Impact of Isocenter Configuration and Flattening Filter Free Delivery on VMAT Planning for Synchronous Bilateral Breast Cancer

作者：J. Zhang, 宏丹 李, Yong Gan, Zewei Chen · 发表于：International Journal of Women s Health · 年份：2026 · DOI：10.2147/ijwh.s609857 · 研究领域：Breast Cancer Treatment Studies、Advanced Radiotherapy Techniques、Lung Cancer Diagnosis and Treatment

Purpose: To evaluate the relative impact of isocenter configuration and flattening filter free (FFF) beam delivery on dosimetric performance, radiobiological outcomes, and treatment efficiency in volumetric modulated arc therapy (VMAT) for synchronous bilateral breast cancer (SBBC). Methods: Twenty-two treatment plans were generated for patients with SBBC using four VMAT configurations, including single-isocenter and dual-isocenter strategies with either flattened (FF) or FFF beams. Target coverage and plan quality were assessed using standard dose volume parameters. Doses to organs at risk (OARs), including the whole lung, heart, left anterior descending artery (LAD), aorta, liver, spinal cord, and skin, were evaluated. Treatment times and total monitor units (MUs) were recorded. Radiobiological outcomes were estimated using tumor control probability (TCP) and normal tissue complication probability (NTCP) models. Statistical comparisons were performed between planning strategies and beam delivery modes. Results: Dual-isocenter VMAT consistently achieved superior target coverage, dose homogeneity, and sparing of thoracic OARs compared with single-isocenter VMAT. In particular, dual-isocenter planning reduced the mean heart dose by approximately 35% (11.83 ± 1.41 Gy vs 7.69 ± 1.11 Gy) and decreased heart V 10Gy by more than 50% (41.19 ± 8.14% vs 20.45 ± 6.27%) compared with conventional single-isocenter VMAT. These improvements translated into more favorable TCP and NTCP estim...