Medical uses of radionuclides

Hospitals and larger medical clinics typically have a Department of Nuclear Medicine. This department is responsible for production, use, and disposal of radioactive materials used at the medical facihty. Medical uses of radionuclides fall into two hroad categories, diagnostic and therapeutic. A large hospital could use as many as 47 different radionuclides in as many as 194 diagnostic procedures and 29 therapeutic procedures. 

It is the purpose of this book to present the facts about the presence of radionuclides in nature. The use of technology can significantly modify the exposure to natural radiation. Among the human activities which should be considered in this context are (i) the electricity generation by coal-fired power plants, (ii) the use of phosphate fertilizers, and (iii) many consumer products. Man-made radioactivity has found many useful applications in everyday life. The best known are medical applications. The use of radionuclides and radioactivity in diagnosis and treatment of diseases is well established practice. 

The largest single use of radionuclides has been in medical science. If a radioactive compound, such as a radioactivefy labeled amino acid, vitamin, or drug, is administered to a patient, the substance is incorporated in... 

Radionuclides find applications in many fields. Their major use, however, is in medicine, in both diagnosis and therapy. The production of radionuclides is carried out using nuclear reactors as well as cyclotrons. The reactor produced radionuclides are generally neutron excess nuclides. They mostly decay by P emission. The cyclotron produced radionuclides, on the other hand, are often neutron deficient and decay mainly by EC or emission. They are especially suitable for diagnostic studies. The reactor production of radionuclides is described in Chap. 38 of this Volume this chapter treats radionuclide production with cyclotrons. It is worth pointing out that today more than 300 cyclotrons exist worldwide (cf. Directory of Cyclotrons, lAEA-DCRP/CD, 2004), many of them in hospitals they produce short-lived radionuclides for medical use. Thus, radionuclide production science and technology at cyclotrons has become a very important feature of modern nuclear medicine. 

A radionuclide generator can be described as a parent-daughter pair from which the daughter nuclide is separated from the parent in as pure a nuclear form as possible throughout the operating life of the system. A variety of publications (1-3) have emphasized the general principles of the medical use and qualitative aspects of radionuclide generators. The most frequent example discussed is the Mo-99/Tc-99m system. 

The search continues for a general tumor-scanning agent. Although several radionuclides have been found to localize tumors of widely different types and regions of the body, current interest is in the use of 67 Ga-citrate, which is undergoing a wide clinical trial and may prove to be useful in the localization of lymphomas as well as some adenocarcinomas. Medical imaging techniques arc discussed in several articles of this encyclopedia. Consult alphabetical index. 

The sources of ionizing radiation are nuclear power plant, nuclear material processing, and radionuclide generation for nondestructive purposes. Medical and chemical laboratories use these radionuclides—for example, iodine, thallium, and barium—as tracers. The danger of mishandling these materials could cause release of these materials into the environment. Other than medical diagnostic tests for fracture of bones and constriction of blood vessels, these are used for the treatment of cancers. 

Numerous sources of ionizing radiation can lead to human exposure natural sources, nuclear explosions, nuclear power generation, use of radiation in medical, industrial and research purposes and radiation-emitting consumer products. Before assessing the radiation dose to the population, one requires a precise knowledge of the activity of a number of radionuclides. The basis for the assessment of the dose to the population from a release of radioactivity to the environment, the estimation of the potential clinical health effects due to the dose received and, ultimately, the implementation of countermeasures to protect the population is the measurement of radioactive contamination in the environment after the release. The types of radiation one should consider include ... 

Most nuclear procedures are of a diagnostic nature. In some instances, however, radionuclides administered to the patient are valuable therapeutic tools. For example, one in every three persons admitted to U.S. hospitals undergoes a nuclear medical procedure for diagnosis or therapy. Many of these procedures employ radioisotopes. Some of the more frequent uses of medical radioisotopes include diagnosis and treatment of several major diseases, sterilisation of medical products such as tissue grafts, nutrition research, and biomedical research into cellular processes. 

There are assessments predicting the use of reverse osmosis for the processing of the wastes from medical application [36,37] and for the removal of caesium-137 from decontamination wastes after accident in the steel production factory [38]. RO is considered as a method for removal of radioactive pollutants from contaminated water (removal of Cs and °Sr) in the vicinity of atomic power plants [39], as well as for removal of small quantities of radionuclides ( Rn, Ra) from... 

The suitability of a radionuclide for a particular medical application will depend upon its availability in a radiochemically pure form, its nuclear properties and its chemical properties. In respect of the first of these considerations it is necessary to eliminate any extraneous radiation sources from a material destined for medical use. This need for very high radiochemical purity has a bearing on the means by which the radionuclide is produced. One potential method is by nuclear fission of a heavy element. This approach has the advant e that carrier free radioisotopes of high specific activity may be produced. However, because the process produces a complex mixture of FPs, painstaking separation and purification of the desired radionuclide will be necessary. The problem is simplified somewhat by using a pure target isotope to produce an FP which has rather unique properties. Thus fission produces which may be separated from the other FPs by virtue of its volatility. Fission in pure may also be used to prepare Mo in carrier free form, although contamination by Ru, I and Te was a problem in early... 

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