The Effect of Beam Direction and Backscattered Radiation on Acute Mortality in X-Irradiated Female CBA Mice

When a primary x-ray beam with the minimum of backscatter was used, the LD/sub 50(30)/ for whole-body irradiation of mice was found to be ll% less when the beam entered the dorsal surface of the animals than when it entered the ventral surface. When full backscatter was added to the primary beam this difference was reduced, as would be expected. Differences in degree of scatter and in beam direction therefore seem likely to account for only a small part of the differences in the LD/sub 50(30)/ for mice given wholebody x irradiation in dtfferent laboratories. (auth)