Design of a "Riesenrad" Ion Gantry for Hadrontherapy

The benefit of hadrontherapy can be maximized by offering the possibility to deliver the particle beam from any direction in space towards the patient with the help of a medical gantry. For carbon ions, their increased (magnetic) beam rigidity yields considerable structural difficulties and has so far prevented a practical realization of an ion gantry. The concept of a 'Riesenrad' ion gantry promises to provide an effective and efficient solution. The basic idea is to deflect the ion beam with a single 90° dipole, which rotates around the incoming beam axis, and direct it towards the eccentrically positioned patient cabin. Inside the cabin similar conditions as exist in a classical isocentric treatment room prevail. The practical design of such a Riesenrad gantry, its structural principles and its function are presented. The underlying beam optics and its integration into the mechanical structure are explained. Aspects of safety, and flexibility are discussed.