Calculations for comparison of different irradiation schemes can be effected in a simplified manner according to the equivalence procedure. This is, in a generalized way, applied to irradiation schemes performed at irregular time intervals, to inhomogeneous dose distributions as well as to the determination of additional fractions from the saturation of partial volumes. The derived formula are appropriate for use in routine procedures. The notion "effect-equivalent dose" is of help for the clear definition of under- or overdosage at irradiation planning.