IMAGING/CONCEPTS

Applications of Justification and Optimization in Medical Imaging: Examples of Clinical Guidance for Computed Tomography Use in Emergency Medicine Paul R. Sierzenski, MD, RDMS; Otha W. Linton, MSJ; E. Stephen Amis, Jr., MD; D. Mark Courtney, MD; Paul A. Larson, MD; Mahadevappa Mahesh, MS, PhD; Robert A. Novelline, MD; Donald P. Frush, MD; Fred A. Mettler, MD; Julie K. Timins, MD; Thomas S. Tenforde, MD; John D. Boice, Jr., ScD; James A. Brink, MD; Jerrold T. Bushberg, MD; David A. Schauer, ScD*

Availability, reliability, and technical improvements have led to continued expansion of computed tomography (CT) imaging. During a CT scan, there is substantially more exposure to ionizing radiation than with conventional radiography. This has led to questions and critical conclusions about whether the continuous growth of CT scans should be subjected to review and potentially restraints or, at a minimum, closer investigation. This is particularly pertinent to populations in emergency departments, such as children and patients who receive repeated CT scans for benign diagnoses. During the last several decades, among national medical specialty organizations, the American College of Emergency Physicians and the American College of Radiology have each formed membership working groups to consider value, access, and expedience and to promote broad acceptance of CT protocols and procedures within their disciplines. Those efforts have had positive effects on the use criteria for CT by other physician groups, health insurance carriers, regulators, and legislators. [Ann Emerg Med. 2014;63:25-32.] A podcast for this article is available at www.annemergmed.com. 0196-0644/$-see front matter Copyright © 2013 by the American College of Emergency Physicians. Copyright © 2013 by the American College of Radiology. http://dx.doi.org/10.1016/j.annemergmed.2013.08.027

INTRODUCTION Background In the 2009 article “Ionizing Radiation Exposure of the Population of the United States,”1 it was reported that from the early 1980s to 2006 the average effective dose per individual from medical procedures increased 6-fold (from 0.53 mSv/year in 1987 [National Council on Radiation Protection and Measurements2] to 3.00 mSv/year in 2006). Approximately half of the collective effective dose from medical imaging in 2006 was from computed tomography (CT) and more than one fourth from nuclear medicine procedures. The increase in CT dose has involved nearly every sector of medicine, and the sustained increase in use in emergency medicine has been reported, recognizing that this is a result of multiple factors, including the proven diagnostic efficacy of CT, defensive medicine, and patient/consultant demands.3 Of the approximately 80 million CT scans performed in the United States each year, about a third are in the emergency setting.1,2,4 Concerns have been expressed that high use of CT in emergency medicine may include scans that have questionable indications and therefore should be avoided.5-12 In August 2011, The Joint Commission published Sentinel Event Alert *This is a joint publication with the Journal of the American College of Radiology.

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Issue 47, “Radiation Risks of Diagnostic Imaging,” which further affirms the significance of this issue to patient safety.13 For many patients in the emergency setting, immediate diagnosis or the exclusion of a critical condition depends on prompt clinical performance and interpretation of radiologic imaging procedures. The choice of diagnostic procedures has relied on advances in radiology from basic radiographs and fluoroscopic examinations to current imaging procedures with CT, ultrasonography, magnetic resonance imaging (MRI), and radionuclide imaging. A significant change has been the rapidly increasing use of CT. The availability of CT scanners to emergency departments (EDs) (sometimes even sited in the ED) and their unparalleled ability to provide rapid high-quality tomographic images to resolve urgent care questions make them an increasingly dominant element of emergency radiologic imaging and patient diagnosis. Availability, reliability, and technical improvements have led to continued expansion of CT imaging. During a CT scan, there is substantially more exposure to ionizing radiation than with conventional radiography. This has led to questions and critical conclusions about whether the continuous growth of CT scans should be subjected to review and potentially restraints or, at a minimum, closer investigation. This is particularly pertinent to populations in EDs, such as children and patients who receive repeated CT scans for benign diagnoses. Annals of Emergency Medicine 25

