title: A three-dimensional algorithm for optimizing beam weights and wedge filters.
abstract: An essential step towards optimizing and automating radiation therapy treatment planning is to develop an effective algorithm to find the optimal beam weights and wedge filters for a given set of beam directions and modalities. This problem is solved by introducing a variable transformation based on the universal and omni wedge principles. Instead of directly optimizing an objective function with respect to wedge angles and orientations, each field is first decomposed into a superposition of an open field and two orthogonal wedged fields. This transforms the problem of finding J beam weights, wedge angles, and orientations to that of optimizing a system with 3J beam weights (J open beams and 2J nominal wedged beams), where J is the total number of incident beam directions. An iterative algorithm based on a method originally developed for image reconstruction is used to find the 3J beam weights. The technique is applied to a few clinical cases. Treatment plans are improved compared to those obtained through the conventional manual trial and error planning process. In addition, planning time and effort are greatly reduced.
authors.affiliation: Department of Radiation Oncology, Stanford University, California 94305-5304, USA. lei@reyes.stanford.edu
authors.forename: L
authors.initials: L
authors.lastname: Xing
authors.forename: R J
authors.initials: RJ
authors.lastname: Hamilton
authors.forename: C
authors.initials: C
authors.lastname: Pelizzari
authors.forename: G T
authors.initials: GT
authors.lastname: Chen
mesh_terms: D000465:Algorithms; D055592:Biophysical Phenomena; D001703:Biophysics; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy; D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy; D008962:Models, Theoretical; D019047:Phantoms, Imaging; D011880:Radiotherapy Planning, Computer-Assisted / Q000706:statistics & numerical data*; D014067:Tonsillar Neoplasms / Q000532:radiotherapy