Dose-survival curves of fractionated irradiation in mice

An analysis was carried out to explain the shape of survival curves in fractionated irradiation. The dose which seemed to remain in the irradiated animals at the time of subsequent exposure was estimated from (differential) survival decrease by the exposure. Single-dose survival curve of the experimental animals was the guide to the estimation. The apparently remained dose in animals surviving previous dose at the time of each successive exposure assumed to be "residual dose" or RD, which was denoted from residual damage to which not differential but total survival decrease was referred. Recovery rate was calculated from our experiment of whole body irradiation in mice. Dose consisted in residual dose at the time of i-th exposure together with the i-th exposure decreasing during the timeinterval to the residual dose at the time of the subsequent i + 1--th exposure, indicated the recovery rate being independent to dose size. However, the recovery did not seem exponential to interval days ; two days recovery seemed most rapid.