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CT scans and cancer risk

March 2010


Recent media reports indicate that there may be an overuse of CT scans in Australia as a first-choice diagnostic tool for conditions such as lower back pain. The number of CT scans is reportedly growing at about 12 per cent each year in Australia. Some radiologists are requesting doctors to be more cautious about ordering CT scans, as there is a concern that CT scans can potentially cause cancer.
CTs can be very useful in appropriate circumstances and often save patients from undertaking more invasive tests. Most CTs ordered by doctors are appropriate.

 What are CT scans?

CT or ‘computerised tomography’ is a medical imaging method employing tomography created by computer processing. CT scans expose a patient to medical ionizing radiation.
CT scans generate higher radiation doses than conventional diagnostic X-rays. For example, a chest CT scan exposes the patient to more than 100 times the radiation dose of a routine chest X-ray.

How dangerous are CT scans?

The risk of developing cancer from a CT scan is relatively small.

It is calculated that more than 400 new cases of cancer each year in Australia could be attributable to diagnostic radiation. This can be compared to the estimated 114,000 Australians who get cancer each year.

Cancer Council recommends that CT scans should not be ordered for patients with back pain unless the pain has been ongoing, and/or whether other issues are present, such as recent significant injury, fever or unexplained weight loss.

What are possible examples of unnecessary CT scans?

  • Long-term follow-up in patients who have been successfully treated for cancer, who remain well and have no symptoms

  • Routinely investigating common symptoms like back pain

  • To avoid medico-legal issues of missing a cancer diagnosis in asymptomatic patients.

 What are examples of good use of CT scans?

  • Ensuring that there is no metastatic disease in a patient before radical surgery

  • Investigating specific symptoms and signs in a patient

  • Follow-up for some cancers

  • Where a CT scan can substitute for an invasive procedure such as a laparotomy.

What should patients do?

If you are concerned that your doctor has ordered at CT scan for you, ask your doctor how this will benefit you. You could also ask your doctor what alternative investigations there are. You may want to seek a second opinion.

It should be kept in mind that while there may be some evidence that CT scans have been overly prescribed in some circumstances in Australia by doctors, many deaths have been delayed or prevented by use of diagnostic imaging. 

The patient should be informed of the risk by the doctor. The patient, in conjunction with the doctor, should weigh up the benefits against the small risk of CT scans.

Summary of Cancer Council’s position:

CT scans can be very useful in appropriate circumstances and often save patients from undertaking more invasive tests. Most CT scans ordered by doctors are appropriate.

If your doctor has recommended a CT scan for you, see our recommendations for patients above.



This page was last updated on: Tuesday, August 7, 2012