A 20 MeV betatron for X-ray therapy

A description is given of a 20 MeV betatron, the first to be installed for X-ray therapy in this country. The machine produces 20MeV X-rays with an intensity exceeding 100 röntgens/min at 1 m as measured on a condenser thimble chamber surrounded by 6cm of polystyrene. The betatron magnet can be rotated about its axis through 120°, and together with its suspending framework it can be moved vertically over a range of travel of 7 ft. After explaining the clinical requirements for such high-energy X-rays, a brief account is given of betatron development and of its principle of operation. A full description of the equipment is then given, followed by an account of its performance and details of its medical application.