Design of a Thorium Metal Target for 225Ac Production at TRIUMF

Abstract

With recent impressive clinical results of targeted alpha therapy using 225Ac, significant effort has been directed towards providing a reliable and sufficient supply of 225Ac to enable widespread using of 225Ac-radiopharmaceuticals. TRIUMF has begun production of 225Ac via spallation of thorium metal with 480 MeV protons. As part of this program, a new 225Ac-production target system capable of withstanding the power deposited by the proton beam was designed and its performance simulated over a range of potential operating parameters. Special attention was given to heat transfer and stresses within the target components. The target was successfully tested in two irradiations with a 72–73 µA proton beam for a duration of 36.5 h. The decay corrected activity at end of irradiation (average ± standard deviation) was (524 ± 21) MBq (14.2 mCi) and (86 ± 13) MBq (2.3 mCi) for 225Ac and 225Ra, respectively. These correspond to saturation yields of 72.5 MBq/µA for 225Ac and 17.6 MBq/µA for 225Ra. Longer irradiations and production scale-up are planned in the future.

Effect of graphite and graphene oxide on thorium carbide microstructural and thermal properties

“…At present, 225 Ac for clinical research is primarily produced from the decay of 229 Th stocks located in the USA, Russia and Germany, in turn obtained from stockpiles of 233 U 3 . Other explored approaches are the use of 226 Ra targets bombarded by protons or neutrons 4 and the direct irradiation of 232 Th with high-energy protons 5 . None of these techniques is free from the necessity of developing several stages of chemical purification to eliminate co-produced and undesired isotopes of actinium and other elements.…”

H2pyhox – Octadentate Bis(pyridyloxine)

“…[ 111 In]­InCl 3 was produced by BXWT (Vancouver, BC, Canada), and [ 64 Cu]­CuCl 2 was produced via a 64 Ni­(p,n) 64 Cu nuclear reaction and module-assisted separation . [ 225 Ac]­Ac 3+ was produced at the TRIUMF 500 MeV Isotope Production Facility (IPF) via irradiation of 232 Th foils; full details of the production are reported. , The radiolabeling of chelators was monitored and evaluated by instant thin layer chromatography (iTLC) plates (aluminum-backed silica gel (Si) or silicic acid impregnated paper (SA)) and evaluated by exposing plates to reusable imaging plates for 1 min, which were then read by a radioluminography laser scanner BAS-1800II (Raytest) and analyzed using the AIDA software or by counting immediately on a BioScan System 200 imaging scanner equipped with a BioScan Autochanger 1000. Radiolabeling and purity were assessed by HPLC on a Knauer Smartline System consisting of a Smartline 1000 pump, K2501 UV detector, Raytest Gabi Star activity detector, Chromgate 2.8 software, and a Smartline 5000 manager with a Phenomenex Synergi 4-μm Hydro/HP, 80 A, 250 × 4.6 mm.…”

A practical solution of the Bethe equation in the energy range applicable to radiotherapy and radionuclide production

“…Indeed, this problem is relatively unexplored on the theoretical front with most authors de-coupling the temperature effects 23–26 . In perhaps the most comprehensive study, O’Brien and her co-workers 25,27,28 couples Monte-Carlo simulation of the beam profile with Reynolds-Averaged Navier-Stokes (RANS) 29 modelling of the transport equations to estimate the temperature, density and beam profile. Interestingly, with these latter two categories, these deviations are not evident in our result in this range, even with gas.…”