Beta, Gamma, and Xray radiation is considered Low Linear Energy Transfer (LET=Low) radiation. They have approximately the same biolegical effects per unit of radiation.
Alpha and Neutron radiation is considered High LET (LET=High). They have far greater toxicity (2-20x)
Damage to cells is caused by ionization occuring within the cells. Most damage is repaired successfully. Nucleur DNA may be damaged leading to inhibition/delay in mitosis or in genetic mutation.
There are two basic effects of ionizing radiation
Stochastic Effects: All or nothing effects, severity does not vary with dose, however risk does vary with dose.
Deterministic Effects: Severity of effect increases with dose. Examples include Reticuloendethelial depression, organ/tissue fibrosis, cataracts, impairment of fertility.
Ionizing Radiation can be measured by either English or SI units.
RAD: Radiation Absorbed Dose. (English Unit) = 1/100 GY
Gy: Gray. (Metric Unit). = 100 RAD
Conversely, differences in biological effect is taken into account in other measuring units. This takes into account variations such as the increased toxicity of alpha particles or neutrons.
REM: Roentgram Equivilent in Man. (English Unit) = 1/100 Sv
Sv: Sievert. (Metric Unit). = 100 REM
The
Helium nuclei stripped of their electrons.
Heavy particles, unable to penetrate past the skin.
May be medically important if internalized
High energy electrons emitted from unstable nuclei.
Only able to penetrate a few centimeters of tissue.
High energy photons.
Pass readily through and into tissue.
Can be attenuated by a thickness of lead
Highly potent. Deep penetration
Sources are rare: Reactors, Nuclear devices, industrial moisture density gauges.