Production and separation of 186gRe from proton bombardment of 186WC

Abstract

A proof of concept study was undertaken where non-carrier added (186 g)Re was produced from the cyclotron bombardment of (186)WC. (186)WC was carbo-thermally generated from a novel precursor synthesized from (186)WO3, aqueous ammonia and hexamethyltetramine. The inherent high electrical and thermal conductivity of this material, coupled with its high melting point, made it an ideal candidate for proton bombardment for production of (186)Re. An18 μA irradiation for 3h and processing via thermo-chromatography, (186)WC yielded 0.93 mCi of (186 g)Re which corresponds to 89% of the calculated theoretical yields. The radiochemical purity of the desired (186 g)Re species was found to be between 95 and 97% with small contaminants of (186)ReO2. The radiochemistry utility of the product was investigated using S-benzoyl-MAG3, and 100% complexation was achieved with stability being maintained for 96 h. The re-oxidation of (186)WC back to(186)WO3 by oxygen in the thermo-chromatography method of processing ensured that the starting material was regenerated and recovered from the process in 94-98% yield.

Deuteron irradiation of W and WO3 for production of high specific activity 186Re: Challenges associated with thick target preparation

“…Sintering of W metal targets is also not possible at our facility, as the available furnaces do not begin to approach its melting point of 3422°C. Recently, Lapi et al have described production and irradiation of enriched tungsten carbide ( 186 WC) targets for production of high specific activity 186 Re (Richards et al, 2015). While this approach is attractive for target fabrication, the effort that is required to conduct the multiple steps and the time involved in the isolation process does not appear to have any advantages to the use of graphite-encased 186 W metal targets.…”

“…The overall goal of this investigation was to demonstrate that production-levels of high specific activity 186 Re can be obtained via the (d,2n) reaction using thick W targets. Prior reported studies have used a variety of target materials for production of 186 Re, including W metal (Bonardi et al, 2010;Zhang et al, 2001;Zhang et al, 1999), WO 3 (Fassbender et al, 2013;Moustapha et al, 2006;Shigeta et al, 1996), Al 2 (WO 4 ) 3 (Zhu et al, 1997), and W carbides (Richards et al, 2015). However, those studies were limited to "thin" target bombardments or thick target investigations using only natural abundance target 3 material.…”

Radiometals for imaging and theranostics, current production, and future perspectives

“…186 Re can be produced in many nuclear reactors throughout the world, depending upon the specific activity requirements. 70 No-carrier-added 186 Re can also be produced by proton or deuteron bombardment of 186 W using a cyclotron [71][72][73] ; however, its availability via this route is still limited because of the lower yields of these reactions. Re with sufficient specific activity in many reactors, although this route has not been widely pursued for 188 Re availability.…”

Bulk production and evaluation of high specific activity 186gRe for cancer therapy using enriched 186WO3 targets in a proton beam

“…A critical review of the two reactions was performed [17], and an upper proton energy limit for the (p,n) reaction of 18 MeV was identified. Radiorhenium formed in matrices of either W metal or WO 3 may be chemically separated via dry distillation [18][19][20], liquid-liquid extraction [21] or anion-exchange controlled liquid-solid sorption [22][23][24] from aqueous target solutions prepared from either the metal (requiring oxidizer and base) or the trioxide (requiring base only).…”