Wang He, Yang Jinzhong, Lee Anna, Phan Jack, Lim Tze Yee, Fuller Clifton D, Han Eun Young, Rhee Dong Joo, Salzillo Travis, Zhao Yao, Chopra Nitish, Pham Mary, Castillo Pam, Sobremonte Angela, Moreno Amy C, Reddy Jay P, Rosenthal David, Garden Adam S, Wang Xin
Department of Radiation Physics, MD Anderson Cancer Center, Houston, TX, USA.
Department of Radiation Oncology, MD Anderson Cancer Center, Houston, TX, USA.
Clin Transl Radiat Oncol. 2024 Mar 7;46:100760. doi: 10.1016/j.ctro.2024.100760. eCollection 2024 May.
MR-guided radiotherapy (MRgRT) has the advantage of utilizing high soft tissue contrast imaging to track daily changes in target and critical organs throughout the entire radiation treatment course. Head and neck (HN) stereotactic body radiation therapy (SBRT) has been increasingly used to treat localized lesions within a shorter timeframe. The purpose of this study is to examine the dosimetric difference between the step-and-shot intensity modulated radiation therapy (IMRT) plans on Elekta Unity and our clinical volumetric modulated arc therapy (VMAT) plans on Varian TrueBeam for HN SBRT.
Fourteen patients treated on TrueBeam sTx with VMAT treatment plans were re-planned in the Monaco treatment planning system for Elekta Unity MR-Linac (MRL). The plan qualities, including target coverage, conformity, homogeneity, nearby critical organ doses, gradient index and low dose bath volume, were compared between VMAT and Monaco IMRT plans. Additionally, we evaluated the Unity adaptive plans of adapt-to-position (ATP) and adapt-to-shape (ATS) workflows using simulated setup errors for five patients and assessed the outcomes of our treated patients.
Monaco IMRT plans achieved comparable results to VMAT plans in terms of target coverage, uniformity and homogeneity, with slightly higher target maximum and mean doses. The critical organ doses in Monaco IMRT plans all met clinical goals; however, the mean doses and low dose bath volumes were higher than in VMAT plans. The adaptive plans demonstrated that the ATP workflow may result in degraded target coverage and OAR doses for HN SBRT, while the ATS workflow can maintain the plan quality.
The use of Monaco treatment planning and online adaptation can achieve dosimetric results comparable to VMAT plans, with the additional benefits of real-time tracking of target volume and nearby critical structures. This offers the potential to treat aggressive and variable tumors in HN SBRT and improve local control and treatment toxicity.
磁共振引导放疗（MRgRT）的优势在于利用高软组织对比度成像来跟踪整个放射治疗过程中靶区和关键器官的每日变化。头颈部（HN）立体定向体部放疗（SBRT）已越来越多地用于在更短时间内治疗局限性病变。本研究的目的是检查Elekta Unity上的步进和射野强度调制放疗（IMRT）计划与我们在Varian TrueBeam上用于HN SBRT的临床容积调强弧形放疗（VMAT）计划之间的剂量学差异。
对14例采用TrueBeam sTx的VMAT治疗计划进行治疗的患者，在Monaco治疗计划系统中为Elekta Unity MR直线加速器（MRL）重新制定计划。比较了VMAT和Monaco IMRT计划之间的计划质量，包括靶区覆盖、适形性、均匀性、附近关键器官剂量、梯度指数和低剂量浴体积。此外，我们使用五名患者的模拟设置误差评估了适应位置（ATP）和适应形状（ATS）工作流程的Unity自适应计划，并评估了我们治疗患者的结果。
Monaco IMRT计划在靶区覆盖、均匀性和同质性方面与VMAT计划取得了可比的结果，靶区最大剂量和平均剂量略高。Monaco IMRT计划中的关键器官剂量均达到临床目标；然而，平均剂量和低剂量浴体积高于VMAT计划。自适应计划表明，ATP工作流程可能会导致HN SBRT的靶区覆盖和危及器官剂量下降，而ATS工作流程可以维持计划质量。
使用Monaco治疗计划和在线自适应可以实现与VMAT计划相当的剂量学结果，同时还具有实时跟踪靶区体积和附近关键结构的额外优势。这为治疗HN SBRT中的侵袭性和可变肿瘤以及改善局部控制和治疗毒性提供了潜力。
