Department of Radiation Oncology, Hiroshima University Hospital, Japan.
Department of Radiation Oncology, Hiroshima University Hospital, Japan.
Phys Med. 2018 Oct;54:34-41. doi: 10.1016/j.ejmp.2018.09.010. Epub 2018 Sep 27.
In volumetric-modulated arc therapy (VMAT), field configurations such as couch or arc angles are defined manually or using a template. A field configuration is reselected through trial-and-error in the case of undesirable resultant planning. To efficiently plan for desirable quality, configurations should be assessed before dose calculation. Design of experiments (DoE) is an optimization technique that efficiently reveals the influence of inputs on outputs. We developed an original tool using DoE to determine the field configuration selection and evaluated the efficacy of this workflow for clinical practice.
Computed-tomography scans of 17 patients and target structures were acquired retrospectively from a brain tumor treated using a dual-arc VMAT plan. The configurations of the couch, arc, collimator angles, field sizes, and beam energy were determined using DoE. The resultant dose distributions obtained using the DoE-selected configuration were compared with the clinical plan.
The averaged differences between the DoE and clinical plan for 17 patients of doses to 50% of the planning target volume (PTV-D50%), Brain-D60%, Brain-D30%, Brain stem-D1%, Left eye-D1%, Right eye-D1%, Optic nerve-D1%, and Chiasm-D1% were 0.2 ± 0.5%, -1.0 ± 4.6%, 1.7 ± 3.5%, -2.5 ± 6.7%, -0.2 ± 4.9%, -1.2 ± 3.6%, -2.8 ± 7.3%, and -2.1 ± 5.7%, respectively.
Our optimization workflow obtained using DoE for various field configurations provided the same or slightly superior plan quality compared with that created by experts. This process is feasible for clinical practice and will efficiently improve treatment quality while removing the influence of the planner's experience.
在容积旋转调强放疗（VMAT）中，床面或旋转角度等射野参数通常由手动或模板定义。在计划结果不理想的情况下，需要通过反复尝试来重新选择射野参数。为了高效地制定理想的治疗计划，在剂量计算之前应评估射野参数。实验设计（DoE）是一种优化技术，可高效地揭示输入对输出的影响。我们开发了一种原始工具，使用 DoE 来确定射野参数选择，并评估该工作流程在临床实践中的效果。
回顾性地获取了 17 例接受双弧 VMAT 计划治疗的脑肿瘤患者的计算机断层扫描（CT）图像和靶区结构。使用 DoE 确定床面、旋转角度、准直器角度、射野大小和射束能量的参数配置。将使用 DoE 选择的配置获得的剂量分布与临床计划进行比较。
17 例患者的计划靶区（PTV）50%等剂量线（PTV-D50%）、脑 60%等剂量线（Brain-D60%）、脑 30%等剂量线（Brain-D30%）、脑干 1%等剂量线（Brain stem-D1%）、左眼 1%等剂量线（Left eye-D1%）、右眼 1%等剂量线（Right eye-D1%）、视神经 1%等剂量线（Optic nerve-D1%）和视交叉 1%等剂量线（Chiasm-D1%）的剂量，DoE 组与临床计划组之间的平均差异分别为 0.2±0.5%、-1.0±4.6%、1.7±3.5%、-2.5±6.7%、-0.2±4.9%、-1.2±3.6%、-2.8±7.3%和-2.1±5.7%。
与专家制定的计划相比，我们使用 DoE 为各种射野参数配置优化得到的计划在质量上相同或略有提高。该过程可用于临床实践，将高效地提高治疗质量，同时消除规划师经验的影响。
