Department of Radiation Oncology, Medical University of Vienna/AKH, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria.
Department of Radiation Oncology, Medical University of Vienna/AKH, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria.
Phys Med. 2020 Jun;74:155-165. doi: 10.1016/j.ejmp.2020.04.027. Epub 2020 May 29.
Magnetic resonance guidance in particle therapy has the potential to improve the current performance of clinical workflows. However, the presence of magnetic fields challenges the current algorithms for treatment planning. To ensure proper dose calculations, compensation methods are required to guarantee that the maximum deposited energy of deflected beams lies in the target volume. In addition, proper modifications of the intrinsic dose calculation engines, accounting for magnetic fields, are needed. In this work, an algorithm for proton treatment planning in magnetic fields was implemented in a research treatment planning system (TPS), matRad. Setup-specific look up tables were generated using a validated MC model for a clinical proton beamline (62.4 - 215.7 MeV) interacting with a dipole magnet (B = 0-1 T). The algorithm was successfully benchmarked against MC simulations in water, showing gamma index (2%/2mm) global pass rates higher than 96% for different plan configurations. Additionally, absorbed depth doses were compared with experimental measurements in water. Differences within 2% and 3.5% in the Bragg peak and entrance regions, respectively, were found. Finally, treatment plans were generated and optimized for magnetic field strengths of 0 and 1 T to assess the performance of the proposed model. Equivalent treatment plans and dose volume histograms were achieved, independently of the magnetic field strength. Differences lower than 1.5% for plan quality indicators (D, D, D, V and V) in water, a TG119 phantom and an exemplary prostate patient case were obtained. More complex treatment planning studies are foreseen to establish the limits of applicability of the proposed model.
磁共振引导在粒子治疗中具有提高临床工作流程当前性能的潜力。然而，磁场的存在挑战了当前的治疗计划算法。为了确保正确的剂量计算，需要补偿方法来保证偏转束的最大沉积能量位于靶区。此外，还需要对固有剂量计算引擎进行适当的修改，以考虑磁场的影响。在这项工作中，在研究治疗计划系统（TPS）matRad 中实现了用于磁场中的质子治疗计划的算法。使用经过验证的 MC 模型为临床质子束线（62.4-215.7 MeV）与偶极磁铁（B=0-1 T）相互作用生成了特定设置的查找表。该算法在水中与 MC 模拟成功进行了基准测试，对于不同的计划配置，伽马指数（2%/2mm）全局通过率高于 96%。此外，还将吸收深度剂量与水中的实验测量结果进行了比较。在布喇格峰和入口区域分别发现了 2%和 3.5%以内的差异。最后，生成并优化了磁场强度为 0 和 1 T 的治疗计划，以评估所提出模型的性能。在水中、TG119 体模和一个示例前列腺患者病例中，独立于磁场强度，实现了等效的治疗计划和剂量体积直方图。在水中、TG119 体模和一个示例前列腺患者病例中，获得了计划质量指标（D、D、D、V 和 V）差异低于 1.5%的结果。预计将进行更复杂的治疗计划研究，以确定所提出模型的适用范围。
