Radioisotopes

There are nearly 100 radioisotopes whose beta or gamma radiation is used in diagnosis investigations in nuclear medicine. Radioisotopes are radioactive isotopes of an element. Different isotopes of the same element have the same number of protons in their atomic nuclei but differing numbers of neutrons. They can also be defined as atoms that contain an unstable combination of neutrons and protons. A very effective role for radioisotopes in nuclear medicine is the use of short-lived positron emitters such as 11C, 13N, 15O, or 18F in a process known as Positron Emission Tomography (PET). Incorporated in chemical compounds that selectively migrate to specific organs in the body, diagnosis is effected by detecting annihilation gamma rays two gamma rays of identical energy emitted when a positron and an electron annihilate each other. The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number of citations to recent articles published in science and social science journals in a particular year or period, and is frequently used as a proxy for the relative importance of a journal within its field. It is first devised by Eugene Garfield, the founder of the Institute for Scientific Information. The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.

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Last date updated on December, 2024