It has been known for several years that there could be some cancer risk for young people from low-dose ionising radiation. With respect to diagnostic imaging, examinations such as nuclear medicine bone scans, CT, fluoroscopy and x-rays are all associated with exposure to ionising radiation.1 In 2001, Brenner et al2 found that there was a significant increase in lifetime cancer risk attributable to radiation from paediatric CT scans relative to adult CT scans. The Image Gently Campaign by the Alliance for Radiation Safety in Paediatric Imaging has aimed to raise public awareness of ‘opportunities to promote radiation protection in the imaging of children’.3 It is thought that young people are at higher risk because cell division is fast and organs are therefore more sensitive to radiation at a younger age.4

BMJ and Lancet studies

Three landmark papers from Lancet5 and BMJ6 published in the past year have confirmed that the theoretical increased risk of cancer does bear out in follow-up studies. Pearce and colleagues’ study in Lancet looked at the excess risk of leukaemia and brain tumours for children and adolescents exposed to CTs. They found that children exposed to cumulative doses of 50 mGy (3–5 CTs) may have triple the risk of leukaemia, and doses of 60 mGy may have almost triple the risk of brain tumours.5 Though this appears to be a very large increase in risk, the authors point out that these cancers are still relatively rare, causing an estimated one excess case of leukaemia and one excess brain tumour per 10 000 head CTs. Moreover, although not specific to the discussion of paediatric patients, the lifetime cancer risk of developing …