DOI: 10.1186/s41181-017-0033-9Pages: 1-17

Production and separation of 43Sc for radiopharmaceutical purposes

1. Paul Scherrer Institute, Laboratory of Radiochemistry

2. University of Bern, Department of Chemistry and Biochemistry

3. Paul Scherrer Institute, Center for Radiopharmaceutical Sciences ETH-PSI-USZ

4. ETH Zurich, Department of Chemistry and Applied Biosciences

5. GSI Helmholtzzentrum für Schwerionenforschung GmbH

6. University of Bern, Albert Einstein Center for Fundamental Physics (AEC), Laboratory for High Energy Physics (LHEP)

Correspondence to:
Nicholas P. van der Meulen
Email: nick.vandermeulen@psi.ch

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Abstract

Background

The favorable decay properties of 43Sc and 44Sc for PET make them promising candidates for future applications in nuclear medicine. An advantage 43Sc (T1/2 = 3.89 h, Eβ+av = 476 keV [88%]) exhibits over 44Sc, however, is the absence of co-emitted high energy γ-rays. While the production and application of 44Sc has been comprehensively discussed, research concerning 43Sc is still in its infancy. This study aimed at developing two different production routes for 43Sc, based on proton irradiation of enriched 46Ti and 43Ca target material.

Results

43Sc was produced via the 46Ti(p,α)43Sc and 43Ca(p,n)43Sc nuclear reactions, yielding activities of up to 225 MBq and 480 MBq, respectively. 43Sc was chemically separated from enriched metallic 46Ti (97.0%) and 43CaCO3 (57.9%) targets, using extraction chromatography. In both cases, ~90% of the final activity was eluted in a small volume of 700 μL, thereby, making it suitable for direct radiolabeling. The prepared products were of high radionuclidic purity, i.e. 98.2% 43Sc were achieved from the irradiation of 46Ti, whereas the product isolated from irradiated 43Ca consisted of 66.2% 43Sc and 33.3% 44Sc. A PET phantom study performed with 43Sc, via both nuclear reactions, revealed slightly improved resolution over 44Sc. In order to assess the chemical purity of the separated 43Sc, radiolabeling experiments were performed with DOTANOC, attaining specific activities of 5–8 MBq/nmol, respectively, with a radiochemical yield of >96%.

Conclusions

It was determined that higher 43Sc activities were accessible via the 43Ca production route, with a comparatively less complex target preparation and separation procedure. The product isolated from irradiated 46Ti, however, revealed purer 43Sc with minor radionuclidic impurities. Based on the results obtained herein, the 43Ca route features some advantages (such as higher yields and direct usage of the purchased target material) over the 46Ti path when aiming at 43Sc production on a routine basis.

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  • Accepted: Nov 10, 2017
  • Online: Nov 25, 2017

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