Due to the widespread availability of 99mTc generators supplied from fission production of 99Mo, alternative supply sources such as technetium radioisotope production directly from conventional medical cyclotrons were long neglected. Given the shortage of 99Mo caused by the unexpected prolonged and/or permanent shutdown of some working reactors in 2008, the need to explore alternative methods of producing technetium radioisotopes attracted significant interest, with particular focus on the cyclotron route. This would allow for the continued use of all existing radiopharmaceuticals designed for 99mTc in nuclear medicine should another shortage occur.
In this Coordinated Research Project (CRP), the focus was on the direct production of 99mTc from proton bombardment of enriched molybdenum. Usable quantities of 99mTc were produced by the 100Mo(p,2n)99mTc reaction which peaked in the cross-section at 15-16 MeV, well within the reach of many commercial cyclotrons.
Eleven Member State participants worked on this project for five years, leading to the development and introduction of at least five automated sample modules for in house radioisotope production. Selected guidelines and formulations were used in the preparation of an IAEA book entitled: Cyclotron-based Production of Technetium-99m:(http://www-pub.iaea.org/MTCD/Publications/PDF/P1743_web.pdf) in 2016. As an outcome of this CRP, many countries have focused on this route when planning their future radiopharmacy programmes.
The CRP opened up a new window for the preparation, quality control and evaluation of cyclotron based Tc-99m pertechnetate and related radiopharmaceuticals, including targetry, irradiation, separation, quality control and recycling of the target materials.
At optimum conditions, a high current cyclotron was used to produce 350 GBq (>9 Ci) of 99mTc, which can supply a large metropolitan area (18 MeV protons, 250μA, six-hour irradiation). Higher yields can be reached with higher energy cyclotrons and/or with a more intense beam current (>1.184TBq (32 Ci) at 24 MeV and 450 μA).
Researchers from Armenia, Canada, Hungary, India, Japan, Italy, Korea, Poland, Saudi Arabia, Syria and the USA participated in this CRP.
The results of the four-year CRP were published in more than 15 internationally recognised scientific journals. At least four PhD dissertations were undertaken within the framework of the project at two CSI centres. Besides the IAEA publication, a monograph on “Sodium Tc-99m pertechnetate radiopharmaceutical” was developed in European Pharmacopea.
For more information, please see the CRP description: