title: Advanced optimization methods for whole pelvic and local prostate external beam therapy.
abstract: OBJECTIVE
  Radiation treatment planning inherently involves multiple conflicting planning goals, which makes it a suitable application for multicriteria optimization (MCO). This study investigates a MCO algorithm for VMAT planning (VMAT-MCO) for prostate cancer treatments including pelvic lymph nodes and uses standard inverse VMAT optimization (sVMAT) and Tomotherapy planning as benchmarks.
  
  
  METHODS
  For each of ten prostate cancer patients, a two stage plan was generated, consisting of a stage 1 plan delivering 22Gy to the prostate, and a stage 2 plan delivering 50.4Gy to the lymph nodes and 56Gy to the prostate with a simultaneous integrated boost. The single plans were generated by three planning techniques (VMAT-MCO, sVMAT, Tomotherapy) and subsequently compared with respect to plan quality and planning time efficiency.
  
  
  RESULTS
  Plan quality was similar for all techniques, but sVMAT showed slightly better rectum (on average Dmean -7%) and bowel sparing (Dmean -17%) compared to VMAT-MCO in the whole pelvic treatments. Tomotherapy plans exhibited higher bladder dose (Dmean +42%) in stage 1 and lower rectum dose (Dmean -6%) in stage 2 than VMAT-MCO. Compared to manual planning, the planning time with MCO was reduced up to 12 and 38min for stage 1 and 2 plans, respectively.
  
  
  CONCLUSIONS
  MCO can generate highly conformal prostate VMAT plans with minimal workload in the settings of prostate-only treatments and prostate plus lymph nodes irradiation. In the whole pelvic plan manual VMAT optimization led to slightly improved OAR sparing over VMAT-MCO, whereas for the primary prostate treatment plan quality was equal.
authors.affiliation: Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria. Electronic address: martin.buschmann@meduniwien.ac.at.
authors.forename: Martin
authors.initials: M
authors.lastname: Buschmann
authors.affiliation: Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria.
authors.forename: Yvette
authors.initials: Y
authors.lastname: Seppenwoolde
authors.affiliation: Department of Radiation Oncology, University Hospital Jena, Jena, Germany.
authors.forename: Tilo
authors.initials: T
authors.lastname: Wiezorek
authors.affiliation: Department of Radiation Oncology, University Hospital Jena, Jena, Germany.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Weibert
authors.affiliation: Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Vienna, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Vienna, Austria.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Georg
mesh_terms: D000465:Algorithms; D006801:Humans; D008207:Lymphatic Metastasis; D008297:Male; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods
keywords: Multicriteria optimization; Tomotherapy; VMAT; Whole-pelvic prostate radiotherapy