E-ISSN 1305-3612
Chest Imaging - Original Article
Fast kilovoltage-switching dual energy CT offering lower X-Ray dose than single energy CT for the chest: a quantitative and qualitative comparison study of the two methods of acquisition
1 Department of Radiology, Yeditepe University School of Medicine, İstanbul, Turkey  
Diagn Interv Radiol ; : -

Abstract

Purpose: To compare the size-specific dose estimates (SSDE), CT dose indices and image quality parameters of the chest CTs obtained with fast kilovoltage-switching (FKS) dual energy (DE) CT versus those with single energy (SE) CT.


Methods
: Patients who had SE chest CT within the last 6 months, were prospectively scanned with the FKS-DE chest CT. Quantitative comparison was made by calculating the mean SSDE, CTDIvol, contrast, noise, contrast-to-noise ratio (CNR) and signal-to-noise ratio (SNR) for both acquisitions. Two radiologists evaluated the SE and DE chest CT images qualitatively blinded to the technique used. The paired Student’s t test was utilized for comparing the quantitative and qualitative data. Inter- and intra-observer agreement were also assessed.


Results
: A total of 42 patients were included. The mean SSDE, CTDIvol, contrast, noise, CNR and SNR for the SE versus DE chest CTs were 12.7±2.2 mGy vs 9.3±1.2 mGy (P = 0.001), 10.9±.2.4 mGy vs 8±1.2 mGy (P < 0.001), 211.9±44.7 vs 216.3±59 (P = 0.350), 12.9±2.4 vs 13.9±3.7 (P = 0.086), 13.5±5.2 vs 13.3±8.4 (P = 0.548) and 12±3.5 vs 11.5±3.4 (P = 0.774), respectively. Inter-observer reproducibility was high for contrast, noise, CNR and SNR (ICC = 0.89, 0.85, 0.93 and 0.82, respectively; all P < 0.05). Inter-observer reproducibility was high for contrast, noise, CNR and SNR (ICC = 0.89, 0.85, 0.93 and 0.82, respectively; all P < 0.05). Intra-observer reproducibility was high for contrast, noise, CNR and SNR (ICC = 0.80, 0.77, 0.85 and 0.88, respectively; all P < 0.05).


Conclusion
: The mean SSDE of the chest CTs obtained with FKS-DECT were 26.8% lower than those with SECT with significant difference for the objective assessment and there was no significant difference for the subjective assessment of the image qualities, in this series.   

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