Experience in Developing Radiation Sources for Personalized Brachytherapy Based on Titanium Alloys

Abstract

Purpose: The study explores the possibility of manufacturing radiation sources for personalized brachytherapy using titanium alloys, activated in a neutron flux reactor, by measuring the radiation composition of applicator implants and their dosimetric characteristics. Material and methods: A 3D implant of a brachytherapy source was made from a titanium alloy using an additive selective laser melting setup. The titanium 3D prototype was irradiated for three days in the horizontal experimental channel of the IR-8 reactor. Subsequently, measurements of the gamma-ray spectrum from the irradiated implant were carried out on a spectrometer, and dose characteristics of the 3D implant were measured using a dosimeter-radiometer. Results: In the experimental 3D implant obtained by us, the radionuclide 47Sc exhibits the highest activity. Currently, 47Sc is considered a promising candidate for brachytherapy. It possesses attractive nuclear and physical properties as a β-emitter, decaying into the ground state (27 %) of 47Ti (Eβmax = 600 keV) and the excited state of 47Ti (Eβmax = 439 keV) with a half-life of 3.4 days. Additionally, 47Sc emits γ-radiation at an energy of 159 keV (68 %), which is suitable for imaging, allowing for SPECT or planar scintigraphy and obtaining a picture of the drug’s distribution in the body. In the experimental implant, small amounts of scandium radionuclides – 46Sc and 48Sc, were also detected, emitting sufficiently hard gamma radiation, which can pose a problem for patient dosage determination. The advantages of using titanium-47 with an enrichment of over 95 %, economically available, have been demonstrated, allowing for high radiochemical yields of 47Sc, sufficient for therapy. Conclusion: The 3D printing technology allows the production of a customized applicator for brachytherapy of specific dimensions and the delivery of arbitrarily-shaped sources to the tumor area for personalized therapy of oncological diseases. When implanting sources based on titanium alloys activated in a neutron flux of a research nuclear reactor, the radionuclide scandium-47 exhibits the highest activity.