Abstract: The process comprises a calibration of the apparatus, in which a virtual volume surrounding the object is generated and broken down into voxels, an acquisition of the set of numbered projected two-dimensional images, and a reconstruction of the three-dimensional image from the projected acquired two-dimensional images, and from an iterative algebraic image reconstruction algorithm. A first iteration of the algorithm is performed with a predetermined initial image resolution so as to obtain, at the end of this first iteration, first density values for the voxels of the volume, at least one part of the voxels of the virtual volume is subdivided into several sets, respectively, corresponding to different image resolutions that are multiples or sub-multiples of the initial resolution, and during each subsequent iteration of the algorithm, the algorithm is successively aplied to each of the sets of voxels.

Abstract: Method of controlling of a radiology device, of the type comprising a means of emission of an X-ray beam and a means of reception of the X-ray beam, after it has crossed a part of the object's body, in which a three-dimensional image of a part of the object's body is reconstructed from a series of two-dimensional films, two-dimensional views of the three-dimensional image are produced at different angles of incidence, the angle of incidence allowing the best visualization of the part of the object's body are selected, the angles of incidence are stored in memory, and the angles of incidence are supplied to the radiology device for its positioning with a view to an intervention or procedure on the part of the object's body under fluoroscopy allowing a visualization in real time of two-dimensional.

Abstract: A set of digital two-dimensional projected images of an object is acquired for different positions of a camera rotating around an object. The projected images are calibrated into a volume containing the object and divided into voxels, the space coordinates of which are identified in a chosen calibration frame of reference. A pretreatment is applied on each acquired image in order to elaborate a rectified image having a predetermined spatial orientation selected as a function of a chosen specific axis of the calibration frame of reference, and an iterative algorithm of algebraic image reconstruction between each rectified image and the set of voxels is applied by successively treating the voxels in a predetermined order linked to the choice of said specific axis, which makes it possible to minimize the duration of reconstruction of the three-dimensional image.

Abstract: Device and process for simulating a patient's body for the testing of a three-dimensional vascular X-ray apparatus of the type comprising a means for emitting an X-ray beam, a means for receiving the X-ray beam, a means for displaying the images obtained, and a means for controlling the injection of opacifying liquid into the patient's vessels. The simulation device comprises a stationary part for simulating the patient's bones and soft tissues and a moving part for simulating the patient's opacified blood vessels, so as to be able to perform at least one acquisition of an image of the stationary part alone and at least one acquisition of an image of the stationary part and the moving part, and to obtain an image of the moving part by means of image.

Abstract: Device for simulating a patient's body for the testing of a vascular X-ray apparatus of the type comprising a means for emitting an X-ray beam, and a means for receiving the X-ray beam after it has passed through a part of the patient's body, the X-ray beam being centered on an axis. The device comprises at least one metal wire disposed at least partially transversely relative.

Abstract: The radiology instrument contains a source emitting X-radiation, a radiological image receiver, a chassis arranged between the X-ray source and the image receiver in order to accommodate an object to be radiographed, and a positioning and guiding device which can be connected to the chassis and can intercept the X-radiation so as to position and guide probes intended to interact with the object. The positioning and guiding device has first means forming a retractable guide grid having holes whose respective axes converge towards the focal point of the source when the first means intercept the conical radiation, and a retractable positioning grid with holes.

Abstract: A filter having compensating plates, each having a first plate element which can be moved translationally with respect to a frame and a second plate element which can be moved relative to the first plate element so that, when the plates are in an active position, the thickness of absorbent material through which the X-ray beam passes is constant.

Abstract: A light box for X-rays is made by using a graphics screen (20) coupled to a microprocessor (23), with the screen being used with inverse brightness. Under these conditions, the graphics screen emits light at nearly all points, other than special locations (I.sup.25) whose positions can be controlled by means of a control box (24). An X-ray negative (6) to be examined is placed over the graphics screen. The control box is used to move the non-illuminated regions of the screen to point to special locations in the negative. The light box is particularly applicable t studying stereographic negatives for mammography. It makes it possible to determine more quickly and more accurately the locations of lesions in breasts under examination.

Abstract: Disclosed is a radiology system of the mammograph type in which there is provision for a radiation controller. The invention lies in the fact that the input aperture of the detector is masked by a belt that absorbs the X-radiation except at zones, the variable dimensions of which are designed to get adapted to the different shapes of breasts. The belt is driven by a motor 24 and stops at the practitioner's command so that the appropriate zone is in correspondence with the input aperture of the detector 22.

Abstract: Disclosed is a radiology system of the mammography type wherein there is provision for a radiation controller having a detector of X-radiation having gone through the breast to be observed, of the type having a converter of X-radiation into photon radiation and a photomultiplier tube for the amplifications of photons emitted by the converter. The invention lies in the fact that the converter is masked by a belt opaque to the photon radiation except in the zones for which variable dimensions are planned so as to get adapted to the different shapes of breasts. The belt is driven by a motor which is turned on and off at the practitioner's command, so that the appropriate zone is in correspondence with the converter.

