No abstract

The objective of this research was to obtain the optimal automatic exposure control (AEC) settings for CT thorax examinations for obese paediatric patients. This was to ensure lower radiation dose for this special cohort while maintaining diagnostic image quality. A layer of fat tissue equivalent material was used to wrap around the torso of a paediatric phantom to simulate an obese patient. Optically stimulated luminescence dosimeters (OSLDs) were inserted at different positions within the thorax region. Three sets of CT images were acquired at DoseRight Indices (DRI) of 13, 15 and 17. The CT images were used for qualitative and quantitative assessments. The contrast to noise ratio (CNR) of images with DRI of 13 (211.08 ± 21.35) were significantly lower than CNR of images with DRI of 15 (231.67 ± 20.35) and 17 (245.10 ± 25.44; p < 0.01). For signal to noise ratio (SNR), there were significant differences among images with all DRI settings (p < 0.01). The mean absorbed dose received by the phantom at DRI of 13, 15 and 17 were 1.07 ± 0.05 mSv, 1.16 ± 0.07 mSv and 1.75 ± 0.08 mSv, respectively. In this study, DRI of 15 was determined as the optimal setting for obese paediatric patients for the age group of 5 to 14 years old. We have demonstrated that there is scope to reduce radiation dose to obese paediatric patients in CT thorax examinations while still maintaining diagnostic quality images.