Pediatric radiopharmaceutical administered doses: 2010 North American consensus guidelines.

Dose reduction has been a work in progress in pediatric imaging for nearly a decade. A 1996 report indicated that the long-term risk of carcinogenesis due to ionizing radiation in atomic bomb survivors was higher than had been previously estimated. For solid tumors, representing about 75% of excess cancer mortality, the likelihood of a radiation-induced malignancy after exposure to ionizing radiation was about 1.0–1.8 times higher in a 10-y-old child than in a young adult. For leukemia, representing the remaining 25% of excess cancer mortality, the likelihood of a radiation-induced malignancy after exposure to ionizing radiation was about twice as high for a 10-y-old child as for a young adult (1). The new risk estimates led to dose-reduction efforts in pediatric imaging that initially focused on CT. Because of the increased use of CT and the relatively high effective radiation dose per study, CT had emerged as a major source of medical radiation received by children in the United States. A careful look at CT image quality and CT exposure parameters indicated that significant reductions in absorbed radiation dose per study were possible without compromising the diagnostic information or image quality of pediatric CT scans (2–6). The ALARA concept, As Low As Reasonably Achievable, was extended to pediatric diagnostic imaging and may be restated as imaging at the lowest absorbed radiation dose that is consistent with quality imaging. The need for reduced CT exposure was then publicized— in the public domain, in the pediatric radiology community, and throughout general radiology. The introduction of reduced-exposure parameters was assessed in a follow-up survey (7–9). Equipment manufacturers made improvements in CT technology that facilitated the reduction of radiation exposures in children. In addition, at this time new dose-reduction efforts are under way in pediatric interventional radiology and fluoroscopy (10). A survey conducted in 2008 revealed a wide variation of pediatric radiopharmaceutical administered doses among 13 leading pediatric hospitals in North America (11). Among the institutions surveyed, the administered activity per kilogram and the maximum administered activity in children older than 1 y varied on average by a factor of 3 and, in 1 case, by a factor of 10. Minimum administered activity varied, on the average, by a factor of 10 and as much as a factor of 20 for 1 procedure. The greatest variability in administered dose occurred in the smallest, youngest, and most at-risk patients. Because the survey included only leading pediatric institutions in North America, concern was raised that the variability among other institutions would be even greater. The survey highlighted the need for a consensus on pediatric radiopharmaceutical administered doses for nuclear medicine imaging in children. The ALARA concept may be extended to pediatric nuclear medicine and restated as the use of the lowest administered activities in children that are consistent with high-quality imaging. The response to this need for dose reduction and uniformity was the formation of a Pediatric Nuclear Medicine Dose Reduction Workgroup, consisting of pediatric nuclear medicine physicians, technologists, and physicists in North America, representing the Society of Nuclear Medicine through the Pediatric Imaging Council, the Society for Pediatric Radiology, and the American College of Radiology (Appendix). The workgroup conducted consensus workshops at annual meetings of the Society of Nuclear Medicine and the Society for Pediatric Radiology. Dose reduction was also featured in categoric courses presented at the 2009 and 2010 Society of Nuclear Medicine annual meetings. Likewise, dose reduction and image optimization in conventional and hybrid imaging were prominently featured in the Pediatric Nuclear Medicine Special Focus Session entitled “New Challenges” at the 52nd Annual Meeting of the Society for Pediatric Radiology in 2009. A symposium on pediatric radiopharmaceutical dosimetry was also held at the Society of Nuclear Medicine 2009 annual meeting. Received Oct. 15, 2010; revision accepted Oct. 26, 2010. For correspondence or reprints contact: S. Ted Treves, Division of Nuclear Medicine and Molecular Imaging, Department of Radiology, Children’s Hospital Boston, Harvard Medical School, 300 Longwood Ave., PV2C12, Boston, MA 02115. E-mail: [email protected] COPYRIGHT a 2011 by the Society of Nuclear Medicine, Inc.