Fast, accurate and non-invasive, CT is a diagnostic medical imaging technique that allows detailed visualization of internal organs and extremities. Most physicians and patients consider that these scans are very safe and have very low risk. Over the last decade, major technical advances have expanded the diagnostic applications for CT scans. The result is a dramatic increase in the number of scans performed in this country from 3 million in 1980 to over 72 million in 2007, and this number continues to grow. CT is now the largest source of ionizing radiation for the U.S. population. Although these scans represent only about 5% of all x-ray imaging in this country, they account for 40-60% of medical radiation. The risks associated with radiation exposure are cumulative which means its effects stay with you for life. Exposure to ionizing radiation is related to a small but real increased risk of developing cancer 10-15 years later.
With the increase in CT utilization, more patients, including children and adolescents who are more sensitive to the long-term effects of radiation than adults, are being exposed to increasing doses of radiation. Not only are we performing more CT scans but each CT scan is exposing the population, including children, to higher doses of ionizing radiation than the CT scans of the 1980s which is directly related to the technical advances such as multidetector CT and the increased use of multiphase scans.
CT is a very valuable diagnostic tool and clinical problem solver. As with any diagnostic test, the risks versus the benefits must always be weighed. When appropriate, CT scans should be performed regardless of the patient’s age. When ordering a CT scan for anyone, but especially for a child or adolescent, clinicians should be sure that the indication is consistent with evidence-based medicine and that the results, whether positive or negative, will impact patient management. CT should not be used as a triage tool in emergency departments. It should never replace a complete history and physical examination and CT scans should never be used to confirm an already established diagnosis. In addition, repeat studies should be performed only if clinically appropriate. Referral to specialists or obtaining a second opinion rarely requires repeat imaging. CT scans and reports can easily and quickly be provided to new clinicians involved in the patient’s care via the web.
For children, the marked increased in the use of CT was confirmed in an article published in the June, 2011 issue of Radiology. In this article, (Rising use of CT in child visits to the emergency department in the United States, 1995-2008, Rad, 2011; 259:793-801), Larson et al., reported that the use of CT scans for children in emergency departments increased from .33 million to 1.63 million between 1995 and 2008 without any corresponding increase in the number of pediatric visits to emergency departments during that same time frame. The most common indication for these scans was head trauma, abdominal pain and headache with the largest increase in the area of abdominal pain. This does not take into account the increased use of CT in children in an outpatient environment.
Another significant problem is highlighted by Smith-Bindman and colleagues in an article published in 2009 (Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of Cancer, Arch Intern Med, 2009; 169:2078-2086). They surveyed imaging facilities in the San Francisco area and found a wide variation in radiation dose from multiphase CT scans of the abdomen and pelvis. According to this paper radiation exposure varied from 31 mSv to 90 mSv for the same multi phase CT scan depending on where it was performed. This wide variation in CT dose is part of the problem. Imaging sites do not always follow the ALARA (as low as reasonably achievable) principle taught to radiologists throughout their training. Scan parameters should always be individualized and take into account patient size, the area to be imaged and the question to be answered.
Recently, both peer-reviewed medical literature and the popular media have addressed the issue of increasing radiation exposure from diagnostic imaging. The main focus of these reports has been the potential for developing cancer years after exposure to as little as one CT scan with the risk increasing with each additional CT scan. Most of the studies estimating the increased risk of developing a cancer from exposure to ionizing radiation from diagnostic imaging have used data from atomic bomb survivors or those exposed to radiation from the Chernobyl nuclear reactor accident The validity of this data has been questioned. However, a new prospective study published online in the journal Lancet (Pearce MS et al, Radiation exposure from CT scans in childhood and subsequent risk of leukemia and brain tumours: a retrospective cohort study, Lancet, 2012; Published Online, June 7, 2012, DOI:10.1016/S01406736(12)60815-0) found that there is a very small but real increased risk of children developing brain tumors or leukemia after exposure to radiation from CT scans of the head. The authors of the study followed a group of children and adolescents who had at least one CT scan of the brain between 1985 and 2008 for a non cancer indication. Based on the findings from this one study, patients should not refuse CT scans when their benefits outweigh the risks.
Questions Parents Should Ask
When a healthcare provider recommends a CT scan for a child, the parent should ask the following questions:
Is the scan really necessary? In many cases CT is the best, fastest and safest test for the clinical problem. Parents should always inquire as to whether or not another test such as ultrasound or MRI can be done.
Does the site performing the study participate in the Image Gently campaign? This program was developed by the Alliance for Radiation Safety in Pediatric Imaging to educate clinicians, technologists, physicists and parents of the importance of radiation protection when imaging children. The program provides educational resources for parents and for imaging providers as to how to achieve excellent quality CT imaging of children while using the lowest possible dose of radiation thus minimizing the risks for any future problems related to radiation exposure.
Is the imaging facility accredited in pediatric CT by the American College of Radiology (ACR)? Is the technologist performing the study certified by the American Registry of Radiologic Technologists (ARRT)? Does the technologist have advanced certification in CT?
Is the physician interpreting the CT scan board certified by the American Board of Radiology?
Parents should also keep records of the imaging tests that their children have had and the associated radiation exposure from those tests.
At CareCore National, we strongly believe in the importance of using evidence-based medicine to determine the appropriate use of diagnostic imaging performed in the safest environment, using state of the art equipment and interpreted by the most qualified clinicians. We work with health plans to decrease unnecessary repeat imaging by providing clinicians access to both the images and reports of prior examinations. Our imaging precertification program is based on well researched criteria for imaging which is constantly changing to keep up with the changes in medicine. These criteria are available to the public and health care providers on our website. In addition, we work closely with health plans to be sure that the facilities participating in their imaging networks provide high quality, low dose, and safe imaging. We recommend that health plans only include radiologists who are board-certified by the American Board of Radiology in their networks. We recommend that all of these radiologists participate in the Image Gently campaign described above and that they are accredited in adult and pediatric CT by the American College of Radiology. We strongly believe that the public should have access to the highest quality most appropriate diagnostic imaging studies performed in the safest possible environment. We have the ability to track the number of CT scans that a patient has received.
We also support the use of dose reduction protocols as well as dose reduction devices on CT scanners without degradation of the diagnostic quality of images and the suggestion that all imaging reports contain the dose or exposure from the examination. In addition, we have a program to track the number of CT scans that individuals have had and can provide this information to ordering physicians. If clinically appropriate, we can recommend alternative imaging that does not involve the use of ionizing radiation.