Analyzing the 3D shape and respiratory motion of the ribs using chest X-ray images

This paper presents a new method for analyzing the 3D shape and respiratory motion of the ribs using 2D X-ray images. Each rib is represented as a curve, and its control points are estimated by a cubic B-spline curve iteration algorithm. In order to recover the 3D motion and the control points of the ribs from these 2D control points, a factor decomposition algorithm for projective structure and motion has been developed. A measurement matrix is generated based on the corresponding control points of each curve. By using these control points rather than all points on the curve, the data capacity and computational times are reduced. Furthermore, the precision of matching pairs of ribs in multiple images is improved. Estimation errors arise not only from the 2D control point approximation but also from the computation of the 3D control points. Experiments with X-ray images have been conducted and the effectiveness of the proposed technique has been confirmed by obtaining results with acceptable errors. This approach may prove useful for the evaluation of chest expansion in the assessment of pulmonary disease. (author)