Justification and Optimization in Medical Imaging During the last several decades, among national medical specialty organizations, the American College of Emergency Physicians (ACEP) and the American College of Radiology have each formed membership working groups to consider value, access, and expedience and to promote broad acceptance of CT protocols and procedures within their disciplines.14-16 Those efforts have had positive effects on the use criteria for CT by other physician groups, health insurance carriers, regulators, and legislators. Because diagnostic radiology procedures are performed on referral to radiology departments by physicians and other health care providers from many disciplines, the American College of Radiology has engaged the participation of other medical specialty groups to work with radiologists on imaging quality and safety initiatives, including clinical guidelines and technical standards, and appropriateness criteria. ACEP also develops clinical guidelines that relate to the Emergency Medical Treatment and Labor Act (EMTALA), according to reports from its clinical policy subcommittee and peer-reviewed medical literature. Many of these evidence-based policy statements and references are intended for and used by physicians and health care systems that need information for emergency protocols. The choice of imaging procedures is made by emergency physicians who may not have access to previous patient records or pertinent patient history when patients present with impaired level of consciousness or acute life-threatening emergencies. Therefore, the emergency physician must decide which imaging procedures are most appropriate in light of multiple factors. The choice of imaging procedure also potentially depends on the needs and preferences of consultants such as surgeons or hospitalists and to locally available imaging equipment and interpretive expertise. The requirements of the EMTALA law on diagnosis strategies including use of imaging also influence use. Examples are presented of clinical guidelines issued by ACEP and appropriateness criteria from the American College of Radiology for CT applications in emergency medicine.

NATIONAL COUNCIL ON RADIATION PROTECTION AND MEASUREMENTS ASSESSMENT OF CT USE IN EMERGENCY MEDICINE As a result of the rapid growth of CT use and nationwide concern about medical radiation exposure, the National Council on Radiation Protection and Measurements undertook a program to investigate the issues of CT in the ED, with input from a wide range of stakeholders. The first step in the program was conducting a workshop on ensuring appropriate use of computed tomography in emergency medicine, which was held in Bethesda, MD. In addition to ACEP and the American College of Radiology, the workshop was cosponsored by the American Association of Physicists in Medicine, the American Society of Emergency Radiology, the Centers for Disease Control and Prevention, Landauer, Inc., the Society for Academic Emergency Medicine, the US Environmental Protection Agency, and the World Health 26 Annals of Emergency Medicine

Sierzenski et al Organization. The workshop was attended by 26 speakers plus observers representing emergency medicine, diagnostic radiology, medical physics, and government regulatory agencies. A summary of the workshop was published by Linton et al.17 The topics discussed and conclusions reached in the workshop included the following: 1. ACEP, the American College of Radiology, and other medical organizations should continue to develop clinical guidelines, appropriateness criteria, and decision support (eg, computerized emergency physician order entry). This information should be evidence based, collaborative, and consensus driven. The incorporation of costs, including use of resources and potential health risks, should be patient centered and ideally immediately available to emergency physicians and acute care consultants at the point of care. The goal is to assist in determining what imaging procedure is most appropriate for and available to the individual emergency patient. Where sufficient evidence-based medicine does not exist, evidence should be developed through nationally funded research as a component of consensus-based guidelines. 2. Many patients presenting to EDs have undergone trauma or have disease circumstances that require immediate attention and treatment. The need for expeditious treatment may require a more rapid diagnostic evaluation that limits checking of patient history and records. For some patients, review of medical records, including recent diagnostic images, may affect the choice of a current imaging procedure. For patients with confusion, significant altered mental status, coma, or an inability to communicate, such as a very young child, the emergency physician must choose imaging on the basis of what modality is the fastest, safest, and most likely to affect immediate care according to limited information. Oftentimes this includes CT imaging. 3. When possible, emergency physicians should reach general agreement with the radiologists and consulting physicians in their institution on common scenarios involving imaging procedures, such as acute abdominal pain, possibly pulmonary thromboembolism, or trauma, especially to the cervical spine. In addition, case-specific consultation when possible allows the radiologist to suggest the optimal procedure and to perform it in a timely manner with a patient-specific protocol. 4. Joint development of and training in pathways and skills to reduce the need for CT imaging when possible and safe, such as the use of radiography, ultrasonography (including clinicianperformed, emergency, point-of-care ultrasonography), and MRI, should be supported and expanded. 5. The radiologist is responsible for supervising the performance of any appropriate requested procedure and for the conduct of a diagnostic-quality examination with a protocol optimized to manage the dose to the patient to be commensurate with the medical purpose. The radiologist should be available to collaborate with clinicians and when appropriate mitigate requests for multiple or repetitive procedures without specific justification by the responsible medical team. Whenever possible, patients transferred for care from outside facilities Volume 63, no. 1 : January 2014

