radionuclide therapy has created the need for steady supplies of a variety of other radionuclides, and the demand is expected to increase (Wagner et al. 1999).
The production of radionuclides in the United States can be traced to the graphite reactor at Oak Ridge National Laboratory (ORNL) shortly after World War II. In its first year of operation, hundreds of shipments of 60 different radionuclides were made. Production of radionuclides for biomedical research continued until the reactor was shut down in 1963. Based on the successes achieved and the interest created by this early work, radionuclides were produced throughout the 1960s and 1970s at universities and national laboratories that had reactors, cyclotrons, or other accelerators available (Sidebar 5.1).
Commercial producers and distributors have played an important role in supplying radionuclides such as molybdenum-99/technetium-99m, thallium-201, gallium-67, indium-111, and iodine-123. With the advent of PET technology, beginning in the late 1970s, the need for a more reliable supply of radionuclides with short half-lives drove industry to develop small cyclotrons for supplying the primary radiopharmaceutical, fluorine-18-fluorodeoxyglucose (FDG). However, the market for radionuclides such as copper-67 and astatine-211 has never been large enough to encourage industry to produce them,2 and they are not readily available from low-energy PET cyclotrons. The issue of such “exotic” radionuclides, or radionuclides requested by a fairly small number of investigators for their research studies, has plagued the field for years. Many of these radionuclides will never be in high demand but could be important for advancing the understanding of fundamental biology or therapeutic efficacy (e.g., bromine-76 and copper-67).
Many of the discoveries associated with radionuclides were made possible by government research funding, particularly DOE research funding. The following examples indicate the variety and complexity of the types of investigations and discoveries that were made possible by these investments:
As mentioned earlier, technetium-99m is the most widely used radionuclide for nuclear medicine procedures in the world, accounting for more than 70 percent of all nuclear medicine procedures (Nuclear Energy Agency
A list of commercially available radiopharmaceuticals is provided in Appendix C.