Spatial Distribution Patterns of Energy Deposition and Cellular Radiation Effects in Lung Tissue Following Simulated Exposure to Alpha Particles

Randomly oriented sections of rat tissue have been digitised to provide the contours of tissue-air interfaces and the locations of individual cell nuclei in the alveolated region of the lung. Sources of alpha particles with varying irradiation geometrics and densities are simulated to compute the resulting random pattern of cellular irradiation, i.e. spatial coordinates, frequency, track length, and energy of traversals by the emitted alpha particles. Probabilities per unit track length, derived from experimental data on in vitro cellular inactivation and transformation, are then applied to the results of the alpha exposure simulations to yield an estimate of the number of both dead and viable transformed cells and their spatial distributions. If lung cancer risk is linearly related to the number of transformed cells, the carcinogenic risk for hot particles is always smaller than that for a uniform nuclide distribution of the same activity.