Minimizing the radiation dose associated with pediatric imaging procedures has been seen as an important issue for decades. For the past several years, there has been an emphasis on reducing the radiation dose associated with pediatric CT within the radiology community. Attention was focused on this topic by a series of featured articles in the February 2001 issue of the AJR [1–3]. These articles discussed the potential risks associated with the dose of radiation being used for pediatric CT, a lack of attention to pediatric CT protocols within the radiology community, and suggestions for how CT technical parameters can be adjusted to minimize radiation dose [1–3]. Although the risk of carcinogenesis above the baseline cancer rate associated with a pediatric CT scan is low and this exact relationship is controversial [4], there is growing evidence that minimizing dose in children is important. Carcinogenesis above the baseline cancer rates is a risk associated with radiation doses lower than previously believed [1], and these doses can be achieved in children when nonadjusted adult protocols are used. We also know that the tissues of children are up to 10 times more radiosensitive than those of adults [1]. In this commentary, I review the progress that has been made in changing practices of the radiology community and attention given to dose reduction by CT manufacturers and emphasize the importance of decreasing unnecessary CT examinations in children.

It can be argued that there has been marked progress in this area since the February 2001 AJR articles [1–3] appeared. Certainly, the attention given to the issue of radiation dose in imaging procedures has escalated dramatically during that time. Scientific articles, presentations at meetings, and review courses on the topic are now common. In fact, the monthly issues of the AJR often have a section dedicated to articles on dose reduction. All this attention in academic radiology most likely has had a positive effect on the practice of pediatric adjustments to CT protocols in the general radiology community. According to a recent publication [5], approximately 43% of imaging departments now report that they have programs to adjust CT parameters for children. Although this still leaves marked room for improvement, this change is a dramatic one compared with the near universal lack of such practices as recently as 2001 [3].

Likewise and just as important, the attention given to technology to reduce dose associated with CT by the manufacturers of CT equipment has dramatically increased. Before 2001, none of the CT manufacturers had programs of much priority in the area of dose reduction for CT. Currently, virtually all the CT manufacturers have such programs [6–9]. Now multiple initiatives are in place to develop technologies such as improving geometric efficiency of MDCT scanners, reducing technical errors, automated exposure control, improving image filtration, using cardiac gating of the CT X-ray source, and researching noise simulation [6–9]. Other dose-reducing programs such as the institution of in-plane shielding for radiosensitive areas such as the pediatric breast have been advocated and implemented at some institutions [10].

Although advances in the use of pediatric protocols in the general radiology community and technical advances by the CT manufacturers are all important, the most effective way to reduce the radiation dose associated with CT in pediatric patients is to reduce or eliminate unnecessary or inappropriate CT referrals. On the basis of 2003 data [5], CT examinations are estimated to account for approximately 15% of all imaging examinations that use ionizing radiation. Estimates also indicate that CT examinations account for approximately 70% of the dose to patients for medical imaging studies. On the basis of 2000 data [5, 11], it was estimated that approximately 2.7 million CT examinations per year are performed in children younger than 15 years. This number is likely even higher in 2004.

Related to the volumetric imaging acquisition and rapid speed at which CT images are now obtained, the number of indications and volume of CT scans are greatly increased over recent years. It is a common opinion in the pediatric radiology community that the performance of unnecessary pediatric CT examinations is a public health problem in the United States. Multiple factors contribute to the performance of unnecessary examinations including overcautious ordering of CT examinations by referring clinicians because of concern related to potential malpractice litigation, financial incentive to perform more CT examinations related to fee-for-service financial arrangements, and pressure to use high-end technical examinations by the American public. Given the option, many American parents might opt to have a CT examination performed on their child with immediate results rather than deal with the time invested in a period of observation and return visit to the medical provider. Time management is a difficult problem for many American families, and impatience for proposals that take large amounts of time is increasing. Because of these reasons, there is often pessimism regarding whether pediatric radiologists can have a positive effect on decreasing the amount of inappropriate examinations. I would like to describe an intervention that affected the rate of growth in utilization of abdominal CT.

