摘要
本文应用蒙特卡罗算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的射束分布。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过程,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。通过比较6MV光子束3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。通过对不规则野剂量分布的计算和测量结果的等剂量线进行比较,在90%和50%等剂量区吻合较好,在10%低剂量区稍有差异。本文提出的光子虚拟源模型能够较为精确地模拟计算任意形状和强度的外照射放射治疗射束分布。
A photon virtual source model was developed for simulating arbitrary shape and intensity distributions of external beam using Monte Carlo method. The source model consists of a photon fluence grid that is composed of a matrix of square elements, and is located 20 cm underneath the linear accelerator target. The fluence map is reconstructed from fluence and energy spectra acquired by modeling the transmission process in the components of the linear accelerator treatment head using the Monte Carlo code BEAMnrc. Depth dose and profile calculation results for three standard square fields are in good agreement with the measurement results for 6 MV photon beam. The compar- ison between irregular field dose calculation result and film measurement result shows that good agreement is observed in 90% and 50% isodose regions; however, difference is noted in 10% region. The proposed photon virtual source model is suitable for accurately simulating arbitrary shape and intensity distributions of external beam.
出处
《仪器仪表学报》
EI
CAS
CSCD
北大核心
2007年第4期699-702,共4页
Chinese Journal of Scientific Instrument
基金
广东省科技计划(2005B30301017)资助项目
关键词
放射治疗
剂量计算
蒙特卡罗
radiotherapy
dose calculation
Monte Carlo