Radiology: Will guidelines improve radiopharmaceutical use in kids?
Citing significant variations in pediatric radiopharmaceutical doses and package inserts lacking pediatric doses, the authors of an article appearing in the November issue of Radiology indicated recently approved consensus guidelines for pediatric administered radiopharmaceutical doses may help solve the problem.

Over the past several decades, a wide variety of pediatric dose schedules have been used by nuclear medicine practitioners across the country, which indicates some patients are receiving unnecessary radiation exposures.

In the article, S. Ted Treves, MD, of Children’s Hospital Boston; Marguerite T. Parisi, MD, MS, of Seattle Children’s Hospital; and Michael J. Gelfand, MD, of Cincinnati Children’s Hospital, wrote about the implications of the new guidelines.

“We hope that the wide availability of these guidelines will be helpful to physicians responsible for pediatric nuclear medicine imaging procedures,” wrote the authors. “We believe that wide adoption of these guidelines could result in reduction in radiation exposure in many children undergoing nuclear medicine examinations.”

The guidelines were approved in late 2010 by the Society of Nuclear Medicine, the Society for Pediatric Radiology and the American College of Radiology. The Alliance for Radiation Safety in Pediatric Imaging also encouraged the development of the guidelines.

The radiopharmaceuticals covered by the guidelines are:

  • 18F-FDG
  • 18F-sodium fluoride
  • 123I-MIBG
  • 99mTc (for cystography)
  • 99m Tc-IDA
  • 99m Tc-DMSA
  • 99m Tc-MAA
  • 99m Tc-MAG3
  • 99m Tc-MDP
  • 99m Tc-pertechnetate (Meckel diverticulum imaging)
  • 99m Tc-sulfur colloid (for oral liquid gastric emptying)
  • 99m Tc-sulfur colloid (for solid gastric emptying)
Treves et al added that these guidelines are designed to assist practitioners and do not guarantee accurate diagnosis.

“Therefore, it is expected that each practitioner will follow a reasonable course of action based on his or her good clinical judgment, current knowledge, available resources and the specific needs of each patient, to perform safe and effective pediatric nuclear medicine studies,” wrote the authors. “The sole purpose of these guidelines is to assist practitioners in achieving this objective.”

Most of the guidelines adjust the administered doses according to patient weight alone, though some other adjustments were made to certain radiopharmaceutical guidelines based on advances in image reconstruction. For instance, the use of ordered subset expectation maximization iterative reconstruction, 3D with resolution recovery (OSEM-3D) has been explored in pediatric 99mTc-MDP skeletal SPECT and 99mTc-DMSA renal SPECT and demonstrated that images of equal or superior quality can be obtained with half the radiopharmaceutical administered activity of filtered back projection, according to the authors.

Treves et al also provided some survey results that underscored the necessity of updating the dose guidelines. Administered dose schedules among patients older than one year of age varied by an average factor of three and as much as a factor of 10 between a group of prominent pediatric hospitals in North America. Minimum doses for the youngest children varied by a factor of up to 20, according to the survey. The authors also cited a review of package inserts which indicated that only four of 22 package inserts included recommended pediatric doses.

“One obvious consequence of this wide variation in administered doses is unnecessarily large variation in the pediatric radiation exposures received by children who undergo nuclear medicine examinations,” wrote Treves et al.

The authors blamed the variances on a lack of information on pediatric administered doses, pressures to quickly obtain studies and inexperience in handling pediatric patients. They concluded by saying the new guidelines should serve as a baseline for future efforts to reduce radiation doses in children.