The Effect of Fractionation on Four Day Survival of Mice after Whole-body Neutron Irradiation

Abstract

The proportion of animals surviving 4 days after whole body neutron irradiation is not altered by giving the radiation in 2 fractions separated by 4 to 6 hours. This result is compared with previously reported data after 250 k V X irradiation when it was found that a dose higher by 400-600 rads was necessary to produce the same killing effect if the radiation was given in 2 fractions rather than a single dose. This results in a larger RBE (250 k V/neutron) for the fractioned radiation than for single-dose irradiation and any increase in the number of fractions would increase the RBE further. These results may be relevant to the use of neutrons for therapy.