RBE-LET relationships for lethal, potentially lethal and sublethal damage in mammalian cells: implications for fast neutron radiotherapy.

The dependence of relative biological effectiveness (RBE) on the linear energy transfer (LET) of radiations is described for different types of cellular damage which contribute to reproductive death. The influence of the capacity for repair of sublethal and of potentially lethal damage of mammalian cells is discussed. The analysis leads to interpretations of differences in the RBE of fast neutrons among tumours and among normal tissues and to suggestions for the application of high LET radiation in radiotherapy.