A MATHEMATICAL-DESCRIPTION OF SUBLETHAL DAMAGE REPAIR AND INTERACTIONDURING CONTINUOUS LOW DOSE-RATE IRRADIATION

A mathematical formalism that calculates survival probabilities for ce lls exposed to ionising radiation while progressing through the mitoti c cycle is described. The formalism, based on the linear quadratic exp ression -lnS(D) = alphaD + betaD2, includes phase specific cellular pa rameters and recovery constants for sublethal damage, the interaction between sublesions produced at different stages of the cell cycle, and the time spent by cells in each phase of the cycle while being irradi ated. Survival curves calculated with this formalism are compared with model calculations where the overall survival probability is obtained (in the authors' view, incorrectly) as a simple product of phase spec ific probabilities.