Abstract: A high frequency antenna is provided for an apparatus measuring nuclear magnetic resonance, of the type whose radiating means comprise conductors forming high frequency resonators with a metal casing. They are frequency tuned by adjustment capacitors situated at their ends. For simplifying the frequency tuning of two paired resonators through which flow currents in phase opposition, it is proposed to join together galvanically two ends of these two resonators by a high frequency line section whose length is substantially equal to half the wave length of the energization wave to be emitted. The frequency matching of the antenna may be made by adjusting simultaneously all the adjustment capacitors by means of a common control knob. Coupling of the energization energy is provided magnetically in the middle of this high frequency line section.

Abstract: A structure is provided for connection between Bitter coils in a magnet with homogeneous field. The magnet is formed of several Bitter coils joined side by side and whose disks are of different thicknesses and two adjacent coils are connected together by a transition disk forming a turn and having for example a set-back on each of its faces for adapting it to the different thicknesses of the disks of two coils.

Abstract: An equipped forced-convection housing unit for a rotating-anode X-ray tube comprises a flow-initiating device which is integrated in the housing unit and has the function of circulating the coolant fluid surrounding the X-ray tube. This arrangement simplifies the problems relating to supply of electric power to the motor which drives the flow-initiating device and the motor which drives the anode of the X-ray tube in rotation.

Abstract: The present invention concerns an X-ray examination apparatus allowing to produce images of an object through the scanning of the object by at least two fan-shaped beams having different energy spectra, and obtained from a single X-ray source, thereby allowing to obtain simultaneously images of the object adapted to contain different informations.

Abstract: The invention relates to a supply circuit for an X-ray emitter usable in radiology. The circuit has a transformer, whereof the primary is connected to the three-phase power supply and whereof the secondary is connected to the X-ray emitter. The primary circuit is put into operation by the closing of a controlled switch. This switch has a set of closing thyristors. The switch also has a correctly charged capacitor connectable to the set of thyristors. For opening the circuit, the capacitor is connected in such a way that it supplies a reverse current to the thyristors of the set of thyristors. Thus the capacitor is recharged with the reverse polarity. During a following closing - opening sequence of the switch, the terminals of the capacitor are connected to the set of thyristors by switching their connection. In this way, the capacitor is always correctly connected for fulfilling its function during the blocking of the thyristors.

Abstract: The method and the device provides for the automatic processing of digitalized signals in order toremove speckle from the said signals by comparing the digitalized signal with a noise model obtained after learning its statistical properties,extract, from the signals, echos not characteristic of the contour of the organ to be displayed,extract the characteristic parameters of the contour from the said signals,calculate the contour from these parameters by likening them to a pre-established model of variable parameters,combine the digitalized signal, before or after eliminating noise, with the signal that is characteristic of the estimated position of the contour,display the resultant signal in which the contour appears as an overlay.

Abstract: The invention provides a method and device for forming images by nuclear magnetic resonance in which an image is constructed by discrimination of the intrinsic parameters of the tissues examined. The image is formed by putting forward the degrees of attachment and mobility of the nuclei of the tissues. The parameters displayed represent the field heterogeneities at the microscopic and molecular levels. The method consists in acquiring a first image using conventional methods then, after slightly varying the orientater magnetic field, in acquiring another image using the same methods. Then an image of another type is formed by representing the relative variations of the relaxation times between this first and this second image.

Abstract: A gradient coil is provided for a nuclear magnetic resonance image forming apparatus, the gradient coil being formed of four identical arrangements symmetrical with respect to the centre of a predetermined examination space. These arrangements comprise conductors formed in the shape of a saddle. In a particular embodiment for each arrangement two groups of conductors are provided. They may moreover be superimposed. In the invention, the conductors are flat conductors. Preferably their section is rectangular, the large side being greater than or equal to two and a half times the small side. The choice of flat conductors reduces the self-inductance of the system thus constructed. Finally, it is the necessary driving power which is reduced for establishing a field gradient. The temperature behavior of the whole of the apparatus is improved thereby.

Abstract: An assembly consisting of a high-voltage generator and an X-ray device comprises a shield housing containing an X-ray tube supplied with high voltage by a high-voltage generator. The high-voltage generator comprises a step-up transformer which is located outside the shield housing and supplies a voltage-multiplier device mounted within the housing.

Abstract: The invention relates to a process for the production of a multidetector with ionization chambers and to the multidetector obtained by this process. The partitions of the ionization chambers of the multidetector are maintained with respect to one another and transported together by means of a tool above a bath of resin to be polymerized. Following the hardening of the resin, the detector has resin bases. For containing the resin bath, the invention provides for the production of a mould cut in a solid resin block, which permits handling throughout the process without any risk of deterioration.

