Improved efficiency in Monte Carlo simulation for passive-scattering proton therapy.
Improved efficiency in Monte Carlo simulation for passive-scattering proton therapy.
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DOI：
10.1088/0031-9155/60/13/5019
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发表时间：
2015-07-07
影响因子：
3.5
通讯作者：
Faddegon B
中科院分区：
文献类型：
--
作者：
Méndez JR;Perl J;Schümann J;Shin J;Paganetti H;Faddegon B
这项工作的目的是提高通过质子治疗头跟踪质子时蒙特卡罗模拟的计算效率。考虑了两个质子治疗设施，即马萨诸塞州总医院的弗朗西斯·H·伯尔质子治疗中心 (FHBPTC) 和加州大学旧金山分校 (UCSFETF) 使用的克罗克实验室眼科治疗设施。对在治疗头出口处评分的相空间文件的计算效率进行评估，以确定最佳参数以提高效率，同时保持剂量计算的准确性。对于 FHBPTC，粒子在第二个散射体上游和孔径上游被分裂为 8 倍。俄罗斯轮盘赌区域的半径设置为孔径半径的 2.5 或 1.5 倍，并应用 50 毫米的二次颗粒生产切割 (PC)。对于 UCSFETF，颗粒在吸水柱上游和孔径上游被分裂为 16 倍。此处，俄罗斯轮盘赌区域的半径设置为孔径半径的 4 倍，并应用 0.05 mm 的 PC。在这两种设置中，都利用质子束的圆柱对称性来定位围绕束轴随机间隔的分裂粒子。当为后续水模型模拟相空间时，FHTPC 设置的效率增益为 19.9±0.1 至 52.21±0.04，UCSFETF 设置的效率增益为 57.3±0.5。对于用作患者几何形状模拟输入的相空间 (PHSP)，增益为 78.6±7.5 倍。水中的横向剂量曲线在可接受的临床耐受性 2% 范围内，两个机构的统计不确定性为 0.5%。对于患者几何形状，并考虑 2% 和 2mm 标准，98.4% 的体素显示伽马指数低于统一。对剂量分布的分析导致 20% 的体素的系统偏差低于 0.88%，剂量为最大剂量的 20% 或更高。
The aim of this work was to improve the computational efficiency of Monte Carlo simulations when tracking protons through a proton therapy treatment head. Two proton therapy facilities were considered, the Francis H Burr Proton Therapy Center (FHBPTC) at the Massachusetts General Hospital and the Crocker Lab eye treatment facility used by University of California at San Francisco (UCSFETF). The computational efficiency was evaluated for phase space files scored at the exit of the treatment head to determine optimal parameters to improve efficiency while maintaining accuracy in the dose calculation. For FHBPTC, particles were split by a factor of 8 upstream of the second scatterer and upstream of the aperture. The radius of the region for Russian roulette was set to 2.5 or 1.5 times the radius of the aperture and a secondary particle production cut (PC) of 50 mm was applied. For UCSFETF, particles were split a factor of 16 upstream of a water absorber column and upstream of the aperture. Here, the radius of the region for Russian roulette was set to 4 times the radius of the aperture and a PC of 0.05 mm was applied. In both setups, the cylindrical symmetry of the proton beam was exploited to position the split particles randomly spaced around the beam axis. When simulating a phase space for subsequent water phantom simulations, efficiency gains between a factor of 19.9±0.1 and 52.21±0.04 for the FHTPC setups and 57.3±0.5 for the UCSFETF setups were obtained. For a phase space (PHSP) used as input for simulations in a patient geometry, the gain was a factor of 78.6±7.5. Lateral-dose curves in water were within the accepted clinical tolerance of 2%, with statistical uncertainties of 0.5% for the two facilities. For the patient geometry and by considering the 2% and 2mm criteria, 98.4% of the voxels showed a gamma index lower than unity. An analysis of the dose distribution resulted in systematic deviations below of 0.88% for 20% of the voxels with dose of 20% of the maximum or more.
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影响因子：
3.8
作者：
Ma, CM;Mok, E;Boyer, AL
通讯作者：
Boyer, AL
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作者：
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Fragoso, Margarida;Kawrakow, Iwan;Chetty, Indrin J.
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