THE INDIANA-UNIVERSITY PROTON RADIATION-THERAPY PROJECT

A fixed horizontal beam line at the Indiana University cyclotron facil ity (IUCF) has been equipped for proton radiation therapy treatment of head, neck, and brain tumors. The complete system will be commissione d and ready to treat patients early in 1993. IUCF can produce external proton beams from 45 to 200 MeV in energy, which corresponds to a max imum range in water of 26 cm. Beam currents over 100 nA are easily att ained, allowing dose rates in excess of 200 cGy/min, even for large fi elds. Beam spreading systems have been tested which provide uniform fi elds up to 20 cm in diameter. Range modulation is accomplished with a rotating acrylic device, which provides uniform depth dose distributio ns from 3 to 18 cm in extent. Tests have been conducted on detectors w hich monitor the beam position and current, and the dose symmetry. Thi s report discusses those devices, as well as the cyclotron characteris tics, measured beam properties, safety interlocks, computerized dose d elivery/monitoring system, and future plans.