蒙特卡罗方法在放疗计划中的应用

Application of Monte Carlo techniques in radiation treatment planning

本文就蒙特卡罗方法在放射外科治疗计划中的应用做了初步的研究和分析。首先利用Beam程序模拟了Varian公司Clinac2100C6MVX射线加速器治疗头,得到源皮距为100cm、射野大小为5cm×5cm的开放野治疗平面上的粒子相–空间信息,并与文献进行了比较。然后把粒子相–空间信息作为输入,利用Dosxyz程序计算了体模中吸收剂量的空间分布,并与一基于解析剂量计算方法的商用治疗计划软件的结果进行了比较,两种结果基本一致。另外,本文还重点介绍了由患者的医学CT图像建立蒙特卡罗输运几何的方法和过程。

Application of Monte Carlo techniques in radiation treatment planning is described in the paper. The Monte Carlo code BEAM is used to model Varian Clinic 6 MV X-ray treatment head and also a CT based HEAD phantom is simulated with DOSXYZ code using the BEAM output phase space data as the incident radiation source. Results of the simulations are presented, and compared with the Off-Axis Ratio （OAR） based method with tissue-air ratio algorithm for inhomogeneity corrections in photon beam dose calculations. The isodose lines and the cumulative dose-volume histogram of the TARGET in the two kinds of methods are in good accordance, with just slight deviation in some regions. In addition, the method of how to build a Monte Carlo geometry from the CT images of a patient is discussed in the paper.