RADIATION exposure from CT scans in childhood could triple the risk of leukaemia and brain cancer, according to research led by North- East scientists.

Children and young adults scanned multiple times by computed tomography (CT), a commonly used diagnostic tool, have a small increased risk of leukaemia and brain tumours in the decade following their first scan.

The findings, published online today in The Lancet, from a study of more than 175,000 children and young adults, was led by researchers at Newcastle University as well as the National Cancer Institute, part of the National Institutes of Health, in the US.

The researchers emphasise that when a child suffers a major head injury or develops a life-threatening illness, the benefits of clinically appropriate CT scans should outweigh future cancer risks.

Lead author and epidemiologist Dr Mark Pearce, from Newcastle University said: “CT scans are accurate and fast, so they should be used when their immediate benefits outweigh the long-term risks.

“However, now we have shown that CT scans increase the risk of cancer, we must ensure that when they are used they are fully justified from a clinical perspective.”

CT imaging is a vital diagnostic technique and it is one that is used more frequently in countries such as the US and Japan. However, CT scans deliver a dose of ionising radiation to the body part being scanned and to nearby tissues.

Even at relatively low doses, ionising radiation can break the chemical bonds in DNA, causing damage to genes that may increase a person’s risk of developing cancer.

Children typically face a higher risk of cancer from ionising radiation exposure than adults exposed to similar doses.

In the study, the researchers estimate that for every 10,000 head CT scans performed on children aged ten or younger, one more case of leukaemia and one more brain tumour would occur than would normally be expected.

The investigators obtained CT examination records from radiology departments in hospitals across Britain and linked them to data on cancer diagnoses and deaths.

The study included people who underwent CT scans at NHS hospitals from birth to 22 years, between 1985 and 2002.

Information on cancer incidence and mortality from 1985 through 2008 was obtained from the National Health Service Central Registry.