On the problem of time, dose and fractionation (TDF) in the linear-quadratic model.

In many problems of modern radiotherapy such as multifractionation, interstitial and intracavitary therapy with implanats the NSD-formula is hardly applicable. Serious difficulties arise, when this formula is used for an estimation of late responses of tissues, because it mainly appreciates acute effects. On the basis of the linear-quadratic survival model S = exp (-alpha D - beta D2) the TDF-problem is investigated with the help of kinetic principles.