title: Fast optimization and dose calculation in scanned ion beam therapy.
abstract: OBJECTIVE
  Particle therapy (PT) has advantages over photon irradiation on static tumors. An increased biological effectiveness and active target conformal dose shaping are strong arguments for PT. However, the sensitivity to changes of internal geometry complicates the use of PT for moving organs. In case of interfractionally moving objects adaptive radiotherapy (ART) concepts known from intensity modulated radiotherapy (IMRT) can be adopted for PT treatments. One ART strategy is to optimize a new treatment plan based on daily image data directly before a radiation fraction is delivered [treatment replanning (TRP)]. Optimizing treatment plans for PT using a scanned beam is a time consuming problem especially for particles other than protons where the biological effective dose has to be calculated. For the purpose of TRP, fast optimization and fast dose calculation have been implemented into the GSI in-house treatment planning system (TPS) TRiP98.
  
  
  METHODS
  This work reports about the outcome of a code analysis that resulted in optimization of the calculation processes as well as implementation of routines supporting parallel execution of the code. To benchmark the new features, the calculation time for therapy treatment planning has been studied.
  
  
  RESULTS
  Compared to the original version of the TPS, calculation times for treatment planning (optimization and dose calculation) have been improved by a factor of 10 with code optimization. The parallelization of the TPS resulted in a speedup factor of 12 and 5.5 for the original version and the code optimized version, respectively. Hence the total speedup of the new implementation of the authors' TPS yielded speedup factors up to 55.
  
  
  CONCLUSIONS
  The improved TPS is capable of completing treatment planning for ion beam therapy of a prostate irradiation considering organs at risk in this has been overseen in the review process. Also see below 6 min.
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany; Department of Radiation Oncology, University Clinic Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany; and Institute for Medical Physics and Radiation Protection, University of Applied Sciences, 35390 Giessen, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Hild
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Graeff
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Trautmann
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kraemer
authors.affiliation: Institute for Medical Physics and Radiation Protection, University of Applied Sciences, 35390 Giessen, Germany and Department of Radiotherapy and Radiooncology, University Hospital Giessen-Marburg, 35043 Marburg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Zink
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany and Faculty of Physics, Technische Universität Darmstadt, 64289 Darmstadt, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Durante
authors.affiliation: Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64289 Darmstadt, Germany and Department of Radiation Oncology, University Clinic Erlangen and Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 91054 Erlangen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Bert
mesh_terms: D000465:Algorithms; D006801:Humans; D007477:Ions / Q000627:therapeutic use*; D008297:Male; D011471:Prostatic Neoplasms / Q000532:radiotherapy; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D013997:Time Factors
chemical_list: D007477:Ions