Cyclotron production of 99mTc: Recycling of enriched 100Mo metal targets

Abstract

There is growing interest in the large scale cyclotron production of 99mTc via the 100Mo(p,2n)99mTc reaction. While the use and recycling of cyclotron-irradiated enriched molybdenum targets has been reported previously in the context of 94mTc production, to the best of our knowledge, previous recycling studies have been limited to the use of oxide targets. To facilitate reuse of high-power enriched 100Mo targets, this work presents and evaluates a strategy for recycling of enriched metallic molybdenum. For the irradiated 100Mo targets in this study, an overall metal to metal recovery of 87% is reported. Evaluation of “new” and “recycled” 100Mo revealed no changes in the molybdenum isotopic composition (as measured via ICP-MS). For similar irradiation conditions of “new” and “recycled” 100Mo, (i.e. target thicknesses, irradiation time, and energy), comparable levels of 94gTc, 95gTc, and 96gTc contaminants were observed. Comparable QC specifications (i.e. aluminum ion concentration, pH, and radiochemical purity) were also reported. We finally note that [99mTc]–MDP images obtained by comparing MDP labelled with generator-based 99mTc vs. 99mTc obtained following the irradiation of recycled 100Mo demonstrated comparable biodistribution. With the goal of producing large quantities of 99mTc, the proposed methodology demonstrates that efficient recycling of enriched metallic 100Mo targets is feasible and effective.