Superconducting 250 MeV proton Cyclotron for cancer treatment

Starting in 2001 ACCEL Instruments GmbH has designed a superconducting cyclotron in collaboration with the National Superconducting Cyclotron Laboratory (NSCL), Michigan, USA, for proton therapy. This design is based on a proposal from NSCL from 1993. Currently two cyclotrons have been built, tested with respect to magnetic and cryogenic performance and delivered to the customer's site. Important issues taken into account when building a machine for medical use as well as design features, operating parameters and results from the in-house tests are presented.