Development and Engineering Design of a Novel Exocentric Carbon-Ion Gantry for Cancer Therapy: The "Riesenrad" Gantry

Mechanical structures capable of delivering a therapy beam for cancer treatment from any direction to the patient are called medical gantries. Typically, a gantry rotates around the patient who is kept in the supine position (rotating gantries). In Europe several currently proposed clinic facilities for ion therapy want to install an ion gantry equipped with a pencil-beam scanning system. Such a treatment apparatus allows the optimisation of the dose-to-target conformity, but the active pencil-beam scanning increases the demands considerably on the beam transport accuracy. Usually, a sub-millimetre precision of the beam position at the patient (i.e. in the gantry isocentre) is required in order to treat tumours in the vicinity of critical organs, which is one of the main domains of ion therapy...