title: Dose-painting intensity-modulated proton therapy for intermediate- and high-risk meningioma.
abstract: BACKGROUND
  Newly diagnosed WHO grade II-III or any WHO grade recurrent meningioma exhibit an aggressive behavior and thus are considered as high- or intermediate risk tumors. Given the unsatisfactory rates of disease control and survival after primary or adjuvant radiation therapy, optimization of treatment strategies is needed. We investigated the potential of dose-painting intensity-modulated proton beam-therapy (IMPT) for intermediate- and high-risk meningioma.
  
  
  METHODS
  Imaging data from five patients undergoing proton beam-therapy were used. The dose-painting target was defined using [68]Ga-[1,4,7,10-tetraazacyclododecane tetraacetic acid]- d-Phe(1),Tyr(3)-octreotate ([68]Ga-DOTATATE)-positron emission tomography (PET) in target delineation. IMPT and photon intensity-modulated radiation therapy (IMRT) treatment plans were generated for each patient using an in-house developed treatment planning system (TPS) supporting spot-scanning technology and a commercial TPS, respectively. Doses of 66 Gy (2.2 Gy/fraction) and 54 Gy (1.8 Gy/fraction) were prescribed to the PET-based planning target volume (PTVPET) and the union of PET- and anatomical imaging-based PTV, respectively, in 30 fractions, using simultaneous integrated boost.
  
  
  RESULTS
  Dose coverage of the PTVsPET was equally good or slightly better in IMPT plans: dose inhomogeneity was 10 ± 3% in the IMPT plans vs. 13 ± 1% in the IMRT plans (p = 0.33). The brain Dmean and brainstem D50 were small in the IMPT plans: 26.5 ± 1.5 Gy(RBE) and 0.002 ± 0.0 Gy(RBE), respectively, vs. 29.5 ± 1.5 Gy (p = 0.001) and 7.5 ± 11.1 Gy (p = 0.02) for the IMRT plans, respectively. The doses delivered to the optic structures were also decreased with IMPT.
  
  
  CONCLUSIONS
  Dose-painting IMPT is technically feasible using currently available planning tools and resulted in dose conformity of the dose-painted target comparable to IMRT with a significant reduction of radiation dose delivered to the brain, brainstem and optic apparatus. Dose escalation with IMPT may improve tumor control and decrease radiation-induced toxicity.
authors.affiliation: Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland. indira.madani@ugent.be.|Ghent University, Ghent, Belgium. indira.madani@ugent.be.
authors.forename: Indira
authors.initials: I
authors.lastname: Madani
authors.affiliation: Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland. tony.lomax@psi.ch.
authors.forename: Antony J
authors.initials: AJ
authors.lastname: Lomax
authors.affiliation: Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland. francesca.albertini@psi.ch.
authors.forename: Francesca
authors.initials: F
authors.lastname: Albertini
authors.affiliation: Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland. petra.trnkova@psi.ch.
authors.forename: Petra
authors.initials: P
authors.lastname: Trnková
authors.affiliation: Center for Proton Therapy, Paul Scherrer Institute, Villigen, Switzerland. damien.weber@psi.ch.|Department of Radiation Oncology, University Hospital of Zürich, Zürich, Switzerland. damien.weber@psi.ch.
authors.forename: Damien C
authors.initials: DC
authors.lastname: Weber
mesh_terms: D000328:Adult; D000368:Aged; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008579:Meningioma / Q000473:pathology / Q000532:radiotherapy*; D008875:Middle Aged; D060787:Neoplasm Grading; D058958:Organs at Risk; D049268:Positron-Emission Tomography / Q000379:methods; D011379:Prognosis; D061766:Proton Therapy; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014018:Tissue Distribution
chemical_list: D019275:Radiopharmaceuticals