Radioisotope instruments

The greatest impact of radioisotopes in industry has resulted from the use of radioisotope instruments. Due to the nature of the ionising radiation emitted from radioisotopes, a few unique advantages are provided with this technique ... 

Radioisotope instruments became available for all kinds of measurements just when the trend towards automation in industry was strong. Radioisotope instruments can perform certain measurements such as mass per unit area which cannot be made by other equipment. For other measurements, like level or distance, there are now other competing methods available. 

Source Adapted from J. F. Cameron and C. G. Clayton, Radioisotope Instruments, New York Pergamon Press, 1971, by permission of the publisher. 

In 1947 W. F. Libby and collaborators [17-19] measured for the first time 14C produced by cosmic radiation in the atmosphere. He then proposed the use of this radioisotope for dating of organic material. A unique constellation of factors makes the 14C dating technique a most fascinating and powerful instrument for studies of the last 50,000 y ... 

At Los Alamos National Laboratory in New Mexico the Analytical Chemistry Group (C-AAC) supports the Pu-238 Heat Source Project that fabricates heat sources for use in the space industry. These heat sources have been used on NASA s deep-space probes and on instruments exploring the surface of Mars. The chemical and isotopic purity of the heat sources are critically controlled to ensure dependable service. The Radiochemistry Task Area performs analyses of the heat source material for four radioisotopes americium-241, plutonium-238, neptunium-237, and uranium-235. 

Fig. 7.16 Separate radioisotope counting using LSC spectrometry from LKB Instruments (Manual 1214/1219, LKB Australasia)...

For this method, the drug candidate is labeled with a radioisotope, such as carbon-14. The AD ME of the compound within the body can be monitored by analyzing samples using high sensitivity instrumentation, for example, accelerator mass spectroscopy. 

III. American Chemical Society. Division of Nuclear Chemistry and Technology. IV. American Chemical Society Meeting (185th 1983 Seattle, Wash.) V. Series. [DNl.M 1. Radionuclide generators— Instrumentation— Congresses. 2. Radioisotopes— Congresses. WN 150]... 

X-ray fluorescence, mass spectroscopy, emission spectrography, and ion-conductive plasma—atomic emission spectroscopy (icp—aes) are used in specialized laboratories equipped for handling radioisotopes with these instruments. 

TABLE 6 REPRESENTATIVE RADIOISOTOPE PROCESS INSTRUMENTATION APPLICATIONS... 

Radiophannaceuticals are almost ideal diagnostic tools because radioisotope tracers do not alter body physiology, and they permit external monitoring with minimal instrumentation. Presently, there are three major areas of nuclear medicine (1) physiological function studies, (2) radionuclide imaging procedures, and (3) therapeutic techniques. 

Instrumentation for radioisotope counting http.//www ruf rice edu/ bioslabs/methods.html... 

Hand-held portable XRFs, such as the one used for analyzing our coins, have improved considerably over the last few years. The quality of the instruments and their accuracy has increased and has become quite reliable. The development and commercialization of small XRF devices was, until recently, limited by the poor energy resolution of the detectors and by problems associated with transportation of radioisotopic X-ray sources (5,6). These shortcomings have now been overcome due to the development of thermo-electrically cooled detectors with improved energy resolution and the production of small dedicated X-ray tubes with good stability (7). This offers the ability to analyze elements from Ti(Z=22) to U(Z=92). 

The principle approach to immunoassay is illustrated in Figure 1, which shows a basic sandwich immunoassay. In this type of assay, an antibody to the analyte to be measured is immobilized onto a solid surface, such as a bead or a plastic (microtiter) plate. The test sample suspected of containing the analyte is mixed with the antibody beads or placed in the plastic plate, resulting in the formation of the antibody—analyte complex. A second antibody which carries an indicator reagent is then added to the mixture. This indicator may be a radioisotope, for RIA an enzyme, for EIA or a fluorophore, for fluorescence immunoassay (FIA). The antibody-indicator binds to the first antibody—analyte complex, free second antibody-indicator is washed away, and the two-antibody—analyte complex is quantified using a method compatible with the indicator reagent, such as quantifying radioactivity or enzyme-mediated color formation (see Automated instrumentation, clinical chemistry). 

A small dose of a soluble fast-decay positron-emitting artificial radioisotope (produced as needed not too far from the PET instrument 6C11, 8015, 9F18 or 37Rb82) is put into human tissue (e.g., blood) the positron typically travels about 1 mm, meets an electron from within the human body, and the pair decays into two y photons of energy 0.51 MeV each, within microseconds to nanoseconds. Two spin states are possible for the positron— electron ion pair before their annihilation singlet and triplet. The annihilation rate for the triplet state depends sensitively on the electron density of the body tissue. Two y counters are set in coincidence mode, and several hundred thousand coincidence events are used to provide valuable tissue information (in addition to a CT scan). 

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