Use of Radio-Isotopes


Radioisotopes are used in two major ways in Medicine

  • Diagnosis: This is when a radioisotope is used to examine the condition of one's health.
    • An example would be Technetium-99m, that is inserted into the body via intravenous injection
    • It is used to check bone and lungs
    • When inside the body, it undergoes gamma decay, and the result can be picked up using a Geiger or Scintillation counter.
    • It can then be compared with a healthy body's to check for any abnormalities
    • These radioisotopes should have short half-lives to minimise their patients exposure to radiation.
      • Technetium-99m has a half life of around 6 hours.
  • Radiotherapy: This is when high powered radiation is used to kill off unwanted cells and tumours.
    • An example would be Cobalt-60, which is used to destroy malignant tumours
    • These radioisotopes should have a long half-life to make it more economically feasible.
      • Cobalt-60 has a half life of about 6 years.


  • Radiography Similar to diagnosis, it is often used to examine structural defects
    • An example of one used is Iridium-192 to emit the gamma radiation needed for radiography.
    • Common use is to have a photosensitive sheet around the inspected part, then place the Iridium pellets near the part.
    • It produces an image, and any significant weaknesses turn up as a blackened part on the photo.
    • Iridium-192 has a half life of about 75 days.
  • Another application would be in a Thickness Gauge
    • This is when a processed material has radiation passed through it to a detector, and the amount detected determines whether the material is of the right thickness or not.
    • This can then automate a signal to change the processing device to fix any abnormalities.


  • Radioisotopes are used in the Irradiation of food
  • This is when a radioisotope's radiation supposedly is used to sterilise food and prevent disease.
    • There is not much basis for this, however.
  • Cobalt-60 would be a good candidate for this.