Usefulness of a New Effective Dose Conversion Factor Using Size-Specific Dose Estimate (SSDE) in Abdominopelvic...

The purpose of this study was to determine a new conversion factor (k_SSDE-LP) that would allow more accurate calculation of the effective dose that is minimally influenced by patient body size, using the Dose Management Software (DMS), and to verify its accuracy in estimating patient-specific effective dose compared to existing methods. A simple regression equation was obtained using the product of the size-specific dose estimate (SSDE) and scan length on the horizontal axis and the effective dose on the vertical axis, and the slope was taken as the effective dose conversion coefficient, k_SSDE-LP. Similarly, the slope obtained from another simple regression equation, using the dose-length product (DLP) on the horizontal axis and effective dose on the vertical axis, was defined as k_DLP. The effective dose conversion factors and coefficients of determination (R²) were compared for males, females, and both sexes. The DLP, SSDE, scan length, and effective dose, which are dose indices necessary for determining effective dose conversion coefficients, were obtained from the DMS. The k_SSDE-LP values in males, females, and both sexes were 0.012 (R² = 0.997), 0.014 (R² = 0.996), and 0.013 (R² = 0.993), respectively. Using the SSDE, a dose index that takes into account information about the patient's physique, we calculated the k_SSDE-LP, which reflects the current tissue weighting coefficients and mathematical voxel phantom and does not easily deviate from the regression equation even in the high-weight group.