A method for segmenting bronchial trees from 3D chest X-ray CT images

This paper presents a new method for extracting bronchus regions from 3D chest X-ray CT images based on structural features of the bronchus. This method enhances bronchial walls by applying a sharpening operation and segments each bronchial branch by recognizing the tree structure starting from the trachea. During the extraction process, the volumes of interest (VOI) which contains a bronchial branch currently being processed are defined. Region growing is performed only inside a VOI so that a bronchial branch is extracted by a suitable threshold value. The final bronchus region is obtained by unifying the extracted branches. The tree structure of the bronchus is also extracted simultaneously. The proposed method was applied to three cases of 3D chest X-ray CT images. The experimental results showed that the method significantly improved extraction accuracy. About 82% branches are extracted for 4th-order bronchi, 49% for 5th-order bronchi, and 20% for 6th-order bronchi, compared to 45%, 16%, and 3% by the previous method using the region growing method with a constant threshold value.