关键词: 阈值处理, 形态学重构, CT血管造影（CTA）, 肋骨和脊椎骨分割

Abstract: The segmentation of the spines and ribs is an important preprocessing work in the segmentation of liver from liver CTA images.Usually thresholding is chosen，but this method will result in integrant or over-segmentation.To solve this problem，the paper proposes a method combining regional anatomy with threshold to remove the spine and ribs.Based on the basic theory of regional anatomy，the method first builds four border characteristics lines，and then removes the spine and ribs through binary morphological reconstruction.The proposed method not only adapts to different images of the spine and ribs with different gray values，but also eliminates the impact of adjacent tissues with the similar gray scale.The experimental results show that the proposed method can segment the spines and ribs from liver CTA images efficiently and accurately.

Key words: thresholding, morphological reconstruction, Computed Tomography Angiography（CTA）, spines and ribs segmentation