The uses of radioactive isotopes are forever becoming more widespread as new methods of adaptation are being devised. Here are just a few of the ways in which radioactive isotopes are used today.

  • Cancerous tissue can be destroyed by radioactivity in preference to healthy tissue. A cobalt-60 source which is a gamma emitter with a half life of 5 years is used to irradiate the cancer patient. The dose which the patient receives must be carefully calculated to destroy only the cancer cells without harming the patient's healthy tissues.

  • Surgical instruments can be sterilised more effectively with the use of radioactivity compared to that of boiling.

  • Underground leaks in water or fuel pipes can be detected by introducing a short-lived radioisotope into the pipe. The level of radioactivity on the surface can be monitored. A sudden increase of surface radioactivity shows where water/fuel is escaping.

  • Carbon-14 dating can be used to calculate the age of plant and animal remains. Living plants and animals take in carbon, which includes a small proportion of the radioactive isotope carbon-14. When a plant or animal dies, it takes in no more carbon-14, and that which is already present decays. The rate of decay decreases over the years, and the activity that remains can be used to calculate the age of the plant or animal material.

  • Tracer studies use radioactive isotopes to track the path of an element through the body. Radioactive iodine(iodine-131) is administrated to patients with defective thyroids to enable doctors to follow the path of iodine through the body. As the half-life is only 8 days, the radioactivity soon falls to a low level.

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ANDREW SIDELL / June 2002 /