S2767
RTT - RTT contouring, target definition, and treatment planning
ESTRO 2026
949 Clinical Feasibility of ESAPI-Driven Automated 3- Arc VMAT Planning for Hippocampus-Sparing Whole Brain Radiotherapy JINHUEI JI 1 , Ti-Hao Wang 2 , SHUSHENG LI 2 1 Research and Development, EverFortune. AI, Taichung, Taiwan. 2 Department of Radiation Oncology, China Medical University Hospital, Taichung, Taiwan Purpose/Objective: Hippocampus-sparing whole brain radiotherapy (HS- WBRT) preserves cognitive function but is challenging due to strict RTOG 0933 dose constraints. Automated planning can improve workflow efficiency. This study evaluated an ESAPI-based automated workflow for HS- WBRT. Material/Methods: Five retrospective HS-WBRT cases, prescribed 30 Gy in
10 fractions, were analyzed. Auto-plans were generated in Eclipse ESAPI v15.6 on a Varian
TrueBeam linac, using the same 3-arc VMAT geometry with a single isocenter. Each collimator was set to 90°: the cranial beam covered brain above the hippocampi (excluding hippocampi), the hippocampal beam covered the hippocampi-containing region, and the caudal beam covered brain below the hippocampi (excluding hippocampi). Machine constraints and optimization priorities mirrored clinical plans. Dosimetric quality, hippocampal sparing, target coverage, total MU, and planning time were assessed. Results: All automated plans fully complied with RTOG 0933 constraints and met clinical standards. The automated plans maintained consistent target coverage while showing modest improvements in dose uniformity and hotspot control, and preserved/slightly improved hippocampal sparing. Total Monitor Units (MU) were slightly lower. Crucially, planning time was reduced dramatically from 1 − 2 hours to approximately 10 minutes, eliminating inter-planner variability. Conclusion: This ESAPI-based automated HS-WBRT planning approach successfully reproduced clinical plan quality using standard 3-arc VMAT configurations with region- specific fields and significantly improved workflow efficiency by reducing planning time by over 80%. These findings affirm the clinical feasibility of translating established parameters directly into a standardized and scalable auto-planning solution for HS-WBRT, establishing a robust foundation for integrating automation into future adaptive and AI- assisted radiation therapy systems. Keywords: Hippocampus-Sparing Whole Brain Radiotherapy
Conclusion: RAD provides a viable solution to help reduce doses to organs of interest while maintaining target coverage conventionally achieved with VMAT in a range of multi- dose level head and neck radiotherapy plans. Using a two arc, 4 STAMP per arc approach, has shown to be beneficial for a range of head and neck cases relative to VMAT in clinical practice. References: 1. Thompson K, Laferlita C, Fua T, Daniels C, Panettieri V, Hardcastle N, et al. 2278 Clinical Acceptability of the Next Generation in Modulated Arc Therapy for Nasopharyngeal Carcinoma. Radiotherapy and Oncology. 2025;206:S3494-S6.2. Varian Medical Systems. RapidArc Dynamic Quick Start Guide. 2025.3. Laferlita C, Thompson K, Hardcastle N, Panettieri V, Devereux T, Fua T, et al. 2280 Weighting Preferences for RapidArc Dynamic: An Evaluation of the Impact on One Arc and Two Arc Approaches for Treating Nasopharyngeal Carcinoma. Radiotherapy and Oncology. 2025;206:S4353-S5. Keywords: Rapid Arc Dynamic, Head & Neck, Treatment Planning Digital Poster
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