Preparation of carrier-free radioactive thallium for medical use

Radioactive thallium for medical use have been prepared by proton or deuteron bombardment of HgO or metallic Hg. The carrier free thallium is separated from mercury by ether extraction of the chloride. The yield of production for the isotopes 198m to 202 is given for different energies of protons and deuterons. The irradiated substances consisted of red mercury oxide containing less than 1 ppm iron, and high-purity (99.999%) metallic mercury. The red mercury oxide targets were irradiated with 15 MeV deuterons (M.R.C. cyclotron, Hammersmith Hospital-London and Saclay Van de Graff tandem) or 50 and 14 MeV protons (Grenoble Nuclear Physics Institute cyclotron and S.H.F.J. compact cyclotrons). The metallic mercury target was irradiated with 14, 16 and 20 MeV protons (S.H.F.J. compact cyclotron and Saclay variable-energy cyclotron). The particle current never exceeded 10 μA for irradiation times between 15 minutes and a few hours. (F.Gy.)