An operator positioning apparatus for a proton treatment system includes: a proton beam nozzle to emit a proton beam to a targeted region of a patient； a gantry wheel having a front face to support the proton beam nozzle to direct the proton beam to an isocenter of the gantry wheel corresponding to a center of the targeted region, wherein the gantry wheel rotates the proton beam nozzle around the isocenter； an active floor that horizontally translates across the front face of the gantry wheel, the active floor having an opening having a width through which the proton beam nozzle protrudes when the proton beam nozzle is located below the targeted region.
