Bismuth radionuclides

It has been demonstrated that monoclonal antibodies may be chemically modified by reaction with metal chelates without loss of antibody activity or specificity. A radionuclide generator has been made to provide a source for Bi-212 to be used for attachment of bismuth chelates to antibody. Such antibody-metal-chelate conjugates appear to be stable in vivo and may provide a new method for radiotherapy. 

The radionuclides commercially available and most commonly used for a number of the foregoing applications include anhmony-125 banum-133, 207 bismuth-207 bromine-82 cadmium-109, 115 m calcium-45 carbon-14 cerium-141 cesium-134, 137 chlorine-36 chromium-51 cobalt-57, 58, 60 copper-64 gadolimum-153 germanium-68 gold-195. 198 hydrogen-3 (tritium) indium-111, 114 m iodine-125, 129, 131 iron-55, 59 krypton-85 manganese-54 mercury-203 molvbdenum-99 nickel-63 phosphorus-32. 33 potassium-42 promethium-147 rubidium-86 ruthenium-103 samarium-151 scandium-46 selenium-75 silver-110 m sodium-22, strontium-85 sulfur-35 technetium-99 thallium-204 thulium-171 tin-113, 119 m, 121 m. titamum-44 ytterbium-169, and zinc-65. 

The oldest, most well-established chemical separation technique is precipitation. Because the amount of the radionuclide present may be very small, carriers are frequently used. The carrier is added in macroscopic quantities and ensures the radioactive species will be part of a kinetic and thermodynamic equilibrium system. Recovery of the carrier also serves as a measure of the yield of the separation. It is important that there is an isotopic exchange between the carrier and the radionuclide. There is the related phenomenon of co-precipitation wherein the radionuclide is incorporated into or adsorbed on the surface of a precipitate that does not involve an isotope of the radionuclide or isomorphously replaces one of the elements in the precipitate. Examples of this behavior are the sorption of radionuclides by Fe(OH)3 or the co-precipitation of the actinides with LaF3. Separation by precipitation is largely restricted to laboratory procedures and apart from the bismuth phosphate process used in World War II to purify Pu, has little commercial application. 

Internally deposited naturally occurring radionuclides also contribute to the natural radiation dose from inhalation and ingestion of these materials when contained in air, food, and water. Included are radionuclides of lead, polonium, bismuth, radium, potassium, carbon, hydrogen, uranium, and thorium. Potassium-40 is the most prominent radionuclide in normal foods and human tissues. The dose to the total body from these internally deposited radionuclides has been estimated to be 39mremyear. ... 

Polonium (ii) The radioisotopes of polonium (usually Po) have been difficult to analyze with accuracy using the conventional methods. The procedure outlined here is, however, simple, rapid, and accurate. With the sample in solution, add 3 to 5 mL of concentrated phosphoric acid and evaporate to remove other acids. Transfer this phosphoric acid solution to a small equilibration vessel using 3 to 5 mL of water. Add 1 mL of 0.1 M HCl. Add a measured volume, 1.2 to 1.5 mL, of a solution of TOPO, 0.1 to 0.2 M, in toluene and equilibrate. This is a highly selective separation of polonium from other radionuclides with the possible exception of the beta/gamma emitting bismuths. Quantitative stripping and transfer of the polonium to a plate is difficult but the use of an extractive scintillator and counting on a PERALS spectrometer is rapid and simple and the results are quite accurate. Because of the minimal chemical manipulations required, the accuracy of this determination can easily be better than 1%. 

DOTA (Figure 6.7-9) is a also useful bifunctional chelator for labeling antibodies with radionuclides of lead, bismuth, and actinium for targeted in situ radiotherapy... 

Since each radionuclide has its own characteristic decay-constant, its half-life has a definite value. Half-lives of radionuclides vary over a very large range. For instance, one radioactive isotope of boron has a half-life of about 3 x 10 sec, whereas the half-life of naturally occurring bismuth is greater than 2 x 10 years. 

Radioanalytical chemistry was first developed by Mme. M. Curie, with contributions by many other distinguished researchers, notably E. Rutherford and F. Soddy. These pioneers performed chemical separations and radiation measurements on terrestrial radioactive substances during the 20 years following 1897 and in the process created the very concept of radionuclides. Their investigations defined the three major radiation types, confirmed the emission of these radiations by the nucleus and the associated atomic transformations, established the periodic table between bismuth and uranium, and demonstrated the distinction between stable and radioactive isotopes. 

Currently, only a few routinely measured radionuclides such as H, " C, Fe, 90sr, 99tc, l, and many of the elements heavier than bismuth remain... 

V I. OUSANOV, D. V. PANKRATOV et al, Long-lived Radionuclids of Sodium, Lead-bismuth and Lead Coolants at Fast Reactors . Atomnaia Energia,V.87, 9,pp. 204-210, 1999(Rus). 

Thus, the residual activity of lead-bismuth and lead coolants is expected to be as high as millions of years. As it is pointed out in [7.4], purification of lead-bismuth and lead coolants from the long lived radionuclides of bismuth and lead (if it is possible) would be too expensive. 

The specific feature of LBC is the formation of a-active polonium-210 radionuclide with a half-life of 138 days when bismuth is irradiated with neutrons. 

Bismuth-212 is a 60.6-min daughter of the natural decay chain. This radionuclide has two... 

Bismuth-213 has a 45.6-min half-life and ot-particle emission is associated with each of its decays, either directly to 2.2-min ° T1 (2%) or after P decay to 4.2- xs Po (98%), followed by a emission to 3.25-h ° Pb. A radionuclide generator system has been developed using 10-day Ac as the parent that can provide cKnically useful levels of Bi (McDevitt et al. 1996, 1999b Ma et al. 2001). The generator consists of an AGMP-50 column and is eluted with 0.1 M HCl/Nal. 

Windscale The Windscale (now called Shellafield) Reactor No. 1 was partially consumed by combustion in October 1957, resulting in the release of fission products to the surrounding countryside. The reactor was an air-cooled graphite-moderated natural-uranium reactor employed primarily for plutonium production. The radionuclides (740 TBq), Cs (22 TBq), Ru (3 TBq), and Xe (1.2 PBq) were released. In addition to those fission products, 8.8 TBq of Po was also released, because the nuclide was produced by neutron irradiation of bismuth. The released radionuclides moved from Windscale to the south, southeast, and to London, and they contaminated vast grasslands. The collective dose is estimated to be 2,000 man-Sv in the contaminated area. 

The radiation safety was ensured under the generation of polonium-210 during the operation of lead-bismuth cooled reactor installations, including primary circuit equipment repair and removal of spilled lead-bismuth coolant, there was no personnel irradiation over the permissible limits for this radionuclide [XIX-3] ... 

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