Studies Indicate CT Scan Overuse, Radiation Overexposure

August 09, 2012

Recently the medical literature has documented the growing use of CT scans. It is certainly no secret that, when circumstances warrant, Sonosite advocates for the consideration of ultrasound first over other imaging modalities. A CT scan is a powerful and valuable test when used appropriately and—as with all medical procedures—when its therapeutic value is carefully weighed against its potential harm. Yet, while acknowledging CT’s value, I can’t ignore mounting evidence indicating CT scans are being ordered more often than are necessary or safe.

According to a June 13, 2012, JAMA report “Use of Diagnostic Imaging Studies and Associated Radiation Exposure for Patients Enrolled in Large Integrated Health Care Systems, 1996-2010,” which collected data on patients enrolled in six major HMOs, the use of CT scans tripled during the 1996-2010 study period. The patients’ exposure to ionizing radiation increased even more. Per the report:

  • In 1996, CTs were ordered at a rate of 52 scans per 1,000 patients; they accounted for 5.7% of examinations and 30.3% of enrollees’ exposure to ionizing radiation.
  • By 2010, CTs were ordered at a rate of 149 tests per 1,000 patients; they accounted for 12.0% of examinations and 67.8% of radiation exposure—a 4-fold increase in per capita radiation exposure from CT.

In addition, a retrospective cohort study published in the British journal Lancet found a positive association between leukemia and brain cancer in children and the radiation doses they had received from CT scans. For study participants, cumulative doses of about 50 mGy (mSv) almost tripled their risk for leukemia while doses of about 60 mGy (mSv) appeared to triple their risk for brain cancer.

Many experts agree that CT scans are unnecessarily ordered when radiation-free modalities like ultrasound might make adequate substitutes. A June 12 feature in the Los Angeles Times reported that, when the American Board of Internal Medicine asked a variety of medical specialist to list the top clinical procedures they felt were overused, all of them listed CT scans among the top five.

It is my hope that, by increasing awareness of radiation risk, in the right clinical scenarios clinicians will think first of using ultrasound for imaging, and they’ll think twice before ordering CTs.