Time-dose factors (TDFs) in brachytherapy

Abstract

The time, dose, and fractionation (TDF) factor simplification of the nominal standard dose concept in fractionated radiotherapy has been extended to brachytherapy. The method automatically compensates for the variation of biological effect with dose-rate and time of application and is therefore applicable to irradiation at effectively constant dose-rate (with 226Ra, 137Cs, 60Co, etc.) and at varying dose-rate (with 222Rn, 198Au, 192Ir, 182Ta, etc.), and to permanent and temporary implants. Tables of brachytherapy TDFs are easy to use and, in combination with fractionated radiotherapy TDF tables, can be applied to the analysis of “mixed” external and internal régimes.