title: Simulated annealing applied to IMRT beam angle optimization: A computational study.
abstract: Electing irradiation directions to use in IMRT treatments is one of the first decisions to make in treatment planning. Beam angle optimization (BAO) is a difficult problem to tackle from the mathematical optimization point of view. It is highly non-convex, and optimization approaches based on gradient descent methods will probably get trapped in one of the many local minima. Simulated Annealing (SA) is a local search probabilistic procedure that is known to be able to deal with multimodal problems. SA for BAO was retrospectively applied to ten clinical examples of treated cases of head-and neck tumors signalized as complex cases where proper target coverage and organ sparing proved difficult to achieve. The number of directions to use was considered fixed and equal to 5 or 7. It is shown that SA can lead to solutions that significantly improve organ sparing, even considering a reduced number of angles, without jeopardizing tumor coverage.
authors.affiliation: Faculdade de Economia, Universidade de Coimbra, Portugal; Inesc-Coimbra, Portugal. Electronic address: joana@fe.uc.pt.
authors.forename: Joana
authors.initials: J
authors.lastname: Dias
authors.affiliation: Inesc-Coimbra, Portugal.
authors.forename: Humberto
authors.initials: H
authors.lastname: Rocha
authors.affiliation: I3N, Departamento de Física, Universidade de Aveiro, Portugal.
authors.forename: Brígida
authors.initials: B
authors.lastname: Ferreira
authors.affiliation: I3N, Departamento de Física, Universidade de Aveiro, Portugal; Serviço de Física Médica, IPOC-FG, EPE, Coimbra, Portugal.
authors.forename: Maria do Carmo
authors.initials: Mdo C
authors.lastname: Lopes
mesh_terms: D000465:Algorithms; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012189:Retrospective Studies
keywords: Beam angle optimization; Metaheuristics; Simulated annealing