RADIATION-DOSIMETRY OF TECHNETIUM-99M-DMSA IN CHILDREN

Radiation dosimetry was performed on 24 children (aged 5 wk to 14.8 yr ) who were undergoing routine diagnostic investigation of renal impair ment with Tc-99m-DMSA. Methods: Organ doses were calculated using MIRD OSE 3 with biokinetic data obtained in previously described studies, a nd effective doses and effective dose equivalents were estimated, Inte rpolation by inverse weight between pediatric anthropomorphic phantoms was compared with age-matching to discrete phantoms. Administered act ivities were scaled by body surface area from the adult activity of 10 0 MBq and the resulting radiation doses in normal children were compar ed with those that would have resulted from a schedule based on body w eight, Results: The effective doses estimated by interpolation differe d by up to 46% from those based on discrete phantoms and showed less v ariation, In children with normal bilateral renal function, the mean e ffective dose per administered activity was 0.91 +/- 0.08 mSv or 0.98 +/- 0.29 mSv by the two methods, respectively. Renal pathology reduced the effective dose, on average, by 15% of the value for normal patien ts. Conclusion: Over the pediatric age range, the uniformity of effect ive dose values was improved by scaling the administered activity acco rding to body surface area rather than to body weight.