Radiation

Classification

  1. Electromagnetic
    1. Infra-red
    2. Ultraviolet
    3. X-ray
    4. Gamma-ray
    5. cosmic rays
  2. Particulate
    1. alpha particles (electron)
    2. beta particles(hydrogen nucleus)

Cellular damage mechanisms

  • Direct DNA damage (TT dimers, base deletions, cross linkages)
  • Indirect damage to proteins, membranes, enzymes (via free radicals - unpaired electron)

 

Rad Effect

100,000
10,000
1000
100

Death in minutes (nuclear bomb)
Death within hours from CNS effects
Death in weeks from pancytopenia
Nausea & vomiting

 

Radiation sensitivity is not commensurate with a tissues capacity to regenerate.

Radiosensitive (radidly growing) Intermediate Resistant
Bone marrow
Gonads
Growing cartilage/bone
Lens of eye (risk from UV)
Bowel
Thyroid
Pituitary
Kidney
Heart
Lung
Liver
Brain
Skin (risk from UV)
Adult bone / cartilage
Mouth mucosa
Oesophagus
Bladder
Uterus
Vagina
Adrenal gland
Pancreas