Radiation Biology for Physical Scientists/Radiation Sensitivity of Cells

Interaction of Radiation with Matter · Radiation Induced Damage and Repair

The sensitivity of cells to radiation depends on cell cycle phase, level of differentiation, metabolic rate and rate of division.

Basic events in the cell cycle courtesy of Kelvinsong

Based on Cell CycleEdit

Cells propagate through division through a series of events. Radiation resistance through the cell cyle correlates with the level of sulfhydryls which are natural radiation protectors.Cells are most sensitive in the M phase and often G2. Slow cycling cells are resistant in early G1 and sensitive in late G1. Cell resistance is greatest in the last S phase because of the effective repair through homologous recombination.

Based on FunctionEdit

The Law of Bergonié and Tribondeau states cells that are dividing quickly, have less specialized functions and high metabolic rate are sensitive to radiation.

Less Resistant Spermatogonia
Epidermal Stem Cells
More Resistant Nerve Cells

The difference in radiation sensitivity of tissues is based on the differences in the level of specialization and proliferation inherent in their critical cells.

Acute Responding Tissues Late Responding Tissues
Gut Brain
Skin Spinal Cord
Bone Marrow Kidney
Mucosa Lung

One exception to the law are T-lymphocyte cells which are sensitive to radiation and highly differentiated.

Classification of cell radiation sensitivity has also been done based on histologic observation of cell death (Casarett's Classification) and reproductive kinetics (Michalowski's Classification).


Hall, Eric and Giaccia, Amato. Radiation Biology for the Radiologists. Lippincott Williams & Wilkins, 2006.