Today, CT is an invaluable diagnostic and management planning tool for health care providers caring for both children and adults. However, the cumulative ionizing radiation burden to the United States population from diagnostic imaging examinations is growing and is now close to that from natural sources [2
]. This increase in radiation exposure is considered a public health issue [3
]. This potential risk is receiving considerable attention in the medical literature and lay press [4
]. As physicians and scientists strive to better understand the safety issues of medical radiation, should patients, and the parents of pediatric patients, be informed? How should they be informed? The Alliance for Radiation Safety in Pediatric Imaging believes that providing information to parents about potential radiation risks to their child from CT scans is an opportunity to improve physician–patient communication and enhance medical professionalism.
Current Use of CT in the United States
CT is one of the most important health care tools of the 21st century [9
]. The technique is accessible, well-tolerated by patients, and rapid. At times it is the only technique that can answer a specific clinical question. The speed and precision of CT directly impact appropriate clinical care, increasing the physician's confidence in the diagnosis and often obviating additional testing or exploratory surgery [10
]. In a study from Boston Children's Hospital, investigators reported that CT scans not only made the diagnosis of appendicitis with > 95% accuracy but also accelerated triage of the patient and saved health care dollars [11
]. In addition to being informed of possible hazards of ionizing radiation, parents and patients should be informed of the advantages CT provides.
The utilization of CT continues to increase in the United States and the world [3
]. Since its introduction in the early 1970s, CT use has risen from 2 million studies per year to more than 65 million annually. Each new CT unit purchased from 1995 to 2004 averaged more than 2,200 new studies per year [9
]. There are now more than 10,000 CT units estimated to be in operation. Approximately 7 million CT scans were obtained in children in 2007. Although CT examinations make up 11% of the number of radiologic procedures, radiation from CT delivers as much as 70% of the diagnostic imaging–related radiation dose [12
]. Broder et al. [13
] have indicated dramatic changes in CT use in children. In their pediatric emergency department, visit volume from 2000 to 2006 remained stable, but chest CT increased 435% and cervical spine CT, 366%.
Potential Risks of CT
CT carries recognized risks: first, extravasation at the IV site and central or peripheral catheter rupture at the time of administration of iodinated contrast material; second, allergic reaction to iodinated contrast material; and, third, exacerbation of renal failure in children with preexisting renal disease. In children, the allergic reaction risk using nonionic contrast is low and reported to be between 1:10,000–100,000 [14
]. For young children or others who cannot cooperate, sedation adds a risk to CT as well. Consent must be obtained before sedation or anesthesia for any reason. The other risks—allergy to iodine, renal function, and pregnancy—are screened verbally or by a written questionnaire before the examination in most radiology departments.
One risk that is not typically discussed is the possible radiation risk from low-level ionizing radiation (< 100–150 mSv). This lack of discussion occurs for several reasons: first, a lack of consensus among medical and scientific experts about the actual radiation risk from low-level radiation; second, a lack of awareness on the part of referring physicians as to possible risk; third, current “community standards” that do not discuss radiation as a potential risk; and, fourth, difficulty in conveying this complex topic to parents and caregivers in a straightforward format [15
]. Each of these reasons that potentially hinders the discussion about radiation risk will be reviewed.
Lack of Consensus About Radiation Risk
Risk associated with medical radiation imaging remains controversial with data supporting several differing perspectives. Some experts propose that low-level radiation has no effect (i.e., that there is a threshold below which no harm occurs). Most scientific and medical organizations and experts, however, believe that radiation even at low levels may have a harmful effect [16
]. These organizations support the concept of the linear, no-threshold model for ionizing radiation risk of cancer induction. Several studies of large populations exposed to various doses of radiation show an increase in cancer risk even at low levels of radiation exposure [16
]. Children are at increased risk from radiation because of their greater sensitivity to radiation and a longer lifetime to manifest those changes [4
]. Many national and international organizations responsible for evaluating radiation risk agree that to be safe, we should act as if low doses of radiation cause harm using the ALARA (as low as reasonably achievable) principle routinely [24
Current “Community Standards” Do Not Discuss Radiation as a Potential Risk
Patients often have a poor understanding of what a radiology examination entails, including what information it can and cannot provide and its potential risks [26
]. Most health care experts promote the need to discuss both benefits and risks for any medical intervention, including diagnostic tests. To counterbalance the explosive growth in the use of CT, an understanding of the radiation risks is essential. Just as clinicians must communicate evidence about a treatment and, when evidence is lacking, their expert opinion and experience, radiologists should provide an objective assessment of what CT can do for the health of children.
