Abstract: The invention relates to high-voltage power supplies for X-ray tubes in radiological apparatuses. The invention lies in the fact that the secondary windings of the transformer, the capacitors, and the diodes of the rectifier and voltage-doubler circuits, are all disposed in an enclosure made from two half-shells, whereas the primary winding and the magnetic circuit are disposed outside the enclosure.

Abstract: Problems of thermal resistance both of the anode and of the cathode of an x-ray tube are solved by constructing a flat cathode which is set within a stair-step focusing device. It is shown that, depending on the shape of this device, the heat output on the anode is constant irrespective of the load on the x-ray tube.

Abstract: The formation of a NMR machine phantom having a homogeneous material serving for forming the image which is confined to precise positions. The precise positions are evenly distributed in the form of a matrix so that a particular image formation method may be used. The combination of the image formation method and the matrix distribution allows for obtaining information with respect to the field at numerous points and increases the speed at which these points are determined.

Abstract: The invention relates to detectors of ionizing radiation which use a photoconductor as the detecting element. The invention lies in an electrode moving in a direction OX through a photoconductive medium disposed between two grids of electrodes extending parallel to OX. During the irradiation time, the grid electrodes of one grid are raised to a positive potential relative to the electrodes of the other grid and electrons and positive ions are created in the photoconductor. The electrons are removed by maintaining the positive potential on the electrodes of said one grid for a period of time longer than the irradiation. During displacement of said moving electrode, only the positive ions give rise to current in the electrodes. The invention is applicable to radiotherapy and radiography.

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: Images representing one and the same scene, but acquired under conditions such taht the subject has moved, are automatically reset by making an automatic selection of a homogenous population of landmarks and by computing the shift vectors associated with these landmarks. It is shown that, in order to select the landmarks, it is worthwhile to characterize the image by a certain number of characteristic mangitudes representing the solidity of these landmarks. The solidity of the landmarks is the ability of a landmark to be the site of an exact measurement of shift for a required precision.

Abstract: The electric connection between the control circuits (13,14) of a probe and the metallized faces (5,6) of the piezoelectric elements (2) of said probe is provided by metallizations (6,8) made on parts, support (1) or blade (4) in contact with said metallized faces. The mechanical and electric connection between said metallizations may be provided by a thin layer of conducting glue (19,20).

Abstract: Problems of thermal resistance of the cathode of an x-ray tube are solved by constructing a flat cathode in the form of a hollow beam. This ensures rigidity of the cathode which is inherent in its beam shape without being attended by the disadvantages of excessive thermal inertia.

Abstract: In order to make a probe having a concave attack face, a continuous acoustic transition blade (5) is used. Said blade is metallized (7) and is common contact with all the front metallizations (6) of the piezoelectric elements of the probe. The rear metallizations (8) of the elements terminate electrically and independently backwards of the probe. As a result, the electric connection of the piezoelectric elements is simplified. Said probe is usable in experiments with ultrsounds where good focusing is desired.

Abstract: In order to compensate for the influence of magnetic fields on charged-particle beams, in particular in imaging devices provision is made for a coil constituted by a support plate of substantially constant thickness and by patterns deposited on the support in such a manner as to ensure that the absorption of electromagnetic energy is constant over the entire surface of the coil within a predetermined pass-band.In a first embodiment, the patterns are transparent to the electromagnetic energy of a desired frequency band. In a second embodiment, complementary patterns are employed in order to obtain constant absorption over the entire surface of the coil.

Abstract: Problems of thermal resistance of the anode of an x-ray tube are solved by constructing a flat cathode which is set within a stair-step focusing device. It is shown that, depending on the shape of this device, the heat output on the anode is limited by a saturation value which is lower than a limit of thermal resistance of the x-ray tube. In order to improve the thermal resistance of the cathode, a cathode is constructed in the form of a hollow beam. This ensures rigidity of the cathode which is inherent in its beam shape without being attended by the disadvantages of excessive thermal inertia.

Abstract: The invention relates to X-ray tubes, and more particularly to cathodes for such tubes. The invention lies in the cathode, which includes an electron-emitting filament (26), being made in the form of a main body (10) of insulating material having metal electrodes (16 and 19) deposited thereon which are insulated from one another by the main body. The filament (26) and the electrodes (16 to 19) are connected to conductors (27, 21 to 23) which pass through the main body.

Abstract: In a nuclear magnetic resonance imaging installation, monitors of the cathode tube type are shielded from the effect of an intense magnetic field. For this purpose, the installation according to the invention has a flat coil which creates a second magnetic field, the direction of which is opposite to that of the intense magnetic field.

Abstract: When making curved bar probes it is necessary, particularly at high frequency, to provide circuits for the connection of piezoelectric elements of the bars which are compatible with the curvature imposed to the bar after it has been fabricated flat. The invention overcomes such difficulty by adjoining on both sides of the elements a generally parallelepipedic relay metallized on at least two (12,13) of its adjacent faces to transpose one connection face (7) situated in plane which must be curved into one connection face (13) which is perpendicular and of which the orientation remains unchanged and parallel to a same plane during the curvature operation. As a result, the connection is simplified.

Abstract: Problems related to acquistion time with reconstructed image type tomographs are resolved by causing step by step rotations of the X-ray tube/multiple detector set of this tomograph and, at each step, by causing a translational movement of this set in order to scan the entire region to be examined of a body under examination. It is shown that, by using a multiple row multidetector, it is possible, at equal speeds, to improve the quality of the images produced or, at equal quality, to increase the acquisition speed. Furthermore, this mode of operation is especially well suited to the monitoring of radiotherapy action where the practitioner, when acquiring images, needs to be able to touch the patient.

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 disclosure concerns rotating-anode type X-ray tubes. According to the disclosure, the rotor is supported by passive magnetic bearings, the respective positions of which are such that the rotor is shifted in the direction opposite to that of the anode. The rotor is kept shifted by a thrust-bearing acts, at the same time, as an electrical conductor for the anode current.

Abstract: The acquisition of images of moving parts by NMR experiments requires the prolonged use of two series of excitation sequences. In the invention, only one sequence is enough. The radiofrequency electromagnetic excitation is itself modified to impose, from the very outset, a piece of information, representing the speed of the concerned moving parts, on the free precession signal. The imaging encodings which follow this particular excitation are standard ones. This particular excitation comprises, in principle, two excitations at 90.degree., having opposite directions, applied to one and the same axis and separated in time by a period during which a bipolar pulse of a magnetic field gradient is applied. It is shown that the magnetic moments of the fixed particles are re-aligned, at the end, with the orienting field while the magnetic moments of the moving particles are flipped with respect to this orientation, by an angle proportionate to their speed.

Abstract: The disclosure concerns X-ray tubes that are placed in a sealed casing and filled with a cooling liquid. The disclosed safety device is constituted by a thermostat and/or a pressure-sentitive switch, series connected in the power supply circuit of the filament of the cathode. In the case of a cathod with two filaments, the thermostat and/or the pressure-sensitive switch is or are connected to the common conductor. Thus, should a temperature or pressure threshold be exceeded, the supply to the filament is cut off, thus cutting-off the X-radiation.

Abstract: In an electrical device for supplying x-ray tubes, the primary and secondary windings of the transformer are wound on circular coil forms which are adapted to fit within two half-shells. The half-shells are constituted by a recessed annular structure in which capacitors are housed. The output terminals of the secondary windings are placed on one side in order to be connected to the capacitors and to diodes over very short distances.