【作者】 宋钢；

【导师】 邓小玖；

【作者基本信息】 合肥工业大学 ， 课程与教学论， 2005， 硕士

【摘要】 放射治疗(简称放疗)是肿瘤治疗最重要的手段之一,治疗计划系统(TPS)是供放疗医生和放疗物理师设计治疗方案并对治疗方案的效果进行事前验证的软件系统。剂量计算是TPS系统中最重要的组成部分之一,快速精确的剂量计算对肿瘤放疗效果有着很大的影响,目前正向和逆向计划系统都需要快速精确的剂量计算工具。 RBM(Regular Beam Model)是一种基于测量数据库的解析剂量计算方法,可以用来计算三维纯水箱中的剂量分布信息;Batho系列组织非均匀性修正方法可以根据病人的医学影像数据计算出修正因子,将三维水箱的剂量分布修正为人体中的剂量分布。 在本文中,分别编程实现了基于Batho修正、基于改进Batho修正的RBM剂量计算方法。在纯水箱算例和水肺水模型算例的基础上,以蒙特卡罗三维粒子输运计算程序EGS4的计算结果为参考标准,对上述两种剂量计算方法的结果进行了验证,并在综合了Batho和改进Batho两种方法优点的基础上,提出并程序实现了一种基于混合Batho修正的RBM剂量计算方法,该方法在没有增加计算时间的前提下所得计算结果精度较上述两种方法的精度有较大提高,更加接近于EGS4的计算结果。因此,本文中提出的基于混合Batho修正的RBM剂量计算方法可以快速且较为精确地计算出人体内的剂量分布信息,具有很强的临床适用性,可以满足常用的放疗手段对于剂量计算精度和速度的要求。 虽然基于混合Batho修正的RBM剂量计算方法可以在均匀组织和小块非均匀组织区域取得较好的计算精度,但在真实病例中大块非均匀组织区域和空腔区域仍然存在较大误差。因此,将基于混合Batho修正的RBM剂量计算方法与Monte—Carlo方法相结合,是下一步工作的方向之一。更多还原

【Abstract】 Radiotherapy is one of the most important means to treat tumours. Treatment Planning System (TPS) is a software tool, with which radiotherapy doctors and radiotherapy physicists can design and optimize the treatment plan before dose delivery. Now both the routine and inverse planning systems need fast and accurate dose calculation tools. The aim of this work is to improve the performance of the Regular Beam Model (RBM) method to meet the clinical requirement.RBM (Regular Beam Model) dose engine is a kind of analytical method based on the measured database, which can calculate the dose distribution of the 3-D water box. With the Batho inhomogeneity correction, RBM can be used to evaluate the dose distribution of the patient based on the medical images like CT images.In this work, the RBM dose engine is programmed with the Batho and the Modified Batho inhomogeneity correction methods, respectively. In the pure water and water-lung-water examples, the above two engines are tested and compared with the result of the EGS4 code. In addition, a mixed Batho correction scheme is proposed and implemented in the RBM program. The test results demonstrate that this engine can improve the precision without increasement of the calculation time. Because the mixed Batho based RBM can calculate the dose distribution with high speed and accuracy, and can satisfy the clinical requirement for velocity and precision, it can be used as a reliable dose calculation tool for clinical utilization.In addition, the results show that in the area which is near to large inhomogeneity and air region, considerable discrepancy appears. In the future work, the coupling method of RBM and Monte-Carlo will be investigated to handle this problem.更多还原