PHANTOM ASSESSMENT OF LUNG DOSE FROM PROTON ARC THERAPY

Purpose: To compare resultant lung dose from proton are therapy of the chest wall to that from electron are therapy, Methods and Materials: A 200 MeV proton beam from the Indiana University Cyclotron was range shifted and modulated to provide a spread out Bragg peak extending fro m the surface to a depth of 4 cm in water, The chest wall of an Alders on Rando phantom was irradiated by this beam, collimated to a 20 X 4 c m field size, while it rotated on a platform at approximately 1 rpm, F or comparison, electron are therapy of the Rando phantom chest wall wa s similarly performed with 12 MeV electrons and the resultant lung dos e measured in each case. Results: Dose-volume histograms for the Rando phantom left lung indicate a reduced volume of irradiated lung for pr otons at all dose levels and an integral lung dose that is half that f or electron are therapy in the case studied, In addition, a more unifo rm dose coverage of the target volume was achieved with the proton the rapy. Conclusion: This study demonstrates a potential role for proton are therapy as an alternative to electron are therapy when lung dose m ust be minimized, (C) 1997 Elsevier Science Inc.