Sierzenski et al should be accompanied by their outside imaging examination results, which should be available for review by emergency physicians and radiologists. 6. The responsible radiologist in the institution should inform emergency physicians and other referring physicians about new and useful imaging techniques, including their potential benefits and risks, so that an informed conversation on their use can be conducted with patients, when possible. In considering the usefulness of CT imaging in the ED, workshop participants emphasized that well-executed, accurately interpreted CT scans with prompt communication of salient findings are vital to current emergency and acute care and are essential for emergency physicians to meet both the EMTALA and standard of care for emergency care in the United States. In December 2010, the National Council on Radiation Protection and Measurements convened a meeting with experts in emergency medicine, radiology, and medical physics to draft clinical guidance for some common applications of CT in the ED setting. This meeting was supported by the same organizations that cosponsored the 2009 workshop. It was agreed by the participants that appropriateness criteria and clinical guidelines previously issued by the American College of Radiology and ACEP, respectively, should form a basis for clinical guidance in the use of CT in emergency medicine.

CLINICAL GUIDANCE FOR CT USE IN EMERGENCY MEDICINE According to Hentel et al,18 CT of the head accounts for approximately 50% of CT scans performed in EDs. In addition, the Centers for Medicare & Medicaid Services estimates that approximately 8 million CT scans of the head are performed each year on Medicare beneficiaries. These CT use data are consistent with results of the 2006 analyses reported by the National Council on Radiation Protection and Measurements.1 As a result of these data, a decision was made to focus on clinical guidance for use of CT in mild head trauma. Minor head trauma represents an area with sufficient evidence-based medicine to derive a valid clinical guideline. This process is intended to serve as an example that can be applied to other common medical conditions observed in the ED for which CT scans are routinely used. American College of Emergency Physicians Clinical Guidelines for CT Use in Adult Mild Traumatic Brain Injury In recent years, as a key national medical specialty organization and patient care advocate, ACEP has developed a series of clinical policy statements related to trauma to various parts of the body that require imaging, including CT examinations.8,15,19-23 Mild traumatic head injury is a common circumstance that leads emergency physicians to request immediate CT evaluation. Headaches and other neurologic symptoms indicative of mild traumatic brain injuries are factors requiring clinical assessment. Volume 63, no. 1 : January 2014

Justification and Optimization in Medical Imaging ACEP clinical policy statements are published in issues of Annals of Emergency Medicine.8,15,19-22,24 An example of an ACEP clinical policy statement is titled “Neuroimaging and Decisionmaking in Adult Mild Traumatic Brain Injury in the Acute Setting.”22 Clinical findings and strength of recommendations about patient management are available according to the following criteria: Level A recommendations. Generally accepted principles for patient management that reflect a high degree of clinical certainty. Level B recommendations. Recommendations for patient management that may identify a particular strategy or range of management strategies that reflect moderate clinical certainty. Level C recommendations. Other strategies for patient management that are based on preliminary, inconclusive, or conflicting evidence, or in the absence of any published literature, based on panel consensus. ACEP has published 2 sets of recommendations for performing CT studies for determining which patients with mild traumatic brain injury should have a nonintravenous contrastenhanced head CT scan in the ED. Level A recommendations. A noncontrast head CT is indicated in head trauma patients with loss of consciousness or posttraumatic amnesia only if 1 or more of the following is present: headache, vomiting, aged greater than 60 years, drug or alcohol intoxication, deficits in short-term memory, physical evidence of trauma above the clavicle, posttraumatic seizure, Glasgow Coma Scale (GCS) score less than 15, focal neurologic deficit, or coagulopathy. Level B recommendations. A noncontrast head CT should be considered in head trauma patients with no loss of consciousness or posttraumatic amnesia if there is a focal neurologic deficit, vomiting, severe headache, aged 65 years or greater, physical signs of a basilar skull fracture, GCS score less than 15, coagulopathy, or a dangerous mechanism of injury (ie, dangerous mechanism of injury includes ejection from a motor vehicle, a pedestrian struck, and a fall from a height of more than 3 feet or 5 stairs). American College of Radiology Appropriateness Criteria for CT Use in Adult Mild Traumatic Brain Injury For half a century, the American College of Radiology has created policy recommendations for uses of radiographic imaging on patients with specific signs and symptoms. Most of these recommendations have been developed by American College of Radiology task forces, with substantial input and agreement of physician groups in various medical specialties.14 In recent decades, the American College of Radiology has encouraged its members to conduct efficacy tests on the use of various medical imaging procedures, particularly with the introduction of imaging techniques such as positron emission tomography, ultrasonography, angiography and angioplasty, CT scanning, and MRI. In 1993, the American College of Radiology established a Taskforce on Appropriateness Criteria that developed ratings for medical imaging tests in major elements of current practice.25 The task force invited participation of Annals of Emergency Medicine 27

