- Emission
- 4 α particles over its decay chain (via ²²¹Fr, ²¹⁷At, ²¹³Bi); ~28 MeV total
- Production
- Legacy: decay of ²²⁹Th from US ²³³U stockpile (DOE/ORNL, TerraPower). Accelerator: ²²⁶Ra(p,2n)²²⁵Ac on cyclotrons (Eckert & Ziegler, Bayer/Nusano route), photonuclear ²²⁶Ra(γ,n)²²⁵Ra→²²⁵Ac (NorthStar), high-energy spallation of ²³²Th (DOE Tri-Lab, contains ²²⁷Ac impurity).
- Suppliers
- DOE Isotope Program, TerraPower Isotopes (Philadelphia plant under construction, ~20× capacity), Eckert & Ziegler, NorthStar Medical Radioisotopes, Nusano, Ionetix, Bayer (in-house), RayzeBio/BMS (in-house), Niowave.
- Supply
- The binding constraint on targeted alpha therapy. Global supply in the mid-2020s was roughly enough for low thousands of patient doses per year; multiple phase 3 programmes (Novartis, Bayer, BMS, AstraZeneca) need far more. Commercial-scale expansion is described as a 3 to 5 year effort.