Radiation protection issues of Auger electron emitters

Radionuclides that emit Auger electrons are widely used in nuclear medicine and biomedical research. If the radionuclide is part of a chemical compound which binds to DNA or preferentially enters the cell nucleus, the biological effects of the Auger electrons can be as severe as from high LET alpha particles. Neither the recommendations of the International Commission on Radiological Protection (ICRP) in Publication 60, nor the International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources provide any detailed guidance on how to calculate the equivalent dose for these radionuclides. Recently, however, a Task Group of the American Association of Physicists in Medicine (AAPM) has proposed that the component of dose from the Auger electrons for radionuclides bound to DNA should be given a preliminary radiation weighting factor of 10 for deterministic effects and 20 for stochastic effects. The dose equivalent calculated with these weighting factors must be modulated by experimentally determined subcellular distributions of the Auger electron emitters.