Enhanced mutation and neoplastic transformation in human cells by 29 kVp relative to 200 kVp X rays indicating a strong dependence of RBE on photon energy

The fundamental assumption implicit in the use of the atomic bomb survivor data to derive risk estimates for occupation and medical exposures is that the gamma rays of Hiroshima and Nagasaki are considered as equal efficiencies to other low LET radiations up to an LET of 10 keV.μm-1. For breast cancer induction, neoplastic cell transformation, mutation, reciprocal translocations and dicentrics in human lymphocytes, a strong and very similar dependence of the RBE values on photon energy or on LET is observed. Experimental data on mutation induction and neoplastic cell transformation in human data are in excellent agreement with the data in the literature. (author)