Speaker
Summary
Target manufacturing methods are key for radionuclide production. On the one hand, thin targets are useful for research activities such as cross section measurements using the stacked foils technique or to develop new chemical separation schemes using radiotracer. On the other hand, thick targets are mandatory for cost effective production of large radionuclide quantities as needed for radiopharmaceuticals. At GIP ARRONAX [1], we are focusing our work on innovative radionuclides for nuclear medicine and as such, we have to develop and characterized our own targets using the most appropriate technique. Over the last 15 years, we have developed the following techniques for target preparation:
Electrodeposition
Radiopharmaceuticals such as Cu-64, Cu-67 and Pb-203 are produced at GIP Arronax through irradiation of enriched target with light particles: Ni-64 for Cu-64, Zn-70 and Zn-68 for Cu-67 [2] [3] and Tl-205 for Pb-203 [4]. These enriched targets are manufactured by electrodeposition, which allows the preparation of both thin and thick layers.
Deposition under vacuum
Natural Bi targets are prepared by deposition under vacuum and subsequently irradiated with alpha particles to produce At-211, a promising α-emitter for targeted therapy. Thus technique allows for uniform thin or thick targets.
Molecular plating and co-electrodeposition
Obtaining enriched lanthanide deposits suitable for irradiation using electrodeposition or vacuum deposition remains challenging. In the case of electrodeposition, very negative standard potentials prevent metallic deposition, while vacuum deposition gives low yields and is problematic due to the high cost of enriched lanthanides. Molecular plating offers an alternative, yielding well-adhering, non-metallic deposits that require additional characterization. This technique has proven effective for lanthanide targets. Co-electrodeposition has also been developed, in which insoluble oxides (e.g., Gd2O3) are trapped in a nickel deposit [5]. Although deposition yields are low, residual particles in solution can be recycled for further use. These approaches are particularly suited for preparing thin deposits.
Pelletizing
Pelletizing provides an efficient method for preparing thick targets when electrodeposition or vacuum deposition is not feasible. Materials investigated include RbCl for Sr-82 production, Gd2O3 for Tb-155 production and Mo for Ru-97 production.
In this work, we intend to present an overview of the target manufacturing techniques currently applied at GIP Arronax, along with the characterization that have been developed to validate them and explain the choice of the most suitable method based on the physicochemical properties of each element.
[1] F. Haddad et al., “ARRONAX, a high-energy and high-intensity cyclotron for nuclear medicine,” Eur J Nucl Med Mol Imaging, vol. 35, no. 7, pp. 1377–1387, 2008, doi: 10.1007/s00259-008-0802-5.
[2] G. Pupillo et al., “New production cross sections for the theranostic radionuclide 67Cu,” Nucl Instrum Methods Phys Res B: Beam Interactions with Materials and Atoms, vol. 415, pp. 41–47, Jan. 2018, doi: 10.1016/j.nimb.2017.10.022.
[3] E. Nigron et al., “Is 70Zn(d,x)67Cu the Best Way to Produce 67Cu for Medical Applications?,” Front. Med., vol. 8, 2021, doi: 10.3389/fmed.2021.674617.
[4] T. Sounalet et al., “Manufacture of Tl targets by electrodeposition for the study of excitation functions of 203Pb,” EPJ Web Conf., vol. 285, p. 09001, 2023, doi: 10.1051/epjconf/202328509001.
[5] Y. Wang et al., “Electrochemical co-deposition of Ni–Gd2O3 for composite thin targets preparation: Production of 155Tb as a case study,” Appl Radiat Isot, vol. 186, p. 110287, Aug. 2022, doi: 10.1016/j.apradiso.2022.110287.