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Justification and Optimization in Medical Imaging physicians from disciplines with knowledge of diagnosis and management for the various medical conditions under consideration. For example, pediatricians participated in panels considering health problems of children, and neurologists and neurosurgeons contributed to panels addressing neurologic conditions. The June 2012 update of the American College of Radiology appropriateness criteria covers 180 medical topics with more than 850 variants. The appropriateness criteria are organized in tables for a specified clinical condition (eg, head trauma) and variant (eg, minor or mild acute closed head injury [GCS score
13], without risk factors or neurologic deficit). The tables list the relative appropriateness for the imaging tests that may be considered for the specified clinical condition and variant and also give an assessment of the relative radiation level for the imaging procedures.25 This is followed by a narrative account of the problem and its clinical assessment. The ranges of possible imaging procedures are listed and rated on a scale of 1 to 9, with 1 through 3 meaning that a procedure is usually not appropriate, 4 through 6 meaning the procedure may be appropriate, and 7 through 9 meaning usually appropriate. The American College of Radiology appropriateness criteria for minor or mild acute closed head injury (GCS score
13), without risk factors or neurologic deficit, are summarized in Table 1. For patients with minor head and cervical trauma, several validated clinical decision rules that aid in imaging selection and appropriateness exist. The New Orleans Criteria26 and the Canadian CT Head Rule27 are clinical decision tools for imaging

in minor head trauma, with high sensitivity for detecting intracranial injuries that require neurosurgical intervention. Papa et al28 compared the performance of these 2 rules in a prospective cohort study, showing that both rules demonstrated 100% sensitivity in detecting cases requiring neurosurgical intervention, clinically important brain injuries, or any traumatic intracranial lesion on CT. These clinical decision rules provide a potential opportunity to reduce the number of CT scans when possible. Specific to the pediatric population, the National Emergency X-Radiography Utilization Study II trial29 prospectively evaluated 1,666 children who experienced head trauma with resultant head CT imaging. The incidence of intracranial injury was 8.3%, with 136 of 138 children identifiable by the derived clinical decision rule used, including all cases for children aged 3 years and younger. Another related issue involves repeated CT scans to rule out possible progression of bleeding after an initial CT scan that reveals intracranial hemorrhage caused by traumatic brain injury. Repeated CT scans for this scenario are a standard of care in many trauma centers. However, a recent study concluded that “the available evidence indicates that it is unnecessary to schedule a repeat CT scan after mild head injury when patients are unchanged or improving neurologically.”30 These issues demonstrate the complexity that such clinical guidelines embody. Several studies have demonstrated that clinical decision support tools integrated with computerized physician order entry aid in improving clinicians’ compliance with care guidelines.31-37 Furthermore, the American Recovery and Reinvestment Act defined meaningful use of certified electronic health records. The Centers for Medicare & Medicaid

Table 1. American College of Radiology appropriateness criteria for minor or mild acute closed head injury (GCS score
13), without risk factors or neurologic deficit.* Radiologic Procedure

Rating†

CT head without contrast

7

MRI head without contrast MRA head and neck without contrast MRA head and neck without and with contrast CT head without and with contrast

