Ultimate Maximum Values of the RBE of Fast Neutrons and Gamma-rays for Chromosome Aberrations

Summary

If for some radiobiological effect the form of the dose-response is different for two radiations, the value of the RBE will vary with the dose, and a single value at just one level of effect will by itself alone convey little information. If, however, a linear term were present in the dose-response, it would predominate at low doses or long exposure times and then the RBE of two radiations would approach a constant limit.

This situation has been investigated for chromosome aberrations in Tradescantia microspores produced by short and long exposures to fast neutrons and gamma-rays. The data indicate that at low doses or long exposure times the RBE of the fast neutrons is high and must in the limit approach values of the order of 100.