title: Phantom assessment of lung dose from proton arc therapy.
abstract: OBJECTIVE
  To compare resultant lung dose from proton arc therapy of the chest wall to that from electron arc therapy.
  
  
  METHODS
  A 200 MeV proton beam from the Indiana University Cyclotron was range shifted and modulated to provide a spread out Bragg peak extending from the surface to a depth of 4 cm in water. The chest wall of an Alderson Rando phantom was irradiated by this beam, collimated to a 20 x 4 cm field size, while it rotated on a platform at approximately 1 rpm. For comparison, electron arc therapy of the Rando phantom chest wall was similarly performed with 12 MeV electrons and the resultant lung dose measured in each case.
  
  
  RESULTS
  Dose-volume histograms for the Rando phantom left lung indicate a reduced volume of irradiated lung for protons at all dose levels and an integral lung dose that is half that for electron arc therapy in the case studied. In addition, a more uniform dose coverage of the target volume was achieved with the proton therapy.
  
  
  CONCLUSIONS
  This study demonstrates a potential role for proton arc therapy as an alternative to electron arc therapy when lung dose must be minimized.
authors.affiliation: Department of Radiation Oncology, Indiana University Medical Center, Indianapolis, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Sandison
authors.forename: E
authors.initials: E
authors.lastname: Papiez
authors.forename: C
authors.initials: C
authors.lastname: Bloch
authors.forename: J
authors.initials: J
authors.lastname: Morphis
mesh_terms: D002138:Calibration; D008168:Lung; D019047:Phantoms, Imaging; D011522:Protons; D011829:Radiation Dosage; D011874:Radiometry / Q000379:methods*
chemical_list: D011522:Protons