CT scans can triple the risk of children developing leukaemia and brain cancer, a study has found. Despite a very small absolute risk, scientists called for greater efforts to ensure use of the 3D X-rays is justified.

British-led scientists studied data on around 180,000 patients under the age of 22 who had CT scans at UK hospitals between 1985 and 2002. Their cancer rates were compared with those from the general population, reported in the UK National Health Service Registry.

The results showed children younger than 15 would receive enough radiation from two to three head CT scans to triple their risk of developing brain cancer.