Effect of heterogeneous radio sensitivity on the survival, alpha beta ratio and biologic effective dose calculation of irradiated mammalian cell populations

Variance of the distribution of α of a heterogeneous cell population lowers the effective value of the quadratic survival constant β of the population, as a whole, and increases the α/β ratio in the low dose range. Heterogeneous appearance of tumor cells (pleomorphism) and necrosis on biopsy or imaging studies reflect heterogeneity of the radio sensitivity of the cells. Greater heterogeneity implies a tendency to higher α/β ratio. This may furnish a clinically accessible way to estimate a value of the α/β ratio specific to an individual patient and tumor.