(CBS News) The number of CT scans and other medical imaging procedures are increasing at a rate that has researchers concerned about increased exposure to radiation.
According to a new study published in The Journal of the American Medical Association on June 13, between 1996 and 2010, the number of CT scans tripled.
"The doses are not at a level that people should really be concerned," Dr. Rebecca Smith-Bindman, the study's lead author and a radiologist and epidemiologist at the University of California, San Francisco, told the New York Times. "It's rather that we need to minimize unnecessary exposures wherever possible."
Scientists were particularly concerned about the ionizing radiation that patients were being exposed to. Of the 1467 imaging codes, 1068 were associated with the delivery of ionizing radiation, including angiography/fluoroscopy, CT, nuclear medicine, and radiography. Ultrasounds and MRIs do not use ionizing radiation and were not included.
Radiation has been known to increase a person's risk of getting cancer, according to the study's authors. Some research shows that 2 percent of all future cancers will be caused by current imaging use. Another recent report in The Lancet showed a direct association between CT exposure in children and cancer risk. Children who get five to 10 scans triple their risk of developing leukemia,reported.
The study looked at millions of health records of patients within the HMO Research Network, a group of 19 HMOs across the United States and in Israel. The specific records they looked at belonged to patients in several western and Midwestern states.
Researchers found that the amount of radiation in patients had doubled over the last two decades, as well as the number of medical imaging procedures. In 2010, 20 CTs were performed for every 100 patients. Three percent of patients overall, and four percent who underwent imaging, received radiation above the limit that the U.S. Nuclear Regulatory Commission sets for people who work at nuclear power plants and double what European regulators recommend.
For those in the 65 to 75 age group, the number increased to 35 CTs per 100 patients. Ten to 20 percent of children who had a single head CT had radiation doses known to triple the risk of brain cancer or leukemia.
The bigger problem is that a lot of these patients are exposed to multiple tests, which is significantly increasing their radiation levels, Smith-Bindman said.
"It's not just that we're doing more advanced imaging tests, but we are also doing these tests in such a way that the tests deliver higher - and more variable - doses of radiation," Smith-Bindman said in the press release. "I am concerned that physicians have lowered their threshold for advanced imaging so much that it is now used even when they may not believe it is necessary or will really change their management of the patient."
At "fee-for-service" hospitals and clinics, these procedures often provide a monetary benefit. But, the study revealed that medical imaging is increasing even for patients under health maintenance organizations (HMOs), which do not derive any financial benefits from doing the costly procedures.
"You would have imagined that the rate of increase would be lower," Smith-Bindman explained in the press release. "Our results showed very similar growth in imaging within these integrated settings as has been shown outside of these settings."
Smith-Bindman and her team said patients need to be more aware and "insist of the necessity and safety of all radiological scans ." The researchers encouraged patients to talk to their doctors to see if these procedures are justified, and added that facilities should monitor when patents are receiving repeated scans or more radiation doses than necessary.
Correction: This article originally suggested that MRIs were responsible for raised exposure to radiation. While the rate of MRIs has increased, MRIs do not use "ionizing radiation" and therefore were not included in the study's results.