Abstract: To make a gradient coil, it is decided to cut the conductors of this coil out of a plate. Thus flat conductors can be used. This helps reduce the self-inductance of the coil to be made. The coil is, moreover, optimized. A calculation is made of the coefficients of the breakdown into spherical harmonics of the field created by the coil. The coil's structure is modified so as to cancel those coefficients of this breakdown which generate a divergence in this field. It is shown that, in this way, the solution is an optimum one.

Abstract: The apparatus comprises an X-ray source (6) to generate a beam of radiations (7) through an object (4) or the body of a patient to be examined and a multichannel detector (8) to provide information concerning the intensity of the radiation retransmitted by the object examined. Both the source and detector are mounted on a rotor (2) integral with the stator (1) which surrounds the object (4) examined. It also comprises at least one lateral diffusion light guide (14, 15) wound round the rotor (2) or on the internal surface of the stator (1) to transmit optically between optical receiver and emitter means (9, 10) of the rotor (2) and corresponding optical means (16, 17) of the stator (1), the information provided by the multichannel detector (8) and the control information of the X-ray source (6).

Abstract: Radiology installation comprising a set of instruments between which there is a flow of data signals. For the transmission of these signals, the installation comprises at least two loops between which the data can flow. Each loop is capable of transmitting data which does not flow through another loop. Preferably, there is a main loop and secondary or specialized loops.

Abstract: The apparatus comprises an X-ray source (6) to generate a beam of radiations (7) through an object (4) or the body of a patient to be examined and a multichannel detector (8) to provide information concerning the intensity of the radiation retransmitted by the object examined. Both the source and the detector are mounted on a rotor (2) integral with the stator (1) which surrounds the object (4) examined. It also comprises at least one lateral diffusion light guide (14, 15) wound round the rotor (2) or on the internal surface of the stator (1) to transmit optically between optical receiver and emitter means (9, 10) of the rotor (2) and corresponding optical means (16, 17) of the stator (1), the information provided by the multichannel detector (8) and the control information of the X-ray source (6).

Abstract: A device and method are provided for adjusting a radiofrequency antenna of a nuclear magnetic resonance apparatus. In the invention, using capacities preset in the factory, the antenna detuning of an NMR apparatus is limited to a range such that the standing wave rate of a high frequency line which conveys the radiofrequency signal is limited. This line is cut and, at a short distance, a tuning adjustment circuit is inserted. This circuit may be automated: the electric adjustment motors, thus spaced away, do not disturb the magnetic fields of the apparatus. By measuring the real part of the admittance at the input of the adjustment circuit and the phase shift between voltage and current this circuit can be adjusted.

Abstract: To compress the values of the pixels of a digitalized image, the values of the pixels neighboring the pixel to be processed are memorized and, according to their respective values, a code number is produced leading to the encoding process according to a composed code or to the encoding of the pixel itself, with a prefix. The successive codes are formatted and concatenated to be memorized.

Abstract: A sealing device for an enclosure containing an expandable fluid, particularly for high-voltage connectors, ensures fluid-tightness over a broad temperature range and provides a safety function by accommodating variations in volume of the fluid by the use of an O-ring seal displaceably clamped within an annular recess. A sectional length L1 of the recess in which the seal can take up n positions is constituted by an initial-clamping space and by a clearance space into which the seal can penetrate under the pressure of fluid.

Abstract: A method of measuring the strength of a DC current and a device for implementing this method are provided, forming an NMR shunt for measuring high currents. A magnetic coil is placed in series in the circuit in which the current to be measured flows, the temperature of the magnet is stabilized and the magnetic field is measured in the center of the magnet using an NMR probe.

Abstract: A system is provided for regulating the field of a high homogeneity magnet. The fluid used for cooling the main magnet is placed in thermal contact with a high homogeneity auxiliary magnet in which is placed an NMR probe which controls the current supply to the two magnets connected in series.

Abstract: The diaphragm comprises at least one chamber in which there flows a deformable material that attenuates the radiation beam, the chamber being shaped so that the attenuating material can be introduced from outside the chamber and so that it can surround the passage zone of the beam inside the chamber in such a way that the surface of the passage zone varies constantly with the volume of the material present in the chamber.

Abstract: In a method for interactive adjustment of the parameters of a gray-scale window in a system for reproduction of a digitized image such as an x-ray image, one of the parameters designated as the mean-level parameter is modified at the instant of each elementary control action by a computed value of the other parameter designated as the width parameter.

