A Systematic Planning Strategy for Venezia Hybrid HDR Brachytherapy: Improving Dosimetric Parameters While Reducing Treatment Delivery Time
Abstract
Purpose
To develop and evaluate a treatment planning method for the Venezia HDR applicator that utilizes interstitial needles to enhance High Risk Clinical Target Volume (HRCTV) coverage and reduce dose to organs at risk (OARs) through a structured sequential workflow.
Methods
Treatment plans were generated in Oncentra Treatment Planning System using a multi-step approach. A baseline plan was created for the intracavitary portion using point-normalization and point-optimization to generate a balanced dose distribution. To lock the dwell times for this baseline plan, optimization was changed to Graphical and the weight of the reference dwell position was fixed at 1.0. The interstitial portion of the plan was added by activating dwell positions in the appropriate portion of each implanted needle. The optimization was then switched to Manual to allow the dwell weights for the needles to be modified. Dwell weights were iteratively refined (typically 6 to 10 percent) to manually optimize HRCTV coverage and OAR dose.
Results
Implementation of this method consistently yielded superior dosimetric parameters compared to standard Tandem and Ring plans while maintaining the general pear shape dose distribution. Target coverage, defined by the D90 and V100 of the HRCTV, was improved. Simultaneously, sparing of each of the OARs was similarly improved, with reductions observed in both the D0.1cc and D2cc metrics for each OAR for each case. Additionally, this strategy also reduced the total plan delivery time.
Conclusion
This planning workflow provides a practical and efficient method for maximizing clinical advantages of the Venezia applicator. Systematically integrating the dose from needles into a baseline plan results in high-quality, reproducible treatment plans that increase target coverage, reduce dose to organs at risk, and improve treatment delivery through reduced total delivery time.