Mécanismes biologiques des effets tardifs des radiations ionisantes

Summary ily practice of radiation oncology is increasingly influenced by the late tolerance of normal tissues. The treatment decision must be based on detailed arguments and the physicianʹs duty to extensively inform his patients is emphasised every day. The incidence and severity of radiation-induced sequelae and late complications can be reduced by decreasing the total dose to the normal tissues, and by decreasing the dose protraction, provided that the interval between fractions remains longer than 6 to 8 hours. This approach yields a selective protection of late responding normal tissues, since tumours are less sensitive to the effects of fractionation. Despite its own limitations, the linear- quadratic model is nowadays the standard method to compare the biological effects of different radiation treatments.