In Vivo Comparison of Radiation Exposure in Third Generation versus Second Generation Dual-Source Dual-Energy CT for Imaging Urinary Calculi.

PURPOSE To investigate the potential for decreasing radiation dose when utilizing a third generation versus second generation dual-source dual-energy CT scanner, while maintaining diagnostic image quality and acceptable image noise. MATERIALS AND METHODS Retrospective analysis of patients who underwent dual-source dual-energy CT (dsDECT) for clinical suspicion of urolithiasis from 10/2/2017 - 9/5/2018. Patient demographics, body mass index, abdominal diameter, scanning parameters, and CT dose index volume (CTDIvol) were recorded. Image quality was assessed by measuring the attenuation and standard deviation (SD) regions of interest in the aorta and in the bladder. Image noise was determined by averaging the SD at both levels. Patients were excluded if they had not undergone both 3rd and 2nd generation DECT, time between DECT was more than 2 years, or scan parameters were outside standard protocol. RESULTS 117 patients met inclusion criteria. Examinations performed on a 3rd generation DECT had an average CTDIvol 12.3 mGy, while examinations performed on a 2nd generation DECT had an average CTDIvol 13.3 mGy (p<0.001). Average image noise was significantly lower for the 3rd generation DECT (SD=10.3) as compared to the 2nd generation DECT (SD=13.9) (p<0.001). CONCLUSIONS The third generation dsDECT scanners can simultaneously decrease patient radiation dose and decrease image noise as compared to second generation DECT. These reductions in radiation exposure can be particularly important in patients with urinary stone disease who often require repeated imaging to evaluate for stone development and recurrence as well as treatment assessment.