Recycle of enriched Mo targets for economic production of 99Mo/99mTc medical isotope without use of enriched uranium

Studies on electrochemical dissolution of sintered molybdenum discs as a potential method for targets dissolution in 99mTc production

Electrochemical dissolution of pressed into discs and sintered metallic molybdenum powder with the mass of 712 ± 10 mg (n = 15) in potassium hydroxide solution was studied in detail. The technique was considered to apply for dissolution of irradiated 100Mo target in the 99mTc production. The effect of various parameters, e.g., the concentration of the electrolyte solution, temperature, current density, and surface area of the platinum cathode, was investigated. The shortest time for total dissolution of molybdenum target was 70 min. This result was achieved using an electrolyte solution of 5 M KOH, temperature 55 °C and the current density of 365 mA/cm2.

Electron-tracking Compton camera imaging of technetium-95m

Imaging was conducted using an electron tracking-Compton camera (ETCC), which measures γ-rays with energies in the range of 200-900 keV from 95mTc. 95mTc was produced by the 95Mo(p, n)95mTc reaction on a 95Mo-enriched target. A method for recycling 95Mo-enriched molybdenum trioxide was employed, and the recycled yield of 95Mo was 70%-90%. Images were obtained with the gate of three energies. The results showed that the spatial resolution increases with increasing γ-ray energy, and suggested that the ETCC with high-energy γ-ray emitters such as 95mTc is useful for the medical imaging of deep tissue and organs in the human body.

95gTc and 96gTc as alternatives to medical radioisotope 99mTc

We studied 95gTc and 96gTc as alternatives to the medical radioisotope 99mTc. 96gTc (95gTc) can be produced by (p, n) reactions on an enriched 96Mo (95Mo) target with a proton beam provided by a compact accelerator such as a medical cyclotron that generate radioisotopes for positron emission tomography (PET). The γ-rays are measured with an electron-tracking Compton camera (ETCC). We calculated the relative intensities of the γ-rays from 95gTc and 96gTc. The calculated γ-ray intensity of a 96gTc (95gTc) nucleus is as high as 63% (70%) of that of a 99mTc nucleus. We also calculated the patient radiation doses of 95gTc and 96gTc, which were larger than that of 99mTc by a factor of 2-3 based on the applied assumptions. A medical PET cyclotron which can provide proton beams with energies of 11-12 MeV and a current of 100 μA can produce 12 GBq (39 GBq) of 96gTc (95gTc) for operation time of 8 h, which can be used for 240 (200) diagnostic scans.

Cyclotron production of 99mTc: Comparison of known separation technologies for isolation of 99mTc from molybdenum targets

Intensive efforts were undertaken during the last few decades for the separation of cyclotron-produced ^99mTc from ⁹⁹Mo and new papers have been published on this topic since the last review [1]. In the future the cyclotron-based methods can replace reactor-based technology in producing this medical radioisotope and the nuclear reaction ¹⁰⁰Mo(p,2n)^99mTc appears to be the most worthwhile approach. New ways of producing of ^99mTc require efficient separation methods. Several strategies for separation of ^99mTc from ⁹⁹Mo have been already developed. The advantages, disadvantages and technical challenges toward application potential of investigated methods to separate ^99mTc from irradiated ¹⁰⁰Mo target are discussed. These methods include column chromatography, solvent extraction, chemical precipitation and thermochromatography.