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APPLIED CHEMISTRY Nuclear Separations for Radiopharmacy: The Need for Improved Separations To Meet Future Research and Clinical Demands Andrew H. Bond,*,† Robin D. Rogers,‡ and Mark L. Dietz† Chemistry Division, Argonne National Laboratory, Argonne, Illinois 60439, and Department of Chemistry, The University of Alabama, Tuscaloosa, Alabama 35487
Several recent national and international reports have predicted that the demand for radionuclides used in medicine will increase significantly over the next 20 years. Separation science is an integral part of the production and development of new radionuclides for diagnostic and therapeutic applications and will play a major role in process improvements to existing radiopharmaceuticals to meet increasing demands. The role of separation science in the production of radionuclides for medical applications is briefly discussed, followed by an overview of the manuscripts from the American Chemical Society symposium “Nuclear Separations for Radiopharmacy”. A listing of the most widely used radionuclides in clinical application and medical research serves as a foundation for the discussion of future research opportunities in separation science. Introduction Because of the success of diagnostic imaging using radionuclides such as 99mTc (now capable of imaging virtually every part of the human anatomy), 201Tl (cardiac imaging), and 18F (brain, metabolic, and tumor imaging), nuclear medicine now holds a prominent position among the diagnostic techniques available to the medical practitioner. As of 1995, ten million diagnostic nuclear medical procedures were performed each year in the U.S. alone.1-3 In the past four years, the annual number of radiodiagnostic procedures performed in the U.S. has risen to approximately 13 million/year. Stated differently, one of every four hospital patients can expect to undergo a nuclear medical procedure.1,3 The use of radiopharmaceuticals in medicine has benefited from favorable economics. For example, a typical course of treatment for a cardiac patient using either 99mTc or 201Tl may cost ≈$1800, whereas average surgical procedures often exceed $25,000, and not all patients may benefit from surgery.2,3 The diagnostic and economic efficiency of nuclear medicine has been appreciated by the greater health care community, and it is the hospitals’ ability to obtain reimbursement for such procedures that has helped to foster its acceptance.3-5 A recent report by an expert panel commissioned by the U.S. Department of Energy (DOE) to predict the future demand for radionuclides for medical uses anticipates that the need for diagnostic radionuclides will increase annually in the 7-16% range over the next 20 years.3,6 More exciting than the growth for radiodiag* Author to whom correspondence should be addressed. Current address: PG Research Foundation, Inc., 8205 S. Cass Ave., Suite 111, Darien, IL 60561. Telephone: 630-963-0320. Fax: 630-963-0381. E-mail:
[email protected]. † Argonne National Laboratory. ‡ The University of Alabama.
nostics is the anticipated annual growth of 7-14% for therapeutic radionuclides, which were used in approximately 80 000 procedures worldwide in 1990.1 Radiotherapeutics are more stringently regulated by the U.S. Food and Drug Administration (FDA) because of their greater potential risk to the patient,3,7 and presently only a few radionuclides have been approved by the FDA for therapeutic applications.3,7,8 With significant growth anticipated over the next 20 years,1,3-6 concerns raised in the past about the reliability of the future supply of radiopharmaceuticals1,9 are gaining credibility. For example, of the ≈36 000 nuclear medical procedures performed daily in the U.S., ≈ 80-90% of the nuclides (primarily 99Mo, the parent of 99mTc) are produced by foreign sources.1,3,6 Because the U.S. government-sponsored facilities required to generate the needed radionuclides are operating at reduced capacities or are being decommissioned, the dependence on non-U.S. sources for radionuclides for both medical and research purposes is increasing, as are concerns about their reliable production and distribution.1,3,6,7,9 Opposing the anticipated growth of radionuclides for medical applications is the fact that commercial radiopharmaceutical producers are bound by shareholder obligations and, therefore, must focus on producing only the most profitable radionuclides.1,4,5,10 Because significant expertise, capital expenditures, and governmental approval are required before profits may be garnered, the number of commercial radiopharmaceutical suppliers remains finite and production capabilities remain limited. Several recent studies have recommended that the DOE partner with academic and/or commercial entities to develop a reliable means of supplying radionuclides to support not only clinical requirements but also the research activities upon which medical advances are dependent.1,3
10.1021/ie990765j CCC: $19.00 © 2000 American Chemical Society Published on Web 07/08/2000
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regularly with the goal of identifying new applications to nuclear medicine. To highlight recent advances in separation science involving radionuclides of medical importance and to foster collaborations between research groups involved in radiopharmaceutical production and use, the symposium “Nuclear Separations for Radiopharmacy” was organized in the Separation Science and Technology Subdivision of the Division of Industrial and Engineering Chemistry of the American Chemical Society at its National Meeting in Boston, MA, in the Fall of 1998. An objective of this collection of manuscripts is to complement the 1987 proceedings of the International Atomic Energy Agency seminar on “Radionuclide Generator Technology”11,13-20 and the other reviews that have since appeared.10,21,22 This collection of manuscripts adds to the principally wet-chemical separations reviewed previously,10,21,22 as both membrane- and resin-based chromatographic systems are discussed, as are high-temperature gas thermochromatographic separations. Papers presenting chemical characterization or improved production and/or separations methods involved in the manufacture of 99Mo by fission of high-enriched (g20%) 235U, lowenriched (
