Quantitative assessment of carcinogenic risks associated with 'hot particles'.

We have examined the hot particle problem in terms of the number of irradiated cells and the doses to which they are subjected, assuming both linear and nonlinear dose-response functions typical of those reported in the radiobiological literature. We assess the risk associated with point sources of alpha, beta and gamma activity compared with uniform irradiation, as well as the effects of fractionation of a single particle, and the change in risk if the particle moves. Finally, although the biological data are insufficient for firm estimates, we have tentatively attributed absolute carcinogenic risks in these various situations.