OXYGEN AND IONIZING-RADIATION

After a presentation of the physicochemical action of ionizing radiati on, the interactions with cellular and tissular materials will be deta iled, with a special focus on human tumor cells. The radiosensitivity of mammalian cells varies as a function of oxygen concentration. The o xygen enhancement ratio is around 3. There could be differences in cel lular radiosensitivity as a function of the oxygen partial pressure (p O(2)) (K constant) between murine and human cell lines. Tumor areas wi th low oxygen tension have been found by direct measurements of pO(2) in solid tumors (ENT, uterine cervix, or metastatic melanoma).