Dose optimisation in paediatric CT examination: Assessment on current scanning protocols associated with radiation dose

Abstract

Request for paediatric CT imaging has been increasing recently, and thus assessment of current paediatric CT protocols is of crucial importance as to assess the associated potential risk and possibly identify the need to modify the current practice. The aim of this study was to optimize the current local practice through investigation on the radiation dose distribution and existing routine scanning protocols of paediatric head and abdomen CT examinations at Radiology Department, HUSM, Kelantan, Malaysia. A total of 250 paediatric (age between 0‒12 years) CT examinations (134 of head CT and 116 of abdomen CT scans) were retrospectively collected from PACS and further analysed. The dose metrics in volume CT dose index (CTDIvol) and dose length product (DLP) with combination of exposure parameters (kV, mAs, pitch, scan length and acquisition time) for paediatric CT imaging were evaluated. Third quartile values of local dose distribution were then compared with selected international DRLs. The third quartile values for CTDIvol (mGy) and DLP (mGy.cm) for head and abdomen CT scans with respect to the age groups were 0–3 years (32/557 and 7/232), 4–6 years (61/1105 and 9/251), 7–9 years (117/1454 and 11/405), 10–12years (117/2203 and 14/566) respectively. From the comparative study, the local dose received from paediatric head CT scans were higher than the recommended levels. This is mainly due to selection of scanning parameters which were higher than the optimised paediatric protocols. Tube voltage selection was ranged from 100‒120 kV for all age groups except the head CT scan in group 4 that used a constant 120 kV. Applied mAs varied in the ranges from 100‒410 mAs for head CT scan and 35–100 mAs for abdominal CT scans and increases as the paediatric age increased. From the findings, review and optimisation on the current scanning protocols is required especially for head CT scan to complement the corresponding age groups and sizes while maintaining the diagnostic values.