Radioisotopes ionizing radiation

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 process of radioactive decay (also known as radioactivity) involves the ejection from a nucleus of one or more nuclear particles and ionizing radiation. Nuclear fission is a reaction in which the nucleus splits into smaller nuclei, with the simultaneous release of energy. Most radioisotopes undergo radioactive decay processes and are converted into different smaller atoms. 

Isotopes are atoms of the same elements having different mass numbers. Radioisotopes are the isotopes of an element that are radioactive or emit ionizing radiation. All elements are known to form artificial radioactive isotopes by nuclear bombardment. 

The availability of energy in the form of ionizing radiations has recently increased markedly. This increase is likely to continue for some years. A portion of this energy will be potentially available as a result of accelerator development and facilities for the production of radioisotopes. Another large supply of this energy will be produced as a necessary consequence of the anticipated wide-scale use of the power reactor. 

Because the CO2 containing carbon-14 is used to trace the progress of carbon tbrough the reaction, it is referred to as a radiotracer. A radiotracer is a radioisotope that emits non-ionizing radiation and is used to signal the presence of an element or specific substance. The fact that all of an element s isotopes have the same chemical properties makes the use of radioisotopes possible. Thus, replacing a stable atom of an element in a reaction with one of its isotopes does not alter the reaction. Radiotracers are important in a number of areas of chemical research, particularly in analyzing the reaction mechanisms of complex, multi-step reactions. 

Ionizing radiation is an effective killer of microorganisms and cancerous tissues. Accordingly, it is used to sterilize medical devices, to irradiate food, and to treat tumors. Ionizing radiation includes emissions from radioisotopes and x-rays. X-rays have numerous beneficial uses and are tolerated well by humans in small doses. It is well known that exposure to excessive quantities of ionizing radiation can induce mutations and carcinogenesis and, in extreme cases, cause death. 

Radioisotopic (risks of ionizing radiation) Time cbnsuming ... 

Since the use of radioisotopes in nuclear power stations, in anti-cancer radiotherapy or in nuclearweapons, noxious effects of ionizing radiation on human cells are better known. According to the amount and distribution of exposure, ionizing radiation can locally eliminate tumors, but can also damage normal tissues. The biological effects of such radiation result from chemical processes as ionization or excitation of the biological macromolecules, such as DNA, either in a direct way or in an indirect way via water molecule radiolysis (Chapter 12). In both cases, many radical species appear then, which have various consequences on cellular scales such as mutations of DNA, cellular death, or cancer. 

A comprehensive description of the nature of radioactivity and its interaction with matter is beyond the scope of this chapter, and such information can easily be found elsewhere (Shleien et al., 1998 CPEP, 2003 Tykva, 2004). Here we give only a brief sketch of the basic principles. Radioactivity is a natural phenomenon, discovered in 1896 by Henri Becquerel. The nuclei of some atoms are unstable and decay spontaneously, emitting ionizing radiation to attain a more energetically favorable state. Radioisotopes are characterized by the nature of the... 

The fact drat radioisotopes decay to produce ionizing radiation does not influence their biological role. Radioisotopes are taken up and assimilated in the same way as are stable isotopes. Enzymes may be sufficiently sensitive to discriminate slightly between isotopes of the same element, leading to changes in relative isotopic abundance, but the effect is small (Marechal et al., 1999 Anbar et al., 2000 Marechal and Albarede, 2002 Zhu et al., 2002 Beard et al., 2003 Weiss et al.. 

The commonly used radioisotopes emit j3-particles (electrons H, C, 2p) oj- gamma, ionizing radiation (X-ray) and electrons... 

In the UK, the Ionizing Radiations Act (1985) provides details of local arrangements for the supervision of radioisotope work. 

Tositumomab and iodine I-tositumomab is a monoclonal antibody that blocks (complement-dependent cytotoxicity) CD20 antigen, which is found on the surface of normal and malignant B lymphocytes. Cell death is associated with ionizing radiation from the radioisotope. It is indicated in the treatment of patients with CD20-positive, follicular, non-Hodgkinr s lymphoma, with and without transformation, whose disease is refractory to rituximab and has relapsed following chemotherapy. 

To be used as a tracer, a radioisotope need emit only low-energy detectable radiation. Many other uses of radioisotopes, however, depend on the damage that high-energy, ionizing radiation can inflict on living systems. 

Radioisotopic tracers emit nonionizing radiation and have been used to study reaction mechanisms, material flow, elemental composition, and medical conditions. Ionizing radiation has been used to destroy cancerous tissue, kill organisms that spoil food, and control insect populations. 

The material in this text refers only to ionizing radiation. Specifically, it deals with detection instruments and methods, experimental techniques, and analysis of results for radiation in the energy range shown in Table 1.1. Particles with energies listed in Table 1.1 are encountered around nuclear reactors, around installations involving production or use of natural or manufactured radioisotopes, and also around low-ener accelerators. Not included in Table... 

Four diagnostic radioisotopes are listed in Table 13.4. Each produces gamma radiation, which in low doses is less harmful to the tissue than ionizing radiations such as beta or alpha particles. By the use of special carriers, these radioisotopes can be made to accumulate in specific areas of the body. For example, the pyrophosphate ion (P O ), a simple polyatomic ion, can... 

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