[Fractionation and radiation injury--clinical aspect].

The late effect of normal tissues in altered fractionation was analyzed with our experience and review in clinical trial. In hypofractionation late effect in normal tissues increased in frequency with increased dose per fraction. In the other hand, the optimal ERD or fractionations in MFD were found in larynx, lung and esophagus. The ERD and the frequency of severe late effect in clinical trial with accelerated or accelerated hyperfractionation tended to be less than those of hyperfractionation. However the tolerance ERD in brain and abdominal organ have not been able to determine due to short life span, combined modality and few clinical trial.