Future Directions Permanent prostate cancer brachytherapy is an effective, curative option for patients with clinically localized disease. Based on current data, the role of external beam radiation and the need for the androgen deprivation remains controversial. Future, prospective trials are needed to answer these questions. Based on the current results with excellent biochemical freedom from recurrence rates, the ABS recommendations remain an important guide for treatment options 96. More importantly, the ability to achieve an acceptable implant for all patients remains the goal for all programs performing permanent prostate brachytherapy. However, the learning curve remains steep and not all centers utilize currently accepted methods for evaluating their implants. With techniques such as inverse planning used in intensity modulated radiation therapy available, the future direction of permanent prostate brachytherapy involve the use of these computer systems to assist the brachytherapist with the intra-operative procedure to assure a favorable dose profile to the prostate and surrounding normal tissues. The process of intraoperative planning to interactive dose planning to dynamic dose evaluations is still evolving and new technology will be required for this process. Ultimately, the process of interactive treatment planning will account for critical structures relative to active disease based on biologic radiology studies with real-time updating of the process based on actual seed positions derived during the implant itself 97-100. Commercially available systems in 2002 that come close to this reality include the Interplant system (Burdette Medical System, Champaign, IL), PIPER (Rtek, Pittsford, NY), SPOT (Nucletron Corporation, Veenandaal, Netherlands), Strata (Rosses Medical Systems, Columbia, MD) and VariSeed (Varian Medical Systems, Palo Alto, CA). Institution-based systems include those at Memorial Sloan-Kettering Cancer Center (MSKCC) and Boston’s Brigham and Women’s Hospital. As has been seen, historically and currently, the success of modern brachytherapy remains with dosimetry. To that end, all efforts to ensure the best possible implant are necessary. Using some of these techniques for interactive dosimetry, the MSKCC system demonstrated consistent dose coverage of the prostate 31. In a comparative dosimetric analysis of three implant techniques used at MSKCC, lower maximal urethral doses were observed significantly more frequently with the intraoperative computer-generated conformal plan compared to a CT pre-plan approach or an intraoperative ultrasound manual optimized approach. Ultimately, it is hoped that intraoperative, interactive planning will eliminate the need for post-implant dosimetry studies. At this time, dynamic dose calculation is not available for permanent prostate brachytherapy since it is currently difficult to image individual seeds on TRUS. However, dynamic dose calculation has been used for high-dose-rate prostate brachytherapy 101, and it is possible that some of its components could be adapted for permanent prostate dynamic dose calculation (Figure 7). As reported by Nag et. al., 96 the ABS has identified future enhancements in interstitial brachytherapy such as: Auto seed loading with higher capacity cartridges, a seed counting mechanism, and an improved withdrawal format. Improvements in delivering fixed space sources such as RapidStrand. Use of a motorized device to automatically push the needle tip position by a predetermined distance to facilitate the implant procedure [47] with optical encoders that would allow feed back of the needle position. The seed surface can be “dimpled” to potentially enhance its echogenicity. Conclusion Ultrasound-guided transperineal interstitial permanent prostate brachytherapy has been proven as a legitimate treatment option for patients with localized prostate cancer. This treatment option offers PSA relapse-free survivals that rival that of external beam radiotherapy and radical prostatectomy. With long-term data and acceptable toxicity profiles, this approach is widely considered a curative treatment option for patients with localized prostate cancer. Up | Brachytherapy Page 1 | Brachytherapy Page 2 | Brachytherapy Page 3 | Brachytherapy Page 4 | Brachytherapy Page 5 | Brachytherapy Page 6 | Brachytherapy Page 7 | Brachytherapy Page 8 |