The Use of Compact Cyclotrons for Producing Fast Neutrons for Therapy in a Rotatable Isocentric Gantry

This paper discusses the design and performance of a fast neutron therapy system which transports a cyclotron beam onto a beryllium target mounted in a rotatable isocentric gantry structure. Fast neutrons produced by either the proton or deuteron on beryllium reaction are directed towards the isocenter with appropriate shielding, collimation and dosimetry to control and monitor the radiation delivered onto a defined patient area. The beam optics and shielding considerations of such a radiotherapy apparatus are discussed. This paper also presents the dosimetric properties of neutron beams from different proton energies on beryllium and lithium targets.