Room: AAPM ePoster Library
Purpose: To propose a body mass index (BMI)-based method for size-specific dose estimates (SSDE) during computed tomography (CT) examination in adults.
Methods: According to the scanning results of adult patients using a 64-row CT (SOMATOM Definition Flash, Siemens, Germany), a retrospective analysis was carried out by screening 87 cases without obvious abnormal imaging performance changes. The selected patients were divided into three groups: group A with thorax scan, group B with midsection scan, and group C with total abdominal scan. Based on AAPM reports No. 204 and No. 220, we collected cross-sectional area (A(ROI), cm²) and mean CT value (CT(ROI), HU) to calculate water equivalent diameter (Dw, cm), ƒ(Dw) and SSDE(Dw) (mGy), on the most intermediate layer within the scanning volume range of CT images. The height and weight of all patients were recorded prior to the examination, and corresponding relationship between adult BMI and SSDEDw of CT examination sites was obtained using two-paired one-sample t-test analysis and one-way anova analysis.
Results: There were significant differences between BMI and SSDEDw in group A, B and C (t=29.261, 27.837 and 19.065, respectively,P<0.01). Besides, BMI also showed positive correlation with SSDE(Dw), Dw and ƒ(Dw) in all three groups (R²=0.63-0.66, 0.75-0.84 and 0.75-0.84, respectively, P<0.01). In addition, independent one-way anova analysis showed that there were significant differences in Dw (F=17.363, P<0.01), ƒ(Dw) (F=16.419, P<0.01), and SSDEDw (F=12.876, P<0.01) among the three groups.
Conclusion: The BMI-based method may be effective to estimate size-specific radiation dose based on Dw value.
Funding Support, Disclosures, and Conflict of Interest: This study received fundings from the Taishan Scholars Program of Shandong Province.
Helical CT, Radiation Dosimetry, In Vivo Dosimetry