Studies on the separation of 99mTc from large excess of molybdenum

BACKGROUND: Due to aging and unexpected prolonged shutdown of nuclear reactors producing 99Mo for 99Mo/ 99mTc generators it was necessary to explore the alternative methods of technetium-99m production. The first choice were the accelerators. Three years ago IAEA (International Atomic Energy Agency) initiated the Coordinated Research Project “Accelerator-based Alternatives to Non-HEU production of Mo-99 /Tc-99m” aimed at direct production of 99mTc in proton accelerators using the 100Mo(p,2n)99mTc reaction. POLATOM is participating in this enterprise together with the Heavy Ion Laboratory of Warsaw University and the Institute of Nuclear Chemistry and Technology. MATERIAL AND METHODS: 99Mo/99mTc solutions and pure 99mTc used for generators production or milked from ready to use generators were used in experiments. Commercial chromatographic and laboratory-prepared columns were used for separation. The peristaltic pumps were used for solutions delivery onto the columns. Radioactivity of eluted 99Mo and 99mTc was measured using high resolution gamma spectrometry or ionisation chamber in case of high radioactivity. For separation, three different chromatographic methods were used, one based on ion exchange and two on extraction. RESULTS: Synthetic mixtures simulating the real solutions were used. 99mTc is quantitatively bound in the Dowex-1 × 8 column whereas molybdenum is only slightly retained and totally rinsed with 2M NaOH. 99mTc is eluted with TBAB. The elution yield has been reproducible and amounted to 78%. The AnaLig Tc-02 resin column was used for 99mTc retention. Residual Mo was removed by rinsing with 2M NaOH and 99mTc eluted using small volume of water. The recovery was equal to about 85%. Using C-18 column coated with PEG over 80% of 99mTc was recovered in about 50 mL of water. The reduction of volume was necessary. CONCLUSIONS: The recovery of 99mTc was the highest using AnaLig Tc-02 resin. Time of 99mTc separation is the shortest for AnaLig Tc-02 resin and it is not higher than 100 minutes and it can further be shortened

Improved procedures of Sc(OH)3 precipitation and UTEVA extraction for 44Sc separation

BACKGROUND: 44Sc is becoming attractive as a PET radionuclide due to its decay characteristics. It can be produced from 44Ca present in natural calcium with 2.08% abundance. MATERIALS AND METHODS: The targets were mostly prepared from natural CaCO3 or metallic calcium in the form of pellets. After irradiation they were dissolved in 3 M hydrochloric acid and 44Sc was separated from excess of calcium by precipitation of scandium hydroxide using ammonia. Alternatively, targets were dissolved in 11 M hydrochloric acid and 44Sc was separated by extraction chromatography on UTEVA resin. As the next step, in both processes 44Sc was further purified on a cation exchange resin. Initially, the separation procedures were developed with 46Sc as a tracer. Gamma spectrometry with a high purity germanium detector was used to determine the separation efficiency. Finally, the CaCO3 pellet with 99.2% enrichment in 44Ca was activated with protons via 44Ca(p,n)44Sc nuclear reaction. RESULTS: Altogether twenty two irradiations and separations were performed. The working procedures were developed and the quality of separated 44Sc solution was confirmed by radiolabeling of DOTATATE. The chemical purity of the product was sufficient for preclinical experiments. At the end of around 1 hour proton beam irradiation of CaCO3 pellet with 99.2% enrichment in 44Ca the obtained radioactivity of 44Sc was more than 4.8 GBq. CONCLUSION: 44Sc can be produced inexpensively with adequate yields and radionuclidic purity via 44Ca(p,n)44Sc nuclear reaction in small cyclotrons. The recovery yield in both investigated separation methods was comparable and amounted above 90%. The obtained 44Sc was pure in terms of radionuclide and chemical purity, as shown by the results of peptide radiolabeling

Chemistry and bifunctional chelating agents for binding (177)Lu

A short overview of fundamental chemistry of lutetium and of structural characteristics of lutetium coordination complexes, as relevant for understanding the properties of lutetium-177 radiopharmaceuticals, is presented. This includes basic concepts on lutetium electronic structure, lanthanide contraction, coordination geometries, behavior in aqueous solution and thermodynamic stability. An illustration of the structure and binding properties of the most important chelating agents for the Lu(3+) ion in aqueous solution is also reported with specific focus on coordination complexes formed with linear and macrocyclic polydentate amino-carboxylate donor ligands