We have developed an improved generator for the production of the alpha emitting radionuclide 212Bi and its parent, 212Pb. These radionuclides are well suited to use as radiotherapeutic agents due to their relatively short half lives and appropriate particle particle emissions. The parent, 224Ra, is available from a long-lived parent and can be isolated on a generator which produces the daughters in good yield and low breakthrough. The 212Bi can be eluted by itself or in equilibrium with its parent.