CRITERIA AND TECHNIQUES FOR ANALYZING CELL-SURVIVAL DATA

Cell survival was studied by analyzing the inactivation probability density function and its fundamental parameters. Mean {Mathematical expression}, variance σ2 and mode Dmode were evaluated and a set of equations relating these parameters to the usual parameters of the multitarget, multihit and linear-quadratic models Do and n, α and β, k and λ are reported. The multihit equation used was an extension of the usual equation, to allow parameter k to assume values that are not necessarily integers. In the multitarget curve, the mode of inactivation probability density function, proved to be the quasi-threshold dose Dq =Do ln(n). Relative variance, degree of asymmetry and degree of peakedness can be calculated from the shape parameters n in the multitarget model, k in the multihit model, and {Mathematical expression} in the linear-quadratic model. From an analysis of eight published cell survival sets of data, on C3H10T1/2 cells exposed to low LET radiations, it was found that {Mathematical expression}, σ, and SF2 are the parameters which exhibit the least variation from experiment to experiment and the least variation in selecting the range of data available for estimation. © 1991 Springer-Verlag.