Calculation of Normalized Organ Doses for Pediatric Patients Undergoing CT Examinations on Four Types of CT Scanner

Patient doses due to Computed Tomography (CT) are becoming increasingly important in diagnostic radiology, with there being particular concern about examinations on children owing to their increased radiosensitivity. We have computed organ doses normalized to CTDIair using the University of Florida (UF) voxelized pediatric phantoms in relation to the General Electric 9800, Philips LX, Siemens DRH and Siemens Sensation 16 CT scanners. For a whole body examination, the normalized effective dose E103 (as a convenient summary of organ doses) increases by 30% when the age decreases from 14 years to 9 months. This trend is consistent with published results from our previous study based on pediatric and adult mathematical phantoms. Further calculations of normalized effective doses for adult mathematical phantoms also show good agreement with that study under similar conditions of modeling, although updated dose coefficients differ from the previously published data by +35% ± 2%, +16% ± 8% and 6% ± 5%, for examinations of the head & neck, chest, and abdomen & pelvis, respectively. These differences are due to changes in both the definition of effective dose (E60 to E103) and the adult MIRD-like phantom (from NRPB18+ to HPA18+) to incorporate the new risk and remainder organs.