Beam angle optimization for intensity-modulated radiation therapy using a guided pattern search method
Beam angle optimization for intensity-modulated radiation therapy using a guided pattern search method
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DOI：
10.1088/0031-9155/58/9/2939
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发表时间：
2013-05-07
影响因子：
3.5
通讯作者：
Lopes, Maria C.
中科院分区：
文献类型：
--
作者：
Rocha, Humberto;Dias, Joana M.;Lopes, Maria C.
通常，放射治疗的逆向计划主要包括剂量优化。调强放射治疗（IMRT）中的射束角度优化（BAO）包括选择适当的辐射入射方向，并可能影响IMRT计划的质量，以提高更好的器官保留和改善肿瘤覆盖。然而，在临床实践中，大多数时候，射束方向继续由治疗计划者手动选择，而没有客观和严格的标准。本文的目标是介绍一种新的方法，使用波束的眼睛视图剂量射线跟踪度量的模式搜索方法的框架内的高度非凸BAO问题的优化。模式搜索方法是无导数的优化方法，其需要一些函数评估来进行和收敛，并且具有更好地避免局部陷入的能力。模式搜索方法框架由每次迭代的搜索步骤和轮询步骤组成。轮询步骤在网格邻域中执行局部搜索，并确保收敛到局部最小值或稳定点。搜索步骤为全局搜索提供了灵活性，因为它允许搜索远离当前块的邻域。射束视角剂量度量为每个辐射射束方向分配分数，并且可以在提供问题的先验知识的模式搜索框架内使用，使得首先测试具有较大剂量测定分数的方向。一组在葡萄牙肿瘤研究所的科英布拉的头颈部肿瘤治疗的临床病例被用来讨论这种方法在优化的BAO问题的潜力。
Generally, the inverse planning of radiation therapy consists mainly of the fluence optimization. The beam angle optimization (BAO) in intensity-modulated radiation therapy (IMRT) consists of selecting appropriate radiation incidence directions and may influence the quality of the IMRT plans, both to enhance better organ sparing and to improve tumor coverage. However, in clinical practice, most of the time, beam directions continue to be manually selected by the treatment planner without objective and rigorous criteria. The goal of this paper is to introduce a novel approach that uses beam's-eye-view dose ray tracing metrics within a pattern search method framework in the optimization of the highly non-convex BAO problem. Pattern search methods are derivative-free optimization methods that require a few function evaluations to progress and converge and have the ability to better avoid local entrapment. The pattern search method framework is composed of a search step and a poll step at each iteration. The poll step performs a local search in a mesh neighborhood and ensures the convergence to a local minimizer or stationary point. The search step provides the flexibility for a global search since it allows searches away from the neighborhood of the current iterate. Beam's-eye-view dose metrics assign a score to each radiation beam direction and can be used within the pattern search framework furnishing a priori knowledge of the problem so that directions with larger dosimetric scores are tested first. A set of clinical cases of head-and-neck tumors treated at the Portuguese Institute of Oncology of Coimbra is used to discuss the potential of this approach in the optimization of the BAO problem.