School of Biomedical Engineering, Southern Medical University, Guangzhou, Guangdong, China.
Department of Radiation Oncology, Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou, Guangdong, China.
Med Phys. 2023 Apr;50(4):2429-2437. doi: 10.1002/mp.16077. Epub 2022 Nov 17.
To propose a novel magnetic field dose calculation method based on transformation from pencil beam (PB) to Monte Carlo (MC) distribution for MRI-Linac online treatment planning.
The novel magnetic field dose calculation algorithm was established by a PB dose engine and a magnetic field with tissue inhomogeneity influence correction network. The correction network was constructed with a Res-UNet framework, including residual modules and an encoding-decoding path, by inputting three-dimensional PB dose and patient electron density map, and outputting transformed dose distribution. The influences of magnetic fields and tissue heterogeneity were considered and corrected simultaneously in the correction model. A total of 110 clinically treated static beam IMRT plans were collected, including plans for brain, head-and-neck, lung, and rectum cases. A total of 90 cases were used and enhanced to train and validate the model, and the other 20 cases were for test. By comparing the proposed pipeline-generated dose distribution with original input PB dose and corresponding MC dose, the feasibility and effectiveness of the method was evaluated.
Results on both beam dose and plan dose accuracy comparisons on all investigated four tumor sites show great consistency between the cross-dose-engine transformation generations and the MC results, with averaged plan mean absolute error of 0.90% ± 0.13% for the voxel-wise dose difference and 98.33% ± 1.07% gamma passing rate at the 2%/2 mm criteria. The whole PB calculation and transformation process can be completed within second.
We have successfully developed a fast novel magnetic field dose calculation pipeline based on transformation from PB distribution to MC distribution for MRI-Linac online treatment planning.
提出一种新的基于笔束（PB）到蒙特卡罗（MC）分布转换的磁场剂量计算方法，用于 MRI-Linac 在线治疗计划。
新的磁场剂量计算算法是通过 PB 剂量引擎和具有组织不均匀性影响校正网络建立的。校正网络采用 Res-UNet 框架构建，包括残差模块和编码-解码路径，通过输入三维 PB 剂量和患者电子密度图，输出转换后的剂量分布。在校正模型中同时考虑和校正磁场和组织不均匀性的影响。共收集了 110 例临床治疗的静态束调强放疗计划，包括脑、头颈部、肺和直肠病例。其中 90 例用于训练和验证模型，另外 20 例用于测试。通过比较提出的流水线生成的剂量分布与原始输入 PB 剂量和相应的 MC 剂量，评估了该方法的可行性和有效性。
在所有四个肿瘤部位的束剂量和计划剂量准确性比较中，交叉剂量引擎转换生成的结果与 MC 结果非常一致，平均每个体素的剂量差异的计划平均绝对误差为 0.90%±0.13%，2%/2mm 标准的伽马通过率为 98.33%±1.07%。整个 PB 计算和转换过程可以在秒内完成。
我们成功地开发了一种新的快速基于笔束分布到 MC 分布转换的磁场剂量计算管道，用于 MRI-Linac 在线治疗计划。
