Radioisotopes in medicine

摘要

Radioisotopes are extensively used in medicine for diagnosis, either in vivo or in vitro, for therapeutics and also for investigation purposes. Nuclear medicine (NM) studies in vivo are used to detect minimal amounts of radiopharmaceuticals in organs (the morphology) and their course over time (the function), resulting from physico-chemical interactions of the tracers within the body, in the sequence of specific physiological processes. In vitro applications of radioisotopes have become a most important tool in biochemical analysis. Therapeutic uses of radioisotopes cover from external gamma-ray sources in teleradiotherapy to direct cell irradiation in metabolic therapy. The information, which is conveyed by NM, is essentially metabolic and differs from that supplied by the other imaging techniques, which is basically structural. This quality is important in early detection and diagnosis. Efforts have steadily been made to bring NM imaging as close as possible to an ideal medical diagnostic tool: non-invasive and allowing studies yielding functional, morphological, three-dimensional and quantitative information simultaneously. Of the two tomographic techniques available in NM, positron emission tomography (PET) is probably closer to this goal than single-photon emission tomography (SPECT). High-contrast functional images of the dynamics of labelled molecules (native or functionally similar) that are metabolized by the organs under investigation, are obtained with these techniques. Nuclear medicine has progressed as a result of advances in four strategic areas: the development of new radiopharmaceuticals, the technology and reliability of detectors, the capacity for modelling the metabolic fate of the inputs in the biological systems, and finally the ability to extract and process data.