Models for cellular survival in ionizing radiation fields

Together with experimental methods, biophysics uses models to describe the processes in living systems at various organization levels from macromolecules to the biosphere as a whole. Some successful examples of application of models to cellular survival in ionizing radiation fields are presented. The inactivation of individual biologic structures by radiation is one of the postulates on development of models of the effects of radiation on cells. In these models two possibilities of interaction must be considered: direct action and indirect action, the latter resulting from the participation of intermediary products. Cell cultures from different tissues and tumours show a wide variation in the shape of their survival curves. L-Q and target theory models have been considered. Survival curves for high-LET radiations such as particles, neutrons and very slow electrons are linear in both models (irreparable damage dominates). For low LET radiation the L-Q curves retain curvature even at very high doses whilst target theory curves become linear at high doses. (author)