School of Advanced Sciences, Vellore Institute of Technology, Vellore, Tamil Nadu, 632014, India.
Department of Radiation Oncology, Gleneagles Global Hospitals, Chennai, India.
Radiol Med. 2019 Jun;124(6):546-554. doi: 10.1007/s11547-019-00994-1. Epub 2019 Jan 30.
To find an optimal arc design for hybrid volumetric modulated arc therapy (H-VMAT), a combination of conventional 3DCRT and VMAT plans for left-sided whole breast radiation therapy.
A total of 26 left-sided early-stage breast cancer patients were selected for this study. To find the superior plan, H-VMAT with three different arc designs including, two partial arcs (2A), four partial arcs (4A) and four tangential arcs (TA) were created for each study case by combining 3DCRT and VMAT with 75% 3DCRT/25% VMAT dose proportion of prescription dose.
All H-VMAT plans achieved the expected target coverage. A higher conformity index and homogeneity index were achieved for 2A and 4A H-VMAT plans and significantly differ from TA H-VMAT (p < 0.003). The heart and ipsilateral lung dose parameters were comparable among all plans except heart V which was significantly less in 4A H-VMAT plan (p < 0.05). The contralateral lung, contralateral breast, spinal cord, normal tissue doses and MU were significantly less in TA H-VMAT (p < 0.03). The beam-on time was significantly less in 2A H-VMAT (p < 0.0001).
2A and 4A H-VMAT techniques are effective in improving the PTV dosimetric parameters as well as reducing the OAR doses. Further, 2A H-VMAT delivers less MU and beam-on time compared to 4A H-VMAT.
为了找到一种最佳的混合容积调强弧形治疗（H-VMAT）的弧形设计，这是一种将传统的 3DCRT 和 VMAT 计划相结合的左半全乳放疗方法。
本研究共选择了 26 例左侧早期乳腺癌患者。为了找到更好的方案，我们为每个研究病例通过结合 3DCRT 和 VMAT，用 75%的 3DCRT/25%的 VMAT 剂量比例来创建三种不同的弧形设计，包括两个部分弧形（2A）、四个部分弧形（4A）和四个切线弧形（TA）的 H-VMAT。
所有 H-VMAT 计划都达到了预期的靶区覆盖要求。2A 和 4A H-VMAT 计划的适形指数和均匀性指数更高，与 TA H-VMAT 相比有显著差异（p<0.003）。除了 4A H-VMAT 计划中的心脏 V 显著更低（p<0.05）外，所有计划中心脏和同侧肺剂量参数都相当。对侧肺、对侧乳房、脊髓、正常组织剂量和 MU 均显著减少，TA H-VMAT 计划的 MU 减少更为明显（p<0.03）。2A H-VMAT 的照射时间显著减少（p<0.0001）。
2A 和 4A H-VMAT 技术可有效改善 PTV 剂量学参数，同时降低 OAR 剂量。此外，与 4A H-VMAT 相比，2A H-VMAT 的 MU 和照射时间更少。
