Size-Specific Dose Estimate and Effective Dose for Pediatric Computed Tomography

The purpose of this study is to present the multivariate analysis of the size-specific dose estimate (SSDE) and E in pediatric computed tomography (CT) imaging. Pediatric patients scheduled for CT scans of the head, thorax, and abdomen from July 2022 to February 2024 were included in the prospective study. The water-equivalent diameter (<i>D</i> _w), SSDE, and E were computed for each examination using the dose report of CT console display computed tomography dose index (<i>CTD1</i> _vol) and dose length product (DLP). The correlation between SSDE and E on <i>CTD1</i> _vol, <i>D</i> _w, <i>Area</i> _ROI, body mass index, <i>Size⁄(LAT+AP)</i>, age, <i>f_size</i> , and <i>HU</i> _mean in the region of interest was examined using the multivariate statistical analysis with 95% level of significance (<i>P</i> < 0.05). The relationship between <i>D</i> _w and <i>Size⁄(LAT+AP)</i>, <i>Size⁄(LAT+AP)</i>, and <i>f_size</i> versus age was investigated using linear regression analysis. The mean values of SSDE for noncontrast head CT and contrast-enhanced CT were found 71.36 <i>mGy</i> and 97.38 <i>mGy</i>, respectively. While as, the mean SSDE for contrast-enhanced thorax CT was observed to be 5.82 <i>mGy</i>, which is less than the mean SSDE of 6.40 <i>mGy</i> for noncontrast thorax CT imaging. The range of the SSDE for contrast-enhanced abdomen CT is 2.05 <i>mGy</i> to 22.13 <i>mGy</i> with a mean SSDE of around 5.71 <i>mGy</i> and for noncontrast abdomen imaging, mean value of SSDE was 5.58 <i>mGy</i>. The mean value of "E" for noncontrast thorax CT imaging was observed to be 2.7 <i>mSv</i> with minimum and maximum 1.17 <i>mSv</i> to 10.10 <i>mSv</i> respectively, which less than the mean effective dose is of 3.64 <i>mSv</i> observed for contrast enhanced thorax CT imaging. The multivariate analysis suggests that SSDE is significantly correlated with <i>CTD1</i> _vol, <i>D</i> _w, and E is found significantly dependent on DLP for both contrast enhanced and noncontrast imaging with <i>p</i> < 0.05. A strong positive correlation was found between <i>D</i> _w and <i>Size⁄(LAT+AP)</i>, form linear regression analysis. The SSDE is crucial for radiologists evaluating pediatric CT scans and is now an international standard expected to be widely adopted. The strong positive correlation between <i>D</i> _w versus <i>Size⁄(LAT+AP)</i>, indicates that <i>Size⁄(LAT+AP)</i>,can be used as surrogate in estimate SSDE when <i>D</i> _w calculation is not feasible for pediatric CT imaging.