Brachytherapy ("brachy") is an alternative method of administering radiation treatment. In brachytherapy, radiation is not administered as a beam from the linear accelerator; instead very small radioactive “sources” are placed directly inside the prostate where they emit gamma rays. This irradiates the tissue directly, eliminating the need to direct radiation through other parts of the body. There are two kinds of brachytherapy commonly used for prostate cancer: “high dose rate” (HDR) or “temporary needle” brachytherapy; and “low dose rate” (LDR) or “permanent seed” brachytherapy. These two forms of brachytherapy are quite different and are used on different groups of patients.

A seed implant. Tiny radioactive seeds are carefully positioned in the prostate gland in a small day-procedure, shown in this Xray taken immediately at the end of the procedure. The seeds in the prostate are the small black ‘dots’, while contrast in the bladder makes the bladder obvious, dark above the seeds.