In 1896, Henri Becquerel discovered radioactivity. It was only a little over a quarter of a century until the first radioactive tracer study in animals was performed by George de Hevesy, and the next year the first diagnostic tracer study in humans was performed by Herman Blumgart and Otto Yens. Some of the earliest applications of radioisotopes were therapy of hematologic malignancies and therapy of both benign and malignant thyroid disease. In the 1950s radioimmunoassay was developed by Solomon Berson and Rosalyn Yalow. Dr. Yalow was co-winner of the 1977 Nobel Prize in Physiology or Medicine. Radioimmunoassay was used extensively in clinical medicine but more recently has been largely replaced by non-radioactive methods. In 1950, human imaging of both gamma and positron emitting radioisotopes was performed. Benedict Cassen's work with a directional probe lead to the development of the first imaging with a rectilinear scanner. Gordon Brownell developed the first positron scanner. In the same decade the Society of Nuclear Medicine was organized in Spokane, Washington, and Hal Anger developed the gamma scintillation camera, which could image a whole region at the same time. Initial introduction of radioisotopes into medicine required individuals to acquire of a considerable background information which was foreign to their medical training. Often a particular application drove the introduction of radioisotopes into a health care facility. As other applications developed the physician or group that had developed knowledge of and experience with radioisotopes usually provided the new service. Consequently, the radioisotope service found homes in several established specialties – commonly in radiology due to an interest in imaging, in pathology due to an interest in radioimmunoassay, and in endocrinology due to the early application of 131I to thyroid disease. Nuclear medicine became widespread and there was a need to develop a new specialty. In the United States, the American Board of Nuclear Medicine was formed in 1972. At that time, the specialty include all of the uses of radioisotopes in medicine – radioimmunoassay, diagnostic imaging, and therapy. As use of and experience with radioisotopes became more widespread in medicine, radioimmunoassay generally transferred from nuclear medicine to clinical pathology. Today, nuclear medicine is based on the use of the tracer principle applied to diagnostic imaging and therapy.
Practice
Procedures
Examples of the most common clinical nuclear medicine procedures are
* glucose metabolic imaging with 18F-fluorodeoxyglucose for cancer,
Nuclear medicine procedures are performed by Nuclear Medicine Radiographers, who require extensive training both in underlying principles but also in the clinical applications. Nursing support, especially in the hospital setting, is valuable, but may be shared with other services. Nuclear medicine is a technology embedded specialty depending upon a large number of non-physician professional, including medical physicists, health physicists, radiobiologists, radiochemists, and radiopharmacists. Residency trained nuclear medicine physicians have the most extensive training and highest level of certification, including all aspects of diagnosis and radionuclide therapy. However, current U.S. regulations do not prohibit other physicians from interpreting nuclear medicine studies and perform radionuclide therapy. Radiologists who are not sub-specialty trained in the specialty, nonetheless often limit their practice to practicing nuclear medicine. Some cardiologists, especially non-invasive cardiologists, will interpret diagnostic cardiology studies including nuclear medicine studies. Radiation oncologists perform all forms of radiation therapy, sometimes including radionuclide therapy. Some endocrinologists treat hyperthyroidism and thyroid cancer with 131I. The mix of physicians rendering nuclear medicine services varies both between different countries and within a single country.
