Technetium-99m radioisotope

Many radiology laboratories have small generators containing molybdenum-99, which decays to the technetium-99m radioisotope. 

The technetium-99m radioisotope decays by emitting gamma rays. Gamma emission is desirable for diagnostic work because the gamma rays pass through the body to the detection equipment. 

Technetium-99m (the m signifies a metastable, or moderately stable, species) is generated in nuclear reactors and shipped to hospitals for use in medical imaging. The radioisotope has a half-life of 6.01 h. If a 165-mg sample of technetium-99m is shipped from a nuclear reactor to a hospital 125 kilometers away in a truck that averages 50.0 kmh. what mass of technetium-99m will remain when it arrives at the hospital ... 

The utilization of radioisotopes in the field of nuclear medicine has been promoted for various purposes. Among them, diagnostic applications have had much success during the past two decades. Technetium-99m, thallium-210 and iodine-123, for example, have been used as radioisotopes for imaging studies. 

A Technetium-99m, a short-lived radioisotope used for brain scans, is obtained by neutron bombardment of molybdenum-99 and then stored in a "molybdenum cow" in the form of Mo042. Small amounts are removed by passing a saline solution through the cylinder. 

The radioisotope most widely used today is technetium-99m, whose short half-life of 6.01 hours minimizes a patient s exposure to harmful effects. Bone scans using Tc-99m, such as that shown in Figure 22.12a, are an important tool in the diagnosis of cancer and other pathological conditions. 

Radiochemical purity determinations consist of separating the different chemical substances containing the radionuclide. The radiochemical purity of labeled pharmaceuticals is typically determined by paper chromatography (paper impregnated with silica gel or silicic acid). The most frequently used radioisotope is technetium-99m obtained by daily elution with saline... 

Radionuclide angiocardiography (performed with technetium-99m, a radioisotope) is used to measure ejection fraction, regional ventricular performance, cardiac output, ventricular volumes, valvular regurgitation, asynchrony or wall motion abnormalities, and intracar-... 

Explain why radioisotopes with long half-lives are not administered internally in medical procedures. What are the half-lives of iodine-131, technetium-99m, and gadolinium-153, which are used in many medical procedures ... 

The isotopes typically emit only gamma rays because alpha and beta radiation are more likely to harm the patient. Technetium-99m is a commonly used isotope for diagnostic radiology. Many radioisotopes are used in diagnostic medicine outside the body for blood tests. 

The decay curve for the medically useful radioisotope technetium-99m. Note that the number of radioactive atoms remaining—hence the radioactivity— approaches zero. 

Technetium-99m is used in diagnostic imaging studies involving the brain. What fraction of the radioisotope remains after 12 hours have elapsed See Table 10.2 for the half-life of technetium-99m. 

Rampon S, Bussiere JL, Prin P, Sauvezie B, Leroy V, Missioux D et al (1974) 250 studies of bone radioisotope scanning by tin pyrophosphate labeled with technetium 99m. Analytical and clinical study. Rev Rhum Mai Osteoartic 4 745-751... 

Fig. 6.2 (a) Fl5t tomographic radioisotope scanner, invented by David Kuhl atthe University of Pennsylvania in the 1960s.The patient had a stroke, and the tracer was technetium-99m albumin, (b) Dr. David Kuhl and Dr. R. Q. kiwards. (c) Schematic drawing of the first tomographic scanner. 

The continual availability of technetium-99m in the department greatly simplifies the logistics of supply of this short half-life radioisotope and the economy of scale associated with its use reduces its cost by an order of magnitude compared with 1-123 and In-111. Because technetium-99m is so widely available, it is... 

Image of hands with extensive rheumatoid arthritis. This image was produced by recording the gamma emissions of a small amount of the radioisotope, a compound containing technetium-99m, which was injected into the patient. 

Thallium-201 is a radioisotope used to determine whether a person has heart disease (caused by narrowing of the arteries to the heart). This isotope decays by electron capture and emits x rays and gamma rays, which can be nsed to obtain images similar to those obtained from technetium-99m (Figure 21.13). Thallium-201 injected into the blood binds particularly strongly to heart muscle. Diagnosis of heart disease depends on the fact that only tissue that receives sufficient blood flow binds thallium-201. When someone exercises strenuously, some part of the person s heart tissue may not receive sufficient blood because of narrowed arteries. These areas do not bind thallium-201 and show up on an image as dark spots. 

Technetium-99m, progenitor of molybdenum-99, was a leading seller among the radioisotopes that propelled Nordions growth. By the late 1980s, two-thirds of the world market for hulk isotopes was supplied by Nordion. 

In its nuclear medicine business, MDS Nordion remains the world s number one producer of medical isotopes. Radiopharmaceutical producers on five continents use its radioisotopes to make their products. It supplies two-thirds of the reactor-produced isotopes used in the world as well as a wide variety of cyclotron-produced isotopes. Its market leadership continues to be based in its position as the leading supplier of molybdenum-99, the source of technetium 99m, the most important isotope for nuclear medicine. While planning to strengthen its position as the leading supplier of bulk isotopes, MDS Nordion continues to look to the development of its own radiopharmaceutical products as the key to growth in the future. Many of these products help detect medical conditions, but some of the latest ones can aaually treat diseases. MDS Nordion is already selling radiopharmaceuticals for certain types of cancer therapy. 

Technetium-99m is a radioisotope used in nuclear medicine for several diagnostic procedures, including the detection of brain tumors and examinations of the liver and spleen. The source of technetium-99m is molybdenum-99, which is produced in a nuclear reactor by neutron bombardment of molybdenum-98. 

Naturally occurring isotopes of the elements usually have long half-hves, as shown in Table 16.7. They disintegrate slowly and produce radiation over a long period of time, even hundreds or millions of years. In contrast, the radioisotopes used in nuclear medicine have much shorter half-hves. They disintegrate rapidly and produce almost all their radiation in a short period of time. For example, technetium-99m emits half of its radiation in the first six hours. This means that a small amount of the radioisotope given to a patient is essentially gone within two days. The decay products of technetium-99m are totally eliminated by the body. 

Technetium-99m is an ideal radioisotope for scanning organs because it has a half-hfe of 6.0 h and is a pure gamma emitter. Suppose that 80.0 mg were prepared in the technetium generator this morning. How many miUigrams... 

Iodine-12 3 concentrates in the thyroid gland, liver, and certain parts of the brain. This radioisotope is used to monitor goiter and other thyroid problems, as well as liver and brain tumors. One of the most useful radioisotopes in medical applications in recent years is an isotope of technetium, an element that does not occur naturally on earth. This isotope, 99m P(, jg produced by the decay of Mo. 

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