THE MINIMUM D-0 FOR CELL-KILLING FOR ALPHA-PARTICLE EMITTERS UNIFORMLY DISTRIBUTED IN AN EXTENDED MEDIUM

For cells irradiated by or particles in suspension, there is presently no simple test to show that the cell killing can be attributed to alp ha-particle passages through the nuclei. In this communication, for a uniform distribution of alpha-particle sources and spherical nuclei, a D-0 is calculated such that at least 63% of the cell nuclei have at l east one alpha-particle passage. For a uniform distribution of alpha-p article sources and spherical nuclei, it is shown that the average dos e for 63% of the cell nuclei to be hit (37% not hit) is equal to the a verage dose per hit. For this condition an energy deposition of any si ze would result in cell death and the average dose is the minimum D-0 possible. Minimum D-0 values are calculated using a Monte Carlo treatm ent for nuclear diameters from 4 to 10 pm and initial alpha-particle e nergies between 3.18 and 8.38 MeV. (C) 1998 by Radiation Research Soci ety.