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目的:建立一种基于危机器官避让原理(Organ at Risk Avoidance Theory)及混合整数线性法(Mixed Integer LinearProgramming(MILP))的射野方向自动优选算法,并用于三源调强治疗装置提供的非共面射野池(Non-coplanar BeamsPool)的射野方向的优选。方法:(1)利用基于危机器官避让原理的自编程序从已知非共面射野池中初选出30个较优射野;(2)利用MILP程序LPSolve IDE对初选出的30个射野进行调强优化,筛选出预先设定的射野方向数组合,同时计算出射野强度分布;(3)对前列腺癌和鼻咽癌病例,对比分析了相同射野数的共面均分角射野计划和经射野方向优化的计划的DVH图,剂量分布图及危机器官平均剂量。结果:射野方向自动优选算法能够有效的筛选出临床所需要的射野方向数组合,得到相应的调强治疗计划,靶区剂量相同的情况下,危机器官所受剂量显著减少。结论:我们提出的自动优化非共面射野方向的算法可以很好的用于已知射野方向池(如三源调强治疗装置)的射野方向优选和射野强度优化问题。
OBJECTIVE: To establish an automatic radiometric direction selection algorithm based on Organ at Risk Avoidance Theory and Mixed Integer Linear Programming (MILP) Non-coplanar BeamsPool in the field direction of the preferred. Methods: (1) Thirty candidate fields were preliminarily selected from known non-coplanar field-pool based on the self-programming program based on the principle of avoidance of crisis organs. (2) The MILP program LPSolve IDE was used to select the first 30 shots Field intensity optimization, screening out a predetermined combination of radiation field direction number, and calculate the intensity distribution of the radiation field; (3) for prostate cancer and nasopharyngeal carcinoma cases, comparative analysis of the same number of co-ray field coplanar angle DVH maps, dose distribution maps, and average organ dose at risk for the Shino Project and Shinagawa’s optimized project. Results: The auto-optimization algorithm of shooting field direction can effectively screen out the combination of shooting direction and field direction required by clinic, and get the corresponding intensity-modulated treatment plan. Under the same target dose, the dose of the crisis organ is significantly reduced. CONCLUSION: Our proposed algorithm to automatically optimize the non-coplanar field direction can be well used in the field optimization and field intensity optimization of known field direction pool (such as triple source IMRT).