Dr. Rebecca Smith-Bindman of the University of California, San Francisco, said past studies showed an increase in the public's exposure to radiation because of medical imaging at "fee-for-service" hospitals and clinics, which make more money the more scans done.
In HMOs, all clinical operations fall under the same umbrella as the insurance and payment operations, and if anything, more medical scans would seem to be financially discouraged, Smith-Bindman said.
"You would have imagined that the rate of increase would be lower," Smith-Bindman said in a statement. "Our results showed very similar growth in imaging within these integrated settings as has been shown outside of these settings."
Steps to lower doses of radiation in MRIs used for medical diagnosis include new software that reduces doses, new lower-dose equipment, and reducing the use of certain high-dose procedures.
The study, published in the Journal of the American Medical Association, found the number of ultrasound examinations doubled, the number of CTs tripled and the number of magnetic resonance imaging scans quadrupled from 1996 to 2010.
"This is significant," Smith-Bindman said, "because on the national level, a lot of hope for countering the rise in imaging rates and radiation exposure has been pegged to removing financial incentives by changing the fee structure of radiological exams and capping reimbursements, as Medicare done."