Abdoli Mohammad Amin, Hassanvand Maryam, Nejatbakhsh Navid
Department of Physics, Isfahan University of Technology, Isfahan, Iran.
Knowledge-based Company Behyaar Sanaat Sepahan, Isfahan, Iran.
J Med Signals Sens. 2024 Aug 6;14:22. doi: 10.4103/jmss.jmss_54_22. eCollection 2024.
Monte Carlo (MC) techniques are regarded as an accurate method to simulate the dose calculation in radiotherapy for many years. The present paper aims to validate the simulated model of the 6-MV beam of OMID linear accelerator (BEHYAAR Company) by EGSnrc codes system and also investigate the effects of initial electron beam parameters (energy, radial full width at half maximum, and mean angular spread) on dose distributions. For this purpose, the comparison between the calculated and measured percentage depth dose (PDD) and lateral dose profiles was done by gamma index (GI) with 1%-1 mm acceptance criteria. MC model validating was done for 3 cm × 3 cm, 5 cm × 5 cm, 8 cm × 8 cm, 10 cm × 10 cm, and 20 cm × 20 cm field sizes. To study the sensitivity of model to beam parameters, the field size was selected as 10 cm × 10 cm and 30 cm × 30 cm. All lateral dose profiles were obtained at 10 cm. Excellent agreement was achieved with a 99.2% GI passing percentage for PDD curves and at least 93.8% GI for lateral dose profiles for investigated field sizes. Our investigation confirmed that the lateral dose profile severely depends on the considered source parameters in this study. PDD only considerably depends on the initial electron beam energy. Therefore, source parameters should not be specified independently. These results indicate that the current model of OMID 6-MV Linac is well established, and the accuracy of the simulation is high enough to be used in various applications.
多年来，蒙特卡罗（MC）技术一直被视为模拟放射治疗中剂量计算的一种精确方法。本文旨在通过EGSnrc代码系统验证OMID直线加速器（BEHYAAR公司）6兆伏射线束的模拟模型，并研究初始电子束参数（能量、径向半高宽和平均角展度）对剂量分布的影响。为此，通过伽马指数（GI）以1%-1毫米的验收标准对计算得到的和测量得到的百分深度剂量（PDD）及侧向剂量分布进行了比较。对3厘米×3厘米、5厘米×5厘米、8厘米×8厘米、10厘米×10厘米和20厘米×20厘米的射野尺寸进行了MC模型验证。为了研究模型对射束参数的敏感性，选择的射野尺寸为10厘米×10厘米和30厘米×30厘米。所有侧向剂量分布均在10厘米处获得。对于PDD曲线，GI通过率达到99.2%，对于所研究的射野尺寸，侧向剂量分布的GI至少为93.8%，取得了极佳的一致性。我们的研究证实，侧向剂量分布在很大程度上取决于本研究中所考虑的源参数。PDD仅在很大程度上取决于初始电子束能量。因此，源参数不应独立指定。这些结果表明，当前的OMID 6兆伏直线加速器模型已得到很好的确立，模拟精度足够高，可用于各种应用。
