Abstract

In radiotherapy applications, Monte Carlo (MC) simulation for dose calculations is well acknowledged for its accuracy in predicting dose deposition in the patient. The full modeling of a high-energy photon beam from Varian Clinac 2100C 18 MV medical linear accelerator is presented here by using the GATE/GEANT4 Monte Carlo codes. To evaluate dose distributions associated with the simulated linac head model, dosimetric quantities including the Percentage Depth Dose (PDD), transverse dose profiles, and a set of beam-quality indicators were measured and calculated in a water phantom for square field sizes of \(4\times 4\) cm\({}^{2}\) and \(10\times 10\) cm\({}^{2}\). Simulations accuracy was validated through Gamma Index analysis using different acceptance criteria within 2\(\%/\)2 mm, 3\(\%/\)2 mm, 2\(\%/\)3 mm, and 3\(\%/\)3 mm. In terms of Gamma Index comparison, good agreements were found between the calculated and measured dose distributions for all field sizes. The differences between simulation and measurement of beam quality indicators were smaller than 2\(\%\).

中文翻译：

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使用GATE / GEANT4对18 MV医用直线加速器光子束的蒙特卡罗模拟

摘要

在放射治疗应用中，用于剂量计算的蒙特卡洛（MC）模拟因其在预测患者体内剂量沉积方面的准确性而广为人知。本文通过使用GATE / GEANT4蒙特卡洛代码对Varian Clinac 2100C 18 MV医用线性加速器的高能光子束进行了完整建模。为了评估与模拟直线加速器头部模型相关的剂量分布，在水模型中测量并计算了剂量百分比，包括剂量深度剂量（PDD），横向剂量分布图和一组光束质量指示剂，以用于\（ 4 \乘4 \）厘米\（{} ^ {2} \）和\（10乘10 \）厘米\（{} ^ {2} \）。通过使用2毫米（\％/ \） 2毫米，3毫米（\％/） 2毫米，2毫米（\％/） 3毫米和3毫米（3）（ \％/ \） 3毫米。在伽玛指数比较方面，对于所有领域的尺寸，在计算和测量的剂量分布之间都找到了很好的一致性。光束质量指标的仿真与测量之间的差异小于2 \（\％\）。