title: Assessment of improved organ at risk sparing for meningioma: light ion beam therapy as boost versus sole treatment option.
abstract: OBJECTIVE
  To compare photons, protons and carbon ions and their combinations for treatment of atypical and anaplastical skull base meningioma.
  
  
  METHODS
  Two planning target volumes (PTVinitial/PTVboost) were delineated for 10 patients (prescribed doses 50 Gy(RBE) and 10 Gy(RBE)). Plans for intensity modulated photon (IMXT), proton (IMPT) and carbon ion therapy ((12)C) were generated assuming a non-gantry scenario for particles. The following combinations were compared: IMXT+IMXT/IMPT/(12)C; IMPT+IMPT/(12)C; and (12)C+(12)C. Plan quality was evaluated by target conformity and homogeneity (CI, HI), V95%, D2% and D50% and dose-volume-histogram (DVH) parameters for organs-at-risk (OAR). If dose escalation was possible, it was performed until OAR tolerance levels were reached.
  
  
  RESULTS
  CI was worst for IMXT. HI<0.05±0.01 for (12)C was significantly better than for IMXT. For all treatment options dose escalation above 60 Gy(RBE) was possible for four patients, but impossible for six patients. Compared to IMXT+IMXT, ion beam therapy showed an improved sparing for most OARs, e.g. using protons and carbon ions D50% was reduced by more than 50% for the ipsilateral eye and the brainstem.
  
  
  CONCLUSIONS
  Highly conformal IMPT and (12)C plans could be generated with a non-gantry scenario. Improved OAR sparing favors both sole (12)C and/or IMPT plans.
authors.affiliation: EBG MedAustron GmbH, Wiener Neustadt, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Austria.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Mock
authors.affiliation: Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Austria; Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Austria. Electronic address: Dietmar.Georg@meduniwien.ac.at.
authors.forename: Dietmar
authors.initials: D
authors.lastname: Georg
authors.affiliation: Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Austria; Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Austria.
authors.forename: Lukas
authors.initials: L
authors.lastname: Sölkner
authors.affiliation: EBG MedAustron GmbH, Wiener Neustadt, Austria; Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Austria.
authors.forename: Christian
authors.initials: C
authors.lastname: Suppan
authors.affiliation: EBG MedAustron GmbH, Wiener Neustadt, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Austria.
authors.forename: Stanislav M
authors.initials: SM
authors.lastname: Vatnitsky
authors.affiliation: EBG MedAustron GmbH, Wiener Neustadt, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Flechl
authors.affiliation: EBG MedAustron GmbH, Wiener Neustadt, Austria; Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Austria.
authors.forename: Ramona
authors.initials: R
authors.lastname: Mayer
authors.affiliation: Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Austria.
authors.forename: Karin
authors.initials: K
authors.lastname: Dieckmann
authors.affiliation: Christian Doppler Laboratory for Medical Radiation Research for Radiation Oncology, Medical University of Vienna, Austria; Department of Radiation Oncology, Comprehensive Cancer Center, Medical University of Vienna/AKH Wien, Austria.
authors.forename: Barbara
authors.initials: B
authors.lastname: Knäusl
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002244:Carbon / Q000737:chemistry; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000532:radiotherapy*; D008579:Meningioma / Q000532:radiotherapy*; D008875:Middle Aged; D058958:Organs at Risk; D017785:Photons / Q000627:therapeutic use; D061766:Proton Therapy; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D019292:Skull Base Neoplasms / Q000532:radiotherapy*
chemical_list: D002244:Carbon
keywords: Carbon ion therapy; Meningioma treatment; Planning comparison; Proton therapy