Cancer Therapy with Protons at Paul Scherrer Institut

PSI has been actively involved in particle beam radiation therapy for many years. Conventional scattering technology has been used for eye tumors since 1981 with more than 4000 patients successfully treated. In 1996, PSI initiated the spot-scanning program for the treatment of deep seated tumors of various sizes with protons up to 220 MeV in a compact gantry. In 2006 a dedicated 250 MeV cyclotron for medical applications was commissioned and patient treatments restarted in 2007. Meanwhile a new Gantry 2 is being developed. It is based on double-parallel magnetic scanning and will make use of beam intensity modulation inside the cyclotron and of fast dynamic changes of the beam energy.