Most radioisotopes used in nuclear medicine are currently produced with either research nuclear reactors or cyclotrons, the production method depending upon the desired isotope. Several of the most heavily used isotopes (Mo-99/Tc-99m, Y-90, I-131, and others) are derived from fission of uranium in reactors, although some isotopes can also be formed by neutron irradiation of material in a reactor. Since there are only a few research reactors in the world with the capability of producing large amounts of isotopes for nuclear medicine, the half-life of the isotopes needs to be long enough (preferably several days or more) to allow time for distribution to radiopharmacies and production of radiopharmaceuticals.
Supply disruptions and constraints are the key concern of radioisotope buyers and over 90% of professionals said they have suffered from recent Tc-99m shortages. Current supply constraints and disruptions are caused by the unreliability of the aging nuclear reactors that currently produce the radioisotope source material .
Medical isotopes come with the unique challenge of decay – for example Tc-99m has a half-life of only six hours, which means much of the Tc-99m is wasted in shipment from the nuclear reactors where they are produced.
Given the short half-lives of the isotopes and resulting decay of the key ingredient, the supply chain is incredibly time critical. It is not possible to stock-pile inventory of the isotope in the event of shortages.. Given the lack of diversity in supply sources and the linear nature of the supply chain, an issue with one source or at one link in the supply chain can immediately affect medical facilities’ ability to adequately care for patients.
At CIIC, we use linear accelerators to produce and ship pure Cu-67 and Mo-99 (which decays naturally into Tc-99m), both of which take 66 hours to decay. This halves the conventional reactor supply chain distribution time and greatly reduces the distribution costs.
Current Reactor Isotope Supply Chain
Currently, the Mo-99 supply chain is quite complicated, requiring several points of processing. The first step involves the irradiation of Highly/Low Enriched Uranium targets in a nuclear reactor to produce Mo-99 along with various other isotopes. This process takes approximately six days. The product is then sent to Mo-99 processing facilities where the Mo-99 is chemically separated. The raw Mo-99 once isolated is then shipped to a generator facility as a bulk liquid so it can be used to make Mo-99 generators. The generators that meet quality criteria are then sent through the distribution channel, during which it decays into Tc-99m. Hospitals and radio-pharmacies receive the generators and extract the Tc-99m to make diagnostic radio-pharmaceuticals.
CII’s Isotope Supply Chain
CII’s supply chain is greatly simplified. The LINAC produces a mix of Mo-100 and Mo-99 in solution from the Mo-100 target. The Mo-100/Mo-99 is shipped to radio-pharmacies and hospitals, where, once extracted, the resulting Tc-99m can be used to create diagnostic injections.
Another benefit of CII’s process is that the Mo-100 can be recycled and reused as a target to make more Tc-99m. Our shipments are made in returnable containers that we retrieve and reuse with no loss of quality. The Tc-99m is as pure as the first.