Comprehensively evaluating the performance of Elekta high-definition dynamic radiosurgery for hypo fractionated stereotactic radiotherapy of multiple brain metastases

Purpose: To evaluate the dosimetric and delivery performance of Elekta high-definition dynamic radiosurgery (HDRS) in hypo fractionated stereotactic radiotherapy (HSRT) for multiple brain metastases (BMs) by comparison with a conventional single-isocenter non coplanar volumetric modulated arc therapy (VMAT) technique using the Ray Station treatment planning system (TPS). Materials and methods: From June 2022 to October 2023, thirty-two patients (a total of 140 BMs) treated with HSRT (30-48 Gy/3-6f) via HDRS-based single-isocenter non coplanar VMAT (HDRS-VMAT) were retrospectively selected for this study. Each patient was re planned using Ray Station TPS-based single-isocenter non coplanar VMAT (Ray Station-VMAT). HDRS-VMAT and Ray Station-VMAT plans were compared in terms of the gradient index (GI), conformity index (CI), normal brain tissue (NBT) dose exposure, monitor units (MUs), homogeneity index (HI), delivery accuracy, and beam-on time (BOT). Results: Compared with the Ray Station-VMAT plan, the HDRS-VMAT plan achieved superior CI (1.14 ± 0.09 vs. 1.23 ± 0.12, ρ < 0.001) and GI (5.23 ± 1.18 vs. 7.83 ± 2.75, ρ < 0.001) but had greater HI values. Compared with the Rya Station-VMAT plan, the HDRS-VMAT plan also yielded significantly lower NBT dose exposures (V23 Gy, V21 Gy, V18 Gy, V12 Gy and D mean) but at the cost of increased MUs (3659.16 ± 1225.28 vs. 2536.23 ± 785.80, ρ<0.001). The difference in BOTs was minimal (<1 min), which was not considered clinically significant. Furthermore, the HDRS-VMAT exhibited a higher gamma passing rate across all criteria (ρ<0.001), particularly under stricter criteria (2%/1 mm), achieving an approximately 3% increase. Conclusion: Compared with Ray Station-VMAT, HDRS-VMAT offers superior target conformity, better NBT sparing, and higher delivery accuracy while maintaining comparable delivery efficiency. This represents a promising approach for HSRT of multiple BMs