摘要
目的:基于蒙特卡罗方法建立了一个光子虚拟源模型,用于模拟计算任意形状和强度的外照射放射治疗射束的剂量分布.方法:建立的源模型包含一个由方形网格元素组成的光子通量矩阵,定位于距离加速器靶下方20cm处.通过使用蒙特卡罗模拟代码包BEAMnrc,模拟粒子加速器治疗头各部件中的传输,获得源模型所在平面的光子通量和能谱分布,并进行重构,以反映物理射束经过加速器射束成形部件后所引起的形状改变.结果:通过比较6MV光子束三个标准方野的深度剂量和离轴比分布的计算结果和测量结果,取得了较好的吻合.通过比较不规则野剂量分布的计算和测量结果的等剂量线,在90%和50%等剂量区吻合较好,在10%低剂量区稍有差异.结论:我们建立的光子虚拟源模型能够较为精确的模拟计算任意形状和强度的外照射放射治疗射束分布.
AIM: To develop a photon virtual source model for simulating arbitrary, external beam, and calculating intensity distributions using Monte Carlo method. METHODS: The source model consisted of a photon fluence grid composed of a matrix of square elements, located 20-cm downstream from the linear accelerator target. The fluence map was reconstructed from fluence and energy spectra acquired by modeling components of the linear accelerator treatment head using the Monte Carlo code BEAMnrc. RESULTS: Depth dose and profile source calculations for 6-MV photon beams, for 3 standard square field sizes, were in good agreement with measurement. Irregular field calculations compared with film measurement showed that good agreement was observed in the 90% , and 50% isodose regions, however, differences were noted in the 10% region. CONCLUSION: The photon virtual source model is suitable of accurately simulating arbitrary, external beam, and calculating intensity distributions.
出处
《第四军医大学学报》
北大核心
2006年第21期2002-2004,共3页
Journal of the Fourth Military Medical University
基金
广东省科技攻关(2002C30204)
关键词
放射疗法
剂量计算
蒙特卡罗
radiotherapy
dose calculation
Monte Carlo