Safety in Radiology
The use of medical imaging to depict and to help diagnose illness and injury as well as to guide therapeutic interventions has expanded greatly during the past two decades. Nowadays, imaging is ubiquitous in health care, and patients with a wide spectrum of afflictions benefit from imaging procedures. Many imaging modalities deploy ionizing radiation, and, as a consequence, the exposure of patients to radiation has increased as medical imaging has expanded.(1) Accordingly, such exposure is now often thought of as a potential harm to patients, bringing radiation safety under the broad umbrella of the patient safety field.
Radiation protection in medicine is underpinned by the concepts of justification and optimization. Over the past 20 years much successful work has focused on developing and consolidating approaches to optimization—using the least possible radiation dose to achieve the desired result. Less effort has been committed to justification—ensuring that the test is appropriate. This is not surprising, as historically it has not been seen as a problem until recently. Radiology has been remarkably successful in achieving unprecedented growth and impact in a relatively short time. However, the extent of radiology use has become a matter of concern for many reasons, including population dose, individual dose, and budgetary and financial issues. Such concerns have led to new questions regarding the appropriateness of many radiologic studies.(2)
Many (but not all) radiology procedures utilize ionizing radiation. When a procedure using radiation is proposed, the anticipated benefits to the patient are almost always identifiable and are sometimes quantifiable. On the other hand, the risks of adverse consequences are often difficult to estimate (they generally require statistical techniques to infer) and may be challenging to communicate. In its 1990 and 2007 recommendations, the International Commission on Radiological Protection stated as a principle of justification, "Any decision that alters the radiation exposure situation should do more good than harm."(3,4)
The radiology procedure that has seen the most rapid growth, and raised the most concerns, is computed tomography (CT) scanning. Tremendous advances have occurred in CT since its widespread clinical implementation in 1973.(5) Recent technical advances, including faster scan times, improved spatial resolution, and enhanced multiplanar reconstruction techniques, have increased the usefulness of CT for virtually every anatomic abnormality. In fact, multidetector row CT technology and advanced protocols have revolutionized the diagnosis and treatment of disease processes throughout the body.(6) This increased utility, coupled with a rise in defensive medicine and ownership interest in CT centers by referring physicians, has resulted in a dramatic rise in utilization.(7,8)
Concerns regarding the amount and effect of radiation exposure to CT cannot be ignored. CT scanning systems used in the early 1990s generated an average radiation dose of 40 to 60 mGy (4 to 6 rads) for head scans and 10 to 40 mGy (1 to 4 rads) for body scans. Radiation doses to patients with multidetector CT are 30% to 50% greater than with older single-slice CT scanners.(9) CT has received the greatest scrutiny because of its relatively high radiation dose per examination, far more than plain-film radiography. Although it accounts for about 17% of all medical imaging procedures, it produces approximately half of the population's medical radiation exposure, with nuclear medicine contributing around one-quarter of the collective dose to the population and fluoroscopy and conventional radiograph examinations making up the remainder.(10-12) Collectively, the growth in these studies, particularly CT, have resulted in a marked increase in the overall population exposure to ionizing radiation.
Children are particularly susceptible to radiation injury, and care should always be exercised to keep doses as low as possible while consistent with acquiring needed diagnostic information. A well-known practice mandate in radiology is ALARA: "as low as reasonably achievable." This concept is strongly endorsed by the Society for Pediatric Radiology, particularly in procedures and modalities that deliver higher radiation doses, such as CT and fluoroscopic examinations.(13) Reducing the radiation dose and its associated risks in children starts with performing CT in children only when properly indicated. To achieve this goal, adequate communication between the referring physician and radiologist is essential. Only with a complete clinical picture will the radiologist be able to make a well-considered decision regarding which imaging modality is the best choice to answer the clinical question. Moreover, this information will help the radiologist optimize the CT technique, reducing the risk of failed and repeated examinations.
The risks associated with the use of ionizing radiation in medical imaging are real.(14) It is incumbent upon the radiology community to take the lead in protecting patients from unnecessary radiation. In doing so, it is crucial to educate referring providers about the potential risks related to CT. In the face of uncertainty about the biologic effects of radiation exposure at low doses, the prudent course of action with regard to medical imaging is to adhere to the ALARA principle while ensuring that information is sufficient for accurate diagnoses and the guidance of interventional procedures.(15)
Moreover, communicating the risks associated with medical radiation promotes patient autonomy. Although the risk to any individual patient from diagnostic radiology examinations might well be very low, it is not nil. Based on legal and bioethical principles that pertain to informed consent, it is not sufficient for physicians simply to weigh the risks and benefits of a radiologic examination. Instead, the patient needs to be informed. Given the complexity of the information and its long-time horizon (some risks are theoretical and may play out over decades), research needs to be done to help clinicians find better ways to convey the information so that it promotes informed patient choice.
In an era in which inappropriate use of radiographs, or undue doses of radiation, are correctly seen as significant problems for patient safety, radiologists must function as both gatekeepers and imaging experts. The former role requires that requested examinations are clinically appropriate and the potential benefits outweigh the risks. It also requires new channels of communication between ordering clinicians and radiologists. The latter is necessary to ensure that recommendations for alternative imaging modalities lacking ionizing radiation, or using the least possible radiation dose, are used when possible.
Antonio Pinto, MD, PhDDepartment of RadiologyCardarelli HospitalNaples, Italy
2. Malone J, Guleria R, Craven C, et al. Justification of diagnostic medical exposures: some practical issues. Report of an International Atomic Energy Agency Consultation. Br J Radiol. 2012;85:523-538. [go to PubMed]
7. Gazelle GS, Halpern EF, Ryan HS, Tramontano AC. Utilization of diagnostic medical imaging: comparison of radiologist referral versus same-specialty referral. Radiology. 2007;245:517-522. [go to PubMed]
8. Levin DC, Rao VM, Parker L, Frangos AJ, Sunshine JH. Ownership or leasing of CT scanners by nonradiologist physicians: a rapidly growing trend that raises concern about self-referral. J Am Coll Radiol. 2008;5:1206-1209. [go to PubMed]
11. Mettler FA Jr, Bhargavan M, Faulkner K, et al. Radiologic and nuclear medicine studies in the United States and worldwide: frequency, radiation dose, and comparison with other radiation sources—1950–2007. Radiology. 2009;253:520-531. [go to PubMed]
13. Strauss KJ, Kaste SC. ALARA in pediatric interventional and fluoroscopic imaging: striving to keep radiation doses as low as possible during fluoroscopy of pediatric patients—a white paper executive summary. J Am Coll Radiol. 2006;3:686-688. [go to PubMed]
15. Boone JM, Hendee WR, McNitt-Gray MF, Seltzer SE. Radiation exposure from CT scans: how to close our knowledge gaps, monitor and safeguard exposure—proceedings and recommendations of the Radiation Dose Summit, sponsored by NIBIB, February 24–25, 2011. Radiology. 2012;265:544-554. [go to PubMed]