The construction of Gantry 3 was undertaken as a scientific collaboration with Varian Medical Systems and integrated in the existing treatment and accelerator facility at PSI. Technically, Gantry 3 offers the same treatment capabilities as Gantry 2 and but with an irradiation fields of 30x40 cm2 goes even beyond that.
Gantry 3 can be rotated 180 degrees to the right or to the left. Nine primary magnets, which surround the vacuum pipe, steer the protons to the patient as a beam with one-millimetre precision. With a total weight of 270 tons and a diameter of 10.5 metres, Gantry 3 is the largest machine installed to date at CPT. Gantry 3 also utilises the active scanning technique to deflect the proton beam with two orthogonal magnets to be able to cover any 3 dimensional tumour shape.
An on-board integrated imaging system is employed to verify the placement of the patient directly in the treatment position. The gantry’s ability to deliver large irradiation fields, fast energy changes and high dose rates allows the radiation duration per patient to be kept short. The irradiation facility Gantry 3 was financed with money from the lottery of the canton of Zurich as well as PSI's own funds.
The clinical collaboration of this treatment unit will be done with the Radiation Oncology Department of the University Hospital of Zürich.