Abstract: To make a gradient coil, it is decided to cut the conductors of this coil out of a plate. Thus flat conductors can be used. This helps reduce the self-inductance of the coil to be made. The coil is, moreover, optimized. A calculation is made of the coefficients of the breakdown into spherical harmonics of the field created by the coil. The coil's structure is modified so as to cancel those coefficients of this breakdown which generate a divergence in this field. It is shown that, in this way, the solution is an optimum one.

Abstract: An imaging installation, especially for digital type radiology, comprises a pick-up tube television camera with no remanence or low remanence with a non-linear element producing a remanence of the image signal given by the camera. The remanence varies with the level of the signal. When a recursive filter is used to obtain this remanence which is variable with the signal level, the modulation f.sub.2, introduced by the modulator connected to the output of this filter by a frames memory, is defined by the function: f.sub.2 (x)=x[.lambda.(1-g(x))+.mu.g(x)],a formula in which x is the ratio between the signal applied at the input of this modulator and the maximum value of the input signal, .lambda. and .mu. are constants, and g (x) is a linear function of x meeting the conditions: g (0) and g (1)=1.

Abstract: A method is provided for bridging between disjointed contour elements in an image by searching for an optimum bridging path between the facing ends of disjointed contour elements in the image. The method of the steps of defining a search window between each of the facing ends of the disjointed controur elements, considering in the window the different image points as nodes on a graph, determining an elementary cost associated with each path connecting each node to its neighboring nodes from amplitude and/or orientation data of the luminance function used for detecting the contours and in determining the optimum path by following, from the costs obtained, a line for which the luminance gradient of the detected points appears to be a maximum.

Abstract: A device and method are provided for adjusting a radiofrequency antenna of a nuclear magnetic resonance apparatus. In the invention, using capacities preset in the factory, the antenna detuning of an NMR apparatus is limited to a range such that the standing wave rate of a high frequency line which conveys the radiofrequency signal is limited. This line is cut and, at a short distance, a tuning adjustment circuit is inserted. This circuit may be automated: the electric adjustment motors, thus spaced away, do not disturb the magnetic fields of the apparatus. By measuring the real part of the admittance at the input of the adjustment circuit and the phase shift between voltage and current this circuit can be adjusted.

Abstract: A block of magnetized material for adjusting and correcting a magnetic field produced by a magnet provides adjustable correction by modifying the orientation of the magnetic moment of the block with respect to the field. A device which includes an intermediate member rotatably mounted in an orientable support and a fixing member rotatably mounted in the intermediate member makes it possible to orient a preferred direction of the block in a predetermined direction. This results in modification of magnetic disturbances produced by the block in the zone of interest of the magnet. Quantization of pointing of the orientable support is obtained by means of graduated index marks on the support, on the intermeidate member and on the fixing member.

Abstract: Digital imaging system wherein a digital value is assigned to each point or zone of the image, and this value is transformed in such a way that only a range or window of values representing luminances for a display device is selected. Control means are provided to modify the two parameters which characterize the window in the transforming device.Since the system is designed to form images of one and the same category, for example X-rays of blood vessels, a pre-determined relationship is established between the two characteristic parameters of the window so that this window can be modified by actuating a single setting element.

Abstract: A device is provided for exploring the inner volume of a cylinder, including a probe holder driven with a translational movement by a shaft and with a pivoting movement by a mandrel along and about the axis of the cylinder. By placing probes in housings previously formed in the probe holder, all the points inside the cylinder may be reached. The operations are carried out from inside the cylinder. The device further includes apparatus for fixing and adjusting the position of a framework holding the shaft. Associated devices allow predetermined positions to be reached not only along the axis but also in angular orientation.

Abstract: In a high-voltage transformer of particularly small size comprising a magnetic circuit and a coil shell on which is wound a secondary winding consisting of one or a number of separate secondary coils, each secondary coil is contained within a channel closed by an insulating ring made up of two segments. The two ring segments are assembled around the channel in a movement performed in the same plane as that of the channel.

Abstract: The invention proposes an imaging process by nuclear magnetic resonance in which a calculated image is given corresponding to the molecular diffusion value at each point of an investigated medium. The diffusion image is obtained by comparing images relative to same sections of the medium and acquired during two excitation sequences, whereof one is not very sensitive to the diffusion and the other is particularly sensitive thereto. These two images undergo comparison in order to produce a diffusion image.