Applications of Radioactive Substances:
1. In 1901, radium was the first radionuclide used in medicine. This nuclide was the most important medical radionuclide in use up to 1946.
2. Current medical procedures employ more than 50 radionuclides in a wide variety of chemical and physical forms.
3. Radionuclides are used in medicine and pharmacy in two different ways: as radiation sources or radioactive tracers.
4. As radiation sources, their principal roles are in (a) therapy and (b) calibration of radiation detection and instrumentation.
5. Radioactive tracers available in the form of radiopharmaceuticals, are used in medicine principally, for diagnostic purposes.
6. Radiopharmaceuticals are used for diagnosis and therapy.
7. For diagnostic applications, a radiopharmaceutical should not be pharmacologically active, it should not produce any physiological effect.
8. Radiopharmaceuticals intended for therapy should produce enough radioactivity.
9. Radioisotopes may be used internally or externally.
10. Various examples of radioisotopes used are:
(a) Gold (198Au) used in the treatment of abdominal and pleural effusions associated with malignant tumours.
(b) Au also finds use in the treatment of carcinoma of the uterus and urinary bladder.
(c) Cobalt labelled (Co-57 and Co-58) cyanocobalamine (Vitamin B₁2) find uses in the diagnosis of pernicious anaemia.
(d) Sodium iodide (131I) preparation finds use in the treatment of thyroid disorders.
(e) Ferric citrate (5eFe) injections haematological disorders.
(f) Calcium (Ca -44 and Ca – 45) has been used to study the bone structure and in the treatment of carcinoma of bones.
(g) Strontium – 90, one of the most dangerous isotopes formed during the fission of uranium in atomic bomb blasts, is used for radiotherapy of superficial carcinomas.
(h) The deuterium (H-2) and tritium (H-3) are the isotopes of hydrogen, which are useful to determine the total body water.
11. Excellent biological and medicinal studies have been carried out with radioactive isotopes as tracers.
12. Strong radiation sources are used for sterilizing pharmaceuticals in their final packed containers and surgical instruments in hospitals. The radiation does not destroy or harm most pharmaceuticals. Example: 6027Co or Cesium137 may be used for sterilizing surgical instruments.
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