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- Title
Improved precision of noise estimation in CT with a volume-based approach.
- Authors
Wisselink, Hendrik Joost; Pelgrim, Gert Jan; Rook, Mieneke; Dudurych, Ivan; van den Berge, Maarten; de Bock, Geertruida H.; Vliegenthart, Rozemarijn
- Abstract
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.
- Subjects
COMPUTED tomography; CONE beam computed tomography; OBSTRUCTIVE lung diseases; NOISE measurement; NOISE
- Publication
European Radiology Experimental, 2021, Vol 5, Issue 1, p1
- ISSN
2509-9280
- Publication type
Article
- DOI
10.1186/s41747-021-00237-x