Intraoperative planning and evaluation of permanent prostate brachytherapy: Report of the American Brachytherapy Society

Purpose: The preplanned technique used for permanent prostate brachytherapy has limitations that may be overcome by intraoperative planning. The goal of the American Brachytherapy Society (ABS) project was to assess the curre nt intraoperative planning process and explore the potential for improvemen t in intraoperative treatment planning (ITP). Methods and Materials: Members of the ABS with expertise in ITP performed a literature review, reviewed their clinical experience with ITP, and explor ed the potential for improving the technique. Results: The ABS proposes the following terminology in regard to prostate p lanning process: Preplanning-Creation of a plan a few days or weeks before the implant procedure. Intraoperative planning-Treatment planning in the operating room (OR): the patient and transrectal ultrasound probe are not moved between the volume s tudy and the seed insertion procedure. Intraoperative preplanning-Creation of a plan in the OR just before the imp lant procedure, with immediate execution of the plan. Interactive planning-Stepwise refinement of the treatment plan using comput erized dose calculations derived from image-based needle position feedback. Dynamic dose calculation-Constant updating of dose distribution calculation s using continuous deposited seed position feedback. Both intraoperative preplanning and interactive planning are currently feas ible and commercially available and may help to overcome many of the limita tions of the preplanning technique. Dosimetric feedback based on imaged nee dle positions can be used to modify the ITP. However, the dynamic changes i n prostate size and shape and in seed position that occur during the implan t are not yet quantifiable with current technology, and ITP does not obviat e the need for postimplant dosimetric analysis. The major current limitatio n of ITP is the inability to localize the seeds in relation to the prostate . Dynamic dose calculation can become a reality once these issues are solve d. Future advances can be expected in methods of enhancing seed identificat ion, in imaging techniques, and in the development of better source deliver y systems. Additionally, ITP should be correlated with outcome studies, usi ng dosimetric, toxicity, and efficacy endpoints. Conclusion: ITP addresses many of the limitations of current permanent pros tate brachytherapy and has some advantages over the preplanned technique. F urther technologic advancement will be needed to achieve dynamic real-time calculation of dose distribution from implanted sources, with constant upda ting to allow modification of subsequent seed placement and consistent, ide al dose distribution within the target volume. (C) 2001 Elsevier Science In c.