Université de Strasbourg, IPHC, 23 rue du Loess, 67037 Strasbourg, France; CNRS, UMR7178, 67037 Strasbourg, France.
Division of Medical Physics, Department of Radiotherapy, Paul Strauss Center, Strasbourg, France.
Phys Med. 2019 May;61:112-117. doi: 10.1016/j.ejmp.2019.04.012. Epub 2019 Apr 26.
The accuracy of superficial dose calculations for breast cancer treatments with Volumetric Modulated Arc Therapy (VMAT) is of major importance. For target volumes close to the surface, the inverse dosimetric planning can lead to very high fluences in the build-up region to properly cover the volume to be treated. Various radiotherapy modalities are currently used in parallel with additional protocols to enable a better control on the dose delivery (bolus, target volume margins). One of the difficulties currently facing medical physicists is the lack of available tools to test the impact of these different solutions on the superficial dose distribution. We present a new open source toolkit to assist medical physicists in evaluating the 3D distributions of superficial dose in VMAT breast cancer treatments. This tool is based on the GATE Monte Carlo software, a Geant4 application dedicated to medical physics. A set of macros has been developed to simulate in an easy way a full VMAT plan from the information available in the DICOM-RT files (image, plan, structure and dose). The toolkit has been tested on a 6 MV Varian NovalisTx™ accelerator. The paper presents a precise comparison of 3D surface dose distributions from experimental measurements (EBT3 films), TPS (Varian Eclipse) and Monte Carlo simulation (GATE). The comparison made it possible to highlight both the TPS biases for the surface dose calculation and the good performances of the developed toolkit. The simulation of surface dose distributions on a real patient has also been performed to illustrate the potential clinical applications.
体部调强弧形治疗（VMAT）乳腺癌治疗中表面剂量计算的准确性非常重要。对于接近表面的靶区，反剂量规划可能会导致在建成区产生非常高的通量，以适当地覆盖要治疗的体积。目前有各种放射治疗方式与附加方案同时使用，以更好地控制剂量输送（敷贴器、靶区边界）。目前，医学物理学家面临的一个难题是缺乏可用的工具来测试这些不同解决方案对表面剂量分布的影响。我们提出了一种新的开源工具包，以帮助医学物理学家评估 VMAT 乳腺癌治疗中表面剂量的 3D 分布。该工具基于 GATE 蒙特卡罗软件，这是一款专门用于医学物理的 Geant4 应用程序。开发了一组宏，以便能够轻松地从 DICOM-RT 文件（图像、计划、结构和剂量）中的信息模拟完整的 VMAT 计划。该工具包已在 6 MV 瓦里安 NovalisTx™加速器上进行了测试。本文对来自实验测量（EBT3 胶片）、TPS（瓦里安 Eclipse）和蒙特卡罗模拟（GATE）的 3D 表面剂量分布进行了精确比较。该比较突出了 TPS 在表面剂量计算中的偏差以及开发的工具包的良好性能。还对真实患者的表面剂量分布进行了模拟，以说明潜在的临床应用。
