Principles and practice of brachytherapy dosimetry

Brachytherapy is an important radiation treatment modality and continues to play important roles in the management of various cancers. In brachytherapy, depending on the location of the target volume, cell type, and treatment convenience, radiation dose can be delivered to the target volume in different ways. Brachytherapy is significantly different from the external beam therapy in the dose delivery and dosimetric distribution. This article is intended to provide brief descriptions to the dose calculation formalism in brachytherapy, dosimetric determination of a brachytherapy source, biophysical characteristics of commonly used sources, and radiation safety during brachytherapy procedures.