RESIDUAL INJURY CAUSED BY IRRADIATION WITH FAST NEUTRONS
The LD/sub 50/ of C/sub 3/H female mice for fission-spectrum neutrons was found to be 274.5 plus or minus 4.2 rad. The previously reported value in the same mice for 250 kvp x ray was 632 rad, giving an RBE of 2.30. Conditioning exposure of the mice to a total neutron dose of 482.3 plus or minus 7.2 rad over an interval of 8 to 10 weeks resulted in lowering the LD/sub 50/ for neutrons by 41.8 plus or minus 5.9 rad, or 8.67 plus or minus 1.23% of the total conditioning dose. The previously reported value in the same mice for 250 kvp x-ray was 9.58% of the conditioning dose. Continued exposure of the mice to 166 rad doses of neutrons at intervals of 4 to 5 weeks gave a median survival time of 22 weeks. This was greater than that produced by exposure to 420 rad and less than that produced by exposure to 280 rad of 250 kvp x ray given at the same time. lt is concluded that the RBE of the mice for residual radiation injury and the RBE for chronic radiation tolerance over short time intervals are the same as that for acute injury tolerance. (auth)
- Research Organization:
- Naval Radiological Defense Lab., San Francisco
- NSA Number:
- NSA-16-011466
- OSTI ID:
- 4807745
- Report Number(s):
- USNRDL-TR-550
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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