4 3 3 3

CTA head and neck with contrast

3

MRI head without and with contrast CT head with contrast

2 1

Radiograph head

1

FDG-PET/CT head

1

US transcranial with Doppler Arteriography cervicocerebral

1 1

Tc-99m HMPAO SPECT head

1

RRL‡

Comments Known to have low yield Rarely indicated with mild trauma

O O O

Rarely indicated with mild trauma O

O

0, 0 mSv; , relative radiation level; MRA, magnetic resonance angiography; CTA, computed tomography angiography; FDG-PET, [18F]-fluorodeoxyglucose positron emission tomography-computed tomography (PET/CT); Tc-99m HMPAO SPECT, Technetium-99m hexametyl propylene amine oxime labeled leukocyte, single photon emission computerized tomography. *Excerpted from the American College of Radiology Web site: http://www.acr.org/w/media/ACR/Documents/AppCriteria/Diagnostic/HeadTrauma.pdf. † Rating scale: 1 to 3¼usually not appropriate; 4 to 6¼may be appropriate; 7 to 9¼usually appropriate. ‡ Relative radiation levels for procedures listed in this table range from an effective dose of 0 to 30 mSv.

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Table 2. ACEP and American College of Radiology approaches to acute onset of flank pain. Acute Onset Flank Pain—Suspicion of Stone Disease Imaging section Radiologic procedures ranked ‡5 CT abdomen/pelvis wo contrast

Rating

Comments

8

Use reduced dose

CT abdomen/pelvis w/wo contrast

6

US kidneys/bladder and KUB

6

Contrast helps assess cause of pain if noncontrast CT does not show stone Good combination for pts with known stone disease

Clinical section Clinical presentation First stone passage (suspected) Recurrent stone passage (similar clinical presentation to initial)

Imaging recommended NCCT US kidneys/bladder plus/minus KUB Complicated clinical cases (consider NCCT)

Relative radiation level

Comments Benefit in establishing diagnosis exceeds radiation risk KUB may show size and location of stone; US will typically show degree of hydronephrosis and can confirm ureteral urine flow into bladder; radiation exposure eliminated or reduced

KUB, kidneys, ureters, and bladder; NCCT, non-contrast CT.

Services have plans for performance milestones and target dates for framework, functionality, and integration of the meaningful use of electronic health records. Integration of imaging guidance such as those specialty-specific guidelines with evidence-based medicine for CT emergency use represents an opportunity to use the right imaging test at the right time. CT Imaging for Flank Pain and Suspected Renal Colic Application of evidence-based medicine clinical guidelines for CT of the head in minor traumatic brain injury results in reduction of head imaging. In contrast, the use of evidence-based medicine guidelines in the evaluation of recurrent renal colic results in the reduction of CT imaging through use of alternate imaging modalities with lower or no ionizing radiation. The goal is similar: reduced radiation exposure. The prevalence of renal calculi continues to increase and is reported to now be 8.8%.38 As the incidence of kidney stones in both adults and children increases, the recurrence rate for renal colic is relatively high, at 50%, increasing the likelihood of recurrent ED visits for acute renal colic and diagnostic evaluation.39 This population is at high risk for repeated CT scans and radiation exposure. Although North American practice is to perform a noncontrast CT for new-onset flank pain/renal colic, the use of ultrasonography and radiography for recurrent visits in patients with previously confirmed renal calculi should be strongly advocated. This diagnostic approach for renal colic is supported both by the ACEP Emergency Ultrasound Guidelines and the American College of Radiology’s appropriateness criteria, as shown in Table 2. Additionally, the European Association of Urology recommends that, “[i]f available, ultrasonography, should be used as the primary diagnostic imaging tool although pain relief, or any other emergency measures should not be delayed by imaging assessments. Kidneys, ureters, and bladder should not be performed if non-contrast CT is considered; however, it is Volume 63, no. 1 : January 2014

