A knock to the head during a football match, a lingering cough that won’t quit, or a strange set of symptoms for which you need an answer.
For these and any number of other reasons, you may find yourself inside a CT scanner.
In modern medicine, it has become a routine and useful way to rule out more serious diagnoses, offer peace of mind to patients, or get to the crux of a health issue more quickly.
Used to create detailed imagery of different parts of the body, Computed Tomography (CT) scans are performed about five million times a year, but concerning new research suggests that overuse of this technology could lead to an increased risk of cancer, with a major American study predicting that excessive CT scanning could be responsible for more than 103,000 new cases of cancer in the future.
Five per cent of all new cancers in the U.S. attributable to CT scans
According to a new modelling study, published in the journal JAMA Internal Medicine, the high number of CT scans carried out in the United States in 2023 could cause five per cent of all new cancers in the country, which is equal to the number of cancers caused by alcohol.
The research team calculated the number of expected cancers that will be linked to the 93 million CT scans carried out on 62 million people in 2023 in the U.S.
‘These future cancer risks can be reduced either by reducing the number of CT scans (particularly low-value scans which are used in situations where they are unlikely to help the patient) or by reducing the doses per exam,’ Dr Rebecca Smith-Bindman, Radiologist and Professor of Epidemiology and Biostatistics, Obstetrics, Gynecology and Reproductive Medicine at the University of California San Francisco, tells Daily Mail Australia.
The overuse of CT scans is rife in Australia, the United States and other nations (stock image)
‘The doses for CT remain highly variable across patients’ hospitals, even in the UK, and there are opportunities to reduce those doses without reducing the accuracy of the tests.’
That CT scans carry an increased cancer risk is not new information – a large Australian study sounded the alarm in 2013, particularly for children – but the JAMA Internal Medicine study is the first to quantify a potential number of cancer cases based on a given year of CT data.
Experts stress that individual risk is low and the benefits of necessary CT scans outweigh the risks – but the researchers warn that rising radiation doses and a 30 per cent increase in CT use since 2009 in the U.S. are cause for concern.
Avoid CTs for back pain unless it’s a last resort
In Australia, a 2022 study found there had been a 211 per cent increase in CT use between 2001 and 2019, in spite of a 2009 Professional Services Review which highlighted concerns of CT overuse, while a 2017 study from one hospital found that 55 per cent of CTs ordered to exclude pulmonary thromboembolism were avoidable by using Wells scores and D‐dimer assays.
‘One of the common calls for X-rays and CT scans is lower back pain,’ says Professor Mark Morgan, Chair of the RACGP Expert Committee – Quality Care, and Professor of General Practice at Bond University.
‘Unless there are warning signs of an unusually dangerous cause of the back pain, then imaging does not change how the back pain is managed.’
The The Royal Australian College of General Practitioners (RACGP) recently produced a guide for doctors and a corresponding guide for patients as part of a series called, ‘First Do No Harm: A Guide to Choosing Wisely in General Practice’.
The rise of the ‘peace of mind’ scan is concerning in light of new research (stock photo)
‘Radiation is not the only harm from doing low-value scans,’ adds Prof Morgan.
‘Sensitive scans will also show up common changes that happen as we age. It is often hard to sort out which of these changes, if any, are behind the reason the scan was requested in the first place. Scans cost money and use up resources, and doing low-value scans also means longer waiting times for people with an urgent need.’
In Australia, guidelines exist to keep the risks of CT scans to a strict minimum. The Australian Radiation Protection and Nuclear Safety Agency (ARPNSA) requires referring physicians to provide justifications for use of the technique, particularly when children are concerned.
‘Scans of any sort should only be done when there is a clear expectation that the result of the scan will change what happens,’ says Prof Morgan.
‘Unborn babies and children are much more vulnerable to the long-term effects of radiation from CT scans because their rapidly dividing cells can be damaged in a way that triggers cancer.
‘Children have a much longer life expectancy, so any cancer cells that are caused by CT scans have longer to grow and become a problem.’
Rise of the ‘peace of mind’ CT scan
In the U.S., a key driver of rising CT scan numbers is the boom in private clinics offering full-body scans to healthy people hoping to ‘get ahead’ of any symptom-free conditions.
Meanwhile, in Australia, several companies offer ‘comprehensive, full-body health checks’ including bloodwork, scans and biometric health tests aimed at identifying early disease markers.
It is these types of scans that experts warn against.
‘Some CT scans and X-rays are done for reassurance or just to check nothing bad is being missed,’ says Prof Morgan.
‘We need to be particularly careful to balance the harm caused by radiation exposure from the scan or X-ray with the potential benefit.
‘It is hard to do this balancing act, for both the doctor and the patient, when there are emotions at play such as fear.
‘Scans and X-rays are rarely reassuring – often accidental or minor findings lead to further uncertainty. This is one of the reasons for having clinical practice guidelines that summarise the collected world evidence into a set of recommendations.’
