Potential margin reduction in prostate cancer proton therapy when using prompt gamma imaging for online treatment verification

An estimation for the potential reduction of clinical margins when using prompt gamma imaging for online treatment verification in proton therapy of prostate cancer is provided. For two adaptive scenarios a potential reduction relative to the clinical practice was evaluated. Using the current trolley-mounted PGI system for online treatment verification to trigger an adaptation, the current range uncertainty margins used at our institute could be reduced by 57%. Additional volumetric imaging at isocenter before irradiation could also reduce the setup uncertainty margins by 66%. A case example illustrates the corresponding dose sparing.