helpful in differentiating between radiolucent and radiopaque stones and for comparison during follow-up.” Consensus Recommendations Based on ACEP’s Clinical Guidelines and the American College of Radiology’s Appropriateness Criteria ACEP’s clinical guidelines and the American College of Radiology’s appropriateness criteria are evidence-based clinical tools that provide an effective way to further ensure that CT scans are medically indicated and that modulation of imaging use is “patient-centered.” The clinical influence of these guidelines and criteria has been reported.40,41 Jung et al40 showed that clinical use of ACEP guidelines in minor blunt head injury could reduce CT use in the ED without significant loss of sensitivity. The American College of Radiology’s appropriateness criteria specify that if medical imaging is ordered, CT is the best study. In addition, the ACEP guidelines direct the use of that study, clinically dictating when it should be used. Further federally funded research is necessary to help define when imaging studies are clinically indicated or can be omitted from the patient’s clinical evaluation at the point of care. The National Council on Radiation Protection and Measurements continues to work with ACEP, the American College of Radiology, and other professional stakeholders to encourage the development of additional consensus guidelines, raise awareness of their potential clinical utility in patient management, and increase their use by incorporating the guidelines into computerized physician order entry systems. CT Exposure Optimization Using Radiation Physics Principles With recent trends toward an increasing number of CT scans in emergency and acute care settings and the awareness of and concern about radiation doses in CT, there has been a greater Annals of Emergency Medicine 29

Justification and Optimization in Medical Imaging effort to reduce radiation dose.42,43 Physicians requesting procedures that expose patients to ionizing radiation must explore options to reduce patient dose in CT examinations. Radiation dose reduction strategies can be adopted for emergency or acute care settings. Once the examination has been determined to be consistent with the clinical imaging guidelines, radiation dose can be reduced by optimizing imaging protocols (eg, numbers of views, limiting the use of multiphase imaging and scan length), optimizing acquisition parameters (eg, adjusting tube current [milliamps], tube voltage [peak kilovoltage] for body habitus, implementation of statistical iterative reconstruction software), and performing periodic quality control on the imaging equipment. Continuous tube current modulation during CT acquisition as a function of body thickness and tissue composition during the acquisition is among the more recent and widely used techniques to reduce patient exposure without compromising image quality (diagnostic utility). For example, reducing the tube current by half while the radiograph beam passes through a thinner and less attenuating part of the anatomy reduces the dose to tissue along the radiograph beam path by half of what it would have been without tube current modulation. Dose reduction can be achieved by confining the scanning region to the body part of interest. For example, a chest CT scan should be tightly collimated to the chest and should not extend to parts of the neck or abdomen unless clinically indicated. Optimization of these and other image acquisition parameters in a state-of-the-art CT scanner can reduce the total radiation dose to many patient by 50% or more without any significant effect on image quality. Implementation of these dose-sparing techniques should be used for all patients. However, their use is especially important for children, for whom the risks of radiation exposure are greater than for adults. Medical physicists have training in the design and function of imaging devices, including the modification of acquisition parameters to achieve an optimal balance between dose to the patient and diagnostic quality of the examination. Dosereduction strategies include the following44-46: a. using automatic exposure control, including tube current modulation and kilovolt modulation (when available); b. confining or limiting the scan region; c. selecting tube voltage according to patient size (lower kilovolt settings for thin and pediatric patients have advantages in reducing dose and improving image quality); d. increasing pitch factor (in helical CT scans) for routine scans; e. considering low-dose protocols for repeated scans or on patients who undergo repeated scans; and f. providing training on these and other dose-control strategies for staff physicians, residents, medical physicists, radiograph technologists, nurses, and equipment service personnel. General Conclusions on Clinical Guidance for CT Use in Emergency Medicine After more than a century of medical radiograph imaging, most patients in the United States have a general impression that 30 Annals of Emergency Medicine

