Department of Radiation Oncology, University of Jena, Jena, Germany.
Radiat Oncol. 2011 Feb 21;6:20. doi: 10.1186/1748-717X-6-20.
Recent developments enable to deliver rotational IMRT with standard C-arm gantry based linear accelerators. This upcoming treatment technique was benchmarked in a multi-center treatment planning study against static gantry IMRT and rotational IMRT based on a ring gantry for a complex parotid gland sparing head-and-neck technique.
Treatment plans were created for 10 patients with head-and-neck tumours (oropharynx, hypopharynx, larynx) using the following treatment planning systems (TPS) for rotational IMRT: Monaco (ELEKTA VMAT solution), Eclipse (Varian RapidArc solution) and HiArt for the helical tomotherapy (Tomotherapy). Planning of static gantry IMRT was performed with KonRad, Pinnacle and Panther DAO based on step&shoot IMRT delivery and Eclipse for sliding window IMRT. The prescribed doses for the high dose PTVs were 65.1Gy or 60.9Gy and for the low dose PTVs 55.8Gy or 52.5Gy dependend on resection status. Plan evaluation was based on target coverage, conformity and homogeneity, DVHs of OARs and the volume of normal tissue receiving more than 5Gy (V5Gy). Additionally, the cumulative monitor units (MUs) and treatment times of the different technologies were compared. All evaluation parameters were averaged over all 10 patients for each technique and planning modality.
Depending on IMRT technique and TPS, the mean CI values of all patients ranged from 1.17 to 2.82; and mean HI values varied from 0.05 to 0.10. The mean values of the median doses of the spared parotid were 26.5Gy for RapidArc and 23Gy for VMAT, 14.1Gy for Tomo. For fixed gantry techniques 21Gy was achieved for step&shoot+KonRad, 17.0Gy for step&shoot+Panther DAO, 23.3Gy for step&shoot+Pinnacle and 18.6Gy for sliding window.V5Gy values were lowest for the sliding window IMRT technique (3499 ccm) and largest for RapidArc (5480 ccm). The lowest mean MU value of 408 was achieved by Panther DAO, compared to 1140 for sliding window IMRT.
All IMRT delivery technologies with their associated TPS provide plans with satisfying target coverage while at the same time respecting the defined OAR criteria. Sliding window IMRT, RapidArc and Tomo techniques resulted in better target dose homogeneity compared to VMAT and step&shoot IMRT. Rotational IMRT based on C-arm linacs and Tomotherapy seem to be advantageous with respect to OAR sparing and treatment delivery efficiency, at the cost of higher dose delivered to normal tissues. The overall treatment plan quality using Tomo seems to be better than the other TPS technology combinations.
最近的发展使基于标准 C 臂旋转机架的线性加速器能够提供旋转调强放疗（IMRT）。这项即将推出的治疗技术在一项多中心治疗计划研究中与静态旋转机架 IMRT 和基于环形机架的旋转机架 IMRT 进行了基准测试，用于复杂的腮腺保护头颈部技术。
使用以下治疗计划系统（TPS）为 10 名头颈部肿瘤（口咽、下咽、喉）患者创建旋转调强放疗计划：Monaco（ELEKTA VMAT 解决方案）、Eclipse（Varian RapidArc 解决方案）和用于螺旋断层放疗（Tomotherapy）的 HiArt。静态旋转机架 IMRT 的计划由基于步进和射击 IMRT 传递的 KonRad、Pinnacle 和 Panther DAO 以及用于滑动窗口 IMRT 的 Eclipse 进行。高剂量 PTV 的规定剂量为 65.1Gy 或 60.9Gy，低剂量 PTV 的规定剂量为 55.8Gy 或 52.5Gy，具体取决于切除状态。计划评估基于靶区覆盖、适形度和均匀性、OAR 的剂量体积直方图（DVHs）以及接受超过 5Gy（V5Gy）的正常组织体积。此外，还比较了不同技术的累积监测单位（MU）和治疗时间。对于每种技术和计划方式，所有评估参数均在所有 10 名患者中平均计算。
根据 IMRT 技术和 TPS，所有患者的平均一致性指数（CI）值范围为 1.17 至 2.82；平均不均匀性指数（HI）值范围为 0.05 至 0.10。 spared parotid 中位数剂量的平均值为 RapidArc 为 26.5Gy，VMAT 为 23Gy，Tomo 为 14.1Gy。对于固定机架技术，step&shoot+KonRad 达到 21Gy，step&shoot+Panther DAO 达到 17.0Gy，step&shoot+Pinnacle 达到 23.3Gy，滑动窗口达到 18.6Gy。V5Gy 值最低的是滑动窗口 IMRT 技术（3499 ccm），最高的是 RapidArc（5480 ccm）。MU 值最低的是 Panther DAO，为 408，而滑动窗口 IMRT 为 1140。
所有具有相关 TPS 的调强放疗输送技术都提供了令人满意的靶区覆盖的计划，同时符合定义的 OAR 标准。与 VMAT 和步进和射击 IMRT 相比，滑动窗口 IMRT、RapidArc 和 Tomo 技术可实现更好的靶区剂量均匀性。基于 C 臂旋转机架和 Tomotherapy 的旋转机架 IMRT 在保护 OAR 和治疗效率方面似乎具有优势，但正常组织的剂量更高。使用 Tomo 的整体治疗计划质量似乎优于其他 TPS 技术组合。
