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: 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: 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: 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: 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: A device for protecting delay-line modulators of this type by detecting turn-off of the discharge thyristor by a comparator so as to prevent closing of the charge thyristor as long as the discharge thyristor is in the conducting state. This has the effect of preventing short-circuiting of the feed source.

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: A device for the dual-face irradiation of a product is disclosed. The disclosure lies in the fact that a scanning of the electron beam is done during the pulse so as to prevent a scanning along the axis of the scanning chamber and that the divergent scanning beam is deflected by electromagnets so as to obtain a parallel beam. The device can be applied to devices for the ionization of food products.

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.

Abstract: A direct-current high voltage obtained by rippling, stepping-up and rectification of a direct-current low voltage is regulated in such a manner as to ensure that the maximum value of direct-current high voltage attains a predetermined peak value at each ripple pulse of the inverter. To this end, a following pulse of the inverter is produced as soon as the high voltage of the direct-current high-voltage signal has become lower than the predetermined peak value reduced by the measurement of a variation in said direct-current high voltage during a preceding pulse.

Abstract: The disclosure concerns X-ray tubes. To obtain greater temperature stability of an X-ray tube, a substance is placed in the circulation space of the cooling fluid of the tube. The latent heat of fusion of this substance is used so that it melts during the examination stage in absorbing heat, and gets solidified during the resting stage. The disclosure is applicable to X-ray tubes.

Abstract: The invention relates to a rotating anode for an X-ray tube, which avoids the anarchical generation of cracks in a target carried by the anode. For this purpose, at least a part of a target area is carved by a plurality of radial slots arranged symmetrically with respect to an axis of symmetry of the anode. The depth of the slots is less than the thickness of the target.

Abstract: The invention relates to mammographs, and more particularly to a device enabling the mammograph to adapt to different sizes of a cassette, and to displace cassettes. The device essentially comprises a sliding member which, when moved, changes the distance between holding pegs to match new lateral dimensions of a the cassette while still pressing the cassette against a reference edge of the table. In addition, the sliding member is carried on a plate member which moves in such a manner that one or other of the side edges of the cassette can be brought into alignment with the corresponding side of the table.

Abstract: The fact that a vascular tree occupies a very small portion of the surrounding space is profitably employed for reducing the number of reconstruction calculations and improving the quality of this reconstruction without thereby making restrictive geometrical hypotheses. A support region of the object is determined. An estimation of the object to be reconstructed is then carried out on the support region by means of an algebraic method. Determination of the object support involves a statistical evaluation of the detected observations and a comparison of this evaluation with a measurement of the intrinsic noise of the measurement chain. Noise problems are overcome by means of the statistical study. By utilizing a second estimation stage, and taking the support into account, one avoids a restrictive implicit assumption on a convex shape of the objects to be studied.

Abstract: A mammograph is made, wherein the X-ray tube and the work top are held facing each other by a stirrup, making it easy for an X-ray technician to reach the breast to be X-rayed. The stirrup is shaped like a ring and can rotate on itself in sliding on a complementary ring, so as to reduce the inertia of the movable masses, to bring about radiography under oblique or even horizontal incidence. Furthermore, the structure is preferably moved away from a control cabinet for the mammograph, to enable an X-ray technician to come between this cabinet and the patient so as to facilitate preparations for taking a picture.