Sierzenski et al radiologic procedures are a broadly accepted element of modern medicine and that technological advances in medical imaging equipment influence the choice of diagnostic procedures. In addition, many patients accept recommendations of their primary care physician that refer to timely diagnostic or therapeutic procedures. The emergency physician, medical colleagues, and the consulting radiologist should confer on the type of imaging procedure most appropriate for the individual patient. Jointly developed diagnostic imaging protocols based on patient history/ clinical presentation and integrated with computerized physician order entry help facilitate and expedite the imaging decision process. Both the emergency physician and the radiologist should be familiar with and use the recommended guidelines from the American College of Radiology and ACEP when deciding which of the available medical imaging modalities is best for the evaluation of injury and illness, whether chronic or in the acute setting. The use of all forms of medical imaging is based on physician decisions, including those of emergency physicians and consulting radiologists, with the understanding that the benefit of the chosen procedure should outweigh the patient’s potential risks of exposure to ionizing radiation (justification). The concept of optimization, managing the radiation dose to the patient to be commensurate with the medical purpose, should also be a primary element in the performance of medically indicated CT scans. This should include optimizing the radiographic exposure parameters and limiting the scan length to the body part under examination. It also should include review of available previous diagnostic images of the patient that may negate the need to repeat a CT scan. The 11th Report on Carcinogens47 added radiographs to the list of “known human carcinogens.” It is this knowledge that forms the basis for the fundamental principles of radiation protection, justification and optimization. Justified and optimized medical imaging examinations such as CT scans are lifesaving tools used across the world every day. If an ordered radiologic procedure is not justified and optimized, it should not be performed. This approach will reduce the costs to our health care system significantly and avoid unnecessary radiation exposure to our patients.48,49 Other Related Factors—Defensive Medicine In November 2008, the Massachusetts Medical Society issued a study that showed that most of the physicians surveyed reported that they practiced defensive medicine. For example, approximately 33% of the CT scans ordered by obstetricians/ gynecologists, emergency physicians, and family practitioners were not motivated by medical need.50 Lee et al6 reported that nonphysician health care providers are less likely to order a CT scan than physicians in similar clinical situations. They reported that one explanation for this finding could be that nonphysician health care providers follow protocoldriven practices about the use of CT scans more strictly than their physician counterparts. This is in contrast to physicians who may be influenced by malpractice liability. As clinical Volume 63, no. 1 : January 2014

Sierzenski et al imaging guidelines continue to be developed and implemented in emergency medicine and other medical specialties, tort reform must be part of the solution so that imaging decisions are driven only by the best evidence-based practice rather than concerns about avoiding potential litigation. The National Council on Radiation Protection and Measurements will continue working with ACEP, the American College of Radiology, other professional organizations, and government agencies to support and promote effective campaigns such as Image Gently, Image Wisely, and Choosing Wisely. These collective efforts represent a significant step in the direction of ensuring justified and optimized uses of medical imaging in emergency medicine and beyond. Supervising editor: Donald M. Yealy, MD Author affiliations: From Section of Emergency Ultrasound, Department of Emergency Medicine, Christiana Care Health Services, Newark, DE (Sierzenski); Potomac, MD (Linton); the Department of Radiology, Albert Einstein College of Medicine and Montefiore Medical Center, Bronx, NY (Amis); the Department of Emergency Medicine, Northwestern University, Chicago, IL (Courtney); Radiology Associates of the Fox Valley, Neenah, WI (Larson); the Russel H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD (Mahesh); Harvard Medical School and Emergency Radiology Division, Massachusetts General Hospital, Boston, MA (Novelline); the Division of Pediatric Radiology, Duke University Medical Center, Durham, NC (Frush); the Department of Radiology, New Mexico VAHCS, Albuquerque, NM (Mettler); Morristown, NJ (Timins); the National Council on Radiation Protection and Measurements, Bethesda, MD (Tenforde, Boice, Schauer); the Department of Radiology, Massachusetts General Hospital, Boston, MA (Brink); and the Department of Radiology, University of California, Davis, Sacramento, CA (Bushberg). Mr. Linton was formerly affiliated with the National Council on Radiation Protection and Measurements, Bethesda, MD. Funding and support: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist. Mr. Linton, Dr. Amis, Dr. Courtney, Dr. Larson, Dr. Mahesh, Dr. Novelline, Dr. Frush, Dr. Mettler, Dr. Timins, Dr. Tenforde, Mr. Boice, Dr. Brink, Dr. Bushberg, and Mr. Schauer report no financial disclosures or conflicts of interest. Dr. Sierzenski did not receive any funding to produce this article, has served on Centers for Medicare & Medicaid Technical Expert Panels for Outpatient Imaging Efficiency Measurement, is a member of the ACEP Quality Performance Committee, and is president and chief executive officer of Emergency Ultrasound Consultants, LLC. Publication dates: Received for publication May 7, 2013. Revision received August 29, 2013. Accepted for publication August 29, 2013. Available online October 15, 2013. Address for correspondence: Paul R. Sierzenski, MD, RDMS, E-mail [email protected].

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