Cyclotron-based production of technetium radioisotopes

Objectives Recent supply disruptions of Mo-99 have seeded efforts to establish alternative methods for producing Tc-99m. We are exploring the feasibility of direct production of Tc-99m from isotopically enriched Mo-100 using existing cyclotron technology. In the event of future supply disruptions, sufficient quantities of Tc-99m can be produced for radiopharmacies without the need for Mo-99 generators. Tc-94m, a PET isotope, can be produced from Mo-94 using a similar approach.

Methods Proof-of-principle studies for producing Tc-99m and Tc-94m have long been known. We seek to demonstrate the practicality of this technology from bench to bedside by developing an appropriate target system and chemical isolation method for Tc-99m/94m. In addition, the chemical, radiochemical and radionuclidic purity of both Tc-99m/94m pertechnetate will be established. Finally, kit-based radiopharmaceutical production for each isotope will be examined and benchmarked using standard quality control measures.

Results Low, mid- and high-current targets will be manufactured and used to produce Tc-99m and Tc-94m from enriched Mo targets. Tc-99m vs. Tc-99g ratios from a 150 μA beam of 19 MeV protons will be determined. An automated target release system will be designed and used prior to testing a strongly basic anion exchange extraction method as a means to isolate Tc from the target material. Radionuclidic purity will be examined prior to testing the incorporation of both Tc-99m and Tc-94m into Tc-Sestamibi, Tc-MDP, Tc-DMSA, Tc-pyrophosphate and Tc-HMPAO kits. The latter radiopharmaceuticals are important due to their sensitivity to the presence of Tc-99g and other impurities.

Conclusions Direct on-target production of Tc-99m/94m from isotopically enriched Mo-100 or Mo-94 targets is a viable approach to enable regional distribution of sufficient quantities of pertechnetate in the event of future supply disruptions.

Research Support This research is supported through NSERC (90%) and CIHR (10%)