Dosimetric comparison of HyperArc, conventional noncoplanar VMAT, and Halcyon-based coplanar VMAT in
Zhen Li1, Xin Yang2, Huaqu Zeng3
1Department of Oncology Radiotherapy, Zhongshan City People's Hospital, Zhongshan, Guangdong, 528400, China.
Abstract:
To assess the dosimetric characteristics of HyperArc (HA), noncoplanar VMAT (NC-plan), and coplanar VMAT (HL3arc) in hippocampal-sparing whole-brain radiotherapy (WBRT). Twenty patients undergoing WBRT at our Hospital from June 2021 to March 2023 were selected. The dose parameters of organs at risk (OARs) were evaluated for all three groups, including D100%, Dmax, and Dmean of hippocampus, Dmax to the lens, eyes, optic nerves, and chiasm, Dmean to the scalp and upper neck, and the dose volume parameters V5Gy, V10Gy, V15Gy, V20Gy for the upper neck. The D98%, V28.5Gy, D2%, HI, CI, GI for PTV, as well as planning time, and beam-on time. HA had the lowest hippocampal Dmax and Dmean. HA's scalp Dmean was lower than HL3arc (p = 0.007). HA's upper neck region Dmean and V5-20Gy(cm3) were significantly higher than NC-VMAT and HL3arc. For PTV, HA's D98 and V28.5Gy were higher than NC-VMAT and HL3arc (p < 0.05). HA exhibited a significant advantage in terms of HI, CI and GI. The average planning times were 84.67, 17.30, and 20.40 minutes. Among the three treatment approaches, HA demonstrated the lowest bilateral hippocampal doses, but it exhibited the highest average dose and low-dose volume in the upper neck region, with the longest planning optimization process.
