20 Years of Clinical Operation with the Fast Neutron Therapy System in Seattle

The Clinical Neutron Therapy System at the University of Washington Medical Center in Seattle has now treated patients with fast neutrons for 20 years. During the past three years roughly 75 % of the treatments were for salivary gland tumors, where neutron therapy is the treatment of choice. After the installation of a small dedicated cyclotron in the Nuclear Medicine department for PET isotope production this service is no longer required from the Scanditronix MC50 cyclotron. Instead, a new beam line has been added for the production of 211-At using an alpha beam. The clinical operation remains very reliable with an 18 month time period where not a single patient session had to be cancelled for machine reasons. During the same time period all major system components were secured seismically, which required considerable construction activity during weekends with normal therapy operation continuing during the week. Besides the continuing upgrade and replacement of system parts a program is under way to migrate the accelerator / beam line controls to an EPICS based control system.