Abstract: To acquire the images around an elongated object, the direction of this object is identified. To this end, in a first image, a point constituting an image of a locus of the object is designated and localized. The image of the epipolar straight line that connects the focal spot of the X-ray tube to the localized point is plotted in the second image. In this image of the epipolar straight line, a point homologous to the point in the first image is designated and localized. From the localizations of these points, the position in space of the characteristic point is deduced. This operation is reiterated for a second characteristic locus. The orientation of the object is deduced from these two characteristic loci. The position of the imaging device is then set accordingly.

Abstract: A phantom constituted by a helix is used. This helix enables an automatic geometrical calibration of any X-ray imaging system that uses a plane detector.

Abstract: In voludensitometry and in cases in which it is necessary to acquire only a small number of views, the artifact ratio resulting from reconstructions is reduced. There is acquired at least one view of the object to be reconstructed, the principal direction of irradiation of which is oriented substantially at right angles to a plane formed by or containing the other directions of irradiation corresponding to the other views.

Abstract: In order to reconstruct the structure of a body by way of iterative algorithms, the first iterations are carried out with lower resolution in order to limit the number of calculations. The image can then be reconstructed when the calculation time is reduced to one-third or even one-quarter. The image thus reconstructed is of better quality than images reconstructed using only a single resolution.

Abstract: In order to carry out a three-dimensional reconstruction of an object acquired by a series of conical projections on a two-dimensional multidetector, the object is estimated by a sampled function. The sampled function is projected and the projections of the sampled function are compared with the measurements resulting from acquisition on the 2D multidetector. A new estimation of the object is deduced therefrom and these operations are repeated until the comparison is satisfactory. In order to project, the sampled three-dimensional object is decomposed on a space of Gaussian basis functions. The contribution of the basis functions is computed for each image of the projection images, these contributions being equal to the integral of the product of the basis functions and of a support for illumination of the image element.

Abstract: In order to represent the bone structure of a patient's body, acquisitions are made with different irradiation energies. The irradiations are compared with these two energies in order to deduce a two-dimensional projected image which is representative of the bone structure alone. To this end, there is assigned to each pixel in the projected images a value corresponding to the thickness of bone traversed by an x-ray which has terminated at said pixel. This value is obtained by calibrating the measuring system, detector cell by detector cell, so as to correct the spatial non-uniformities of the acquisition system.