Rezzoug Mohammed, Zerfaoui Mustapha, Oulhouq Yassine, Rrhioua Abdeslem, Hamzaoui Omar, Bakari Dikra
Laboratory of Theoretical Physics, Particles, Modeling and Energy (LPTPME), Faculty of Sciences, University Mohamed 1st, Boulevard Mohamed VI, BP 717, 60000, Oujda, Morocco.
Department of Radiation Oncology, Hassan II Oncology Centre, Mohammed VI University Hospital, Oujda, Morocco.
Phys Eng Sci Med. 2025 Sep 18. doi: 10.1007/s13246-025-01641-y.
Electron beam radiotherapy is a crucial modality for treating superficial tumors. Accurate dose calculation is essential for treatment efficacy and minimizing side effects. While Monte Carlo (MC) simulations are considered the gold standard for dose calculation, their computational cost can be prohibitive. The electron Monte Carlo (eMC) algorithm offers a faster alternative, but its accuracy, especially in heterogeneous environments, remains a concern.
This study compares electron beam dose distributions calculated using the eMC algorithm in a treatment planning system (TPS) with those obtained from full MC simulations using the GATE platform. We evaluated the eMC algorithm's performance across various electron energies (6, 9, and 12 MeV) and field sizes (6 × 6 cm to 20 × 20 cm), in both homogeneous water phantoms and heterogeneous phantoms incorporating lung-equivalent and bone-equivalent materials.
Results in homogeneous phantoms demonstrated generally good agreement between eMC and GATE, with some discrepancies observed in penumbra regions and at higher energies, particularly for larger field sizes. In heterogeneous phantoms, significant deviations were observed, particularly in lateral dose profiles near density interfaces and at higher beam energies, with percentage of points with less than 3% difference dropping considerably.
These findings highlight the limitations of the eMC algorithm in accurately modeling complex tissue heterogeneities. While eMC provides acceptable accuracy in relatively simple scenarios, its performance degrades significantly in clinically realistic heterogeneous environments, necessitating caution in treatment planning and highlighting the ongoing need for improved dose calculation algorithms.
电子束放射治疗是治疗浅表肿瘤的关键方式。精确的剂量计算对于治疗效果和将副作用降至最低至关重要。虽然蒙特卡罗（MC）模拟被认为是剂量计算的金标准，但其计算成本可能过高。电子蒙特卡罗（eMC）算法提供了一种更快的替代方法，但其准确性，尤其是在异质环境中的准确性，仍然令人担忧。
本研究将治疗计划系统（TPS）中使用eMC算法计算的电子束剂量分布与使用GATE平台进行的全MC模拟获得的剂量分布进行了比较。我们在均匀水模体以及包含肺等效材料和骨等效材料的异质模体中，评估了eMC算法在各种电子能量（6、9和12 MeV）和射野尺寸（6×6 cm至20×20 cm）下的性能。
均匀模体中的结果表明，eMC和GATE之间总体上具有良好的一致性，但在半影区域和较高能量下观察到一些差异，特别是对于较大的射野尺寸。在异质模体中，观察到显著偏差，特别是在密度界面附近的侧向剂量分布和较高射束能量下，差异小于3%的点的百分比大幅下降。
这些发现突出了eMC算法在精确模拟复杂组织异质性方面的局限性。虽然eMC在相对简单的情况下提供了可接受的准确性，但其在临床实际的异质环境中的性能显著下降这一情况，在治疗计划中需要谨慎对待，并突出了对改进剂量计算算法的持续需求。
