An approach for the estimation of effective radiation dose at CT in pediatric patients.

PURPOSE: To estimate the effective radiation dose to pediatric and adult patients at head and abdomen computed tomography (CT). MATERIALS AND METHODS: Cylindrical water-equivalent phantoms were modeled for patients aged newborn to adult, and the energy imparted per unit axial exposure was computed. To determine the energy imparted to the simulated patients of different ages undergoing head and abdomen CT examinations, x-ray technique factors were combined with measured CT axial exposures. Body-region-specific ratios were calculated for effective dose per unit energy imparted, and these ratios were corrected for patient mass to obtain the effective dose to simulated patients. RESULTS: With use of standard techniques, the energy imparted to simulated patients at CT always increased with patient size, but the effective dose was higher in children than in adults. At CT in the head and abdomen, effective doses were highest in newborns. Effective doses ranged from 1.5 to 6.0 mSv in head CT examinations and from 3.1 to 5.3 mSv in abdomen CT examinations. CONCLUSION: The values for energy imparted at CT in pediatric patients were generally lower than in adults. The smaller mass of children, however, caused the corresponding effective doses to be higher than those in adults undergoing similar CT examinations.