Rhenium radionuclides

However, problems are encountered in production of rhenium radionuclides and work is being done to increase the yields of the radionuclides to meet urgent demands for their use in therapy. Moreover, rhenium is not as reactive as technetium. This situation makes rhenium chemistry somewhat specific - optimum conditions in the preparation of rhenium complexes or in antibody labeling using bifunctional ligands must be identified. 

The full exploitation of the wide range of oxidation states of rhenium in radiopharmaceutical design requires not only a wide range of ligand donor types with varied n-donor and acceptor properties, but also suitable reducing agents to provide access to oxidation levels below (VII). This is because for radiopharmaceutical purposes the most conveniently man-factured form of rhenium radionuclides is perrhenate. The traditional routes to reduced rhenium complexes are not particularly amenable to use in a radiopharmaceutical context, where mild, rapid, and preferably... 

The BMEDA method shares some of the same features as the HMPAO method such as good in vitro and in vivo stability with a variety of preformed liposome formulations, and the need for coencapsulation of glutathione. In addition, an advantage of the BMEDA-labeling method is that it can also be used for labeling liposomes with therapeutic rhenium radionuclides (22). Currently, for the BMEDA method, there is no commercially available kit. Also the BMEDA chemical is not currently commercially available and must be synthesized. 

Sebesta et al. describe a method for the separation of Tc and s + issj g adsorption chromatography using a solution of iV-benzoyl-A-phenylhydroxylamine in chloroform sorbed on Chromosorb W DMCS. The mixture of the radionuclides of technetium and rhenium in 5 M HCIO4 is passed through the coliunn. 

The coordination chemistry of rhenium is better known and easier to handle than that of technetium and, in view of their expected analogies, the former metal can be used for nonradioactive model studies for technetium. In addition, Re and Re display attractive properties (Section 1) for nuclear medicine. The biolocalizations of analogous Re and Tc compounds can also be similar. Hence, the Tc and the Re (or Re) radionuclides constitute a potential matched pair for diagnosis and therapy. ... 

The ability of hydroxylapatite to accept foreign ions into its structure and onto the surface has been used to incorporate radionuclides. Radioactive samarium and rhenium have been incorporated into hydroxylapatite microspheres sized at 20-40 pm and injected into knee joints to treat rheumatoid joint synovitis (Chinol et al. 1993). Clinical studies have shown that hydroxylapatite particles are easily labeled with radionuclides, exhibit low leakage of radioactive species, and provide a reduced inflammation of the synovium and restored joint motion to the patient (Clunie et al. 1996). 

The above-cited reactions are used to separate Tc for measurement. Rhenium is a common nonisotopic carrier for precipitation or yield measurement. The shorter-lived Tc (60 days) has been used as isotopic tracer for yield measurement (Anders 1960). Technetium can be separated from rhenium by coprecipitating the +4 state with ferric hydroxide while rhenium remains in solution. Technetium is separated from the fission-produced radionuclides ° Ru and ° Ruby distillation with Re207 from sulfuric acid while ruthenium remains behind because it is volatile only in its... 

Since the specific activity of a radionuclide produced by particle-induced reactions is a direct function of the incident particle flux, an increase in the incident particle flux results in an absolute increase in the specific activity of the product This relationship is linear for simple reactions and nonlinear for complex reactions. It is important to note that the half-lives, production and depletion cross sections, and irradiation time are equally important. Several important radionuclides have long physical half-lives and low production cross sections requiring long irradiation periods even in the highest neutron flux available. An example in this category is tungsten-188 (half-life 69 days parent for rhenium-188). 

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