Operation of the TRIUMF Proton Therapy Facility

The Proton Therapy Facility at TRIUMF is now in routine operation treating ocular tumours using 70 MeV protons extracted from the 500 MeV H^- cyclotron. This paper describes the proton beam line, treatment control and dosimetry systems which are designed to provide accurate treatment dose delivery. The reproducibility of the shape and range of the unmodulated Bragg peak for various operating conditions of the cyclotron is discussed along with the technique for producing a uniform modulated or spread-out Bragg peak. The patient positioning chair, which has six motorized degrees of freedom, the patient mask and bite-block, and the X-ray verification system ensure sub-millimeter positioning accuracy. Patient treatments are scheduled one week per month with the treatment dose of 50 proton-Gy delivered in four daily fractions