Evaluation of (WS2)-W-186 target material for production of high specific activity Re-186 via proton irradiation: separation, radiolabeling and recovery/recycling

Enriched tungsten disulfide ((WS2)-W-186) was evaluated at increasing proton beam currents (20-50 mu A) and times (up to 4 h) on a GE PETtrace cyclotron for production of high specific activity (HSA) Re-186. The HSA Re-186 was separated from the irradiated target as [Re-186][ReO4](-) by a liquid-liquid extraction method and radiolabeled with a new N2S2 ligand (222-MAMA-N-ethylpropionate). The enriched W-186 was recovered from the extraction process, analyzed for purity and enrichment, and converted back to the disulfide ((WS2)-W-186). The results demonstrate that the (WS2)-W-186 is an easily pressed target material that can withstand relatively high currents and can be readily recovered and recycled. The Re-186 produced was isolated in high specific activity and readily formed the radiotracers [Re-186][ReO(222-MAMA-N-ethylpropionate)] and [Re-186][Re(CO)(3)(OH2)(3)] (+).