Recovery kinetics deduced from continuous low dose-rate experiments

Information on the rate of recovery from potentially lethal damage can be obtained from the analysis of the radiation dose-rate effect. Two mathematical models are useful in this respect: the Lethal-Potentially. Lethal (LPL) model of Curtis and the Incomplete Repair (IR) model of Thames. Full cell-survival curves are required at three or more dose rates in order to make a reliable analysis. Studies on human tumour cell lines yield values for recovery half-time in the range 0.1 to 0.9 h, and for each cell line the half-time found in this way is shorter than that obtained from a split-dose experiment. This result may imply that cellular recovery is a multi-component or a saturable process.