Effects of radiation on the cell proliferation kinetics of epithelial tissues—therapeutic implications

The cell kinetic responses of the epithelia of the skin, oral mucosa and intestine to photon irradiation are reviewed. One of the fundamental assumptions made in the development of mathematical models, used to predict the acute response of normal tissues to changes in fractionation protocols, is "equal effect per fraction". There is now accumulating cell kinetic data to indicate that this assumption is unlikely to be valid. The implications of these findings are discussed.