Abstract: In order to solve handling problems which arise during use of a mammograph, the x-ray tube of the mammograph is carried by the end of an arm which rotates about an axis at right angles to the arm. The other elements of the mammograph are carried by another arm which is placed in a plane parallel to the plane of rotation of the first arm and rotates about the same axis. It is shown that, by moving the image receiver away from the breast support plate and by utilizing a parallax effect, it is possible to take stereotaxic photographs without entailing any need to displace either the breast support plate or the image receiver or even a radiation-sensitive film placed in a stationary position within the image receiver.

Abstract: The present invention relates to optical memories for storing data on the surface of an information-supporting medium including pre-formatted patterns. Such a memory may constitute a random access mass memory, and it may be read/write memory or it may be a write-once memory. The operations of writing to the memory and reading from the memory are based on the optical interaction which occurs at the point of impact of an incident optical beam which causes local changes in optical characteristics which are representative of the data when data is being written, and which produce optical modulation detectable by photoelectric means during data reading. The invention provides an optical memory in which the illumination mode common to reading data and to detecting pre-formatting patterns is modified in order to allow for operation in a standby mode or in order to delete areas reserved for storing data, for example.

Abstract: The invention relates to optical memories making use of optical interaction between an incident ray and an information medium (83) capable of having data written thereon and of having data read therefrom, which data is organized in a adjacent track elements which are marked by prerecorded patterns. The invention provides an information medium (83) and a reader device therefor (84, 85, 86, 87, 88) including means (89, 91, 92, 93, 94) for sampled tracking of the track elements on the basis of patterns which are offset from the track scan line, said patterns forming discontinuous periodic wave sequences whose offset edges are symmetrically disposed about the middle of the inter-track gap. The invention is particularly applicable to optical memories using a preformated disk capable of recording, of being read, and where appropriate of being erased, with data in digital form.

Abstract: An optical recording disk comprises a track divided into sectors and having a longitudinal axis. Areas on this track for writing data using a predetermined increment alternate with prewritten marker areas. Each of these comprises at least two patterns having leading and trailing edges. Part of at least one of these patterns is offcenter relative to the track axis and associated with at least one edge of a pair of leading and trailing edges combined with another pair of leading and trailing edges to define along the axis two predetermined distances. Each of these distances is between two consecutive multiples of the data writing increment. The patterns are adapted to be scanned optically in succession by a read spot to detect any track following error, by virtue of interaction of the read spot with at least the offcenter pattern part, and with reference to a timebase synchronization signal resulting from interaction of the read spot with at least two leading edges and at least two trailing edges.

Abstract: The invention relates to the reshaping of a read signal in such a manner as to compensate for possible distortions, in particular of its cyclic ratio. During a time interval selected by a control device as as function of synchronizing data present on the disc, the synchronizing information is integrated by means of an integrator. The voltage threshold obtained is compared with the data read by means of a comparator circuit. The result of the comparison gives rise to a signal of rectangular form. This signal may usefully serve the purpose of adjusting the phase of the read system. The device may be utilized in particular in a device for rephasing the clock emitting the read pulses.

Abstract: The device according to the invention realize the following steps:(a) recording of binary test words on an optical disc associated to distinct engraving optical powers and comprising monotonous series of "1" and "0" logic bits of equal duration;(b) reading of these words;(c) measurement of the durations of these bits in the "1" state and bits in the "0" state,(d) determination of the optical power for which this ratio is closest to one;(d) elaboration and putting in memory of a control signal allowing to obtain this power.In a preferred variant, several test words are recorded and an interpolation is carried out between the measurements.

Abstract: The invention relates to optical reading of a track in a spiral or concentric circles, carried by an information substrate, usually a disc, television signals being recorded along the track. The reading device includes a device for generating track jump pulses in which bits written at the top of pairs of adjacent fields in order to determine whether the fields being read belongs or does not belong to the same frame so that jump control pulses are generated when the bits are found to be identical. The invention is of use inter alia for reading television signals recorded on video-disc and obtained by analyzing film frames particularly to bring about a stop at a frame by jumping a track, either when frames are analyzed in two tracks or in the case of analysis in the sequence 2, 3, 2, 3 etc. . . .

Abstract: A digital process for controlling the correct reproduction of a composite television signal and in particular of a composite color television signal comprising sequential-type chrominance signals, transmitted or recorded on an information-carrying medium such as a videodisk in which binary-coded pulsed signals are inserted during available intervals of the line scanning return, the binary value of these pulsed signals representing a particular state to be controlled. This value is detected during the process reproducing the composite television signals to make the particular state to be controlled dependent on this value. A first coded pulsed signal may be used for identifying the two components of the chrominance signals. A second coded pulsed signal may be used for identifying the face read of a transparent videodisk having information recorded on both its faces.

Abstract: In a system for broadcasting audio-visual television signals, a pure-frequency pilot signal is recorded concurrently with the video signals. The synchronizing signals which are necessary for reproduction of the aduio-visual signals are reconstituted from the pilot signal during the reading process.

Abstract: Process for coding binary image numbering signals to be stored on a recording medium and device for reading these signals. The process aims at protecting these signals from variations encountered during the transcription process onto a recording medium. This protection is obtained by selective inversion and repetition of predetermined parts of the binary signals.Application more specifically to an audio visual signal transmission apparatus incorporating a track jump pulse generating system, the images and the binary numbering signals of these images being recorded on a video disk.