Comparison of image quality and radiation dose between split-filter dual-energy images and single-energy images in single-source abdominal CT

Abstract

Objectives

To compare image quality and radiation dose of abdominal split-filter dual-energy CT (SF-DECT) combined with monoenergetic imaging to single-energy CT (SECT) with automatic tube voltage selection (ATVS).

Methods

Two-hundred single-source abdominal CT scans were performed as SECT with ATVS (n = 100) and SF-DECT (n = 100). SF-DECT scans were reconstructed and subdivided into composed images (SF-CI) and monoenergetic images at 55 keV (SF-MI). Objective and subjective image quality were compared among single-energy images (SEI), SF-CI and SF-MI. CNR and FOM were separately calculated for the liver (e.g. CNR_liv) and the portal vein (CNR_pv). Radiation dose was compared using size-specific dose estimate (SSDE). Results of the three groups were compared using non-parametric tests.

Results

Image noise of SF-CI was 18% lower compared to SEI and 48% lower compared to SF-MI (p < 0.001). Composed images yielded higher CNR_liv over single-energy images (23.4 vs. 20.9; p < 0.001), whereas CNR_pv was significantly lower (3.5 vs. 5.2; p < 0.001). Monoenergetic images overcame this inferiority in CNR_pv and achieved similar results compared to single-energy images (5.1 vs. 5.2; p > 0.628). Subjective sharpness was equal between single-energy and monoenergetic images and diagnostic confidence was equal between single-energy and composed images. FOM_liv was highest for SF-CI. FOM_pv was equal for SEI and SF-MI (p = 0.78). SSDE was significant lower for SF-DECT compared to SECT (p < 0.022).

Conclusions

The combined use of split-filter dual-energy CT images provides comparable objective and subjective image quality at lower radiation dose compared to single-energy CT with ATVS.

Key points

• Split-filter dual-energy results in 18% lower noise compared to single-energy with ATVS.

• Split-filter dual-energy results in 11% lower SSDE compared to single-energy with ATVS.

• Spectral shaping of split-filter dual-energy leads to an increased dose-efficiency.