Cell Radiosensitivity

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).