title: Single-fraction flattening filter-free volumetric modulated arc therapy for lung cancer: Dosimetric results and comparison with flattened beams technique.
abstract: OBJECTIVE
  To report on single-fraction stereotactic body radiotherapy (RT) (SBRT) with flattening filter (FF)-free (FFF) volumetric modulated arc therapy (VMAT) for lung cancer and to compare dosimetric results with VMAT with FF.
  
  
  METHODS
  Overall, 25 patients were treated with 6-MV FFF VMAT (Varian TrueBeam STx LINAC) to a prescribed dose of 24Gy in a single fraction. Treatment plans were recreated using FF VMAT. Dose-volume indices, monitor units (MU), and treatment times were compared between FFF and FF VMAT techniques.
  
  
  RESULTS
  Dose constraints to PTV, spinal cord, and lungs were reached in FFF and FF plans. In FFF plans, average conformity index was 1.13 (95% CI: 1.07 to1.38). Maximum doses to spinal cord, heart, esophagus, and trachea were 2.9Gy (95% CI: 0.4 to 6.7Gy), 0.8Gy (95% CI: 0 to 3.6Gy), 3.3Gy (95% CI: 0.02 to 13.9Gy), and 1.5Gy (95% CI: 0 to 4.9Gy), respectively. Average V7Gy, V7.4Gy, and mean dose to the healthy lung were 126.5cc (95% CI: 41.3 to 248.9cc), 107.3cc (95% CI: 18.7 to 232.8cc), and 1.1Gy (95% CI: 0.3 to 2.2Gy), respectively. No statistically significant differences were found in dosimetric results and MU between FF and FFF treatments. Treatment time was reduced by an average factor of 2.31 (95% CI: 2.15 to 2.43) from FF treatments to FFF, and the difference was statistically significant.
  
  
  CONCLUSIONS
  FFF VMAT for lung SBRT provides equivalent dosimetric results to the target and organs at risk as FF VMAT while significantly reducing treatment time.
authors.affiliation: Medical Physics Division, Centro di Riferimento Oncologico, Aviano, Italy; Specialty School in Medical Physics, University of Pisa, Pisa, Italy.
authors.forename: Sara
authors.initials: S
authors.lastname: Barbiero
authors.affiliation: Radiation Physics Department, Princess Margaret Cancer Centre, University Health Network, Toronto, Canada; Department of Radiation Oncology, University of Toronto, Toronto, Canada.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Rink
authors.affiliation: Radiation Oncology Department, S.Chiara University Hospital, Pisa, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Matteucci
authors.affiliation: Radiotherapy Department, Casa di Cura S. Rossore, Pisa, Italy.
authors.forename: David
authors.initials: D
authors.lastname: Fedele
authors.affiliation: Radiation Oncology Department, S.Chiara University Hospital, Pisa, Italy.
authors.forename: Fabiola
authors.initials: F
authors.lastname: Paiar
authors.affiliation: Radiation Oncology Department, S.Chiara University Hospital, Pisa, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Pasqualetti
authors.affiliation: Medical Physics Division, Centro di Riferimento Oncologico, Aviano, Italy. Electronic address: mavanzo@cro.it.
authors.forename: Michele
authors.initials: M
authors.lastname: Avanzo
mesh_terms: D006801:Humans; D008175:Lung Neoplasms / Q000532:radiotherapy*; D058958:Organs at Risk; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*
keywords: Conformity index; Dose volume; Flattening filter free; Homogeneity; Lung cancer; VMAT