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Dose-modified 256-MDCT of the Abdomen Using Low Tube Current and Hybrid Iterative Reconstruction

Elsevier Inc.
DOI: 10.1016/j.acra.2013.08.004
  • Radiation Dose
  • Abdomen
  • Computed Tomography
  • Iterative Reconstruction
  • Image Quality
  • Medicine


Rationale and Objectives To evaluate the performance of hybrid iterative reconstruction technique (h-IRT) on image quality (IQ) in abdominal dose-modified (DM) scans in phantom and in patients in comparison to filtered back projection (FBP). Materials and Methods An anthropomorphic phantom was scanned using various kVp (80–140) and mAs (25–100) settings. Images were reconstructed with FBP and h-IRT levels (1–6). In 69 adults (59.6 ± 13.54 years; 20 male, 49 female), DM computed tomography (CT) scans were performed using 120 kVp and 100–120 mAs. In 25/69, 5-mm FBP and h-IRT (levels 1–4 and 5) images were analyzed to validate IQ. The subsequent 44/69 had FBP and h-IRT (level 4) images reconstructed. Two readers evaluated 188 image series for IQ, noise, and artifacts. Objective and subjective data were analyzed using t-test and Wilcoxon signed-rank test, respectively. In 46/69 patients, prior dose CT was available for dose comparison. Results In the phantom, noise reduction ranged from 12% (h-IRT level 1) to 50% (level 6). In patients, h-IRT level 4 images were rated diagnostic in 69/69 exams but DM-FBP images were found nondiagnostic in 20/69 patients. The size-specific dose estimate (SSDE) was reduced by 55% in the dose-modified CT group, (SSDE:4.55 ± 1.15 mGy) over the prior dose protocol (SSDE:10.21 ± 3.5 mGy, P < .0001). Conclusion h-IRT improved IQ in abdominal DM-CT scans in phantom and in patients. Dose improvements were greater in smaller patients than larger ones.

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