Children over-exposed to radiation in CT scans, UN atomic agency warns

A physicist measures the CT radiation output

27 April 2010 – The United Nations International Atomic Energy Agency (IAEA) has cautioned that children in some countries are being over-exposed to radiation when undergoing computed tomography (CT) scans, increasing their risk of developing cancer.

A new report by the agency found that although experts have been warning against the practice for the past decade, these children are receiving adult-sized radiation doses during the scans.

It also found great variations in radiation levels and in the frequency of CT scans performed on children under the age of 15 in the 128 facilities in 28 developing countries in Africa, Asia and Eastern Europe that it surveyed.

CT scans provide three-dimensional views of organs or blood vessels and mark a major advance in medical imaging and diagnosis, but they also deliver higher doses of radiation than conventional x-rays.

Children are more sensitive to radiation and have longer to live, according to Madan Rehani, a radiation safety specialist with the IAEA.

“So the use of adult parameters on a child when performing a CT scan means there’s an increased radiation dose and an increased risk of developing cancer in the long term,” he said.

Out of the CT centres studied by the IAEA, 11 of them in six countries exposed children to the same radiation dose as adults. Such errors, Dr. Rehani explained, are usually due to the operators’ lack of awareness, such as scanning too many parts of patients’ bodies, and the use of older models without automatic exposure controls.

But he noted that it is difficult to detect higher exposures from CT scan images themselves because unlike conventional x-ray images, higher exposures make CT scans look better.

The IAEA report is part of the agency’s ongoing efforts to improve awareness of radiation protection worldwide.

“In many situations the benefits outweigh the risks,” Dr. Rehani pointed out, but underlined that unnecessary radiation exposure “needs to be avoided.”

The study found that paediatric CT scans occur more frequently in Africa than in Asia and Eastern Europe, which he attributed to the limited availability of alternative imaging techniques, such as MRI and ultrasound, which do not involve ionizing radiation.

The 11 centres that the IAEA publication found was using adult CT exposure levels on children are now addressing the issue, the agency said.

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