Preliminary study on the yield of 225Ac produced by 35MeV@2mA electron accelerator

Abstract: Targeted alpha therapy, as a shining new star in the field of nuclear medicine, is showing great potential in the treatment of metastatic diseases with its unique advantages. 225Ac, as an important α-emitting medical radionuclide, its current production of less than 1.7 Ci/year restricts its development and widespread application. Therefore, exploring and optimizing the production method of 225Ac to increase its yield is crucial. Using a 35 MeV @ 2 mA electron accelerator to bombard a converter target produces a large number of photons. Through the photonuclear reaction 226Ra(γ, n)225Ra, 225Ra is generated, which can then undergo beta decay to produce 225Ac. Two kinds of isotope target, namely the solid plate radium target (“solid target” for short) and the solution radium target (“solution target” for short), were designed according to the special structure of the neutron source target station in this study. Under each kind of target, three target schemes, namely the internal target, the backend target and the U-shaped target were proposed. The FLUKA program was used to investigate the influence of both geometric and irradiation parameters of isotope and converter targets on the yield of 225Ac. The study shows that, the production capability of 225Ac is stronger with a solid target than with a solution target, and the 225Ac production capability of both solid and liquid targets is directly proportional to the irradiation time. In the internal target scheme, with a radium target containing 1.0 g of 226Ra and an irradiation time of 10 days, it is estimated that a 35 MeV @ 2 mA electron accelerator has an annual production capacity of 117.3 Ci of 225Ac when using a solid target and 12.32Ci when using a solution target. The results indicate that bombarding radium targets with an electron accelerator enables large-scale production of 225Ac, ensuring a stable isotope supply for medical, research, and other applications.