人体与加速器的蒙特卡罗计算建模关键技术研究及应用

发布时间：2018-03-06 10:26

本文选题：蒙特卡罗　切入点：耦合建模　出处：《中国科学技术大学》2015年博士论文　论文类型：学位论文

【摘要】：放射治疗是临床上治疗肿瘤的三大手段之一,剂量计算是放射治疗计划设计与验证的核心技术。基于蒙特卡罗的剂量计算方法被公认为最精确的放射治疗剂量计算方法,而是否能够建立高精度的加速器装置和人体模型是决定剂量计算精度的关键因素之一。基于上述问题本文深入研究了蒙特卡罗模拟放疗计划过程中涉及的加速器治疗头的建模、多叶光栅建模、人体模型建模和加速器装置与人体模型的耦合建模等一系列关键问题。主要的创新点如下： 1、发展了基于直线加速器治疗头CAD模型的精确蒙特卡罗建模方法,实现加速器工程模型到蒙卡模型的转换,为放疗计划模拟提供了真实的射束源。基于该方法建立了某国产加速器治疗头的精确模型,模拟了6MeV加速器的光子射束,通过纯水模例题计算与实测值进行对比,数据一致性验证了所建立的加速器模型的正确性。 2、发展了一种能够模拟多叶光栅(MLC)精细结构的精确建模方法,解决适形或调强放疗计划中复杂限束装置的精确建模的困难问题。参数化的建模界面可以建立MLC特有的弧形端面、舌状和凹槽结构、侧面聚焦于加速器源点的叶片,精细地模拟了MLC叶片的机械几何构造,解决手工建模的复杂性问题。通过纯水模例题计算与实测值的对比,验证了MLC建模的正确性。 3、基于层次化建模思想,发展了加速器治疗头、MLC和人体模型的耦合建模方法,实现了放射治疗射束与人体剂量的整体输运的模拟。通过模拟真实的放疗计划例题与EGSnrc的计算结果进行对比测试,结果的一致性证明了耦合方法的准确性。
[Abstract]:Radiation therapy is one of the three major methods in the treatment of tumor. Dose calculation is the core technology in the design and verification of radiotherapy plan. The dose calculation method based on Monte Carlo is recognized as the most accurate dose calculation method for radiotherapy. Whether it is possible to establish high precision accelerator and human model is one of the key factors to determine the accuracy of dose calculation. Based on the above problems, the modeling of accelerator therapeutic head involved in Monte Carlo simulated radiotherapy planning is studied in depth. A series of key issues, such as multileaf grating modeling, mannequin modeling and coupling modeling between accelerator and human body model, are discussed. The main innovations are as follows:. 1. An accurate Monte Carlo modeling method based on the CAD model of the linear accelerator head is developed to realize the conversion from the accelerator engineering model to the Monka model. Based on this method, an accurate model of the treatment head of a domestic accelerator is established, and the photon beam of the 6MeV accelerator is simulated. The calculated results are compared with the measured values by the example of pure water model. The data consistency verifies the correctness of the accelerator model. 2. An accurate modeling method which can simulate the fine structure of multileaf grating is developed to solve the difficult problem of accurate modeling of complex beam limiting devices in conformal or intensity modulated radiation planning. The structure of tongue and grooves, with the side focusing on the blade of the source point of the accelerator, is used to simulate the mechanical geometry of the MLC blade in detail and to solve the complexity problem of manual modeling. The correctness of MLC modeling is verified. 3. Based on the idea of hierarchical modeling, the coupling modeling method between MLC and human model is developed. The simulation of the whole transport of radiation beam and human dose is realized. The accuracy of the coupled method is proved by comparing the simulated real radiotherapy plan with the calculated results of EGSnrc.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：R730.55

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