HDR brachytherapy involves the temporary placement of tiny plastic catheters into the prostate gland through a template that is sutured to the perineal skin below the scrotum.

Once in place, a tiny radioactive seed is inserted on a temporary basis into the catheters in a sequential pattern. A computer controls the length of time the seed delivers its radiation through the catheter. After the radiation has been given, the catheters are removed, leaving no radioactive material in the gland. This type of treatment requires an overnight stay in the hospital and is usually combined with several weeks of external beam radiation.