Radiotoxicity of 75 Se and 35 S: Theory and Application to a Cellular Model

The radiotoxicity of the Auger electron emitter,75 Se, relative to the negatron emitter,35 S is investigated theoretically and experimentally using ⁷⁵ Se-selenomethionine and35 S-methionine. These analog compounds are mainly incorporated into the cytoplasmic proteins of dividing cells, and their uptake is linear with increasing extracellular radioactivity. On the basis of theoretical dose estimates, we predict that both radionuclides should be equally effective in killing V79 Chinese hamster fibroblasts. Experimental results fully support these expectations and emphasize that Auger electron-emitting radionuclides in the cytoplasm contribute, in general, minimally to radiation-induced cell death.