting cell
• division

•Loss of function

• •Chromosome breakage
• –Can lead to genetic effects
• changes are passed down

• Cell death occurs after cell
• division

• Mitosis occurs after missing a
• division cycle

Immature cells

• –Non-specialized and rapid cell
• division

• –Both conditions that encourage
• radio-sensitivity

mitosis

cells

•Humans

–300 – 400 rads, 3 – 4 grays

• •Expressed as LD50/30
• in most mammals or LD50/60 in humans

• blood cell count problem;GI tract problem
• –The first number is percentage of
• effect (death) second number is how many days for the effect to occur

• •Linear or non-linear
• •Threshold or non-threshold

• Type of curve depends on the effect being
• observed or reported

•Based on a linear non-threshold curve

•Any radiation has the potential for problems

•This is the most cautious curve.

• •Occur within weeks of exposure
• –Nausea
• –Fatigue = no blood cell
• –Erythema
• –Epilation =hair loss
• –Symptoms of these effects

• •Generally, classified as Acute Radiation
• Syndromes

•Stages

• –Prodromal
• Symptoms will be present

• –Latent
• Symptoms will resolve or be
• dormant

• –Manifest
• You got problems

Acute radiation syndrome

• Hematopoietic
• 100 – 1000 rads

• GI
• 600 – 1000 rads

• Cerebrovascular
• Up to 5000 rads

•Death in 2 to 3 days

•Cataracts

•Fibrosis

• •Organ atrophy
• Loss of parenchymal cells

• •Decreased fertility
• sterility

•Cancer

•Genetic defects

• •Most sensitive during organogenesis
• 10 days to 6 weeks
• 2 weeks to 8 weeks

• The idea that exposure to radiation can/may
• induce cancer.

• The result is that radiation
• protection guidelines are based on the possibility of getting cancer not some
• other effect.

minimize cancer

• •All facilities must have a radiation
• protection/safety program in place.

•Radiation Safety Committee

–Radiation safety Officer (RSO)

• •Looks to establish the upper limit of
• exposure to ionizing radiation resulting in a negligible risk of injury or
• genetic defect.

• •Can be whole body, partial body (extremity,
• eye) and individual organs.

• –Non-stochastic (deterministic)
• and stochastic (probabilistic)

• •Occupational limits are based on comparing
• outcomes against other occupational hazards.

•Non-stochastic = Somatic

–Deterministic

–Directly related to the dose received, threshold

•Early

–Erythemia

–Decreased blood count

–Epilation

–Acute Radiation Syndromes (ARS)

•Late

–Cataracts

–Fibrosis

–Sterility

–Organ atrophy

Stochastic = Genetic

–Probabilistic

• –Mutational, non-threshold,
• randomly occurring, all or nothing

• –The greater the dose the greater
• the chance of the effect occurring.  NOT
• is it going to occur.

–Cancer and genetic effects

• While we have already discussed the fact
• different forms have radiation have different effects (equivalent dose) some
• tissues are more sensitive than others.

• •Tissue weighting factor allows overall risk
• to be determined.

•50 mSv or 5 rem annually

•Pregnant

–0.5 mSv per month

• –5 mSv for
• the entire pregnancy

• •The potential that small radiation exposure
• is actually beneficial.

•1 mSv or 0.1 rem or 100 mrem year

•Educational exposure

• –1 mSv or
• 0.1 rem annually

• –Notice it is the same as the
• general public