| Résumé | There has been growing clinical evidence of the value of targeted alpha therapy for the treatment of several cancers. The work has been slowed by the lack of availability of the key alpha emitting isotopes, especially Ac-225. It can be produced by photonuclear reaction, Ra-226(γ,n)Ra-225. The Ra-225 decays via beta-decay to Ac-225 with a half-life of 14.9 days. This paper will provide a technical description of radium targets and a target chamber that would be capable of producing a yield of about 148 GBq (4 Ci) of Ra-225 from a 10-day irradiation of 1 g of radium segmented into two to four separate encapsulated targets at a beam power of 20 kW. These targets could be milked at least three times, yielding nearly 148 GBq (4 Ci) of Ac-225. There is also a description of a method to reduce the activity of co-produced Ac-227 to values less than a few parts per million of the activity of Ac-225. The Monte Carlo code Fluka has been used to model the yields of Ra-225 and support the design concept to reduce the production of Ac-227. It has also been used to model the experimental results by Maslov et al. [Radiochemistry 48(2), 195–197 (2006)] to provide reasonable confidence in the cross section value used by the code. |
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