COMPARATIVE MORTALITY FOLLOWING PARTIAL AND WHOLE BODY IRRADIATION OF RATS WITH FAST NEUTRONS AND X-RAYS
Using acute montality as the endpoint, the relative biological effectiveness (RBE) of simulated fission neutrons with respect to 250 kvp unfiltered x rays was determined in the rat for exposure of whole-body, abdomen- hindquarters only, and head-thorax only. For whole-body exposure, an RBE of 2.8 was obtained for both 5- and 30-day endpoints, the former representing acute intestinal deaths only and the latter including both bone marrow and intestinal deaths. Although these RBE's were identical, neutronirradiated rats appear to show a somewhat greater radiosensitivity of intestine relative to bone marrow than do x-irradiated rats. Thus, at any given 30-day lethal level, the proportion of rats dying early (by 5 days) is slightly greater in the case of neutron-exposed animals. Following exposure of abdomen-hindquarters only, essentially no montality occurred after 5 days. The RBE for intestinal deaths in these rats was also 2.5. The RBE of neutrons for head-thorax exposure, producing oropharyngeal 9 to 16-day deaths, was found to be 3.0. (auth)
- Research Organization:
- Naval Radiological Defense Lab., San Francisco
- NSA Number:
- NSA-15-012724
- OSTI ID:
- 4079006
- Report Number(s):
- USNRDL-TR-456
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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