Accelerator production routes for therapeutic alpha emitters
In plain words
The most promising alpha-emitting drugs are limited by how little of the isotope can be made. Which production reaction is best is not settled.
Precise statement
Determine the optimal production route for Ac-225 and related $\alpha$ emitters by measuring excitation functions and co-produced impurities for proton spallation of thorium-232, photonuclear production from Ra-226, and deuteron or $\alpha$ routes, in the energy ranges used by available accelerators. Key figure of merit: yield per beam hour at required radionuclidic purity, in particular Ac-227 contamination. An answer is cross sections and yields fixing the preferred route.
What would settle it
Measured excitation functions and target tests reporting yield and impurity levels for each route.
Status in the literature
Accelerator routes expanded supply after about 2018 while impurity control and scale-up remained limiting.