Parents have a right to participate in decisions about their child. Risks discussed by a trusted source such as a pediatrician or radiologist are better tolerated than those discovered from an unknown source, such as the Internet [28
]. Families may feel misinformed and distrustful if they are not told about potential risks before a procedure [29
]. By providing information up front, parent–patient autonomy is respected [30
]. When parents assume a risk voluntarily, their acceptance is improved compared with when the risk has been imposed unknowingly on their child [28
There is currently no mandate to require radiologists to obtain informed consent related to radiation risks before CT [32
]. However, policy makers or the consumer may impose such consents if they believe patients are not being protected adequately [30
]. In a survey conducted by Lee et al. [35
], only 15% of academic radiology departments provide radiation risk information before CT. Voluntarily providing information at or near the time of performance of the CT examination is optimal and should be the goal rather than mandated consents.
How Should We Talk to Parents About CT Risk?
There is evidence to support the importance of disclosing information to patients [31
]. Berlin [33
] stated “Both the public at large and the courts are continuously imposing ethical and legal duties on radiologists and other physicians to expand the nature and amount of information that must be disclosed to patients.” By improving parents' and patients' understanding of the benefits and risks associated with CT, the broader mandate to communicate effectively with patients and improve the health literacy is met [36
]. Formal consent is not necessarily indicated; rather, a commitment to provide information about the CT examination, how it is performed, its advantages, and attendant risks should be adequate.
Larson and colleagues [26
] surveyed parents and found convincing evidence that a simple handout that discusses the performance and risks of CT enhanced parents' understanding. In their study, only 13% of parents realized that CT might increase the risk of cancer, but no parent refused the CT scan after being informed about possible risks. Some experts believe that parents may contribute to the increasing demand for CT because they seek rapid diagnosis without understanding the potential risks [37
]. Improving parents' understanding may aid in addressing that problem.
The complexities and uncertainty of the scientific evidence and the cultural reticence of the radiology community to communicate directly with patients and families make radiologists cautious about bringing up the topic of CT radiation risk [38
]. Discussions may be time-consuming and less than satisfying because the presumed risks are theoretic and relate to population risk with a long latent period. With this complexity in mind [40
], the Alliance for Radiation Safety in Pediatric Imaging developed several resources for parents that can be downloaded from their Website including two free versions of a pamphlet for parents and pediatricians. The first is an eight-page color brochure titled “What Parents Should Know About Medical Radiation Safety” [41
]. This pamphlet is targeted to parents and gives detailed information concerning dose equivalents and comparisons with background radiation. A shorter two-page version titled “What Parents Should Know About CT Scans for Children” [42
] is designed for distribution in emergency rooms, imaging centers, and medical offices. Another brochure written specifically for parents has been created for pediatricians to distribute through their offices sponsored by a grant from the American Academy of Pediatrics (AAP). Downloadable information is now also available for pediatricians and parents to access at the AAP Website (www.aap.org).
For many years, the Food and Drug Administration's Center for Devices and Radiological Health (CDRH) has made an X-Ray Record Card [43
] available for consumers to keep track of where and when their x-rays were taken. This card has not been widely used by patients or parents possibly because parents have not been encouraged by their physicians to maintain such a record and may have not had access to one. Conversely, immunization record forms are routinely made available by pediatricians and are in wide use today. The Alliance has adapted these concepts to develop the Image Gently Medical Imaging Record Card [44
]. This card may be distributed by pediatricians or downloaded by parents from the Image Gently Website. It is available in colorful foldable versions in two sizes. Similar to the familiar immunization card, it should be helpful in alerting families and their doctors to the frequency of patient imaging examinations. It also provides a memory aid for parents to track where and when a study is performed. With relocation of families and the use of different hospital centers in the same community, this card may help decrease the number of repeat examinations performed.