Accession Number : AD0713557

Title :   REDUCTION OF BIOLOGICAL EFFECTIVENESS OF X-RAYS AT VERY HIGH DOSE RATES,

Corporate Author : ARMY ELECTRONICS COMMAND FORT MONMOUTH N J INST FOR EXPLORATORY RESEARCH

Personal Author(s) : Kronenberg,Stanley ; Lux,Robert ; Nilson,Kristian

Report Date : 1970

Pagination or Media Count : 12

Abstract : It has been observed that relative biological effectiveness (RBE) of X-rays or gamma rays is independent of dose rate provided that their delivery time is short compared to the recuperation time of the organism. At higher dose rates, however, several effects may modify the RBE. One possible process is considered here: Biological radiation effects are dependent upon the chemical behavior of free radicals produced in the ionization process. These free radicals are usually chemically active, and can produce permanent damage by their interaction with protein chains. Suppose the concentration of these radicals is allowed to come to equilibrium by irradiating a sample at a constant dose rate for a sufficient time. For low and moderate dose rates the radical concentration is so low that direct radical-radical recombination may be neglected. At a sufficiently high dose rate however this recombination may become significant. The reduced radical concentration will reduce the RBE. (Author)

Descriptors :   (*RADIATION EFFECTS, DOSE RATE), X RAYS, RADIATION DOSAGE, RADIATION CHEMISTRY, RADIOBIOLOGY, DOSIMETERS, SEEDS, GERMINATION, FREE RADICALS

Subject Categories : Radiobiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE