Solid targets for 99mTc production on medical cyclotrons

Recent disruptions in the molybdenum-technetium generator supply chain prompted a review of non-reactor based production methods for both Mo-99 and Tc-99m. Small medical cyclotrons (E-p similar to 16-24 MeV) are capable of producing Curie quantities of Tc-99m from isotopically enriched Mo-100 using the Mo-100(p,2n) Tc-99m reaction. Unlike most other metallic target materials for routine production of medical radioisotopes, molybdenum cannot be deposited by reductive electroplating from aqueous salt solutions. To overcome this issue, we developed a new process for solid molybdenum targets based on the electrophoretic deposition of fine Mo-100 powder onto a tantalum plate, followed by high temperature sintering. The targets obtained were mechanically robust and thermally stable when irradiated with protons at high power density.