ACUTE MORTALITY OF CHINCHILLAS EXPOSED TO MIXED GAMMA-NEUTRON RADIATIONS OR 250 KVP X RAYS

The chinchillas acute mortality response to mixed gamma-neutron radiations of the AFRRI-TRIGA reactor and to 250 kVp x rays was studied. Unilateral whole body irradiations were accomplished at doses from 200 to 639 rads of mixed gamma-neutron radiations and from 357 to 1786 rads of x rays. All radiations were delivered at approximately 20 radsmin, and doses are reported as midline tissue doses. The LD5030 values calculated for the mixed gamma- neutron radiations and for the x rays were 295 and 490 rads, respectively. Using 30-day median lethality as the end point, the RBE of the mixed gamma- neutron radiations was 1.7. The wide lethal dose range obtained was attributed to a high degree of variation in age of the chinchillas. In contrast to previous experience in rodents, the chinchilla showed a relative resistance to the classically described gastrointestinal modality of radiation death.