COMPARISON OF MATHEMATICAL-MODELS FOR RADIATION FRACTIONATION

Radiation fractionation data can be plotted in 4 planes: log N-log D, dose-reciprocal total dose, dose-response and dose-recovery dose. Properties of curves in these planes corresponding to 5 models are developed. One model assumes that total dose is a power function of the number of fractions; the other 4 models assume that the dose-log surviving fraction curve is described by a multitarget, a 2 component (product of single-hit and multitarget factors), a quadratic and a cubic function, respectively. Several nonlinear regression criteria are defined and corresponding computer programs were developed. Best fits for the 5 models are found for 3 specific data sets involving normal tissues in mice. One regression criterion and 3 models are shown to be unsuitable.