Abstract: A very fast reconstruction is undertaken in an image reconstruction process by tomography, by dividing measurements through the subject into a series of subsequent sets that are inverted by back projections giving partial result blocks used to search for the change law for the subject. Partial contents of the image can then be predicted at a reference time and their accumulation gives the image. The law for how the subject changes with time is evaluated and is used to compensate for partial results before their accumulation.

Abstract: A very fast reconstruction is undertaken in an image reconstruction process by tomography, by dividing measurements through the subject into a series of subsequent sets that are inverted by back projections giving partial result blocks used to search for the change law for the subject. Partial contents of the image can then be predicted at a reference time and their accumulation gives the image. The law for how the subject changes with time is evaluated and is used to compensate for partial results before their accumulation.

Abstract: Sets of projections of measurements through an object (1) the image of which is to be represented, undergo Fourier transforms before being broken down into blocks according to cutoff frequencies. The blocks are separately reconstructed in order to form a series of thumbnail images of the object, which are then combined in order to reconstruct the final image. The reconstruction calculations on the thumbnail images are rapid and often a large portion of the blocks will be discarded, notably those which are at high frequencies, whereby their contribution may frequently be neglected as well as the noise effects which accumulate therein.

Abstract: The present invention consists of obtaining from a series of measurements or original images of varying precision of a mobile object, such as a beating heart, a sequence of restored images minimizing an error function comprising an adequation term between the restored images and the measurements, a space moving term of images to be restored and a time smoothing term of restored images, taking account of an evaluation of the movement of the object between the original image during the considered phase of the movement and the image of the object in a neighboring phase.

Abstract: Apparatus and process for obtaining three-dimensional images of an object by a planar array of detectors, whose focusing points are located on a circle. The advantage obtained is a wider detection field that in the case of focusing on a single point. Rules are given for using algorithms for inverting characteristic measurements of the conical focusing. Application to medicine and to non-destructive testing in industry.

Abstract: Tomographic process for the reconstruction of three-dimensional images of an object such as the heart or another organ on the basis of sets of measurements relative to a group of different states of the object. An approximate image of the object in each state (f) is reconstituted on the basis of associated measurements and the movements of said object from a reference state to each of the states are evaluated (D.sub.k). The estimation of the image of the object at the reference state (f.sub.0) is obtained by a convergence towards the real image by gradually incorporating in the estimated image information relative to the measurements and to the previously calculated movements of the object.

Abstract: A process provides a cartography of an emission of radiation by a body (2) that is corrected with respect to the attenuation of radiation by the body. A radiation transmissions source (3) is able to assume several positions with respect to the body and emits photons toward the body. The process includes: for each position of the radiation source, determining a transmission measurement (N) of the photons emitted by the radiation source and transmitted by the body and determining an emission measurement projection of the photons emitted by the body, the transmission measurement and the emission measurement projection being performed with the same geometry of the body. Determining, for each position of the radiation source, an attenuation correction coefficient C of radiation due to the body in order to correct the emission measurement projection (E6); and then constructing an emissions map (E2) on the basis of the attenuation-corrected, emission measurement projections.

Abstract: Process and installation making it possible to reconstitute precise images of an area of interest (2) of an object (1) by reducing the errors produced by the contribution of the compliment of the object. A first series of measurements is carried out, where a conical beam (10) only takes in the area of interest of the object (2) and this is followed by a second series of measurements in which the beam takes in the entire object. A combination of the measurements of the two series is carried out in order to make them compatible and obtain a more accurate image of the area of interest (2).

Abstract: Process for the reconstruction of three-dimensional images of an object. Several measurements are performed by displacing a bidimensional array of sensors, sensitive to a radiation passing through the object or coming from the object in at least two circular paths. The digital method for making it possible to synthesize the informations measured and in particular convert the informations obtained into reference frames linked with the paths in a random reference frame is given. Application to medical imaging or to non-destructive inspection.

Abstract: Process for the reconstruction of three-dimensional images of an object (3), in which the reconstruction is obtained by calculating sums of projections on planes extracted from a conical attenuation radiation traversing the object, or an emission from the object in accordance with a conical collimation. The bidimensional detector array (4) used for this purpose has a random inclination (.xi.) with respect to the rotation axis defining the mark in which the image is reconstructed as a result of a voluntary choice. Formulas are given making it possible to obtain a limited distortion reconstruction after measuring the displacement parameters of the array and the conical radiation beam. The position errors resulting from construction defects are also taken into account in the calculations after measurement. A parameter measurement protocol and the associated calculation process are also described.

Abstract: The present invention provides a method for generating three-dimensional images of an object having a network of points. One preferred embodiment of the present invention comprises using a moving two-dimensional sensor network array to take measurements, at successive discrete time intervals, of radiation emanating from the network of points. The sensors generate electrical signals representative of the object at the discrete time intervals, which impulses are used to generate a system of linear equations describing the object at these discrete time intervals. A change function function is generated to describe the object in between the discrete time intervals. Finally, electrical signals representative of a continuous description of the object are generated using the system of equations and the change function, which continuous description are used to generate three-dimensional images of the object.

Abstract: A process for reconstructing three-dimensional images of an object with the aid of measurements performed by bidimensional arrays of sensors on a succession of incidences around the object. There are at least two circular coaxial paths (2,2') on which the arrays (4,4') are displaced. Thus, it is possible either to accelerate the taking of images, or increase the volume of the measurements, or accelerate the calculation of the reconstructed image, through the use of a single reference frame in whose coordinates the sums of the measurements on each sensor are characterized. The process has particular application to medical imaging or to the non-destructive inspection of parts in emission or radiation attenuation tomography.

Abstract: The use of the derivative of the Radon transform is used for obtaining three dimensional images or reconstructions of the examined objects. The derivative provides a precise reconstruction of the image as opposed to the use of Radon transforms themselves. The device is particularly suited for three dimensional imaging and x-ray apparatus.