Abstract: An image reconstruction system and method based on image projection data collected by an imaging system having N tubes of response (TORs) having N? axial translation symmetries and N? in-plane rotation symmetries between the TORs. A system matrix mapping image projection data to pixels of an image is used, where the pixels are positioned according to a polar or cylindrical coordinate grid. During image reconstruction, matrix-vector computations are performed between the system matrix and vectors containing image estimates or image projection estimates. The matrix-vector computations are accelerated by structuring the system matrix coefficients, image vectors, and projection measurement vectors in such a way that symmetric data is stored in contiguous memory locations.

Abstract: An image reconstruction system and method based on image projection data collected by an imaging system having N tubes of response (TORs) having N? axial translation symmetries and N? in-plane rotation symmetries between the TORs. A system matrix mapping image projection data to pixels of an image is used, where the pixels are positioned according to a polar or cylindrical coordinate grid. During image reconstruction, matrix-vector computations are performed between the system matrix and vectors containing image estimates or image projection estimates. The matrix-vector computations are accelerated by structuring the system matrix coefficients, image vectors, and projection measurement vectors in such a way that symmetric data is stored in contiguous memory locations.

Abstract: A rotary contactor, comprising two coaxial parts which are mounted for movement in rotation of one with respect to the other against a flexible tape (8) providing electrical connection and wound between the said parts (2, 7) by being attached at one of its ends to one of the said parts and at its other end to the other said part, in which one of the said parts (2, 7) comprises a rotatable hub (2) and the other part a fixed hollow housing (7), in the interior of which the hub (2) is mounted, the said contactor including, firstly, a rotor (5) mounted for rotation in the housing (7), and secondly, an epicyclic gear train (40, 4, 20) carried by the housing (7) and by the hub (2) and the rotor (5), for driving the rotor (5) in rotation through the hub (2) and for reducing the number of turns between the hub (2) and the housing (7), the rotor (5) carrying, for rotation on the rotor, a pinion (4) adapted to mesh with a set of teeth (40) formed in the interior of the housing (7) and a set of teeth formed on the hub (