We propose an automatic segmentation of Ground Glass Opacity (GGO) nodules on chest CT images by histogram
modeling and local contrast. First, optimal volume circumscribing a nodule is calculated by clicking inside of GGO
nodule. To remove noises while preserving a nodule boundary, anisotropic diffusion filtering is applied to the optimal
volume. Second, for deciding an appropriate threshold value of GGO nodule, histogram modeling is performed by
Gaussian Mixture Modeling (GMM) with three components such as lung parenchyma, nodule, and chest wall or vessels.
Third, the attached chest wall and vessels are separated from the GGO nodules by maximum curvature points linking and
morphological erosion with adaptive circular mask. Fourth, initial boundary of GGO nodule is refined using local
contrast information. Experimental results show that attached neighbor structures are well separated from GGO nodules
while missed GGO region is refined. The proposed segmentation method can be used for measurement of the growth rate
of nodule and the proportion of solid portion inside nodule.
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