title: Multiobjective optimization with a modified simulated annealing algorithm for external beam radiotherapy treatment planning.
abstract: Inverse planning in external beam radiotherapy often requires a scalar objective function that incorporates importance factors to mimic the planner's preferences between conflicting objectives. Defining those importance factors is not straightforward, and frequently leads to an iterative process in which the importance factors become variables of the optimization problem. In order to avoid this drawback of inverse planning, optimization using algorithms more suited to multiobjective optimization, such as evolutionary algorithms, has been suggested. However, much inverse planning software, including one based on simulated annealing developed at our institution, does not include multiobjective-oriented algorithms. This work investigates the performance of a modified simulated annealing algorithm used to drive aperture-based intensity-modulated radiotherapy inverse planning software in a multiobjective optimization framework. For a few test cases involving gastric cancer patients, the use of this new algorithm leads to an increase in optimization speed of a little more than a factor of 2 over a conventional simulated annealing algorithm, while giving a close approximation of the solutions produced by a standard simulated annealing. A simple graphical user interface designed to facilitate the decision-making process that follows an optimization is also presented.
authors.affiliation: Département de Radio-Oncologie et Centre de Recherche en Cancérologie, CHUQ Pavilion L'Hôtel-Dieu de Quebec, Quebec, Quebec, Canada.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Aubry
authors.forename: Frédéric
authors.initials: F
authors.lastname: Beaulieu
authors.forename: Caroline
authors.initials: C
authors.lastname: Sévigny
authors.forename: Luc
authors.initials: L
authors.lastname: Beaulieu
authors.forename: Daniel
authors.initials: D
authors.lastname: Tremblay
mesh_terms: D000465:Algorithms; D003196:Computer Graphics; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D015233:Models, Statistical; D019047:Phantoms, Imaging; D011859:Radiography; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D012984:Software; D013116:Spinal Cord / Q000000981:diagnostic imaging; D013274:Stomach Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D013997:Time Factors