Children who undergo CT scans may be at a higher risk of developing brain cancer, a study warns.
Fears have been raised recent years over the extensive dangers caused by radiation to humans, including cancer.
The new analysis, of nearly 170,000 children who received at least one CT scan, adds to the array of damning trials.
Dutch researchers found the incidence of cancer among the participants was much higher than the average rate.
Doctors have turned to CT scans heavily over the past two decades, as they provide a much clearer picture than X-rays.
Patients sit in an X-ray tube, which rotates around their body to take pictures of their internal organs and other parts of the body.
However, the machines also deliver a much higher dose of ionising radiation, which are known to damage bodily tissues.
The new analysis, of nearly 170,000 children who received at least one CT scan, may finally lead to concrete evidence
The researchers found rates of cancer were 1.5 times higher in the children who had underwent at least one CT scan in their life.
But the amount of cancer diagnoses among youngsters who had undergone the most CT scans were four times higher.
Yet there was no link between the scans and leukaemia – even though an array of evidence suggests there is.
Countless trials have debated the contested issue – but some scientists argue there simply isn’t enough proof.
A landmark study in 2012 found multiple CT scans in childhood can triple the risk of developing brain cancer or leukaemia.
The Newcastle University-led team examined the NHS medical records of almost 180,000 young patients to make the finding, published in The Lancet.
WHAT IS A CT SCAN?
A computerised tomography (CT) scan uses X-rays and a computer to create detailed images of the inside of the body.
CT scans are also sometimes known as CAT scans, which stands for computerised axial tomography.
During a CT scan, which is painless and takes five to 10 minutes, depending on the part of the body being scanned, patients lie on their backs on a bed.
The scanner consists of an X-ray tube that rotates around the body and the patient is usually moved continuously through this rotating beam.
The X-rays are received by a detector on the opposite side of the body and an image of the scan will be produced by a computer.
The images produced by a CT scan are called tomograms and are more detailed than standard X-rays.
A CT scan can produce images of structures inside the body, including the internal organs, blood vessels, bones and tumours.
Source: NHS Choices
The most common malignancies caused by radioactivity among children and young adults are leukemia and brain tumors. Researchers therefore evaluated leukemia and brain tumor risks following exposure to radiation from CT scans in childhood.
Figures show around nine million CT scans are performed each year on children in the US and in excess of 100,000 in the UK
The National Cancer Institute, based in the US, lists paediatric CT scans as a ‘public health concern’.
This is because children are more sensitive to radiation than adults, and live longer, meaning there is more times for radiation damage to occur.
In some cases, children may also receive higher doses of radiation than necessary, if the settings of CT scanners are not adjusted.
The new findings, conducted on 168,394 children, were published in the Journal of the National Cancer Institute.
But the researchers, led by Dr Michael Hauptmann at the Netherlands Cancer Institute, issued caution over the findings.
They said CT scans are sometimes used to identify conditions commonly linked with an increased brain tumour risk.
Dr Hauptmann said: ‘Epidemiological studies of cancer risks from low doses of medical radiation are challenging.’
‘Nevertheless, our careful evaluation of the data and evidence from other studies indicate that CT-related radiation exposure increases brain tumor risk.
‘Careful justification of pediatric CT scans and dose optimization, as done in many hospitals, are essential to minimize risks.’