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Medical radiation

Some imaging tests and some types of cancer treatment use ionizing radiation. Many Canadians are concerned about the use of medical radiation. But the minimal risks from how these technologies are used today must be weighed against their benefits, which are often life-saving.

  • How you’re exposed to medical radiation
    Medical imaging tests

    X-rays and CT scans (which are a series of x-ray images) use ionizing radiation to produce images of body organs in order to diagnose disease or injury.

    During a PET scan, a low-dose radioactive sugar is injected into the body and picked up by a scanner that turns it into 3-dimensional images.

    Radiation therapy (also known as radiotherapy)

    Radiation for cancer treatment uses higher doses of radiation to destroy cancer cells. It works by damaging the cancer cells over and over again. The major use of radiation therapy is to shrink a tumour, but it can also be used in other ways to treat cancer. While radiation therapy is an effective treatment, the problem in the past has been that sometimes the person who’s been treated ends up with a different type of cancer 20 or 30 years later.

    Radiation therapy today is very sophisticated. Significant advances have been made, and continue to be made, in how to deliver the radiation and how much to deliver. This means there is usually less damage to nearby healthy cells and reduces the frequency and severity of side effects.

  • Medical radiation and cancer

    The chance of ionizing radiation causing genetic damage or increasing the risk of cancer is related to the total amount of radiation accumulated by a person. The greatest risk comes from:  

    • larger doses of radiation
    • longer exposure to radiation (such as over a lifetime)
    • high-strength forms of radiation

    The risk that important tools like medical imaging tests or radiation therapy pose must be weighed against their benefits. Often the benefits, which can be life-saving, outweigh the risks. Many important advances in technology have helped lessen the damage to healthy cells and reduced side effects. Steps are also taken to protect people, as much as possible, from being exposed to unnecessary radiation during medical procedures.

  • Tips to reduce your exposure

    If you’re concerned about medical radiation, talk to your doctor about what x-rays or imaging procedures are needed and only have those that are really necessary.

    Occupational exposure

    If you work with medical radiation as part of your job, follow your employer’s health and safety instructions. This should include wearing a dosimeter, which measures the amount of radiation you are exposed to over time. These measurements are analyzed regularly by the National Dose Registry. The amount of radiation that people are allowed to receive in the workplace is strictly regulated.

  • Suggested links for more information
    General information about medical radiation

    Consult these websites for information about sources of medical radiation exposure, potential health risks associated with exposure, advice on how to minimize risk and links to credible sources with more in-depth information.

    Health Canada – X-rays

    World Health Organization – Medical radiation exposure

    RadiologyInfo – Radiology information resource for patients

    Occupational exposures to medical radiation

    This site provides information about how the federal government monitors exposure to radiation, including medical radiation, in the workplace.

    Health Canada – National Dose Registry



Sophie Lebel My family is proud of the work I’m doing that is making a positive change in people’s lives.

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