Comparative Lethality Responses of Neutron- and X-Irradiated Dogs: Influence of Dose Rate and Exposure Aspect

Publisher Website
Google Scholar
Abstract
Dogs were exposed to mixed neutron/gamma (n/gamma) radiation in the ratio of [image] 6:1. Influence of dose rate was evaluated by comparing the LD50/30''s for dogs unilaterally exposed at ~ 40 rads/minute. The midline tissue dose LD50 were 230 and 221 rads, respectively, indicating no dose rate effect. The effect of exposure aspect (unilateral versus bilateral) on LD50 was determined with both n/gamma- and X-irradiated dogs. In n/gamma-irradiated animals, the LD50 was not significantly influenced by exposure aspect, but in X-irradiated animals the unilateral LD50 was significantly higher than the bilateral LD50. With LD50 as the end point, estimates of the relative potency of n/gamma-radiation compared with 1-Mvp X-radiation depend on the point of dose reference. In terms of exposure (air dose) in space or at the midpoint of the exposure volume, the relative potency is [image] 1.0. However, in terms of midline tissue doses estimated from phantom studies, the data indicate that n/gamma-radiation is significantly more potent in production of acute mortality than is 1-Mvp X-radiation. The n/gamma relative potency for bilateral exposure is 1.38, and for unilateral exposure it is 1.49. At radiation doses 1.4 times the LD50, comparatively more n/gamma-irradiated animals die in less than 7 days than do X-irradiated animals. Thus the early-death threshold dose for n/gamma-radiation appears to be closer to the midline tissue LD50 than is the case with X-radiation. The possibility of significant intestinal damage in n/gamma-irradiated dogs is discussed.

This publication has 2 references indexed in Scilit: