[Role of radiation biology in the standardization and optimization of radiotherapy]

New treatment modalities, proposed by radiobiologists, were reviewed to criticize their role in the standardization and optimization of radiotherapy with special reference to hypoxic cell sensitizer and hyperthermia. Most of them, except time-dose-fractionation in the prevention of normal tissue damage, are playing a role rather in the individualization or optimization than in standardization at present. It is necessary to improve the modality itself on one hand and to develop the method to get non invasively the information of biological characteristics of the tumor, for example size of hypoxic fraction, on the other hand, before these biological response modifiers can play an important role in the standardization of radiotherapy.