Dosimetric impact of reduced nozzle-to-isocenter distance in intensity-modulated proton therapy of intracranial tumors in combined proton-carbon fixed-nozzle treatment facilities

摘要

BackgroundIn combined proton-carbon fixed-nozzle treatment facilities with raster scanning delivery, the scattering of proton pencil beams caused by nozzle elements and the relatively large nozzle-to-isocenter distance cause a beam broadening. This may pose limitations to the achievable dose conformity. One way to counteract this effect is by delivering the treatment in a position closer to the nozzle than the room isocenter. Purpose of this study was to assess the potential dosimetric benefit of such solution, in terms of dose conformity and normal tissue sparing, in intensity-modulated proton therapy (IMPT) of intracranial tumors.