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Technetium is a product of nuclear fission of natural and artificial ' and uranium is used in nuclear medicine for scintigraphic and tomographic images of various body compartments ( ^{99m Tc} ).

Carattaristiche

99m Tc to its short half-life (6.01 hours), to be a gamma ray emitter and the ability to bind to several molecules of biochemical interest ( radiopharmaceuticals) is used in medical tests radiodiagnosica based on radioactive isotopes (radionuclides ), in particular, in some imaging techniques such as scintigraphy bone.

Technetium-99 (99m)

For a number of reasons physical, chemical, biological and logistical, technetium 99m is an almost ideal basis for the preparation of most commonly used radiopharmaceuticals in diagnostic nuclear medicine. dalpunto physically the relatively short half-life of this radioisotope (6 hours) dicisivo factor for its widespread use.
Technetium-99 is the product of another son the radioisotope molybdenum-99. This isotope has a half life parent longer that 65 hours (3 days) compared to 6 hours of technetium-99m. The logistical aspect of such a situation is that distribution is permitted also, and especially large-scale deliveries of reaching generators in locations significantly distant from production. Molybdenum-99 is permanently attached to an inert support (eg particle aluminum), so that it can not go into solution. Technetium-99m, on the contrary, continuously produced by its decay (Mo99), is highly soluble and can then be easily eluted in a chromatographic system consisting of a column through which can pass a simple saline solution.

In this way the longer half-life radioisotopes (molybdenum-99m) will supply continuously, using this system, "generator", the with shorter half-life radioisotope (technetium-99m). The half-life corresponding to that of molybdenum-99 provides for a smooth distributions of Technetium-99m to all nuclear medicine located a reasonable distance from power.

A little 'History

Emilio Gino Segrè (Tivoli, February 1, 1905 - Lafayette, April 22, 1989) was an Italian physicist.

He studied physics at the University of Rome "La Sapienza", where he studied under Enrico Fermi, and where he obtained a professorship in 1928, and later became director of the Institute of Physics, University of Palermo (1936). In 1938, following the proclamation of the racial laws in Italy, emigrated to the United States and collaborated with the group of nuclear physicists Berkeley. Then worked at Los Ala mos and in 1946 returned to the University of California.

The researchers identified in a sample of molybdenum sent to them by Ernest Lawrence . The sample consisted of a piece of deflector in elttrostatico molybdenum that had been bombarded with nuclei of deuterium in cyclotron University of California of Berkeley , turning it into ⁹⁷ Tc. Technetium was the first artificially produced element in history, even if it subsequently proved its existence in nature both inside and outside the solar system .

For many years had been a gap in the periodic table instead of the number 43. Dmitri Mendeleev predicted that the missing element would be chemically similar to manganese and therefore ekamanganese baptized. In 1925 Noddack Walter and Ida Tacke , the discoverers of rhenium announced the discovery of element 43 masurium calling (from Mazury region of East Prussia, now Poland), but their ad was never confirmed and now commonly considered incorrect, Although some researchers have challenged this conclusion.

In 1952, technetium was identified by ' American astronomer Paul W. Merrill in the emission spectrum of some stars red giants , strengthening the theory that these stars produce heavy elements. It was also found small quantities in the uranium mines , especially in those where there have been phenomena natural nuclear fission, as in the natural nuclear reactor in Oklo .

In 1937, at Palermo, discovered technetium, then at Berkeley, the astatine, and helped with the production of plutonium. In 1955, using the betatron at Berkeley, was able to produce the antiproton, in collaboration with Owen Chamberlain. Together with the latter received the Nobel Prize for Physics in 1959. In 1974 he was appointed to the chair of nuclear physics at the University of Rome. So as we have just
saw the discovery of technetium dates back to 1937 when Carlo Perrier and Emilio Segrè (photo), who worked in Italy in the laboratories of the Institute of Physics, University of Palermo, were able to isolate the 97 Tc from a sample of molybdenum subjected to bombardment with deuterons (deuterium nuclei) in the cyclotron of the University of California at Berkeley.
component receives 43 was given the official name of technetium immediately after the end of World War II. It was the first artificially produced element in history. Technetium (Tc), a chemical element with atomic number Z = 43, belongs to the second set of metal transizione.Il Technetium is the lightest among the chemical elements is completely devoid of stable isotopes. It is made artificially in concentrations up to 6%, from the fission products of uranium-235 / 238 nuclear power plants.

are known as many as 25 isotopes whose atomic masses ranging from 86 to 118 atomic mass units. All isotopes of technetium are radioactive and have half-lives associated with very diverse: they range from the order of microseconds (eg 86m Tc) to the hundreds of thousands of years (eg 97 Tc, 98 Tc, Tc 99). Merrill in 1956 identified the 99 Tc in the emission spectrum of some red giants, thus fortifying the theories of nucleosynthesis of heavy elements in stars. Technetium-99 is the isotope most common and most readily available because it is the main product of fission of uranium-235. One gram of 99Tc produced 6.2 × 10 8 disintegration per second (0.62 GBq / g).

