Radiation Oncology/Radiobiology/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
• The most radio-sensitive cells:
  1. High division rate
  2. High metabolic rate
  3. Non-specialized type
  4. Well nourished

• Casarett classification:
  1. Group I
  2. Group II
  3. Group III
  4. Group IV

• Michalowski classification (PMID: 7127027):
  1. H-type (hierarchical): like hemopoietic tissues
  2. F-type (flexible): like liver parenchyma