Balaji Subramanian Sitaraman, Balaji Karunakaran, Thirunavukarasu Moorthi, Premkumar Sumana
Department of Radiation Oncology, Global Hospitals, Chennai.
Cureus. 2016 Dec 5;8(12):e914. doi: 10.7759/cureus.914.
The purpose of this planning case report is to share the perceived dosimetric benefits of innovative hybrid volumetric modulated arc therapy (h-VMAT) for bilateral breast cancer radiotherapy in two patients with synchronous bilateral breast cancer. Two patients with early bilateral breast cancer after breast conservation surgery and adjuvant chemotherapy were planned for bilateral breast radiotherapy. On the planning computed tomography (CT) dataset, bilateral breast planning treatment volume (PTV) and organs at risk (OARs) were delineated using standard guidelines. Using the same structure set, volumetric modulated arc therapy (VMAT) and h-VMAT plans were generated and compared dosimetrically. The h-VMAT showed comparable target coverage, conformity and homogeneity while sparing of both lungs and heart were better. The dose to heart was reduced with h-VMAT, with a V and V of 3.2 & 22.3% for h-VMAT versus 11.6 & 84.9% for the VMAT plan. Similarly, the dose to the total lung was better in h-VMAT with a V and V of 12.1 & 46.2 versus 19.9 & 83.3% for VMAT. Overall the results indicate a better sparing of lung and heart at low doses with h-VMAT. Long-term clinical follow-up will give us more insight about the dosimetric benefits of these innovative techniques.
本计划病例报告的目的是分享创新型混合容积调强弧形放疗（h-VMAT）对两名同步双侧乳腺癌患者进行双侧乳腺癌放疗时所带来的剂量学益处。两名保乳手术后并接受辅助化疗的早期双侧乳腺癌患者计划接受双侧乳腺放疗。在计划计算机断层扫描（CT）数据集上，使用标准指南勾勒双侧乳腺计划治疗体积（PTV）和危及器官（OARs）。使用相同的结构集，生成容积调强弧形放疗（VMAT）和h-VMAT计划，并进行剂量学比较。h-VMAT显示出可比的靶区覆盖、适形性和均匀性，同时对双肺和心脏的保护更好。h-VMAT降低了心脏剂量，h-VMAT的V和V分别为3.2%和22.3%，而VMAT计划分别为11.6%和84.9%。同样，h-VMAT对全肺的剂量更好，h-VMAT的V和V分别为12.1%和46.2%，而VMAT分别为19.9%和83.3%。总体而言，结果表明h-VMAT在低剂量时对肺和心脏的保护更好。长期临床随访将使我们对这些创新技术的剂量学益处有更深入的了解。
