The RBE of 14 MeV Neutrons†

Abstract
The effectiveness of 14 MeV neutrons from the D-T reaction was compared with that of 60Co γ-radiation in killing mouse bone-marrow cells capable of forming spleen colonies after transfer to lethally-irradiated isologous recipients. The survival curves for the two radiations were found to have the same extrapolation number (1·38 ± 0·15). The D0 for neutrons was 63·7 ± 3·3 rads, and for γ-rays was 106 ± 5·1 rads. The ratio of these values gave the relative biological effectiveness (RBE) which, for the comparison 14 MeV neutrons/60Co γ, is 1·67 ± 0·06.