4 - Reconstruction d'objets binaires à partir de deux projections orthogonales par une technique inspirée de la théorie des graphes : la recherche du flot maximum à coût minimum

In this article we introduce a three dimensional reconstruction algorithm from tw o mutually orthogonal X-ray projections . The three dimensional reconstruction i s based on a series of parallel slices . These parallel slices are supposed binary. They are reconstructed with the help of their definite density curves on Xray radiographies. However the available information on radiographies is no t complete . We propose to use as a priori information a model to reconstruct curve s of density and to decrease the ambiguity during the reconstruction of the objects. The reconstruction is processed through several steps : the initial positioning of the model, the reconstitution of the density curves, the object's slices reconstructio n from their density curves . The reconstruction uses a maximum flow of minimum cost algorithm derived from the graphs theory and a model of the object's slices . For this reconstruction w e propose a new algorithm for the research of the maximum flows with a minimum cost, and as models the skeleton of the surface to reconstruct . Rates of conformability, obtained between the surface to reconstruct and the resul t surface ofthe reconstruction, are greater than 95% . We present the results obtaine d for elements of differents typical shapes in the case of unnoisy and noisy densit y curves, and the application of the reconstruction process to the the jaw elements .