2. Radio Isotopes


Radiation and radioactivity existed long before life evolved on the earth and are indispensable parts of the environment. We are continuously exposed to natural and artificial radiations. In addition to these, some of the radionuclides such as polonium and radium are present in our bones; our muscle contains radiocarbon and radiopotassium, radon, thoron, and their progeny in our lungs, and they emit ionizing radiation.

The radiation coming from the sun is due to the nuclear fusion; it is very essential for the existence of life on earth. Therefore we live in a natural radioactive world. All organisms including human beings on the earth are getting benefits from radiation in a direct way without realizing it. Therefore, without radiation life does not exist. Scientific understanding of radiation and radioactivity and their benefits and effects on humans, that’s back almost century to the pioneering work of Roentgen (1895) and Becquerel (1896). Further investigation by M. Curie and P. Curie (1898) and Rutherford (1911) showed that radioactivity is exhibited by heavy elements such as uranium, thorium, and radium. The discovery of isotope was one of the results of work on the radioactive elements. The name “isotope” was first suggested by Soddy in 1913.

The radioactive decay law was also proposed by him. More than thousand natural radioisotopes are present in our nature. At present more than 200 radioisotopes were produced from nuclear reactors and accelerators. The application of radioisotopes in medical, industry, and research field has served human civilization over a several decades. The radioisotopes have been a valuable gift to many braches of medicine and biology. Shorter half-lives of radioisotopes are used in medicine because they decay quickly and they are suitable for medical diagnosis and therapy. The World Health Organization (WHO) and International Atomic Energy Agency (IAEA) jointly coordinated a research program on radioactive tracers in cardiovascular diseases and searched for clues to this widespread health problem.

. There are numerous applications of radioisotopes in medical fields; one of the revolutionized techniques is radioimmunoassay; this is used to detect and quantify minute levels of tissues components such as hormones, enzymes, or serum proteins by measuring the components ability to bind to an antibody or other proteins in competition with a standard amount of the same component that had been radioactivity tagged in the laboratory. For this technique, Rosalyn Sussman Yalow was awarded Nobel Prize in 1977.

The precise dose is a life-and-death matter; therefore the IAEA has several program components to assist institutions in the members of the countries and aspect of radiation therapy and diagnosis. The IAEA in cooperation with the WHO offers on intercomparison service to check and improve accuracy of radiation dosimetry due to increase in the effectiveness of the radiotherapy. The release of radioisotopes from nuclear fuel cycles, naturally occurring radioactive materials (NORM) from mining activity, mishandling of radioisotopes in industries and laboratories, and accidental release of radioactive materials could enter into the atmosphere. Therefore, it is necessary to require an urgent decision for protective actions. Therefore, the main objective is to focus on the applications and effects of radioisotopes and radiological protection.

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