Molybdenum-99 for Medical Imaging (2016) / Chapter Skim
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2 Medical Isotope Production and Utilization
2 Medical Isotope Production and Utilization
Pages 25-50
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From page 25... ...
-- can detect anatomical changes in tissues and organs as the result of disease. Nuclear medicine procedures can often detect the physiological and metabolic changes associated with disease before any anatomical changes occur.
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2.1 Tc-99m Tc-99m is used in approximately 80 percent of all nuclear medicine procedures performed worldwide each year. Historically, about half of these procedures have been performed in the United States (Verbeek, 2008)
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. • Can be supplied efficiently to hospitals and clinics using technetium generators2 (see Section 2.5.4 of this chapter)
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It decays with a half-life of ~5.2 days and emits 81 keV gamma rays, which can be detected using existing camera technologies (see Sidebar 2.1)
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2.3.1 Reactor-Based Production Mo-99 has been produced for medical use for decades by irradiating targets containing uranium or molybdenum with neutrons produced by research reactors (see Sidebar 2.2)
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Albumin Aggregated Kit Tc-99m-Mebrofenin Hepatobiliary Imaging Bracco Diagnostics Choletec® 1987 Tc-99m-Medronate Bone Imaging Jubilant DraxImage DraxImage MDP-25 2004 Pharmalucence CIS-MDP 1982 Bracco MDP-Bracco Approved prior to 1982 Tc-99m-Mertiadide Kidney Imaging Mallinckrodt Nuclear Technescan 1990 Medicine LLC MAG3™ ("Mallinckrodt") Tc-99m-Oxidronate Skeletal Imaging Mallinckrodt Technescan HDP 1981 Tc-99m-Pentetate (DTPA)
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From page 31... ...
a For example, to detect gastrointestinal bleeding and evaluate left ventricle function. SOURCE: Adopted from http://www.cardinalhealth.com/content/dam/corp/web/documents/fact-sheet/CardinalHealth-FDAApprovedRadiopharmaceuticalsandApprovedUses.pdf with additional information from some current technetium generator suppliers.
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From page 32... ...
, too low for use in conventional technetium generators. 2.3.2 Accelerator-Based Production Mo-99 and Tc-99m can be produced by irradiating uranium or molybdenum with neutrons, protons, or photons from accelerators (Sidebar 2.2)
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From page 33... ...
Research reactors generate neutrons primarily by fission of U-235 contained in the reactor fuel. These reactors are specifically designed to produce high neu tron fluxes, typically on the order of 1014 neutrons/cm2/s for scientific research, technology development, or production.
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activity (>1,000 Ci/g) ; however, neutron fluxes and corresponding Mo-99 production rates are typically one or two orders of magnitude lower in accelerators compared to reactors.
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erating high-intensity (35-50 MeV) electron beams into high-Z materials.9 The Mo-99 produced using this reaction has a low specific activity (1-10 Ci/g)
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2.5 OVERVIEW OF Mo-99/Tc-99m SUPPLY CHAIN As noted previously, almost all Mo-99 for medical use is produced by irradiating targets containing U-235 in research reactors (reaction (1) in Section 2.3.1)
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4. Technetium generator suppliers: Organizations that manufacture technetium generators for commercial sale.
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The meat is encapsulated in an aluminum alloy cladding that provides a barrier to the release of fission products and transfers heat to the reactor coolant. Targets are typically 3-5 cm in width, 10-15 cm in length, and about 1-2 mm in thickness.
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These reactors are owned by governments or universities but may be operated by private companies. Research reactors sell irradiation services to multiple customers on a contract basis.
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The calibration time is variously stated as time since EOP, time since leaving the Mo-99 supplier's facility, or time since arrival at the technetium generator manufacturer. 70 60 EOB Mo-99 Ac tivity (10 3 C i )
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packaged and shipped by truck to Mo-99 suppliers' facilities.14 Shipping time can vary from less than an hour to about a day depending on distance and transport logistics. 2.5.3 Mo-99 Suppliers Mo-99 suppliers chemically process irradiated targets to recover Mo-99 for commercial sale.
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From page 42... ...
Shipment can take from a few hours to 1-2 days depending on distance and transport logistics. 2.5.4 Technetium Generator Suppliers Technetium generators are systems that store Mo-99 and allow its decay product, Tc-99m, to be recovered for use.
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From page 43... ...
2.5.5 Tc-99m Suppliers Technetium generators are delivered primarily to two types of Tc-99m suppliers: regional nuclear pharmacies and hospital nuclear pharmacies. A small number of generators are also delivered directly to hospital nuclear medicine departments for on-site emergency (on-call)
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From page 44... ...
Centralized nuclear pharmacies typically receive a number of generator deliveries staggered throughout the week, and they have the staff needed to produce and distribute radiopharmaceuticals either in multi-dose vials or as single doses to multiple imaging centers and hospitals. 17 The pertechnetate ion is less tightly bound to the alumina because it has only a single negative charge, versus the double negative charge for molybdate.
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From page 45... ...
2.5.6 Tc-99m End Users Tc-99m is supplied to hospitals and clinics for use in medical isotope procedures. Tc-99m may be supplied as bulk sodium pertechnetate or as single doses of Tc-99m-labeled radiopharmaceuticals for administration to specific patients.
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Spent technetium generators are usually returned to the generator suppliers for dismantlement (IAEA, 1998)
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The facilities that process irradiated targets also have reserve processing capacity. Outage reserve capacity helps to ensure that adequate supplies of Mo-99 are available during planned and unplanned outages of target irradiation and/or processing facilities.
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The HLG-MR has developed six principles to promote full-cost recovery of medical isotope production (see Sidebar 2.4) and the availability of outage reserve capacity to be paid for by higher prices in the supply chain rather than through continued government subsidies.
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Full-cost recovery would eliminate government subsidies for production of Mo-99 in research reactors by increasing prices for reactor irradiation services to cover the costs of reactor capital, general overhead, general operating, deprecia tion of capital costs, and decommissioning as well as the costs associated with provision of outage reserve capacity. According to OECD's HLG-MR, full-cost recovery would have additional benefits beyond reducing government expendi tures on reactors by • ncouraging new infrastructure investment by making production of unpro E cessed Mo-99 economically sustainable; • acilitating the development of non-HEU-based Mo-99/Tc-99m production F sources; and • romoting more efficient use of Mo-99/Tc-99m and therefore reducing P excess production and the associated radioactive waste.
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From page 50... ...
These prices may not be sustainable in the long run, but irradiation services suppliers would lose less in the short run by accepting lower prices. Additional discussion of full-cost recovery is provided in Section 4.5 in Chapter 4.
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