Automatic Rib Detection in Chest Radiographs

This paper presents an overview of an algorithm for rib detection in chest x-rays. The goal of the algorithm is to return the location of the borders of the ribs to a screening system to enable intercostal spaces to be extracted and analysed. The detection of objects in pictures can usually be separated into two steps: image enhancement and feature extraction. The amount of computation required by our algorithm is minimized by processing only that information which is required to achieve the goal of the algorithm, and by using knowledge of the structure of the rib cage to guide the extraction of the rib borders. In particular, significant reduction in computation is achieved by avoiding the enhancement of the entire picture. In addition, not all points in the image need be considered as possible rib border points, nor do all points on each rib border need be detected. The rib borders are returned to the screening system as second degree polynomials. Results or testing the algorithm for a set of chest radiographs are illustrated by superimposing the detected rib borders onto the X-ray images.