In proton therapy, the width of a pristine Bragg peak is too narrow to cover the entire tumor volume, and should be spread out using the Spread out Bragg peak (SOBP) techniques such as energy stacking, range modulator wheel and ridge filter. The main purpose of this study was to demonstrate feasibility of using a simple least square technique to decompose the simulated weight fractions of elemental Bragg peaks of ridge filters used in a clinical wobbling beam nozzle. First, initial simulated beam parameters including mean energy and energy spread at the nozzle entrance for all available clinical energies were commissioned against measurements for the open middle wobbling field at the Proton and Radiation Center of the Linkou Chang Gung Memorial Hospital (LCGMH) using the Particle Therapy Simulation Framework (PTSim) Monte Carlo package. Material composition and geometry of nozzle components were provided by the vendor. Depth dose distribution of beam energies from 70 to 230 MeV at 20-MeV increment were simulated and validated with measurement. Curve fitting to those beam parameters was performed to extend simulation energy range to all available clinical energies. For the reconstructed ridge filter simulation, elemental Bragg peaks (BPs) with layer filters corresponding to ridge filter step thicknesses were obtained as bases of the weight factor decomposition. The least square technique was implemented to decompose weight factors for individual ridge filter at a selected beam energy within its applicable energy range. Finally, the reconstructed ridge filters using decomposed weight factors were tested at one other energy to validate the study design. Four different ridge filters (5 cm-LE, 5 cm-HE, 10 cm and 11 cm SOBP) were examined in this study. Commission results for tuned beam parameter settings showed maximum disagreement of BP characteristics, represented by the 80% dose depth (R_80d) and width of distal fall-off (W_80-20), occurred at 230 MeV and was smaller than 0.2 and 0.5 mm respectively. Furthermore, analyzed outcome for SOBPs from the four ridge filters revealed general improvement of agreement to measurement with decomposition and satisfactory agreement between measurements and those with least square technique. Deviation from measurement of SOBP characteristics evaluated for R_90d, W_80-20 and SOBP flatness after weight decomposition showed values smaller than 1mm/1%. Similar evaluation of SOBP width generated larger difference with maximum value of 2.7 mm for the 11-cm ridge filter. Results of the validation testes were similar with maximum deviation of 1.4 mm, 0.6 mm, 0.2% and 3.8 mm for R_90d, W_80-20, flatness and width respectively.

在质子治疗中，原始布拉格峰的宽度太窄而无法覆盖整个肿瘤体积，应使用扩散布拉格峰 (SOBP) 技术（如能量堆叠、范围调制轮和脊形滤波器）进行扩散。本研究的主要目的是证明使用简单的最小二乘技术分解临床摆动光束喷嘴中使用的脊形过滤器的元素布拉格峰的模拟重量分数的可行性。首先，使用 Particle 对林口长庚纪念医院 (LCGMH) 质子与放射中心 (LCGMH) 的开放式中间摆动场进行测量，委托初始模拟光束参数，包括所有可用临床能量的喷嘴入口处的平均能量和能量扩散。治疗模拟框架 (PTSim) 蒙特卡罗包。喷嘴组件的材料成分和几何形状由供应商提供。以 20-MeV 的增量模拟和验证从 70 到 230 MeV 的光束能量的深度剂量分布。对这些光束参数进行曲线拟合，以将模拟能量范围扩展到所有可用的临床能量。对于重建的脊滤波器模拟，获得具有对应于脊滤波器步长厚度的层滤波器的元素布拉格峰 (BP) 作为权重因子分解的基础。实施最小二乘技术以在其适用的能量范围内以选定的光束能量分解单个脊形滤波器的权重因子。最后，使用分解的权重因子重建的脊形滤波器在另一种能量下进行测试，以验证研究设计。本研究检查了四种不同的脊形过滤器（5 cm-LE、5 cm-HE、10 cm 和 11 cm SOBP）。调谐光束参数设置的委员会结果显示 BP 特征的最大分歧，以 80% 剂量深度 (R_80d ) 和远端下降宽度 (W _80-20 )，发生在 230 MeV，分别小于 0.2 和 0.5 mm。此外，四个脊形过滤器对 SOBP 的分析结果显示，通过分解和测量与最小二乘技术的测量之间的一致性得到普遍改善。_{对于R 90d}、W _80-20和重量分解后的SOBP平整度评价的SOBP特性测量值的偏差显示小于1mm/1％的值。对 SOBP 宽度的类似评估产生了较大的差异，对于 11 厘米脊形过滤器，最大值为 2.7 毫米。_{验证测试的结果相似，R 90d}的最大偏差分别为 1.4 mm、0.6 mm、0.2% 和 3.8 mm, W _80-20 , 平面度和宽度分别。