99mTc

Technetium-99 (99mTc) satisfies many requirements for its use of the water, because its radioactive emissions consists almost exclusively of gamma radiation with a single energy peak (140KeV), enough for good penetration through the body structures, so for a good detection from outside by current instrumentation (gamma-room). Moreover, its relatively short half-life (approximately 6 hours) can be administered to the individual patient to relatively high doses, while maintaining the radiobiological load to extremely low levels. This radioisotope is therefore currently the basis for wider use in the preparation of radiopharmaceuticals used in nuclear medicine for diagnostic conventional.

Technetium-99m is used in 20 million diagnostic nuclear medical Procedures Every year. Approximately 85 percent of Diagnostic Imaging Procedures in nuclear medicine use this isotope.

iso 99 m Tc	NA trace	Half- life 6.01 h	DM IT	DE (MeV) 0.142, 0.002	DP 99 Tc
			γ	0.140	-

Technetium-99m is made from the synthetic substance molybdenum-99 which is a by-product of nuclear fission. It is because of its parent nuclide, that technetium-99m is so suitable to modern medicine. Molybdenum-99 has a half-life of approximately 66 hours, and decays to Tc-99m, a negative beta, and an antineutrino (see equation below). This is a useful life since, once this product (molybdenum-99) is created, it can be transported to any hospital in the world and would still be producing technetium-99m for the next week. The betas produced are easily absorbed, and Mo-99 generators are only minor radiation hazards, mostly due to secondary X-rays produced by the betas (also known as bremsstrahlung ).

⁹⁹ Mo (Negative Beta Decay) → ^99m Tc + β ^- + ν

Where β ^- = a negative beta particle (electron), and ν = an antineutrino.

^99m Tc will then undergo an isomeric transition to yield ⁹⁹ Tc and a monoenergetic gamma emission.

^99m Tc → ⁹⁹ Tc + γ

When a hospital receives molybdenum-99 generator, the technetium-99m from within can be easily chemically extracted. That same molybdenum-99 generator (holding only a few micrograms) can potentially diagnose ten thousand patients because it will be producing technetium-99m, strongly for over a week. The radioisotope is perfect for medicinal purposes. The short half life of the isotope allows for scanning procedures which collect data rapidly. The isotope is also of a very low energy level for a gamma emitter. Its ~140 keV of energy make its use very safe and Substantially reduces the chance of ionization.



Technetium (Tc) plays an important role in modern medicine as one of its isotope, technetium-99 metastable the (Tc-99m) is, to date, the main radionuclide used in the diagnostic field. Currently, more than 90% of the nuclides used in standard diagnostic procedures in nuclear medicine, is based on the use of 99m Tc. Its widespread use is due to the fact that, before it was available, all radionuclides were produced in only a few large nuclear centers (mainly in the U.S. and Canada) which was shipped by air to individual laboratories that had requested. It is not difficult to imagine the cost of this procedure. In addition, the previously used emitting radionuclides, together with gamma radiation necessary to obtain such images, even useless beta radiation for diagnostic purposes, and much more for radiotoxic tessuti.Il Technetium however, due to its almost ideal radiochemical and its wide availability, ( therefore relatively cost can probably be defined as the best compromise in diagnostic nuclear medicine.

Especially since it only emits gamma radiation of energy is not too high, but enough to get pictures, and because it does not contaminate the environment through the shortness of its half-life (the time in which spontaneously halved its radioactivity) of only 6 hours, which means, for example, that if even a modest amount of radioactivity ever enter the sewer system through urine or feces patients, it is self-exhaustion within a few days.
and "economic" because the generator that produces it provides most of the radioactivity necessary for the operation of a Centre for Nuclear Medicine of medium size, for a whole week, at a cost.
found the ideal radionuclide then became the task of the radio-chemical and radio-pharmacists to identify different substances, linked to technetium, were able to focus in different organs.

many radiopharmaceuticals are now available electively able to concentrate in different tissues and organs, thus allowing the study of their NL Nederlands morpho-functional. They may be "marked" easily and quickly (mostly with the introduction of a solution of Tc-99m into the vial containing the drug itself).

All these features have made the use of Tc-imaging technique called a daily routine in any hospital with a Department of Nuclear Medicine. The

99m Tc, is therefore an "imaging agent" as ideal decade, becoming 99 Tc with a half life of 3.6 hours and by issuing gamma-ray energy of 140 keV. This issue is quite high in energy can easily penetrate the tissue but it is also so low that it can be absorbed with very high efficiency, the crystal of NaI (Tl) detector used as the gamma camera. This therefore allows the visualization of structures inside the body without the risk of exposing the patient to ionizing radiation at high power. Another reason to pay attention to the ^{99m Tc} comes from its characteristic half-life: it is long enough to permit the conduct of subsequent marking operations, administration and biodistribution of the radiopharmaceutical without need to handle excessive amounts of the isotope radioactive compensate for losses due to its decay also makes it possible to conduct accurate analysis of imaging, protraibili for a period of several hours, without having to significantly increase the dose of radiopharmaceutical injected.

important invention that allowed the hospitals to dispose of 99m Tc generator was 99 Mo / 99m Tc, developed over the past 50 years at Brookhaven National Laboratory. Its operation is based on the decay of 99 Mo (E b-max = 1.36 MeV, t _{1 / 2} = 67.0 h) in 99m Tc, which occurs with an efficiency of about 87% , While the second is the reaction product 99 Tc, in which the 99 Mo can also decay directly.