Real-time optimized intraoperative dosimetry for prostate brachytherapy: Apilot study

Purpose: To assess the feasibility of real-time intraoperative treatment pl anning for permanent prostate brachytherapy analyzing the impact on operati ve time and adequacy of postimplant dosimetry. Methods and Materials: Seventeen consecutive patients undergoing permanent brachytherapy for prostate cancer had real-time intraoperative computer-bas ed and optimized treatment planning. The first 8 patients were implanted us ing a plan generated before the surgery and served to assure the team quali tatively that this could be performed without greatly increasing intraopera tive time. They served as control group for expected achieved dosimetry res ults reviewing the D90, V100, V150 parameters from the dose-volume histogra ms. The next 9 patients were implanted according to the real-time plan, The times needed to carry out various steps of the procedure were recorded. Th e achieved dosimetry was then compared to the control group to assure that accuracy was unchanged. Results: The median operative time for patients undergoing intraoperative d osimetry was 57 min. Of this, 21 min were devoted to anesthesia and nursing functions. Postoperative dosimetry showed a median achieved V100 (volume o f prostate receiving 100% of prescribed dose) of 97% for the control group. For the real-time dosimetry group, the median V100 was similar at 94%. The V150 (volume receiving 150%) is 49% for both groups, The D90 (dose receive d by 90% of the target) was normalized for easy comparison and,vas consiste ntly slightly greater than the prescription dose. Conclusion: Treatment planning for permanent brachytherapy of prostate canc er has historically been performed as a computer-generated and optimized pl an run weeks in advance of an implant, or according to a set pattern using an intraoperative nomogram. These data show that planning can now be optimi zed intraoperatively using widely available software without compromising t he operative time or implant quality. (C) 2000 Elsevier Science Inc.