Imaging and radiation


  • Plain X-ray, computed tomography (CT scans) and nuclear medicine imaging use ionising radiation to create images of the inside of the body.
  • Exposure to radiation is associated with a very small increase in risk of developing cancer but the benefits generally outweigh the risks when the imaging is necessary to diagnose or manage your medical condition or injury.
  • Talk to your health professional about any questions or concerns you may have about your imaging.

Some types of medical imaging, including plain X-raycomputed tomography (CT) and nuclear medicine imaging, use high-energy, radioactive particles (or rays), known as 'ionising radiation' to create images of the inside of the body.

In comparison, magnetic resonance imaging (MRI) and ultrasound use no ionising radiation.

Background radiation 

We are all exposed to a small but continuous dose of radiation from environmental sources in our daily lives.1 This is often referred to as 'background' radiation.

Additional exposure to ionising radiation above these background levels can slightly increase your chance of developing cancer.1,2 Women are more sensitive to the effects of radiation than men.1 Radiation risks are also greater in children than in adults because children's bodies are still developing, and they have more remaining years of life for the potential effects of radiation to become apparent.1

Radiation exposure varies with type of imaging

Radiation exposure can differ with each imaging type. It also depends on the part of the body being imaged, and the total area exposed.

Computed tomography (sometimes called a CT or CAT scan) uses higher amounts of radiation than plain X-ray or nuclear medicine imaging, particularly when examining the head, chest or abdomen.2

Benefits of imaging outweigh risk

The amount of radiation used in most imaging procedures is relatively small. Your health professional and the radiologist performing your scan will ensure your exposure to radiation from the imaging test is minimised.

When these imaging procedures are necessary to diagnose or guide treatment for a disease or injury, the benefits generally outweigh the risks.1,2

If you are referred for a plain X-ray, CT scan (or nuclear medicine imaging), talk with your health professional about the relative risks and benefits and any other questions or concerns you may have.

For more information

  1. A. Wallace, T. Cain. InsideRadiology: Radiation Risk of Medical Imaging for Adults and Children. Royal Australian and New Zealand College of Radiologists, 2013 [Online] (accessed 16 March 2015).
  2. Radiological Society of North America, American College of Radiology. Radiation dose in X-ray and CT exams. 2014 [Online] (accessed 16 March 2015).