Large scale production of 123I from a flowing liquid target using the (p,5n) reaction

Methods have been developed for production of 123I by decay of 123Xe formed by the reaction 127I(p,5n)123Xe, by bombarding a flowing target of CH2I2/I2 with a current of 10 to 20 micro A of 58 MeV protons produced by the Harwell Variable Energy Cyclotron. At this high current, radiation chemical reactions which are dose rate and total dose dependent caused serious difficulties, and means of overcoming these are reported. A practical production rate (which includes all losses during irradiation, trapping and chemical washing-out of the trap) of 5 to 6 mCi/microAhr has been achieved. The only impurity found is 125I, present to the extent of 0.13% by activity. A total of 107 patients have been treated with pharmaceuticals labelled with approximately 2 Ci of 123I produced in 20 separate runs. (author)