Abstract: An examination table for linear guidance of an examination panel in which the panel is guided by means of longitudinal members rigidly fixed to the panel and formed of the same material in order to obtain a small variation in absorption capacity for ionizing radiation.

Abstract: Ultrasonic sensor and echograph with static sectorial scanning, especially for a wide angle picture, wherein according to a possible embodiment, the sensor comprises several groups of transducer elements forming between one another obtuse angles in such a way as to define overall a convex outline so that the delays or lags necessary to obtain a complete scanning be lower than with a conventional linear strip and thus easier to contol, the sensor being intended to be applied to medical echography.

Abstract: In a tomodensitometric image reconstruction process the detectors 11 of the tomodensitometer are offset by .DELTA.d/4 (.DELTA.d being the pitch of the detectors), and reconstruction is performed during one complete revolution of the detector assembly, the linear absorption values being weighed by a coefficient .alpha. and an equivalent number of intermediary values being produced by summing each time two successive juxtaposed real values (summation device 20) and weighing the resulting sum by a coefficient .beta./2 prior reconstructing the image on the basis of all these data.

Abstract: The present invention relates to a process for modulating the effect of the speed of the moving parts of a body. The machines or processes for measuring the density by nuclear magnetic resonance are too sensitive at the displacement speed of the parts in question. In the invention, the sensitivity of the machines or processes is reduced in such a way that the speed effect can be measured. Prior to the measurement, compensating magnetic field sequences are applied in order to counteract the effect produced by the interfering magnetic field sequences, which are necessary for performing the measurement.

Abstract: The invention provides a device for creating an excitation field in an apparatus using nuclear magnetic resonance. The structure for creating this field comprises a number of conductors spaced evenly apart at the periphery of a circular cylinder. What characterizes the invention is that, for producing a homogeneous field inside this cylinder, it is sufficient to cause a current to flow through these conductors whose intensity is proportional to the cosine of the angle which locates this conductor with respect to a reference axis system.

Abstract: The invention concerns a power modulator provided with a transformer. This transformer having a high transformation ratio receives a low voltage impulse and transforms it into a high voltage impulse directly applicable on a high frequency or hyperfrequency tube in order to create a powerful impulse magnetic field. The transformer is particularized by the realization of its primary composed of a plurality of primary windings, all of which are connected in parallel and which, put end to end, extend along the entire lengths of the secondary. They are wound furthermore around the secondary and not inside it.

Abstract: A method for reconstructing a high resolution image by interpolating intermediate values obtained from data collected over a complete revolution of the tomodensitometer. A shift of ##EQU1## is provided between the middle of the multi detector and the straight line joining the focal point of the X rays and the center of rotation and the views V.sub.i collected over a complete revolution are completed from "views" V'.sub.i resulting from a transformation:T(.theta.,.gamma.))(.theta.+(2k-1).pi.,-.gamma.),the intermediate values s.sub.i being obtained by linear interpolation from samples of the views V'.sub.i of the same ordinate .gamma., in the space [.theta.,.gamma.] and situated on each side thereof respectively.

Abstract: A d.c. voltage is produced from a single-phase electric mains for supplying an X-ray tube. This supply is pulsed under the control of a synchronizing circuit with which it is further possible to adjust the duration of the operating pulses, as well as their phase blocking with respect to the mains. By acting in this way excessive current is not taken during the voltage troughs between two successive half-waves. The losses by the Joule effect in the mains are reduced and the quality of the pulsed high voltage is improved because of the increased stability. There is only a slight increase in the exposure time.

Abstract: The present invention concerns a process for removing all ambiguity from the measurement by the Doppler effect of the speed of a target. It consists in obtaining a signal of Doppler shift relating to a series of ultrasonic pulses sent in the direction of the target and received after their reflection onto this target, the recurrence frequency of the pulses constituting an ambiguity limit of these speed measurements, wherein the measured Doppler shift is transposed by modulating the signal received by a signal at a frequency called determination frequency, so as to bring from a known value the spectral components to be analyzed in the useful measuring band and after measuring the true speed values are worked out by adjunction of a correction that depends upon the determination frequency that is used, this process being applicable to measuring the speed of blood in the medical field.

Abstract: The invention relates to an X-ray apparatus with focus position control, the focus being formed on the anode of an X-ray tube with magnetic bearings. The X-ray apparatus comprises a focus position sensing device cooperating with electronic means associated with the magnetic bearings, in order to control the position of the focus by displacing a rotor under the action of the magnetic bearings.