Institute of Clinical Research, University of Southern Denmark, Odense, Denmark.
Radiother Oncol. 2010 May;95(2):142-8. doi: 10.1016/j.radonc.2010.01.011. Epub 2010 Feb 24.
The quality of Volumetric Modulated Arc Therapy (VMAT) plans is highly dependent on the performance of the optimization algorithm used. Recently new algorithms have become available which are capable of generating VMAT plans for Elekta accelerators. The VMAT algorithm in Pinnacle is named SmartArc and its capability to generate treatment plans for head and neck cancer was tested.
Twenty-five patients with oropharyngeal or hypopharyngeal carcinoma, previously treated with IMRT by means of Pinnacle and Elekta accelerators, were replanned with single arc VMAT. The VMAT planning objectives were to achieve clinical target coverage and sparing of the organs at risk (OAR). Comparison with the original clinically used IMRT was made by evaluating (1) dose-volume histograms (DVHs) for PTVs, (2) DVHs for OARs, (3) delivery time and monitor units (MU), and (4) treatment accuracy.
Equivalent or superior target coverage and sparing of OARs were achieved with VMAT compared to IMRT. Volumes in the healthy tissues receiving between 17.3 Gy and 49.4 Gy were significantly reduced and the conformity (CI(95%)) of the elective PTV was improved from 1.7 with IMRT to 1.6 with VMAT. Compared to step-and-shoot IMRT, VMAT reduced the number of MUs by 8.5% to 460+/-63 MUs per fraction, and delivered on an Elekta Synergy accelerator, the treatment time was on average reduced by 35% to 241 +/- 16s. In Delta4 measurements of the VMAT treatments, 99.6 +/- 0.5% of the detector points passed a 3 mm and 3% gamma criterion, identical to the results of IMRT.
The target coverages obtained in the IMRT and VMAT plans were found to be very similar. SmartArc generated single arc VMAT plans with equivalent or better target coverage and sparing of OARs compared to IMRT, while both delivery time and MUs were decreased. Very good dose accuracy results were obtained delivering the plans on an Elekta accelerator.
容积旋转调强放疗（VMAT）计划的质量高度依赖于所使用的优化算法的性能。最近，出现了一些新的算法，这些算法能够为 Elekta 加速器生成 VMAT 计划。Pinnacle 中的 VMAT 算法称为 SmartArc，对其生成头颈部癌症治疗计划的能力进行了测试。
25 例口咽或下咽癌患者，之前曾接受 Pinnacle 和 Elekta 加速器的调强放疗，采用单弧 VMAT 进行再计划。VMAT 计划的目标是实现临床靶区覆盖和危及器官（OAR）的保护。通过评估（1）PTV 的剂量-体积直方图（DVH）、（2）OAR 的 DVH、（3）治疗时间和 monitor units（MU）以及（4）治疗准确性，对原始的临床使用的调强放疗进行比较。
与调强放疗相比，VMAT 实现了等效或更好的靶区覆盖和 OAR 保护。接受 17.3Gy 至 49.4Gy 之间的健康组织体积显著减少，选择性 PTV 的适形性（CI（95%））从调强放疗的 1.7 提高到 VMAT 的 1.6。与步进-射击调强放疗相比，VMAT 减少了 8.5%的 MU 数，每个部分为 460+/-63MU，在 Elekta Synergy 加速器上治疗，平均治疗时间减少了 35%至 241 +/- 16s。在 VMAT 治疗的 Delta4 测量中，99.6 +/- 0.5%的探测器点通过了 3mm 和 3%伽马标准，与调强放疗的结果相同。
IMRT 和 VMAT 计划中获得的靶区覆盖率非常相似。与调强放疗相比，SmartArc 生成的单弧 VMAT 计划具有等效或更好的靶区覆盖和 OAR 保护，同时减少了治疗时间和 MU。在 Elekta 加速器上输送计划时，获得了非常好的剂量准确性结果。
