Abstract
BACKGROUND: Whole breast irradiation remains the standard in breast-conserving therapy for early-stage carcinoma. Conventional RapidArc™ plans, while dosimetrically efficient, are limited by fixed collimator position. This often leads to unnecessary irradiation to adjacent organs at risk (OARs)—particularly the contralateral breast, ipsilateral lung, and cardiac structures—resulting in increased low-dose exposure. These challenges are exacerbated in Chinese female patients due to characteristic anatomical features, such as smaller, crescent-shaped breasts, and closer heart-to-target distances. The novel RapidArc Dynamic™ system provides dynamic collimator rotation and static angle ports, enabling more beam shaping during volumetric modulated arc therapy. This study evaluates the implementation of RapidArc Dynamic™ for whole breast irradiation, comparing its dosimetric performance against conventional RapidArc™ in Chinese female patients. METHODS: Ten patients with early-stage left breast cancer were retrospectively replanned using RapidArc™ and RapidArc Dynamic™ on Eclipse™ (v18.1). All plans employed 6-MV photons on a TrueBeam™ linear accelerator equipped with a Millennium 120-leaf MLC, prescribed to deliver 40 Gy in 15 fractions to breast planning target volume for evaluation. Dosimetric parameters for PTV and OARs were analyzed using Wilcoxon signed-rank test. RESULTS: The results demonstrated that RapidArc Dynamic™ reduced contralateral breast exposure by 5.7% in maximum dose (29.6 Gy vs. 27.9 Gy) and 27.5% in mean dose (4.0 Gy vs. 2.9 Gy). Significant doses reductions in lungs were observed with a 13% lower mean lung dose (4.6 Gy vs. 4.0 Gy). Cardiac sparing improved with 21.6% lower mean heart dose (3.7 Gy vs. 2.9 Gy). CONCLUSIONS: RapidArc Dynamic™ demonstrates significant improvement in OARs sparing, despite anatomical challenges in Chinese female patients. CLINICAL TRIAL NUMBER: Not applicable. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13014-026-02789-x.