Abstract

The underlying radiobiology of brachytherapy is essentially the same as that for external- beam radiotherapy and this chapter should, therefore, be read in conjunction with Part B. For brachytherapy in particular, the all-pervasive nature of the inverse-square law means that there is a complex interplay between the physical and radiobiological aspects. This interplay influences the way in which brachytherapy treatments should be evaluated, both in absolute and comparative terms. In planning any brachytherapy procedure it is probably true to say that attention to physics should always take precedence over attention to radiobiology, because the radiobiological considerations are of little value when applied to treatments with poor source geometry or that are misplaced.