Topogram-based automated selection of the tube potential and current in thoraco-abdominal trauma CT - A comparison to fixed kV with mAs modulation alone

摘要

Objective: To investigate the impact of automated attenuation-based tube potential selection on image quality and exposure parameters in polytrauma patients undergoing contrast-enhanced thoraco-abdominal CT. Methods: One hundred patients were examined on a 16-slice device at 120 kV with 190 ref.mAs and automated mA modulation only. Another 100 patients underwent 128-slice CT with automated mA modulation and topogram-based automated tube potential selection (autokV) at 100, 120 or 140 kV. Volume CT dose index (CTDIvol), dose-length product (DLP), body diameters, noise, signal-to-noise ratio (SNR) and subjective image quality were compared. Results: In the autokV group, 100 kV was automatically selected in 82 patients, 120 kV in 12 patients and 140 kV in 6 patients. Patient diameters increased with higher kV settings. The median CTDIvol (8.3 vs. 12.4 mGy; -33 %) and DLP (594 vs. 909 mGy cm; -35 %) in the entire autokV group were significantly lower than in the group with fixed 120 kV (p0.05 for both). Image quality remained at a constantly high level at any selected kV level. Conclusion: Topogram-based automated selection of the tube potential allows for significant dose savings in thoraco-abdominal trauma CT while image quality remains at a constantly high level. Key Points: ? Automated kV selection in thoraco-abdominal trauma CT results in significant dose savings ? Most patients benefit from a 100-kV protocol with relevant DLP reduction ? Constantly good image quality is ensured ? Image quality benefits from higher kV when arms are positioned downward