Cyclotron production of rhodium-101m from natural palladium radiochemical methods and preliminary biological studies

Rh coordination complexes having anticancer properties have been known since 1931. sup(101m)Rh has excellent decay properties and can be used to study the biological behaviour of Rh-complexes in vivo. A method for its production using cyclotron technology is described. The yields for 101Pd, 100Pd, sup(101m)Rh, and 100Rh, produced by proton bombardment of natural Pd, are reported for proton energies from 40- to 60-MeV. sup(101m)Rh thick-target yields of 0.9 m Ci/μAh at 32.7 h EOB were measured. A method is proposed to prepare No Carrier Added (NCA) sup(101m)Rh in a chemical form suitable for labelling and/or clinical research. sup(101m)Rh-chloride, sup(101m)Rh-acetate, and sup(101m)Rh-DTPA complexes were prepared and used to determine their in vivo distribution in tumor-bearing laboratory animals. Results of these studies indicated the kidneys and liver being the primary target organs. However, bone and tumor uptakes for sup(101m)Rh-DTPA were significantly different, with bone levels continuing to increase at 48-h and tumor levels maximizing at approximately 24-h post administration. The half-life of sup(101m)Rh was measured as 4.26+-0.01 days. (author)