Deng Wei, Younkin James E, Souris Kevin, Huang Sheng, Augustine Kurt, Fatyga Mirek, Ding Xiaoning, Cohilis Marie, Bues Martin, Shan Jie, Stoker Joshua, Lin Liyong, Shen Jiajian, Liu Wei
Department of Radiation Oncology, Mayo Clinic, Phoenix, AZ, 85054, USA.
Center for Molecular Imaging and Experimental Radiotherapy, Institut de Recherche Expérimentale et Clinique, Université catholique de Louvain, 1200, Brussels, Belgium.
Med Phys. 2020 Jun;47(6):2558-2574. doi: 10.1002/mp.14125. Epub 2020 Apr 13.
To commission an open source Monte Carlo (MC) dose engine, "MCsquare" for a synchrotron-based proton machine, integrate it into our in-house C++-based I/O user interface and our web-based software platform, expand its functionalities, and improve calculation efficiency for intensity-modulated proton therapy (IMPT).
We commissioned MCsquare using a double Gaussian beam model based on in-air lateral profiles, integrated depth dose of 97 beam energies, and measurements of various spread-out Bragg peaks (SOBPs). Then we integrated MCsquare into our C++-based dose calculation code and web-based second check platform "DOSeCHECK." We validated the commissioned MCsquare based on 12 different patient geometries and compared the dose calculation with a well-benchmarked GPU-accelerated MC (gMC) dose engine. We further improved the MCsquare efficiency by employing the computed tomography (CT) resampling approach. We also expanded its functionality by adding a linear energy transfer (LET)-related model-dependent biological dose calculation.
Differences between MCsquare calculations and SOBP measurements were <2.5% (<1.5% for ~85% of measurements) in water. The dose distributions calculated using MCsquare agreed well with the results calculated using gMC in patient geometries. The average 3D gamma analysis (2%/2 mm) passing rates comparing MCsquare and gMC calculations in the 12 patient geometries were 98.0 ± 1.0%. The computation time to calculate one IMPT plan in patients' geometries using an inexpensive CPU workstation (Intel Xeon E5-2680 2.50 GHz) was 2.3 ± 1.8 min after the variable resolution technique was adopted. All calculations except for one craniospinal patient were finished within 3.5 min.
MCsquare was successfully commissioned for a synchrotron-based proton beam therapy delivery system and integrated into our web-based second check platform. After adopting CT resampling and implementing LET model-dependent biological dose calculation capabilities, MCsquare will be sufficiently efficient and powerful to achieve Monte Carlo-based and LET-guided robust optimization in IMPT, which will be done in the future studies.
为基于同步加速器的质子治疗设备启用开源蒙特卡罗（MC）剂量引擎“MCsquare”，将其集成到我们基于C++的输入/输出用户界面和基于网络的软件平台中，扩展其功能，并提高调强质子治疗（IMPT）的计算效率。
我们基于空气中的横向轮廓、97种射束能量的深度剂量积分以及各种扩展布拉格峰（SOBP）的测量结果，使用双高斯射束模型启用了MCsquare。然后，我们将MCsquare集成到我们基于C++的剂量计算代码和基于网络的二次检查平台“DOSeCHECK”中。我们基于12种不同的患者几何结构验证了启用后的MCsquare，并将剂量计算结果与经过充分验证的GPU加速MC（gMC）剂量引擎进行了比较。我们通过采用计算机断层扫描（CT）重采样方法进一步提高了MCsquare的效率。我们还通过添加与线性能量传递（LET）相关的模型依赖生物剂量计算来扩展其功能。
在水中，MCsquare计算结果与SOBP测量结果之间的差异小于2.5%（约85%的测量结果差异小于1.5%）。在患者几何结构中，使用MCsquare计算的剂量分布与使用gMC计算的结果吻合良好。在12种患者几何结构中，比较MCsquare和gMC计算结果的平均3D伽马分析（2%/2毫米）通过率为98.0±1.0%。采用可变分辨率技术后，使用廉价的CPU工作站（英特尔至强E5-2680 2.50 GHz）计算一个患者几何结构的IMPT计划的计算时间为2.3±1.8分钟。除一名全脊髓患者外，所有计算均在3.5分钟内完成。
MCsquare已成功应用于基于同步加速器的质子束治疗系统，并集成到我们基于网络的二次检查平台中。采用CT重采样并实现LET模型依赖生物剂量计算功能后，MCsquare将足够高效和强大，能够在IMPT中实现基于蒙特卡罗和LET引导的稳健优化，这将在未来的研究中进行。
