Protocols-based notification versus diagnostic reference levels as an optimization tool in computed tomography

Abstract

We compare a dose baseline optimization tool built around clinical protocols and notification of dose based on the diagnostic reference level (DRL). In regard to computed tomography (CT), retrospective analysis has been made of the volume CT dose-index (CTDIvol) and dose-length-product (DLP) for a total of 230 adult patients undergoing enhanced CT abdomen and pelvis examinations. From this, a dose baseline was established. The DRL based notification level (NL) was set at twice the Local DRL. The protocol baselines for dose were set at the median and 75th percentiles of dose spectrum. Spearman coefficient and one-way ANOVA tests were used for statistical correlation and differences between DLP and various CT protocols. Significant differences (p < 0.05) were found between DLPs for common CT protocols including routine Abd&Pelv + C, triphasic liver, gastric sleeve, pancreas phases, and tumour. The NL was set at 1194 mGy cm, while the median protocols dose baselines for routine Abd&Pelv + C, triphasic liver, gastric sleeve, pancreas phases, and tumor were 748, 1450, 1530, 1620, and 2040 mGy cm respectively. A significant reduction was observed in the number of dose notification counts when defining dose baselines at the 75th percentile for triphasic liver (26%), gastric sleeve (27%), pancreas phases (25%), and tumour (20%). The observed reductions associated with the established NLs based on CT clinical indications/protocols may limit the counts of notifications alerts and further allow an opportunity for CT protocol standardization and patient dose optimization.