New implant technique for separation of the seminal vesicle and rectal mucosa for high-dose-rate prostate brachytherapy

Purpose For safer treatment of seminal vesicles (SVs), we initiated a new technique using an anchor applicator for high-dose-rate interstitial brachytherapy (HDR-ISBT) of prostate cancer. Methods and materials Between January 2004 and March 2005, 23 intermediate- to high-risk patients were treated with HDR-ISBT as monotherapy. Transrectal ultrasonography guided implantation of the treatment applicator in and around the prostate gland and proximal SV. We used an “anchor” applicator to prevent posterior displacement of the SV. After insertion of the anchor applicator, the actual treatment applicator was implanted at the best position for optimal SV coverage. SV coverage was analyzed using a dose-volume histogram. Results Implantation of the applicator on the posterior side of the SV was successful for 43 of 46 SVs (93%). The median percentage of the SVs receiving the prescribed dose was 41% (range 11–86%). Only one case of acute Grade 2 toxicity (3%) was seen. Conclusions Our anchor applicator technique for HDR-ISBT can separate the SV from the rectum. This is the first report of dose-volume histogram analysis of the SV for HDR-ISBT.