Rhenium-186 (t1/2 = 3.72 d) is a highly desirable radionuclide that emits therapeutic β- particles with a β-max energy of 1.07 MeV, allowing for a targeted tissue range of up to 3.6 mm. In addition, its 137 keV (8.6%) gamma emission makes it suitable for theranostic applications. Currently, low specific activity 186Re is produced in a reactor via the 185Re(n,g)186Re nuclear reaction, but demand for high specific activity 186Re for targeted radiotherapy applications can potentially be met using charged-particle activation of 186W targets via the 186W(d,2n)186Re nuclear reaction. A graphite-encased 186W metal target (99.9% enriched) was prepared by uniaxially pressing 186W metal powder between two layers of graphite flakes with 13.8 MPa of hydraulic pressure. The target was bombarded with 22 MeV deuterons for a total of 27 μAh, with an estimated incident deuteron energy of 19.5 MeV on the 186W metal layer. Following a cool-down period to allow co-produced W-187 to decay, the target was dissolved using 30% H2O2 and then divided into two aliquots. Separation of the 186Re product in these aliquots was evaluated using an Analig Tc-02 resin column procedure and a methyl ethyl ketone (MEK) solvent extraction procedure. The isolated 186Re product was evaluated by radiolabeling a 222-MAMA-N-propionate ligand. Further studies were performed to optimize separation yield conditions by varying resin type, loading solution, and target mass. An EOB 186Re yield of 0.611 GBq (16.5 mCi) was obtained after a 27 μAh deuteron bombardment. We report a method for the production and separation of high specific activity 186Re from the deuteron bombardment of graphite-encased 186W metal targets. Both separation methods resulted in high recovery yields of 186Re, which was then successfully used to radiolabel a 222-MAMA-N-propionate ligand.

Production of high specific activity rhenium-186 via the 186W(d,2n)186Re nuclear reaction using pressed tungsten-186 metal targets and evaluation of separation methods

ACS Spring Meeting 2021

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