Short-lived radionuclide generator

When dealing with a short-lived radionuclide generator, an infusion system will be needed for elution of the generator, recording of patient dose, and administration of the activity. The effective utilization of 76 sec Rb-82 will depend on its rapid extraction from the generator. Thus, the foremost feature of an infusion system will be the attainment of a high and uniform flow... 

Studies of short-lived radionuclide generators (4-6) do not adequately treat the quantitative problems of the daughter nuclide elution or those specific to their optimal clinical use. Two essential physical characteristics of a generator are the yield of the daughter nuclide and its radiochemical and radionuclidic purity. To realize the full potential of a short-lived radionuclide generator for medical studies requires that these two characteristics are optimized and are compatible with parameters important to clinical use such as total perfused volume and duration of the scintigraphic examination. 

GUILLAUME AND BRIHAYE The Short-Lived Radionuclide Generator 187... 

The fundamental conclusion of this study is that the optimal clinical elution flow rate in the case of continuous elution of a short-lived radionuclide from a perfusion generator does not necessarily correspond to the conditions for maximum elution yield. This conclusion was confirmed by experimental studies with various short-lived radionuclide generators such as the Hg-195m/Au-195m and Sr-82/Rb-82 systems. 

Ultra short lived radionuclides, with a half-life of a few seconds to a few minutes are readily available from long-lived parent radionuclides adsorbed to an organic or inorganic ion exchange support matrix (1-3). These radionuclide generator systems are an inexpensive alternative to an on-site cyclotron, especially for positron emitters used for positron emission tomography (PET). 

The main advantage of the generators is that they can serve as top-of-the-bench sources of short-lived radionuclides in places located far from the site of a cyclotron or nuclear reactor facilities. 

Also for conventional radiopharmaceuticals used in diagnostic, it is favorable to use products with short half-lives. Radionuclide generator systems are widely used for supply of short-lived radionuclides/radiopharmaceuticals. Several generator systems are available and routinely in use within nuclear medicine. Some of these are listed in Table 1. 

Application of short-lived radionuclides has the advantage that the activity vanishes after relatively short periods of time. This aspect is of special importance in nuclear medicine. Short-hved radionuclides may be produced by irradiation in nuclear reactors or by accelerators, but their supply from in-adiation facilities requires matching of production and demand, and fast transport. These problems are avoided by application of radionuclide generators containing a longer-lived mother nuclide from which the short-hved daughter nuclide can be separated. 

Nowadays, nuclear medicine has become an indispensible section of medical science, and the production of radionuclides and labelled compounds for application in nuclear medicine is an important branch of nuclear and radiochemistry. The development of radionuclide generators made short-lived radionuclides available at any time for medical application. New imaging devices, such as single photon emission tomography (SPET) and positron emission tomography (PET) made it possible to study local biochemical reactions and their kinetics in the living human body. 

M. Guillaume, C. Brihaye, Generators of Ultra-short-lived Radionuclides for Routine Clinical Applications, Radiochim. Acta 41, 119 (1987)... 

Applications in the Nuclear Fuel Cycle and Radiopharmacy Table 17 Some Short-lived Radionuclides Available from Generators ° ... 

Table 5.1. Generator systems for medical application of short-lived radionuclides...

Technetium-99m ( Tc) is widely used in radiopharmaceutical preparations due to its excellent physical and chemical properties. In fact, more than 80% of all radiopharmaceuticals used in diagnostic nuclear medicine are based on this short-lived radionuclide, which is obtained by elution of a Mo/ Tc generator system that is available in any radiopharmacy and nuclear medicine facility. 

LEW is generated from hospitals, laboratories and industry, as well as from the nuclear fuel and defense program cycle. It comprises paper, rags, tools, clothing, filters, and other lightly contaminated materials that contain small amounts of mostly short-lived radionuclides. It is not dangerous to handle, but must be disposed of more carefully than normal garbage. Often it is buried in shallow monitored landfill sites. To reduce its volume, it can be compacted or incinerated (in a closed container) before disposal. Worldwide it constitutes 90% of the volume but only 1% of the radioactivity associated with all radioactive waste. 

Generators for very short living radionuclides (for example a Sr/ Rb-generator) are situated next to the patient, in an unclassified background. 

Concerning the generation of the radionuclides, the amount produced is determined by the amount of activable substances present in the neutron field, the abundance of the parent nuclide in the target material, the cross section for the respective nuclear reaction, the neutron flux at the position of the substance and, finally, by its residence time in the neutron field. Short-lived radionuclides will reach their... 

Radionuclides are primarily produced in cyclotrons or reactors, depending on the nuclear reaction required. Very short-lived radionuclides such as C, and are available only in institutions that have a cyclotron facility, and this limits their widespread use. Remote facilities rely on commercially available long- and medium-lived radionuclides In, Ga, etc.) and radionuclides produced by generators (e.g., " Tc). The most commonly used radionuclides in PET and SPECT imaging are listed in Table 1.1. A complete discussion about radionuclide production, labeling conditions, and recent progresses in radiochemistry can be found elsewhere (18-20). 

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