Characterizing imaging radiation risk in a population of 8918 patients with recurrent imaging for a better effective...

An updated extension of effective dose was recently introduced, namely relative effective dose ( $E_r$ ), incorporating age and sex factors. In this study we extended $E_r$ application to a population of about 9000 patients who underwent multiple CT imaging exams, and we compared it with other commonly used radiation protection metrics in terms of their correlation with radiation risk. Using Monte Carlo methods, $E_r$ , dose-length-product based effective dose ( $E_{\mathrm{DLP}}$ ), organ-dose based effective dose ( $E_{\mathrm{OD}}$ ), and organ-dose based risk index ( $\text{RI}$ ) were calculated for each patient. Each metric's dependency to $\text{RI}$ was assessed in terms of its sensitivity and specificity. $E_r$ showed the best sensitivity, specificity, and agreement with $\text{RI}$ (R² = 0.97); while $E_{\mathrm{DLP}}$ yielded the lowest specificity and, along with $E_{\mathrm{OD}}$ , the lowest sensitivity. Compared to other metrics, $E_r$ provided a closer representation of patient and group risk also incorporating age and sex factors within the established framework of effective dose.