Radiation doses as high as ten times the annual natural background radiation can occur during cardiac-gated CT angiography in pediatric populations, new research shows.

For this reason, this modality should not be routinely used in children until further work can determine appropriate imaging parameters.

This study is "the first, to the best of our knowledge, to look at gated CT coronary angiography in children. Other studies have assessed dose in adults for this type of exam but children are more 'radiosensitive' due to young age and increased life span during which a complication could develop," lead author Dr. Caroline L. Hollingsworth told Reuters Health.

As they report in the July issue of the American Journal of Roentgenology, Dr. Hollingsworth and colleagues performed ECG-gated cardiac CT angiography on an anthropomorphic phantom of a five-year-old child using a 16-multidetector CT scanner with adult-type settings.

Metal oxide semiconductor field effect transistor technology (MOSFET) was used to measure various organ doses. The effective dose was also determined through calculation of the dose-length product (DLP).

The breasts, lungs, and bone marrow received the highest doses -- up to 12.1 cGy. Lower radiation doses were seen with 80 kVp/385 mA scan settings than with 120 kVp/220 mA settings.

DLP effective doses were higher than those obtained with MOSFET measurement. The highest DLP dose noted was 28.4 mSv, roughly ten times the annual natural background radiation. For comparison, Dr. Hollingsworth said that with non-gated chest CT in children, the dose rarely exceeds 6 mSv.

"I think pediatricians and those who care for children who may need specialized heart evaluation need to be aware that gated CT angiography can impart a very high radiation dose, particularly if appropriate pediatric protocols are not set up by the radiologist responsible for the exam," Dr. Hollingsworth emphasized.

"Caregivers and physicians need to decide that CT angiography is a better choice than another modality such as magnetic resonance, and then protocols need to be adjusted so that the scan technique addresses the clinical question," she added.