Improved precision of noise estimation in CT with a volume-based approach

European Radiology Experimental

Geertruida H. de Bock¹  Maarten van den Berge²  Hendrik Joost Wisselink³  Gert Jan Pelgrim³  Ivan Dudurych³  Rozemarijn Vliegenthart³  Mieneke Rook⁴ 

[1] Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands;Department of Pulmonology, Groningen Research Institute for Asthma and COPD (GRIAC), University Medical Center Groningen, University of Groningen, Groningen, The Netherlands;Department of Radiology, EB44, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands;Department of Radiology, EB44, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands;Department of Radiology and Nuclear Medicine, Martini Hospital Groningen, Groningen, The Netherlands;

关键词: Data accuracy;    Noise;    Pulmonary disease (chronic obstructive);    Thorax;    Tomography (x-ray computed);   

DOI  :  10.1186/s41747-021-00237-x

来源: Springer

【 摘 要 】

Assessment of image noise is a relevant issue in computed tomography (CT). Noise is routinely measured by the standard deviation of density values (Hounsfield units, HU) within a circular region of interest (ROI). We explored the effect of a spherical volume of interest (VOI) on noise measurements. Forty-nine chronic obstructive pulmonary disease patients underwent CT with clinical protocol (regular dose [RD], volumetric CT dose index [CTDIvol] 3.04 mGy, 64-slice unit), and ultra-low dose (ULD) protocol (median CTDIvol 0.38 mGy, dual-source unit). Noise was measured in 27 1-cm2 ROIs and 27 0.75-cm3 VOIs inside the trachea. Median true noise was 21 HU (range 17-29) for RD-CT and 33 HU (26-39) for ULD-CT. The VOI approach resulted in a lower mean distance between limits of agreement compared to ROI: 5.9 versus 10.0 HU for RD-CT (−40%); 4.7 versus 9.9 HU for ULD-CT (−53%). Mean systematic bias barely changed: −1.6 versus −0.9HU for RD-CT; 0.0 to 0.4HU for ULD-CT. The average measurement time was 6.8 s (ROI) versus 9.7 (VOI), independent of dose level. For chest CT, measuring noise with a VOI-based instead of a ROI-based approach reduces variability by 40-53%, without a relevant effect on systematic bias and measurement time.

【 授权许可】

CC BY