To evaluate a novel tin filter-based abdominal CT protocol for urolithiasis in terms of image quality and CT dose parameters.
130 consecutive patients with suspected urolithiasis underwent non-enhanced CT with three different protocols: 48 patients (group 1) were examined at tin-filtered 150kV (150kV Sn) on a third-generation dual-source-CT, 33 patients were examined with automated kV-selection (110-140kV) based on the scout view on the same CT-device (group 2), and 49 patients were examined on a second-generation dual-source-CT (group 3) with automated kV-selection (100-140kV).
Automated exposure control was active in all groups. Image quality was subjectively evaluated on a 5-point-likert-scale by two radiologists and interobserver agreement as well as signal-to-noise-ratio (SNR) was calculated. Dose-length-product (DLP) and volume CT dose index (CTDIvol) were compared.
Image quality was rated in favour for the tin filter protocol with excellent interobserver agreement (ICC=0.86-0.91) and the difference reached statistical significance (p<0.001). SNR was significantly higher in group 1 and 2 compared to second-generation DSCT (p<0.001). On third-generation dual-source CT, there was no significant difference in SNR between the 150kV Sn and the automated kV selection protocol (p=0.5). The DLP of group 1 was 23% and 21% (p<0.002) lower in comparison to group 2 and 3, respectively. So was the CTDIvol of group 1 compared to group 2 (-36%) and 3 (-32%) (p<0.001).
Additional shaping of a 150kV source spectrum by a tin filter substantially lowers patient exposure while improving image quality on un-enhanced abdominal computed tomography for urinary stone disease.
European journal of radiology. 2016 Mar 22 [Epub]
Patricia Dewes, Claudia Frellesen, Jan-Erik Scholtz, Sebastian Fischer, Thomas J Vogl, Ralf W Bauer, Boris Schulz
University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt, Germany., University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt, Germany., University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt, Germany., University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt, Germany., University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt, Germany., University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt, Germany. Electronic address: ., University Hospital Frankfurt, Department of Diagnostic and Interventional Radiology, Frankfurt, Germany.