Brussels, 12 Jan 2004
Doctors should only use brain scans on young children when absolutely necessary because the radiation involved may impair their mental development, new research suggests.
A new study by Swedish and American researchers has uncovered a possible link between computed tomography (CT) scans given to toddlers and impairments in their later intellectual growth. Conducted by Stockholm's Karolinska Institute and Harvard School of Public Health, the researchers studied more than 3 000 men who had received radiation therapy between 1930 and 1959, before they were 18 months old.
The researchers also gathered and analysed the subsequent school records of the subjects and compared them to those of their peers who had not had brain scans. They found a direct connection between the amount of radiation these infants were exposed to and the learning difficulties they suffered in later life.
Weighing up the risks
CT scans - which are more detailed than conventional X-rays – use fairly low levels of ionising radiation to give clear cross-section images of the human body. Past research has suggested that high doses of such radiation can damage the developing human brain, but little was known about lower doses. Exposure to high doses of X-ray radiation has also been linked in the past to an increased risk of cancer.
Writing in the British Medical Journal, the Swedish team – headed by Per Hall – acknowledged the undeniable benefits of CT scans but called on doctors to exercise caution when using the technology. "Computed tomography… is increasingly being used even in young children after minor head trauma," they wrote. "The risk and benefits of computed tomography scans in minor head trauma need re-evaluating."
Hall and his team estimate that 1.5 million CT scans are carried out on children worldwide every year, often with radiation levels higher than those tested in their study. They suggested that new guidelines should be drawn up to ensure doctors do not use CT scans on young infants.