By Dr. Brian McDonough, Medical Editor

PHILADELPHIA (CBS) – Many people talk about the use of unnecessary tests and problems with radiation exposure. But where did this information come from? Most people point to a 2009 study in The New England Journal of Medicine.

A study of 952,000 non-elderly adults found that over two-thirds were exposed to twice as much radiation as they would have received from natural sources because of medical imaging. Women and older individuals were at greater risk for radiation exposure.

The study found that CT scans and nuclear tests accounted for three-quarters of non-treatment-based medical radiation exposure.

An accompanying editorial called for the clinical trials to prove whether or not diagnostic tests and imaging prevented major medical problems or reduced costs, or whether they’re worth the inherent risk of developing cancer from radiation exposure. An organization called The National Council on Radiation Protection and Measurement also monitors this.