The 26-page article with 236 bibliographic references, authored by staff from the U.S. National Cancer Institute (NCI), provides a summary of key epidemiologic and experimental data on cancer risks associated with diagnostic imaging procedures. It also proposes a framework of strategies for reducing future cancer risks to patients who undergo imaging exams at high radiation doses (CA: Cancer J Clin, February 3, 2012).
Rising radiation exposure
When ordered and performed responsibly, imaging exams confer "immense benefit" to patients, the authors noted. That said, numerous studies have associated radiation dose exposure from imaging procedures with an elevated risk of developing cancer.
Since the early 1980s, the estimated per capita dose from medical radiation in the U.S. has increased approximately 600%, from about 0.53 mSv to about 3.0 mSv in 2006. CT scans have been the primary source for the increase, with an estimated 80 million CT scans performed in 2010, compared with 3.3 million over a three-year period from 1980 through 1982.
The best way to reduce unnecessary exposure is for clinicians to become more knowledgeable about the radiation used in imaging studies, according to senior investigator Dr. Martha Linet, chief of the radiation epidemiology branch of the NCI's Division of Cancer Epidemiology and Genetics.
Clinicians should order exams producing the least amount of ionizing radiation -- or no radiation -- to answer the clinical question at hand. Any radiology exam order should be always justified, and clinical staff should always verify that the exam being ordered isn't a duplicate study that was performed by the healthcare provider or at another healthcare facility.
The development of electronic lifetime records of imaging procedures will help make this possible, according to Linet and colleagues. It is "essential for radiology reports of all CT and other radiologic examinations to be incorporated into medical records immediately to reduce the frequency of repetition of the same or similar diagnostic radiologic procedures," they wrote.
The authors also recommended use of evidence-based appropriateness criteria for decisions about imaging procedures, noting that this was not widespread enough among referring physicians. They recommended the American College of Radiology (ACR) Appropriateness Criteria, as well as the Image Gently recommendations for pediatric patients developed by the Alliance for Radiation Safety in Pediatric Imaging.
The use of clinical decision-support software integrated with a computerized physician order-entry (CPOE) system for radiology exams has been proved effective in decreasing the rate of imaging utilization, they wrote.
"Computerized physician order-entry systems have been shown to be of value for improving justification of exams by showing the clinician what examinations have already been obtained, thus preventing unnecessary duplicate examinations, and by providing information to the clinician on the most appropriate examination," Linet told AuntMinnie.com in an email. "The appropriateness of a given radiologic examination is best determined by the requesting clinician, who is much more familiar with the patient than the radiologist, and better able to determine if the examination is justified."
But radiologists should play a role in educating physicians who order exams. One of the most important roles of the radiologist is to provide advice to the referring physician about the appropriate test for the patient, the authors stated. This is especially true with respect to emergency physicians, who need to be very knowledgeable about the relative radiation doses of the various imaging procedures they order, Linet emphasized to AuntMinnie.com.
Reducing radiation exposure from diagnostic imaging exams is a shared responsibility of both the ordering physician and the radiologist. In addition to sharing their knowledge and making recommendations, radiologists are also obligated to use protocols with the lowest radiation dose possible to produce diagnostic-quality images, and to use imaging equipment that optimizes low-dose procedures, the design of which is an obligation of modality vendors. The authors recommended rigorous oversight of the accuracy of settings, safeguards, calibration, and maintenance by manufacturers, users, and governmental agencies.
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