调强放疗射束方向最优化计算中解空间和体元尺寸的影响  

Effect of the Size of Solution Space and the Size of Voxels in Beam Orientation Optimization of IMRT

作　　者：王彬冰 [1] 唐志全 [2] 汪俊 [1] 陈炳周 [1] 侯氢 [1] 

机构地区：[1]四川大学,原子核科学技术研究所辐射物理及技术教育部重点实验室,四川,成都 610064 [2]华西医院,放疗科,四川,成都,610041

出　　处：《中国医学物理学杂志》2005年第5期625-629,共5页Chinese Journal of Medical Physics

基　　金：国家自然科学基金，高等学校优秀青年教师教学科研奖励计划

摘　　要：调强放射治疗中射束方向最优化是个比较困难的问题,主要是计算时间长.为提高计算效率,可预设一些候选射束射束,然后进行组合优化.解空间的大小由候选射束的数目确定.用遗传算法实现组合优化用,对于每个射束组合,用模拟动力学进行强度分布优化,考察了候选射束数时最优化结果的影响,发现候选射束较多的情况下,用较少的遗传叠代数就可最优解.同时还考察了优化计算中体元尺寸对优化结果的影响,发现采用较粗的体元尺寸(0.4×0.4×0.4 cm3),也不会对最优化结果产生明显影响.这些结论可以用于提高射束方向最优化的计算效率.The orientation optimization in IMRT is a difficult problem due to its intensive computer time consumed.The computational efficiency could be improved by preselling a set of candidate beams and performing combination optimizations. The size of the solution space is determined by the number of the candidates. Using the genetic algorithm for the combination optimization and the simulated dynamics for the intensity profile optimization of given beam combinations, the effects of the number of candidates on the final dose distributions and the computational efficiency were studied. It was found that the genetic algorithm could converge in less generation if larger number of candidates were used. The effect of the size of voxels involved in the optimization was also studied. It was observed that using relatively coarse voxels （0.4×0.4×0.4 cm^3） did not induce obvious influence on the final resuhs. These observations could be useful in accelerating the orientation optimization process in IMRT..

关 键 词：调强放疗 方向最优化 遗传算法 模拟动力学方法 

分 类 号：R817.5[医药卫生—影像医学与核医学] O571.33[医药卫生—放射医学]