RBE of CF-252 neutrons by mouse testes weight loss.

Mouse testes weight decreased with increasing radiation dose following exposure to Cf-252 and its mixed neutron plus gamma radiation. The dose response for low dose rate (LDR) Cf-252 followed two components on an exponential plot of log percent weight loss vs. dose. Similar dose-response relationships were observed for acute 60Co or LDR Cs-137 radiations, but these required much larger doses to produce the same effect. The RBE was calculated against acute 60Co and Cs-137. There were no differences between acute 60Co and LDR Cs-137 effects. Cf-252 neutron RBE (n + gamma) was 3.7 for testes weight loss. RBEn for the neutrons-only was 5.1 RBE for the radiosensitive portion was 4.0.