Figure 1From: Dosimetric impact of reduced nozzle-to-isocenter distance in intensity-modulated proton therapy of intracranial tumors in combined proton-carbon fixed-nozzle treatment facilitiesCalculated spread of a proton beam from a nozzle geometry compatible with the ion beam therapy setup at the GSI[8, 9]and with recent Siemens combined ion therapy facilities, like the one at University Medical Center of Marburg. An initially parallel particle beam enters a water absorber (patient) at 1 m distance from the nozzle exit. If the water absorber is shifted closer to the nozzle, the width of the beam entering the water is reduced. The resulting difference in beam width in the patient for a 40 cm shift is explicitly marked (red line) at three exemplary energies (50, 100 and 200 MeV).Back to article page