Moon Young Min, Jeon Wan, Yu Tosol, Bae Sang Il, Kim Jin Young, Kang Jin-Kyu, Choi Chul Won
Department of Radiation Oncology, Dongnam Institute of Radiological and Medical Science, Busan, South Korea.
Front Oncol. 2020 Jul 29;10:1170. doi: 10.3389/fonc.2020.01170. eCollection 2020.
Stereotactic body radiotherapy (SBRT) is currently well-adopted as a curative treatment for primary and metastatic liver tumors. Among SBRT methods, dynamic conformal arc therapy (DCAT) and volumetric-modulated arc therapy (VMAT) are the most preferred methods. In this study, we report a comparison study measuring the dose distribution and delivery efficiency differences between DCAT and VMAT for liver SBRT. All patients who were treated with SBRT for primary or metastatic liver tumors with a curative aim between January 2016 and December 2017 at DIRAMS were enrolled in the study. For all patients, SBRT plans were designed using the Monte Carlo (MC) algorithm in Monaco treatment planning system (version 5.1). The planning goals were set according to the RTOG 0813, RTOG 0915, and RTOG 1112 protocols. A plan comparison was made on the metrics of dose volume histogram, planning and delivery efficiency, monitor unit (MU), and dosimetric indices. PTV coverage was evaluated using the following: D, D95%, D98%, D2%, D50%, D, V95%, heterogeneity index (HI), and conformality index (CI). For DCAT and VMAT, respectively, the D was 5942.8 ± 409.3 cGy and 5890.6 ± 438.8 cGy, D50% was 5968.8 ± 413.1 cGy and 5954.3 ± 405.2 cGy, and CI was 1.05 ± 0.05 and 1.03 ± 0.04. The D98% and V95% were 5580.0 ± 465.3 cGy and 20.4 ± 12.0 mL for DCAT, and 5596.0 ± 478.7 cGy and 20.5 ± 12.0 mL for VMAT, respectively. For normal liver, V40, V30, V20, V17, V5, D, D were evaluated for comparison. The V30, V20, and V10 were significantly higher in DCAT; other parameters of normal livers showed no statistically significant differences. For evaluation of intermediate dose spillage, D2(%) and R50% of DCAT and VMAT were 45.8 ± 7.9 and 5.6 ± 0.9 and 45.1 ± 6.7 and 5.5 ± 1.2, respectively. Planning and delivery efficiency were evaluated using MU, Calculation time, and Delivery time. DCAT had shorter Calculation time and Delivery time with smaller MU. MU was smaller in DCAT and the average difference was 300.1 MU. For liver SBRT, DCAT is an effective alternative to VMAT plans that could meet the planning goals proposed by the RTOG SBRT protocol and increases plan and delivery effectiveness, while also ignoring the interplay effect.
立体定向体部放射治疗（SBRT）目前已被广泛应用于原发性和转移性肝肿瘤的根治性治疗。在SBRT方法中，动态适形弧形放疗（DCAT）和容积调强弧形放疗（VMAT）是最常用的方法。在本研究中，我们报告了一项比较研究，测量DCAT和VMAT在肝脏SBRT中的剂量分布和照射效率差异。2016年1月至2017年12月期间在DIRAMS接受以根治为目的的原发性或转移性肝肿瘤SBRT治疗的所有患者均纳入本研究。对于所有患者，在Monaco治疗计划系统（版本5.1）中使用蒙特卡罗（MC）算法设计SBRT计划。根据RTOG 0813、RTOG 0915和RTOG 1112方案设定计划目标。对剂量体积直方图、计划和照射效率、监测单位（MU）和剂量学指标进行计划比较。使用以下指标评估计划靶体积（PTV）覆盖情况：D、D95%、D98%、D2%、D50%、D、V95%、不均匀性指数（HI）和适形指数（CI）。DCAT和VMAT的D分别为5942.8±409.3 cGy和5890.6±438.8 cGy，D50%分别为5968.8±413.1 cGy和5954.3±405.2 cGy，CI分别为1.05±0.05和1.03±0.04。DCAT的D98%和V95%分别为5580.0±465.3 cGy和20.4±12.0 mL，VMAT的分别为5596.0±478.7 cGy和20.5±12.0 mL。对于正常肝脏，评估V40、V30、V20、V17、V5、D、D进行比较。DCAT的V30、V20和V10显著更高；正常肝脏的其他参数无统计学显著差异。为评估中间剂量溢出，DCAT和VMAT的D2（%）和R50%分别为45.8±7.9和5.6±0.9以及45.1±6.7和5.5±1.2。使用MU、计算时间和照射时间评估计划和照射效率。DCAT的计算时间和照射时间较短，MU较小。DCAT的MU较小，平均差异为300.1 MU。对于肝脏SBRT，DCAT是VMAT计划的有效替代方案，可满足RTOG SBRT方案提出的计划目标，提高计划和照射效果，同时忽略相互作用效应。
