Dose Awareness Movement Gains Steam

Efforts to raise awareness of radiation dose in medical imaging saw significant activity on three fronts this past month, suggesting that radiology may be mobilizing to raise awareness of the issue. The National Council on Radiation Protection & Measurements (NCRP) released preliminary results of a new study showing a five-fold increase in exposure to ionizing radiation from medical devices by the general public. The American College of Radiology released a white paper providing guidance on limiting patient exposure aimed at all stakeholders in radiology. And the National Equipment Manufacturer’s Association released its own report detailing steps vendors are taking to reduce dose. The preliminary results reported by Fred A. Mettler at the NCRP annual meeting, April 16-17, Arlington, Va, are from an ongoing study to update its 1987 report, Ionizing Radiation Exposure in the Population of the United States. In estimating the contribution to that exposure from medical imaging, a team of researchers took into consideration the number and types of procedures performed; the dose per procedure and collective dose; and past and future trends in imaging. Preliminary results showed an approximate total does to the US patient population of about 930,000 sieverts based on an estimated 500 million procedures for a per capita exposure of 3.2 millisieverts (mSv) in 2006, a more than five-fold increase over the per capita dose of .55 mSv from medical imaging in 1980. CT, which has grown 10% annually since 1993 compared to population growth of less than 1% contributed nearly half the cumulative dose to the US population in 2006. Nuclear medicine contributed the next highest percentage of the collective dose at 23%, with cardiac imaging contributing 85% of the total dose attributed to nuclear studies. Mettler’s data showed that approximately one nuclear procedure is performed annually per 15 persons. When the annual 2.8 mSv of radiation received by natural sources is added in, the annual per capita dose was about 6.0 mSv in 2006 compared to 3.6 mSv in 1980. Preliminary results from the NCRP's forthcoming update of its 1987 report, Ionizing Radiation Exposure in the Population of the United States. Reprinted with permission. The White Paper from the ACR reiterates the concerns about the increased exposure of the patient population due to the rapid increase in medical imaging and the introduction of high-dose imaging technology. The report includes recommendations for referring physicians, radiologists, technologists, patients, vendors and regulatory agencies, accrediting bodies, and third-party payors. All parties are well advised to pay close attention to the paper, as it concludes: “…the rapid growth of CT and certain nuclear medicine studies over the past quarter century may result in an increased incidence of radiation-related cancer in the not-too-distant future.” Timed to coincide with the above reports, NEMA also released a wihte paper summarizing the innovations from vendors in reducing radiation dose through pulsed sequences, automatic exposure controls linked to the size of the body, and pediatric protocols based on reduced radiation delivery. A report from Thomas Dehn, MD, medical director of National Imaging Associates/Magellan, Avon, Conn, published on Medscape underscored the danger of a haphazard approach to the application of medical imaging. In undertaking a review of health plan claim files, the company constructed a cumulative dose per member that resulted in some patients receiving as much as 992.24 mSv over 341 procedures.