Effective dose to children and adolescents from radiopharmaceuticals

Published values of tissue weighting factors for adolescents and children derived from the life-span study of the atomic bomb survivors have been used to calculate the effective dose to patients aged 1, 5, 10 and 15 years undergoing a common paediatric procedure requiring one of the following radiopharmaceuticals: 99Tcm-mercaptoacetyltriglycine (MAG3), 99Tcm-diethylenetriaminepentaacetic acid (DTPA), 99Tcm-dimercaptosuccinic acid (DMSA), 99Tcm-pertechnetate, 99Tcm-iminodiacetic acid (IDA) derivatives, 99Tcm-hexamethylpropyleneamineoxine (HMPAO), 99Tcm-labelled leukocytes, 99Tcm-labelled erythrocytes, 99Tcm-phosphates, 99Tcm-methyloxyisobutylisonitrile (MIBI), 201Tl-chloride, sodium 123I-iodide, 123I-metaiodobenzylguanidine (MIBG) and 67Ga-citrate. Administered activities for each age group were based on ARSAC maximum usual values for adult patients and scaling factors listed by the European Association of Nuclear Medicine for different body weights. These effective doses were compared to values derived from ICRP whole-population tissue weighting factors and found to differ by -33% to +71% of these values, and by less than +/- 20% for two-thirds of the procedures. Because these differences were considerably less than the uncertainties in the estimates of organ absorbed dose, we conclude that these published age-specific tissue weighting factors should not be used for the estimation of effective dose to children and adolescents following the administration of radiopharmaceuticals, and that whole-population factors should continue to be used for these estimations.