Gantry 3

After four years of planning, construction and commissioning a new treatment unit, Gantry 3 has come into operation. The construction of Gantry 3 was done with a scientific collaboration with Varian Medical Systems and integrated in our existing treatment and accelerator facility. Technically, Gantry 3 will offer the same treatment capabilities as Gantry 2 and can even treat irradiation fields of 30x40 cm2.

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 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. It is envisioned to treat moving tumours at this irradiation facility using the ‘gating’ principle in the future. 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.