2016 Update of the North American Consensus Guidelines for Pediatric Administered Radiopharmaceutical Activities.

P ediatric nuclear medicine provides important clinical information in the care of children. Although nuclear medicine techniques have been in use in adults for more than half a century, with well-established standards for radiopharmaceutical administered activities, this has not been the case for the pediatric population. As pediatric nuclear medicine grew in use practitioners faced with imaging children used a number of methods to select administered activities. For the most part, pediatric administered activities were influenced by varying combinations of tradition, existing dosage schedules, age of available equipment, practitioner preference, and direct extrapolation from adult administered activities An informal survey in 2009 showed that only 4 of 22 radiopharmaceutical package inserts provided recommended pediatric administered doses (1). Instead, package inserts included the “orphan statement”: “Radiopharmaceuticals should be used only by physicians who are qualified by training and experience in the safe use and handling of radionuclides and whose experience and training have been approved by the appropriate government agency authorized to license the use of radionuclides.” Radionuclide imaging in children was initially limited to those patients with proven oncologic disorders, mainly for diagnosis of extent of disease and to evaluate for metastases. This limited use was the result of radiation exposure concerns with older radiopharmaceuticals with long halflives and relatively high emission energies, low photon flux, b particle emissions, and unfavorable imaging characteristics. In addition, imaging equipment required long acquisition times and produced images with poor spatial resolution. With the development of short-lived radiopharmaceuticals and much lower radiation exposures, as well as the introduction of modern equipment, pediatric nuclear medicine expanded to include evaluation of physiology, benign disorders, and nononcologic diseases. With this expansion and the introduction of novel tracers, identification and dissemination of appropriate administered doses took on new importance. Early methods of calculating doses included the Clark rule, the Young rule, the area method, and the Webster rule. However, these methods provided a very wide range of recommendations. No consensus among practitioners provided dose standards. A 2008 survey of 13 North American pediatric nuclear medicine clinics revealed a wide range of administered radiopharmaceutical activities in children. The survey examined 16 of the most common radiopharmaceuticals used in children. In patients older than 1 year, administered dose variability ranged from a factor of 3 to a factor of 10. However, in children younger than 1 year, this variability ranged by a factor of 10 and, in 1 case, by a factor of 20 (2). After the publication of this survey, the Image Gently Alliance, the SNMMI, and the Society for Pediatric Radiology endorsed the formation of an expert group to develop consensus guidelines on pediatric radiopharmaceutical administered doses. The inherent aim was to reduce the large variability of administered doses, which in turn could have the effect of reducing overall pediatric radiation exposures. This group produced the 2010 North American Consensus Guidelines for Pediatric Radiopharmaceutical Administered Doses (3,4). Both similarities and differences between the European and the North American guidelines were evident (5); these were harmonized in 2014 (6–8). The original North American guidelines included recommendations for 12 radiopharmaceutical applications. Following expert consensus workshops at SNMMI Annual Meetings, additional radiopharmaceuticals were included: 99mTc-HMPAO and 99mTc-Ceretec for brain imaging, 99mTc-sestamibi and 99mTc-tetrofosmin for myocardial perfusion imaging, 123I-NaI for thyroid imaging, 99mTc-red blood cells for blood pool imaging, 99mTc-white blood cells for infection imaging, and 68Ga-DOTATOC and 68Ga-DOTATATE for neuroendocrine tumor imaging. A table with these additions and updates is now available (Table 1, facing page) and is available in a poster format from SNMMI and the Image Gently Alliance. Publication and dissemination of this information has had a positive effect in the practice of pediatric nuclear medicine. Recent surveys have indicated that a large fraction of those familiar with the guidelines have altered their practice in pediatric nuclear medicine to become more compliant (9,10). Therefore, it is apparent that further dissemination of the guidelines is needed. The development of these guidelines for pediatric administered radiopharmaceuticals has filled a long-standing need. It is important to consider that these guidelines should continue to be refined by more experience and new scientific work and that new procedures should be added to the guidelines as they become more routinely available in children. There is a need for more data on radiopharmaceutical biodistribution and biokinetics in children—data that at present are quite scarce or nonexistent. Sophisticated phantom modeling for children