Automatic Reconstruction of 3 D

A method has been developed to reconstruct 3D surfaces from two orthogonal X-ray projections. A 3D geometrical prior model, composed of triangulated surfaces, is deformed according to contours segmented from projection images. The contours are segmented by a new method based on free-form deformation. First, virtual X-ray images of the prior model are constructed by simulating real X-ray imaging. Thereafter , the contours segmented from the virtual projections are elastically matched with patient data. Next, the produced 2D vectors are back-projected onto the surface of the prior model and the prior model is deformed using the back-projected vectors with shape-based interpolation. The accuracy of the method is validated by a data set containing 20 cases. The method is applied to reconstruct thorax and lung surfaces. The average matching error is about 1:2 voxels, corresponding to 5 mm.