The production of iodine-123 on the Harwell variable energy cyclotron

123I has often been called the isotope of choice for dynamic body function studies in nuclear medicine. There has therefore, been a keen interest in the possibility of regular supply of high purity 123I produced by the Harwell Variable Energy Cyclotron (VEC) and Synchrocyclotron (SC). This report describes a three year research and development programme on the VEC which has resulted in a method for the safe and reliable large scale production of 123I by irradiation of di-iodomethane with 58 MeV protons. The quality of the product, and the medical trials which have been carried out with it, are also discussed. The processing and handling of the hundreds of millicuries produced during a run presents serious handling problems. These have been solved and the methods and equipment developed are described. (author)