Abstract
Calculations of total doses for different numbers of fractions are presented, for 2 special assumptions. One is based on published radiotherapy results. The other is based on a cell survival curve model with extrapolation number = 2.8 and D0 = 140 rads. Neither assumption allows fully for cell repopulation, and the significance of this is discussed. The limitations of the calculations as a guide to radiotherapeutic practice are stressed.