Radiosensitivity is the relative susceptibility of cells, tissues, organs, organisms, or other substances to the injurious action of radiation. In general, it has been found that cell radiosensitivity is directly proportional to the rate of cell division and inversely proportional to the degree of cell differentiation. In short, this means that actively dividing cells or those not fully mature are most at risk from radiation. The most radio-sensitive cells are those which:
- have a high division rate
- have a high metabolic rate
- are of a non-specialized type
- are well nourished
Examples of various tissues and their relative radiosensitivities are listed below.
High Radiosensitivity
|
| Lymphoid organs, bone marrow, blood, testes, ovaries, intestines |
Fairly High Radiosensitivity
|
| Skin and other organs with epithelial cell lining (cornea, oral cavity, esophagus, rectum, bladder, vagina, uterine cervix, ureters) |
Moderate Radiosensitivity
|
| Optic lens, stomach, growing cartilage, fine vasculature, growing bone |
Fairly Low Radiosensitivity
|
Mature cartilage or bones, salivary glands, respiratory organs, kidneys, liver, pancreas, thyroid, adrenal and pituitary glands
|
Low Radiosensitivity
|
| Muscle, brain, spinal cord |
Reference: Rubin, P. and Casarett. G. W.: Clinical Radiation Pathology (Philadelphia: W. B. Saunders. 1968).
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