health cancer lec 4 Flashcards
after the discovery of the x-ray how did they work out that radiation was bad
the x-ray was way too high (overdose) causing hair loss and skin redness
risk from rad dose based on the real effect of the radiation dose that is absorbed; calculations based on …
type of rad (type effects tissue differently)
energy it leaves in body (more energy more effect)
where in body
where in body is most vulnerable
tummy, hips, pregnancy, intensines
absorbed does +units
rad=0.01 J/kg, Gy=100rad
measure of energy deposited by the radiation in the material that absorbs it
energy deposited proportional to damage (not for alpha as ionising energy decrease w dist from source)
Effective dose units
Rem=radwr
Sievert=Gywr (=100rem)
Effective dose
only part of the body may be exposed to rad or exposure may vary between tissue types
Effective dose = Σ(ωT × equivalent dose to organ T)
Σ = summation over all the organs concerned
Deterministic effects
have a threshold dose.
Above threshold the frequency and severity of the effect
increases with increasing dose e.g. hair loss
Stochastic effects
have a proportional relationship between
dose and probability of occurrence.
(implies effects can never be eliminated only minimised)
e.g. fatal cancer & hereditary diseases
what cancers can be caused by rad
Thyroid cancer in children and adolescents
* Leukaemia in children and adults
* Cancer in adults
* Other diseases in children and adults
* Effects on pregnancy
* Genetic effects
We estimate the increase in the cancer incidence rate is
about 0.17 percent per rem of radiation dose1
; this is based
on effects seen at high doses. (hard to gage on low doses)
if 100 ppl 5rem then one extra person gets cancer
Radiation-induced cancers do not appear until
10 years after exposure (for tumors) or 2 years after exposure (for leukemia). can extend beyond this time
how will rad kill you fast
central nervous system failure
immune system destroyed body falls apart
radiation hormesis
Some scientists argue a beneficial
effect of low doses of radiation
high background rad, increase white blood cells, body more aware of rad and tumours
Ionising radiation damage
causes massive, non-specific disorganisation or injury of biological cells and tissues.
chromosome damage (breaks DNA chains)
Genomic instability
colonies of stems cells grown from an
irradiated parent show aberrations that are expressed several generations later
