Evaluation of an internal cyclotron target for the production of At-211 via the Bi-209 (alpha,2n)At-211 reaction

Astatine-211 is a 7.2 h half-life alpha-emitting radionuclide which has shown great promise for targeted radiotherapy. It is generally produced by cyclotron bombardment of bismuth metal targets with 28 MeV alpha-particles via the Bi-209(alpha, 2n)(211). At reaction. In order to provide At-211 activity levels anticipated for clinical investigations, an internal target system has been designed and evaluated. The system has a grazing-angle configuration and leading- and trailing-edge monitors. Both aluminum and copper target backings were evaluated. With approx. 28 MeV alpha-particles, the At-211 production efficiency was 41 +/- 7 MBq/mu A . h, compared with 10.6 +/- 1.2 MBq/mu A . h for an external target. Radionuclidic purity of At-211 was high with no evidence of At-210.