title: Automatic interactive optimization for volumetric modulated arc therapy planning.
abstract: BACKGROUND
  Intensity modulated radiotherapy treatment planning for sites with many different organs-at-risk (OAR) is complex and labor-intensive, making it hard to obtain consistent plan quality. With the aim of addressing this, we developed a program (automatic interactive optimizer, AIO) designed to automate the manual interactive process for the Eclipse treatment planning system. We describe AIO and present initial evaluation data.
  
  
  METHODS
  Our current institutional volumetric modulated arc therapy (RapidArc) planning approach for head and neck tumors places 3-4 adjustable OAR optimization objectives along the dose-volume histogram (DVH) curve that is displayed in the optimization window. AIO scans this window and uses color-coding to differentiate between the DVH-lines, allowing it to automatically adjust the location of the optimization objectives frequently and in a more consistent fashion. We compared RapidArc AIO plans (using 9 optimization objectives per OAR) with the clinical plans of 10 patients, and evaluated optimal AIO settings. AIO consistency was tested by replanning a single patient 5 times.
  
  
  RESULTS
  Average V95&V107 of the boost planning target volume (PTV) and V95 of the elective PTV differed by ≤0.5%, while average elective PTV V107 improved by 1.5%. Averaged over all patients, AIO reduced mean doses to individual salivary structures by 0.9-1.6Gy and provided mean dose reductions of 5.6Gy and 3.9Gy to the composite swallowing structures and oral cavity, respectively. Re-running AIO five times, resulted in the aforementioned parameters differing by less than 3%.
  
  
  CONCLUSIONS
  Using the same planning strategy as manually optimized head and neck plans, AIO can automate the interactive Eclipse treatment planning process and deliver dosimetric improvements over existing clinical plans.
authors.affiliation: Department of Radiotherapy, VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. j.tol@vumc.nl.
authors.forename: Jim P
authors.initials: JP
authors.lastname: Tol
authors.affiliation: Department of Radiotherapy, VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. m.dahele@vumc.nl.
authors.forename: Max
authors.initials: M
authors.lastname: Dahele
authors.affiliation: Varian Medical Systems, Paciuksenkatu 21, 00270, Helsinki, Finland. jarkko.peltola@varian.com.
authors.forename: Jarkko
authors.initials: J
authors.lastname: Peltola
authors.affiliation: Varian Medical Systems, Paciuksenkatu 21, 00270, Helsinki, Finland. janne.nord@varian.com.
authors.forename: Janne
authors.initials: J
authors.lastname: Nord
authors.affiliation: Department of Radiotherapy, VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. bj.slotman@vumc.nl.
authors.forename: Ben J
authors.initials: BJ
authors.lastname: Slotman
authors.affiliation: Department of Radiotherapy, VU University Medical Center, De Boelelaan 1117, 1081 HV, Amsterdam, The Netherlands. w.verbakel@vumc.nl.
authors.forename: Wilko F A R
authors.initials: WF
authors.lastname: Verbakel
mesh_terms: D000465:Algorithms; D001331:Automation; D005500:Follow-Up Studies; D006258:Head and Neck Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D006801:Humans; D058958:Organs at Risk / Q000528:radiation effects*; D011874:Radiometry / Q000379:methods; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods / Q000592:standards*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods / Q000592:standards*