SNM standardizes radiation dose in children
The board of directors at the Society of Nuclear Medicine (SNM) and the Society for Pediatric Radiology has approved new North American Guidelines for Radiopharmaceutical Doses for Children. The societies have expanded their pediatric radiation protection initiative by standardizing doses (based on body weight) for 11 nuclear medicine procedures commonly performed in children.

The Alliance for Radiation Safety in Pediatric Imaging has collaborated in this effort and will support efforts to promote the lower radiopharmaceutical doses, said SNM.  

The recommended administered activity (based on weight only) for the radiopharmaceuticals are as follows:
  • 123I-MIBG - 5.2 MBq/kg (0.14 mCi/kg);
  • 99mTc-MDP - 9.3 MBq/kg (0.25 mCi/kg);
  • 18F-FDG - body 3.7-5.2 MBq/kg (0.10-0.14 mCi/kg), brain 3.7 MBq/kg (0.10 mCi/kg);
  • 99mTc-DMSA -1.85 MBq/kg (0.05 mCi/kg);
  • mTc-MAG3 - without flow study 3.7 MBq/kg (0.10 mCi/kg), with flow study 5.55 MBq/kg (0.15 mCi/kg);
  • 99mTc-IDA -1.85 MBq/kg (0.05 mCi/kg);
  • 99mTc-MAA - 2.59 MBq/kg (0.07 mCi/kg) if Tc-99m used for ventilation, 1.11 MBq/kg (0.03 mCi/kg) if no Tc-99m s used for ventilation study;
  • 99mTc-pertechnetate (Meckel diverticulum imaging) - 1.85 MBq/kg (0.05 mCi/kg);
  • 18F-sodium fluoride - 2.22 MBq/kg 0.06 mCi/kg);
  • 99mTc (for cystography) - no weight-based dose; and
  • 99mTc-sulfur colloid (for oral liquid gastric emptying or for solid gastric emptying) - no weight-based dose.

The consensus guidelines differ significantly from the European Association for Nuclear Medicine (EANM) Pediatric Dose Card in several important respects, according to SNM:
(a) Administered activities in the consensus guidelines are slightly lower for infants and small children.
(b) Administered activities for 99mTc-DMSA and 18F-fluoride are considerably lower in the consensus guidelines.
(c) Administered activities for orally administered 99mTc-labeled radiopharmaceuticals and for radionuclide cystography provide a range of administered activities for each type of study rather than an administered activity/kg.
(d) The consensus guidelines more closely represent clinical practice in North American pediatric centers.

The assumptions used by the societies in constructing the consensus guidelines are:
(a) Planar whole body and SPECT imaging studies were performed on a dual-detector gamma camera equipped with a high resolution collimator.
(b) The determination of the administered activity for the pediatric patient is based on body weight alone except for nuclear cystogram and the gastric emptying studies.

Individual practitioners may use lower adminstered activities if their equipment or software permits them to do so. Higher administered activities may be required in selected patients, according to the guidelines.