加速器百分深度剂量蒙特卡罗模拟计算准确性研究

Study on accurateness of percentage depth dose with Monte Carlo simulation algorithm

目的 比较蒙特卡罗模拟计算与实际测量的百分深度剂量差异。 方法 利用模拟加速器机头的蒙特卡罗算法BEAMnrc软件模拟西门子PRIUMS直线加速器6 MV X线,利用DOSXYZnrc程序生成百分深度剂量。实际测量西门子加速器百分深度剂量由PTW公司生产的MP3三维水箱采集得到。计算两种方法不同深度下百分深度剂量偏差[（测量值－模拟计算值）/测量值×100%]。结果 离水面距离〈1.2 cm时偏差〉2%,离水面距离〉1.2 cm时偏差〈2%。结论 在建成区深度内由蒙特卡罗模拟计算的百分深度剂量更为准确。

Objective To study the percentage depth dose difference （PDD） between Monte Carlo method and the measurement method. Methods Based on the detail treatment head structure designing by the manufacture, the BEAMnrc Monte Carlo code was used to simulate the 6 MV photon beams of a Siemens Primus linear accelerator. DOSXYZnrc program generated 6 MV X-ray parameters such as PDD, and it was measured by MP3 three-dimensional water of PTW corporation phantom. The deviation of PDD was calculated using formulas （（measured value-simulation algorithm value）/measured value×100%）. Results Distance from the surface of the water was less than 1.2 cm, the deviation of PDD was〉2%. Distance from the surface greater than 1.2 cm, the deviation of PDD was〈2%. Conclusion In the built-up areas, PDD obtained by the Monte Carlo simulation algorithm is more accurate.