Cyclotron and neutron therapy installation incorporating such a cyclotron

A neutron therapy installation comprising biological shielding means to define the installation, and having a light, compact cyclotron for use in neutron therapy, mounted therein, and capable of being moved to change the direction of an exiting neutron beam,. the cyclotron comprising:

• (a) a pair of opposed, spaced pole shoes having their adjacent inner surfaces defining an accelerator zone, the surfaces being adapted to constitute magnetic equipotential surfaces which establish a magnetic field configuration for the cyclotron during use,
• (b) an electromagnetic coil system around the pole shoes and adapted for connection to an electrical power source for generating the cyclotron magnetic field between the pole shoe surfaces,
• (c) a magnet yoke to provide a magnetic flux return path for the pole shoes, the magnet yoke together with the pole shoes providing a low magnetic resistance relatively to that of the accelerator zone, and the magnet yoke being shaped to substantially enclose the accelerator zone to constitute, together with the pole shoes, a neutron attentuation shield for neutrons produced in the cyclotron,
• (d) at least one hollow accelerating dee electrode positioned in the accelerator zone, and having a radio frequency resonator associated therewith,
• (e) a vacuum chamber enclosing the accelerator zone and each dee electrode,
• (f) means for providing charged particles for acceleration within the accelerator zone,
• (g) a target zone for a target device, and
• (h) a neutron beam outlet in the magnet yoke for emission of a neutron beam produced in the cyclotron.