Medical applications using radioactivity

To detennine the condition of an organ in the body, a radiologist may use a radioisotope that concentrates in that organ. The cells in the body do not differentiate between a non-radioactive atom and a radioactive one, so these radioisotopes are easily incorporated. Then the radioactive atoms are detected because they emit radiation. Some radioisotopes used in nuclear medicine are listed in Table 16.8. 

Isotope Half-Life Radiation Medical Application 

Au-198 2.7 d Beta Liver imaging treatment of abdominal carcinoma 

Ce-141 32.5 d Gamma Gastrointestinal tract diagnosis measuring blood flow to the heart 

1-123 13.2 h Gamma Treatment of thyroid, brain, and prostate cancer 

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There are other medical applications for radioactive strontium isotopes. Strontium-90 is used to treat a variety of eye disorders. And strontium-85 and strontium-87m are used to study the condition of bones in a person s body. 

Chapters 16 (waste disposal). Chapter 17 (radioactive materials transportation), and Chapter 18 (decontamination and decommissioning) are related to many radioactive processes and materials. Radioactive waste is generated wherever radioactive materials are handled and used. This includes medical applications of radioactive isotopes and their production, as well as the facilities and processes involved in nuclear power. This waste must be stored and/or disposed of in a way that isolates it from the environment until the radioactive materials decay. 

The most widely used radioactive isotopes in medical and industrial applications are cobalt 60 ( C), cesium 137 ( Cs), and iridium 192 ( lr). The half-life of is 5.3 years, that of Cs is 30 years, and the half-life of Ir is 74 days. When used for irradiation the isotope is generally in the form of a pellet size, 1.5 x 1.5 mm, loaded into a stainless steel capsule and sealed. Unlike electron beam or x-rays, gamma rays cannot be turned off. 

It is the purpose of this book to present the facts about the presence of radionuclides in nature. The use of technology can significantly modify the exposure to natural radiation. Among the human activities which should be considered in this context are (i) the electricity generation by coal-fired power plants, (ii) the use of phosphate fertilizers, and (iii) many consumer products. Man-made radioactivity has found many useful applications in everyday life. The best known are medical applications. The use of radionuclides and radioactivity in diagnosis and treatment of diseases is well established practice. 

There are assessments predicting the use of reverse osmosis for the processing of the wastes from medical application [36,37] and for the removal of caesium-137 from decontamination wastes after accident in the steel production factory [38]. RO is considered as a method for removal of radioactive pollutants from contaminated water (removal of Cs and °Sr) in the vicinity of atomic power plants [39], as well as for removal of small quantities of radionuclides ( Rn, Ra) from... 

Some actinides have medical applications for example, radioactive cali-fornium-252 (Cf) is used in cancer therapy. Better results in killing cancer cells have been achieved using this isotope of californium than by using the more traditional X-ray radiation. 

The radioactive isotope 89Sr (also known by the pharmaceutical brand name Metastron ) is used as a cancer therapeutic to alleviate bone pain. 85Sr has been used in medical applications, such as radiologic imagining of bones, in minor commercial applications, such as thermoelectric power generation, as a beta-particle standard source, and in instruments that measure thickness and density of materials (Murray 1994). 

The radioactive isotopes of cesium are much more important in technical terms, especially the long-living jCs, which can be obtained relatively simply and cheaply from radioactive waste produced by uranium-based nuclear reactors. jCs is used as a y-irradiation source for technical (metallurgical) and medical applications. 

As you progress through the periodic table each successive atom has one more proton and neutron compared with the previous atom. The protons are useful for attracting electrons, and the neutrons are useful for stabilizing the nucleus. When there is an imbalance between the two nuclear particles (proton and neutron), the nucleus becomes unstable, and these types of atoms are called isotopes. If they are radioactive, they are called radioisotopes, and they can be useful, for example, in medical applications. 

Nuclear chemistry is the study of nuclear reactions, with an emphasis on their uses in chemistry and their effects on biological systems. Nuclear chemistr) affects our lives in many ways, particularly in energy and medical applications. In radiation therapy, for example, gamma rays from a radioactive substance such as cobalt-60 are directed to cancerous tumors to destroy them. Positron emission tomography (PET) is one example of a medical diagnostic tool that relies on decay of a radioactive element injected into the body. 

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