Radiation exposures from medical imaging: cause for concern

Full text: CT usage rates are increasing by 5-10% per year in most countries with high-level health care systems-in the U.S. more than 75 million CT scans are currently performed each year. Because CT is such a superb diagnostic tool and because individual CT risks are small, the CT benefit/risk balance is generally by far in the patient's favor. However, organ doses from CT are typically far larger than those from conventional X-ray exams, and there is epidemiological evidence of a small but significant increased cancer risk at typical CT doses. It follows that it is particularly important that CT should operate under the ALARA (As Low As Reasonably Achievable) principle, and indeed opportunities exist to reduce the significant population dose associated with CT. The first opportunity is to reduce the dose per scan, and improved technology has much potential here. The second opportunity is selective replacement of CT with other modalities, such as for many head and spinal exams (to MRI), and for diagnosing appendicitis (selective use of ultrasound + CT). Finally, a fraction of CT scans could be avoided entirely, as indicated by CT decision rules. Clinical decision rules for CT usage represent a powerful approach for slowing down the increase in CT usage, because they have the potential to overcome some of the major factors that result in some CT scans being undertaken when they are potentially not clinically helpful. Underlying all of the above is the importance of continuing education for all health care providers associated with advanced radiological imaging.