物理图书馆对电子支臂疗法的剂量影响蒙特卡罗研究
Christian Valdes-Cortez1, Iymad Mansour2,3, David Santiago Ayala Alvarez4
1Nuclear Medicine Department, Hospital Regional de Antofagasta, Antofagasta, Chile.
Medical physics
|February 26, 2025
概括
电子支臂疗法 (eBT) 的蒙特卡洛模拟显示在模拟制辐射相互作用方面存在显著差异. 这些差异影响了剂量计算,强调了对物理模型进行进一步研究的需要,以获得准确的剂量测量.
科学领域:
- 医学物理 医学物理
- 计算剂量计计算剂量计.
- 辐射瘤学 辐射瘤学
背景情况:
- 电子支臂疗法 (eBT) 中的低能X射线束由于的深度剂量梯度和探测器材料依赖性,造成了剂量测量方面的挑战.
- 精确的eBT剂量测量需要蒙特卡罗 (MC) 模拟,但物理模型的变化引发了对一致性的担忧,特别是对于制动辐射.
- 制动辐射相互作用的MC建模中的差异可能会影响eBT中剂量计算的可靠性.
研究的目的:
- 评估不同物理方法在最先进的eBTMC系统中的剂量计影响.
- 调查各种MC方法所产生的分歧,以模拟EBT的制动辐射相互作用.
主要方法:
- 对比了Axxent S700,Esteya和INTRABEAMeBT系统的两个EGSnrc应用程序TOPAS和PENELOPE-2018 (PEN18). 这两种应用程序都适用于Axxent S700,Esteya和INTRABEAMeBT系统.
- 使用简化的X射线管模型 (传输/反射目标,材料,厚度,SSD) 并与详细的INTRABEAM应用器模型进行验证.
- 在EGSnrc和PEN18中检查了制动辐射角辐射方法,以及TOPAS中的两个物理清单 (g4em-livermore,g4em-penelope).
主要成果:
- 在传输方式中观察到的显著差异:PEN18显示了比EGSnrc/TOPASliv低15%的bremsstrahlung流动性;深度剂量比EGSnrc/TOPASliv低9%
- 在传输模式下TOPASpen与PEN18相比,由于补偿的光谱差异 (bremsstrahlung与特征) 产生了1%的深度剂量差异.
- 在反射模式下,EGSnrc/PEN18在光谱成分方面达成4%的一致;TOPASpen显示了更大的光谱变化,但与PEN18相比,降低了深度剂量差异到3%左右.
结论:
- 在eBT中模拟制动辐射时,领先的MC系统 (EGSnrc,TOPAS,PENELOPE-2018) 之间存在相当大的分歧.
- 差异与制动辐射角分布和原子放松过程有关,特别是在传输目标模式中.
- 进一步的理论和实验研究对于验证MC模型和确保准确的eBT剂量测量至关重要.
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