Toward the end of the first quarter of the July 2002 academic year, I began to receive multiple complaints from the radiology residents and pediatric radiology fellows that the volume of referrals for abdominal CT from the emergency department was increasing dramatically and that an increasing percentage of the referred examinations were, in their opinion, not indicated. I suspected the perception of the increased volume was most likely inaccurate. I began to gather data to prove this. To my surprise, however, the number of abdominal CT examinations referred from the emergency department during the first quarter of the July 2002 academic year had increased by 65% compared with the same quarter in 2001. In addition, this increase was dramatically disproportionate to the 22% increase in abdominal CT examinations performed in other outpatient settings. Although monitoring the appropriateness of CT referrals is one of the primary roles of the faculty and fellows working in our CT area, referring services often learn the terminology that will move their request through the system.

Although an increase in CT utilization by 65% is most likely disproportionate to that being observed from emergency departments in the United States in general, we do not have an exact explanation as to why we had this magnitude of an increase. While the exact percentage increase in the frequency of CT utilization may not be generalizable to all medical centers, the phenomenon of increased CT utilization most likely can be generalized.

The topic was discussed at our pediatric radiology faculty meeting, and it was agreed that both the 22% increase in outpatient clinic abdominal CT examinations and the 65% increase in abdominal CT scans from the emergency department were both too great. An educational campaign was then mounted. Radiation dose associated with pediatric CT was the topic of pediatric grand rounds. Articles concerning the topic were published in intrainstitutional publications that reached both institutional pediatric subspecialists and community pediatricians. Topics covered in the education campaign included new data about the increased radiosensitivity of children related to radiation doses similar to a CT examination, trends on increased utilization of CT in the workup of pediatric diseases, some of the programs that we had implemented to decrease dose when CT is performed, and the importance of decreasing unnecessary examinations. In addition, a more focused effort was made with the emergency department. Data concerning the disproportionate increase in use of abdominal CT in the emergency department were given to the chief of the division of emergency medicine, and that information was dispersed to the emergency department faculty during a faculty meeting.

Reevaluation of the utilization of abdominal CT 1 year later now shows that the interventions were effective in decreasing the rate of growth of CT utilization. The number of abdominal CT examinations referred from the emergency department decreased by 6% for the first quarter of the July 2003 academic year as compared with the same quarter in 2002—a 71% change in the rate of growth as compared with the increase of 65% the year prior. In addition, the use of CT of the abdomen in other outpatient CT examinations increased by only 12% from 2002 to 2003 as compared with 22% the prior year. Both the emergency department and medical center were busier during the first quarter of the 2003 academic year than in the same period in 2002, further supporting the notion that the decrease in rates of growth in CT referrals was related to the education campaign and not to changes in patient volumes. During the first quarter of the 2003 academic year compared with 2002, patient visits to the emergency department increased by 2.2%, hospital-patient days increased by 17%, and pediatric surgical procedures increased by 13%. Therefore, the decreased rate of referrals for abdominal CT from the emergency department and decreased rate of increase of referrals for other outpatient CT examinations of the abdomen occurred during a time period when institutional growth in patient volume had occurred at Children's Hospital.

By no means do I suggest that our education campaign or our referral patterns for CT are perfect. Despite the fact that my colleagues and I believe that our education campaign did have a positive effect on decreasing the rate of growth of CT of the abdomen, the absolute number of abdominal CT examinations performed in the first quarter of the academic 2003 year—although 6% lower than the same period in 2002—is still 59% higher than those performed during the same period in 2001.

We currently do not have accurate data concerning optimal CT utilization in a pediatric emergency department. We do not know the exact effects of the modulation of the frequency of CT utilization. For example, was there a correlation between the frequency of CT utilization and decrease in negative appendectomy rate, decreased rate of perforated appendicitis, increase in patient and family satisfaction, or increased productivity of the working guardians of the children evaluated? Was there optimization of patient throughput through the emergency department and coordination of flow of patients among the emergency department, operating rooms, and inpatient beds? Was there an effect on the disposition and follow-up of the patients? Exact answers to these questions will require intensive research efforts. However, our hunch is that we have room for improvement in CT utilization.

In conclusion, an educational campaign to increase the awareness of the importance of radiation dose associated with pediatric CT and minimizing dose via decreasing or eliminating nonindicated CT examinations can have a positive effect on reducing the rate of growth of CT utilization. Placing resources and effort into such educational campaigns may be one of the most important mechanisms to minimize the radiation dose associated with pediatric CT and should be encouraged.