Accession Number : AD0737214


Title :   The Relative Effectiveness of Fission Neutrons for Gastronintestinal Death in Miniature Pigs.


Descriptive Note : Scientific rept.,


Corporate Author : ARMED FORCES RADIOBIOLOGY RESEARCH INST BETHESDA MD


Personal Author(s) : Jones,S. R. ; George,R. E. ; West,J. E. ; Verrelli,D. M.


Report Date : DEC 1971


Pagination or Media Count : 34


Abstract : Miniature pigs were bilaterally irradiated either in a neutron field (incident neutron to gamma ratio of 5) or in a gamma ray field (incident gamma to neutron ratio of 15) from the AFRRI-TRIGA reactor. For both fields the dose rate at the midline of the pigs was 250 rads/min and uniform (class A) irradiations to the gastronintestinal (GI) tract were achieved. Midline tissue doses from the neutron field ranged from 360 to 1970 rads; survival times were from 3.6 to 11 days. Midline tissue doses from the gamma ray field ranged from 605 to 2630 rads and survival times from 4.4 to 11.1 days. Median lethal doses for GI death (LD50/7.5 days) were calculated to be 430 rads and 870 rads for the neutron and gamma ray fields, respectively. Relative effectiveness of the neutrons was 2.0. The ratio of the doses corresponding to 7.5 days mean survival time, calculated by the least squares method, was used as an additional estimate of the neutron relative effectiveness. Results were in agreement with those of the LD50/7.5 method. Similar determinations for miniature pigs irradiated in the gamma ray field at 125 rads/min showed no gamma ray dose rate dependence between 250 and 125 rads/min. The relative segmental radiosensitivity of the GI tract and postirradiation bacterial proliferation in the miniature pigs are discussed. (Author)


Descriptors :   (*FISSION NEUTRONS, *GASTROINTESTINAL SYSTEM), (*GAMMA RAYS, GASTROINTESTINAL SYSTEM), (*RADIATION TOLERANCE, GASTROINTESTINAL SYSTEM), RADIATION EFFECTS, RADIATION DOSAGE, DOSE RATE, PARTIAL BODY IRRADIATION, TISSUES(BIOLOGY), BACTERIA, SWINE, LABORATORY ANIMALS, EXPERIMENTAL DATA


Subject Categories : RADIOBIOLOGY


Distribution Statement : APPROVED FOR PUBLIC RELEASE