COMPARISON OF RADIATION-DOSE FROM INTRAVENOUS UROGRAPHY AND TC-99(M) DMSA SCINTIGRAPHY IN CHILDREN

Intravenous urography (IVU) and Tc-99(m) DMSA scintigraphy are possibl e alternative diagnostic techniques in paediatric renal investigation. Radiation dose comparisons between them have been complicated in the past by the lack of paediatric data. In this study, evaluations releva nt to children are used to compare estimates of effective dose from th e two techniques, For the radiographic procedures, standard operating parameters and representative age-dependent values of entrance surface dose were established from recent literature. Conversion factors rela ting effective dose to entrance surface dose and dose-area product are presented and used to obtain values of effective dose for single radi ographs of abdomen, kidneys and pelvis. Suggested IVU procedures consi sting of four (''minimum'') or eight (''average'') radiographs were ad opted to derive the effective dose for full IVU examinations. Tc-99(m) DMSA dose estimates, taken from our published work using an administe red activity schedule based on body surface area, are almost constant at about 1 mSv for all children. In comparison, mean IVU doses based o n the ''average'' number of radiographs are similar to DMSA doses for infants (<1 year) but may be twice as high for older children. Althoug h the differences between procedures at this level of dose do not in t hemselves provide grounds for preference, when coupled with the lower diagnostic sensitivity of IVU they suggest limitations of this procedu re for detection of a renal scar.