Dose response curves for organ function or cell survival

The interesting difference between the dose-effect curves for clonogenic cells (straight or with a small shoulder) and organ function (curved and with a large shoulder) shown in Fig. 6 of the paper by Wheldon et al (1982) was also demonstrated, for a broadly similar but less well-defined reason, in Fig. 2 of Fowler (1967), which was based on a model described by Whitmore and Till (1964). A recent paper by Joshi et al (1982) is relevant to this model. The practical implications concern altered fractionation in radiotherapy.