CALCULATION OF EQUIVALENT DOSE FOR AUGER-ELECTRON EMITTING RADIONUCLIDES DISTRIBUTED IN HUMAN ORGANS

Radionuclides that emit Auger electrons can be extremely radiotoxic de pending on the subcellular distribution of the radiochemical. Despite this, ICRP 60 provides no guidance in the calculation of equivalent do se H-T for Auger electrons. The recent report by the American Associat ion of Physicists in Medicine recommends a radiation weighting factor w(R) of 20 for stochastic effects caused by Auger electrons, along wit h a method of calculating the equivalent dose that takes into account the subcellular distribution of the radionuclide. In view of these rec ommendations, it is important to reevaluate equivalent doses from Auge r electron emitters. The mean absorbed dose per unit cumulated activit y (S-value) from Auger electrons and other radiations is calculated fo r ninety Auger-electron-emitting radionuclides distributed in human ov aries, testes and liver. Using these S-values, and the formalism given in the recent AAPM report, the dependence of the organ equivalent dos es on subcellular distribution of the Auger electron emitters is exami ned. The results show an increase in the mean equivalent dose for Auge r electron emitters when a significant fraction of the organ activity localizes in the DNA.