Diversification in the Supply Chain of (99)Mo Ensures a Future for (99m)Tc

A quantitative description of the compatibility of technetium-selective chromatographic technetium-99m separation with low specific activity molybdenum-99

Technetium-99m generators employing a technetium-selective stationary phase are a chromatographic instrument developed for use with 99Mo having low specific activity (LSA); particularly, 99Mo produced by electron accelerators. This paper presents a mathematical description of technetium-selective chromatographic (TSC) 99mTc separation and analyzes its compatibility with LSA 99Mo. We developed a theoretical formula for TSC 99mTc separation by discretizing its pertechnetate selectivity, and validated it using an electron linear accelerator and activated carbon-based TSC (AC-TSC) 99mTc generators. We confirmed that the activity concentration of 99mTc obtained from a TSC 99mTc generator can be calculated directly from its input 99Mo activity regardless of the 99Mo specific activity. The formula corroborates that TSC 99mTc separation is compatible with LSA 99Mo, and has a practical application in estimating the number of TSC 99mTc generators required for 99mTc demand of interest.

Altered [99mTc]Tc-MDP biodistribution from neutron activation sourced 99Mo

Given potential worldwide shortages of fission sourced ⁹⁹Mo/^99mTc medical isotopes there is increasing interest in alternate production strategies. A neutron activated ⁹⁹Mo source was utilized in a single center phase III open label study comparing ^99mTc, as ^99mTc Methylene Diphosphonate ([^99mTc]Tc-MDP), obtained from solvent generator separation of neutron activation produced ⁹⁹Mo, versus nuclear reactor produced ⁹⁹Mo (e.g., fission sourced) in oncology patients for which an [^99mTc]Tc-MDP bone scan would normally have been indicated. Despite the investigational [^99mTc]Tc-MDP passing all standard, and above standard of care, quality assurance tests, which would normally be sufficient to allow human administration, there was altered biodistribution which could lead to erroneous clinical interpretation. The cause of the altered biodistribution remains unknown and requires further research.

Diversification of 99Mo/99mTc separation: non–fission reactor production of 99Mo as a strategy for enhancing 99mTc availability

This paper discusses the benefits of obtaining (99m)Tc from non-fission reactor-produced low-specific-activity (99)Mo. This scenario is based on establishing a diversified chain of facilities for the distribution of (99m)Tc separated from reactor-produced (99)Mo by (n,γ) activation of natural or enriched Mo. Such facilities have expected lower investments than required for the proposed chain of cyclotrons for the production of (99m)Tc. Facilities can receive and process reactor-irradiated Mo targets then used for extraction of (99m)Tc over a period of 2 wk, with 3 extractions on the same day. Estimates suggest that a center receiving 1.85 TBq (50 Ci) of (99)Mo once every 4 d can provide 1.48-3.33 TBq (40-90 Ci) of (99m)Tc daily. This model can use research reactors operating in the United States to supply current (99)Mo needs by applying natural (nat)Mo targets. (99)Mo production capacity can be enhanced by using (98)Mo-enriched targets. The proposed model reduces the loss of (99)Mo by decay and avoids proliferation as well as waste management issues associated with fission-produced (99)Mo.