Dose-rate considerations in the introduction of low-dose-rate afterloading intracavitary techniques for radiotherapy.

Abstract

An investigation has been made into the changes in total dose required as a consequence of proposed increases in dose-rate in low-dose-rate treatments of cancer of the uterine cervix. The relationship between total irradiation time and dose-rate has been measured using an assay based on mouse-tail radionecrosis, with irradiation schedules similar to existing and proposed human cervix treatments. This relationship, which is similar to that observed in other biological systems, predicts that the total dose for epithelial tolerance should be reduced by about one third when the dose-rate is increased from 1.0 to 3.5 Gy per hour. The clinical implications of this finding are discussed.