Astatine-211: Production and Availability

The 7.2-h half life radiohalogen 211At offers many potential advantages for targeted α-particle therapy; however, its use for this purpose is constrained by its limited availability. Astatine-211 can be produced in reasonable yield from natural bismuth targets via the 209Bi(α,2n)211At nuclear reaction utilizing straightforward methods. There is some debate as to the best incident α-particle energy for maximizing 211At production while minimizing production of 210At, which is problematic because of its 138.4-day half life α-particle emitting daughter, 210Po. The intrinsic cost for producing 211At is reasonably modest and comparable to that of commercially available 123I. The major impediment to 211At availability is attributed to the need for a medium energy α-particle beam for its production. On the other hand, there are about 30 cyclotrons in the world that have the beam characteristics required for 211At production.