Comparison of standard and modified 99Mo/99mTc radionuclide generators

Abstract 99m Tc is the most widely used radionuclide in medical diagnostics and typically obtained from high-specific-activity (HSA) 99 Mo produced in nuclear reactors. However, recent reactor shutdowns have led to supply shortages and prompted efforts to implement alternative production methods. One promising approach is neutron activation of 98 Mo, which yields low-specific-activity (LSA) 99 Mo. Since conventional Al 2 O 3 -based 99 Mo/ 99m Tc generators are designed for HSA 99 Mo, adaptations are required for LSA 99 Mo usage. In this study, we evaluated the feasibility of modifying existing Al 2 O 3 -based 99 Mo/ 99m Tc generators for use with LSA 99 Mo, anticipating production at the planned high brilliance neutron source (HBS) at Forschungszentrum Jülich. Key modifications included adjustments to the amount of Al 2 O 3 on the column and the elution volume of 99m Tc to enhance 99 Mo adsorption and 99m Tc elution efficiency. The performance of the modified “mock-up” system was compared with a standard clinical generator. The results demonstrated that only minor modifications are required for LSA 99 Mo to be effectively utilized in a future generator, with elution efficiencies remaining comparable to conventional generators, while maintaining parameters like size, form, number, activity of the individual generator comparable. However, 99 Mo breakthrough levels exceeded regulatory limits, highlighting the need for further optimization. Nevertheless, these findings support the feasibility of using LSA 99 Mo in clinical applications with minimal changes to existing infrastructure.