Implementation of Multi-Curie Production of ^99mTc by Conventional Medical Cyclotrons

Abstract

99m Tc is currently produced by an aging fleet of nuclear reactors, which require enriched uranium and generate nuclear waste. We report the development of a comprehensive solution to produce 99m Tc in sufficient quantities to supply a large urban area using a single medical cyclotron. Methods: A new target system was designed for 99m Tc production. Target plates made of tantalum were coated with a layer of 100 Mo by electrophoretic deposition followed by high-temperature sintering. The targets were irradiated with 18-MeV protons for up to 6 h, using a medical cyclotron. The targets were automatically retrieved and dissolved in 30% H 2 O 2 . 99m Tc was purified by solid-phase extraction or biphasic exchange chromatography. Results: Between 1.04 and 1.5 g of 100 Mo were deposited on the tantalum plates. After high-temperature sintering, the 100 Mo formed a hard, adherent layer that bonded well with the backing surface. The targets were irradiated for 1-6.9 h at 20-240 μA of proton beam current, producing up to 348 GBq (9.4 Ci) of 99m Tc. The resulting pertechnetate passed all standard quality control procedures and could be used to reconstitute typical anionic, cationic, and neutral technetium radiopharmaceutical kits. Conclusion: The direct production of 99m Tc via proton bombardment of 100 Mo can be practically achieved in high yields using conventional medical cyclotrons. With some modifications of existing cyclotron infrastructure, this approach can be used to implement a decentralized medical isotope production model. This method eliminates the need for enriched uranium and the radioactive waste associated with the processing of uranium targets.

Radioisotopic Purity of Sodium Pertechnetate 99mTc Produced with a Medium-Energy Cyclotron: Implications for Internal Radiation Dose, Image Quality, and Release Specifications

“…Pressing protocol was standardized as much as possible to produce a consistent-density pellet. The 100 Mo packing density in pressed targets is different from crystal density for molybdenum (used in SRIM), but as long as target thickness in units of g/cm 2 remains unchanged, energy attenuation will be the same. Targets were prepared at the Laboratory of Materials Preparation and Characterization of the Brockhouse Institute for Materials Research, McMaster University, Ontario, Canada, according to the specifications provided above.…”

“…Cyclotron production of 99m Tc could be a viable alternative or a complement to the current supply chain of 99m Tc radiopharmaceuticals. The amount of 99m Tc produced using a conventional medical cyclotron operating at 16218 MeV can be sufficient to support local demand (1,2). Higher 99m Tc yields can be obtained with medium-energy cyclotrons capable of accelerating protons up to 24 MeV.…”

“…Theoretic calculations on the extent of 99m Tc radioisotopic purity and experimental evaluation of cross sections on thin foils made of enriched molybdenum were conducted previously by others (3,4). This work evaluated the quality of sodium pertechnetate 99m Tc produced with a cyclotron starting from thick (0.58, 0.72, and 0.88 g/cm 2 ) 100 Mo targets. We present here experimental results of the irradiations at 20224 MeV, including chemical, radiochemical, and radionuclidic purity of produced sodium pertechnetate 99m Tc and its imaging efficacy and explain initial grounds for proposed release specifications.…”

Diversification of 99Mo/99mTc Separation: Non–Fission Reactor Production of 99Mo as a Strategy for Enhancing 99mTc Availability

“…Highly enriched 100 Mo targets are irradiated with 18-to 25-MeV protons to yield 99m Tc [ 100 Mo(p,2n) 99m Tc]. As an example, a 1.5-g 100 Mo solid target irradiated with 18-MeV protons at 240-mA beam current for 6 h can provide about 333 GBq (9 Ci) of 99m Tc at end of bombardment (EOB) (5). The possibility of such a strategy will depend on daily irradiation of 100 Mo targets and radiochemical processing to recover 99m Tc as pertechnetate solution before distribution (Fig.…”

The Study of 99mTc Production Using Medical Cyclotrons in Ukraine

“…Because of the closure of the 2 main production centers (NRU reactor, Canada, and HFR reactor, Netherlands), that cover more than 70 % of the world demand [1], the massive shortage of isotope supply is expected with subsequent price escalation. Thus, today one of the relevant questions in this field is the searching for new suppliers and the development of alternative ways of tracer production, where the cyclotron's technology is considered as a priority method [2][3][4][5][6][7][8]. Despite relatively low isotope yield in comparison with reactors, cyclotron production has its own advantages that are absence of contamination, low cost, and decentralization.…”