Lethal Response of C57BL Mice to 10 MeV X-rays and to60Co Gamma-rays

Abstract
The LD50/30 of female and male C57BL mice was used as an end-point to estimate the r.b.e. of 10 MeV X-rays at a dose-rate of 35 rads/min, and the r.b.e. of 60Co gamma-rays at a dose-rate of 6 rads/min, using the LD50/30 of 60Co gamma-rays at a dose-rate of 35 rads/min as the base-line. The r.b.e. of 10 MeV X-rays at 35 rads/min and that of 60Co gamma-rays at 6 rads/min were found to be 1·00 ± 0·03 and 0·72 ± 0·4 respectively.