title: Automated beam angle and weight selection in radiotherapy treatment planning applied to pancreas tumors.
abstract: OBJECTIVE
  To extend and investigate the clinical value of a recently developed algorithm for automatic beam angle and beam weight selection, for irradiation of pancreas tumors.
  
  
  METHODS
  The algorithm aims at generation of acceptable treatment plans, i.e., delivering the prescribed tumor dose while strictly obeying the imposed hard constraints for organs at risk and target. Extensions were made to minimize the beam number and/or to escalate the tumor dose. For 5 pancreas patients, the clinical value and the potential for beam number reduction and dose escalation were investigated. Comparisons were made with clinical plans and equiangular plans.
  
  
  RESULTS
  Compared to clinical plans, the generated plans with the same number of beams yielded a substantial reduction in the dose to critical tissues. Using the algorithm, an escalated tumor dose of 58 Gy could be achieved for two cases. Maximum dose escalations required a minimum of 3 to 4 beam orientations. For 13 CT slices and an in-slice resolution of 0.5 cm, the total calculation times were 23-55 min, including precalculation of 180 input dose distributions (15 min).
  
  
  CONCLUSIONS
  The algorithm yielded acceptable treatment plans with clinically feasible numbers of beams, even for escalated tumor doses. Generated plans were superior to the clinically applied plans and to equiangular setups. Calculation times were clinically acceptable. The algorithm is now increasingly used in clinical routine.
authors.affiliation: Department of Radiation Oncology, Daniel den Hoed Cancer Center, Erasmus Medical Center, Rotterdam, The Netherlands. e.woudstra@erasmusmc.nl
authors.forename: Evert
authors.initials: E
authors.lastname: Woudstra
authors.forename: Ben J M
authors.initials: BJ
authors.lastname: Heijmen
mesh_terms: D000465:Algorithms; D006801:Humans; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D020266:Radiotherapy, Conformal; D014057:Tomography, X-Ray Computed