Proton irradiation parameters and chemical separation procedure for the bulk production of high-specific-activity ~(186g)Re using WO_3 targets

摘要

Rhenium-186g (T_(1/2) = 89.2h) is a β~- emitter suitable for therapeutic applications. Current production methods rely on reactor production via ~(185)Re (n, γ) which results in low specific activities, thereby limiting its use. Production by p, d activation of enriched 186 W results in a ~(186g)Re product with a higher specific activity, allowing it to be used for targeted therapy with limited receptors. A test target consisting of pressed, sintered ~(nat)WO_3 was proton irradiated at Los Alamos (LANL-IPF) to evaluate product yield and impurities, irradiation parameters and wet chemical Re recovery for proof-of-concept for bulk production of ~(186g)Re. We demonstrated isolation of ~(186g)Re in 97% yield from irradiated ~(nat)WO_3 targets within 12 h of end of bombardment (EOB) via an alkaline dissolution followed by anion exchange. The recovery process has potential for automation, and WO_3 can be easily recycled for recurrent irradiations. A ~(186g)Re batch yield of 42.7 ±2.2 μCi/|μAh or 439plusmn;23 MBq/C was obtained after 24 h in an 18.5 μA proton beam. The target entrance energy was determined to be 15.6 MeV. The specific activity of ~(186g)Re at EOB was measured to be 1.9 kCi (70.3 TBq) mmol ~(-1), which agrees well with the result of a previous ~(185,186m)Re coproduction EMPIRE and TALYS modeling study assuming similar conditions. Utilizing enriched ~(186)WO~3 we anticipate that a proton beam of 250 μA for 24 h will provide batch yields of 256 mCi (9.5 GBq) of ~(186g)Re at EOB with specific activities even higher than 1.9 kCi (70.3 TBq) mmol ~(-1), suitable for therapy applications.