3D reconstruction method from biplanar radiography using non-stereocorresponding points and elastic deformable meshes

Standard 3D reconstruction of bones using stereoradiography is limited by t he number of anatomical landmarks visible in more than one projection. The proposed technique enables the 3D reconstruction of additional landmarks th at can be identified in only one of the radiographs. The principle of this method is the deformation of an elastic object that respects stereocorrespo nding and non-stereocorresponding observations available in different proje ctions. This technique is based on the principle that any non-stereocorresp onding point belongs to a line joining the X-ray source and the projection of the point in one view. The aim is to determine the 3D position of these points on their line of projection when submitted to geometrical and topolo gical constraints. This technique is used to obtain the 3D geometry of 18 c adaveric upper cervical vertebrae. The reconstructed geometry obtained is c ompared with direct measurements using a magnetic digitiser. The order of p recision determined with the point-to-surface distance between the reconstr uction obtained with that technique and reference measurements is about 1 m m, depending on the vertebrae studied. Comparison results indicate that the obtained reconstruction is close to the actual vertebral geometry. This me thod can therefore be proposed to obtain the 3D geometry of vertebrae.