Radioisotopes stable

Generators radioisotope -Stable current -Require additional duration missions,... 

RMsfor Radioisotopes, Stable Isotopes and Rodiopharmaceuticals 145 Tab. 4.6 Overview of available reference materials for "Am, and °Sr... 

Alpha decay All nuclei with more than 83 protons are radioactive and decay spontaneously. Both the number of neutrons and the number of protons must be reduced in order to make these radioisotopes stable. These very heavy nuclei often decay by emitting alpha particles. For example, polonium-210 spontaneously decays by alpha emission. 

More confident attribution usually is possible when radionuclides in a sample can have only limited origin from, say, atmospheric fallout and one or two nuclear facilities. For tritium, I, or uranium in the environment, for example, the specific activity (radioisotope/stable isotope ratio) can indicate the origin. Certain activation products can be attributed to specific nuclear medicine or reactor facilities. 

Series Half-Life of Parent (Years) Parent Radioisotope Stable Decay Product... 

Thirty isotopes are recognized. Only one stable isotope, 1271 is found in nature. The artificial radioisotope 1311, with a half-life of 8 days, has been used in treating the thyroid gland. The most common compounds are the iodides of sodium and potassium (KI) and the iodates (KIOs). Lack of iodine is the cause of goiter. 

Each element that has neither a stable isotope nor a characteristic natural isotopic composition is represented in this table by one of that element s commonly known radioisotopes identified by mass number and relative atomic mass. 

Unstable niobium isotopes that are produced in nuclear reactors or similar fission reactions have typical radiation hazards (see Radioisotopes). The metastable Nb, = 14 yr, decays by 0.03 MeV gamma emission to stable Nb Nb, = 35 d, a fission product of decays to stable Mo by... 

Radiochemical tracers, compounds labeled with radioisotopes (qv), have become one of the most powerful tools for detection and analysis in research, and to a limited extent in clinical diagnosis (see Medical IMAGING TECHNOLOGY). A molecule or chemical is labeled using a radioisotope either by substituting a radioactive atom for a corresponding stable atom in the compound, such as substituting for H, for or for P, and for for... 

A radioisotope is an atom the nucleus of which is not stable and which decays to a more stable state by the emission of various radiations. Radioactive isotopes, also called nucHdes or radionucHdes, are important to many areas of scientific research, as well as ia medical and iadustrial appHcations (see... 

Radioisotopes Abundance, % Half-hfe, yr Decay Q-value, keV Stable daughter... 

At least 21 tellurium isotopes are known, with mass numbers from 114 to 134. Of these, eight are stable, ie, 120, 122—126, 128, 130. The others are radioactive and have lifetimes from 2 min to 154 d the heaviest six, 131m, 131,132, 133m, 133, and 134, are fission products (see Radioisotopes). 

Because normal radioisotopic decay lowers the thermal output by about 2.5%/yr in these units, they are purposefully overdesigned for beginning of life conditions. Several of these generators have successfully operated for as long as 28 years. This is approximately equal to the half-life of the strontium-90 isotope used in the heat sources. The original SNAP-7 series immobilized the strontium-90 as the titanate, but the more recent ones have used it in the form of the fluoride, which is also very stable. A number of tiny nuclear-powered cardiac pacemaker batteries were developed, which have electrical power outputs of 33—600 p.W and have been proven in use (17). 

Radioactive cobalt, Co, produced by bombarding stable Co with low energy neutrons, has appHcation in radiochemistry, radiography, and food steriliza tion (26-28) (see FoOD PROCESSING RADIOISOTOPES STERILIZATION TECHNIQUES). 

Elements with multiple stable isotopes may produce several radioisotopes that can be measured to assure the accuracy of the analysis. For example, Zn has five stable isotopes. The isotope Zn will produce the radioisotope Zn, and Zn will produce the radioisotope Zn. Both of these radioisotopes can provide an independent measurement of the Zn concentration and therefore can be used to check the consistency and quality of the analysis. On the other hand, Zn will produce Zn, which is nonradioactive and therefore cannot be used in NAA. 

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 ... 

Wolfe, R.R. 1984 Tracers in Metabolic Research Radioisotope and Stable Isotope/Mass Spectrometry Methods. A.R. Liss, NY. 

Eighteen isotopes of sulfur, 17 of selenium, 21 of tellurium, and 27 of polonium have been registered of these, 4 sulfur, 6 selenium, and 8 tellurium isotopes are stable, while there is no stable isotope of polonium. None of the naturally occurring isotopes of Se is radioactive its radioisotopes are by-products of the nuclear reactor and neutron activation technology. The naturally occurring, stable isotopes of S, Se, and Te are included in Table 1.2. 

For human studies, the choice of stable isotopes is limited because radioisotopes are associated with ionization radiation and thus with some potential harmful effects for humans. Studying the bioavailability of compounds labeled with stable isotopes requires complex techniques such as gas chromatography coupled with mass spectrometry (GC-MS), liquid chromatography coupled with MS (LC-MS), and atmo-... 

The structure of some isotopes, generally referred to as stable isotopes, is immutable (see Textbox 13). Others, known as radioactive isotopes or radioisotopes, are unstable in time they undergo what is known as... 

Radioisotopes may occur in the earth naturally as primordial radioisotopes, formed when the planet was created, or be produced by natural or artificial processes. Most fast decaying primordial radioisotopes have long disappeared from the planet since the earth originated about 4.5 billion years ago, such isotopes have decayed and reached a final, stable form. The relatively few primordial radioisotopes still extant in the earth today, therefore, decay very slowly. Among these are potassium-40 and some isotopes of uranium, such as uranium-235 and uranium-238, which are of use for dating archaeologically related minerals and rocks (see Textboxes 15 and 16). 

The half-life (t1 ) of a radioisotope is the amount of time it takes for that isotope to undergo radioactive decay and be converted into another. It is also a measure of the stability of the isotope the shorter its half-life, the less stable the isotope. The half-life of radioisotopes ranges from fractions of a second for the most unstable to billions of years for isotopes that are only weakly radioactive. In the case of radiocarbon (carbon-14), for example, the half-life is 5730 years (see Fig. 61). 

DTPA has also been used in the peptide-based " in-DTPA-octreotide. Octreotide is a shortened peptide analog of somatostatin designed to be more stable in vivo. Radiolabeling of octreotide for diagnostic imaging applications with radioisotopes for PET or SPECT has been investigated,... 

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