The earliest technique developed uses single photons detected by a gamma camera which can view organs from many different angles. They can be given by injection, inhalation, or orally. These tracers are generally short-lived isotopes linked to chemical compounds which permit specific physiological processes to be scrutinized. Diagnostic techniques in nuclear medicine use radioactive tracers which emit gamma rays from within the body. In using radiopharmaceuticals for diagnosis, a radioactive dose is given to the patient and the activity in the organ can then be studied either as a two dimensional picture or, using tomography, as a three dimensional picture. In combination with imaging devices which register the gamma rays emitted from within, they can be used for imaging to study the dynamic processes taking place in various parts of the body. Radioisotopes are an essential part of medical diagnostic procedures. Nuclear medicine diagnosis, nuclear imaging * Some Tc-99m is produced in accelerators but it is of lower quality and at higher cost. However, the main radioisotopes such as Tc-99m cannot effectively be produced without reactors.* In recent years specialists have also come from radiology, as dual PET/CT (positron emission tomography with computerized tomography) procedures have become established, increasing the role of accelerators in radioisotope production.
Nuclear medicine was developed in the 1950s by physicians with an endocrine emphasis, initially using iodine-131 to diagnose and then treat thyroid disease. The use of radiopharmaceuticals in diagnosis is growing at over 10% per year. In Australia there are about 560,000 per year, 470,000 of these using reactor isotopes. In the USA there are over 20 million nuclear medicine procedures per year, and in Europe about 10 million, with 2 million of these being therapeutic. In developed countries (about one-quarter of world population) the frequency of diagnostic nuclear medicine is 1.9% per year, and the frequency of therapy with radioisotopes is about one-tenth of this. The most common radioisotope used in diagnosis is technetium-99 (Tc-99), with some 40 million procedures per year, accounting for about 80% of all nuclear medicine procedures and 85% of diagnostic scans in nuclear medicine worldwide. Over 10,000 hospitals worldwide use radioisotopes in medicine, and about 90% of the procedures are for diagnosis. Five Nobel Laureates have been closely involved with the use of radioactive tracers in medicine. In some cases radiation can be used to treat diseased organs, or tumours. The thyroid, bones, heart, liver, and many other organs can be easily imaged, and disorders in their function revealed. In most cases, the information is used by physicians to make a quick diagnosis of the patient's illness. Nuclear medicine uses radiation to provide information about the functioning of a person's specific organs, or to treat disease. In developed countries (a quarter of the world population) about one person in 50 uses diagnostic nuclear medicine each year, and the frequency of therapy with radioisotopes is about one-tenth of this. There is widespread awareness of the use of radiation and radioisotopes in medicine, particularly for diagnosis (identification) and therapy (treatment) of various medical conditions. The attributes of naturally decaying atoms, known as radioisotopes, give rise to several applications across many aspects of modern day life (see also information paper on The Many Uses of Nuclear Technology). Sterilization of medical equipment is also an important use of radioisotopes.Over 40 million nuclear medicine procedures are performed each year, and demand for radioisotopes is increasing at up to 5% annually.Radiotherapy can be used to treat some medical conditions, especially cancer, using radiation to weaken or destroy particular targeted cells.Diagnostic procedures using radioisotopes are now routine. Nuclear medicine uses radiation to provide diagnostic information about the functioning of a person's specific organs, or to treat them.
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