Abstract: An MRI scanner generates a temporally constant (B0) magnetic field through an examination region (10), as well as a surrounding fringe field. The fringe field tends to decrease in strength with distance from the examination region and includes a 5 Gauss line (70, 70′) and a 1 Gauss line (74). In a vertical field magnet, the 5 Gauss line can extend more than 3 or 4 meters above and below upper and lower pole assemblies (12, 14). By placing permanent magnets (70, 76) above and below the upper and lower pole assemblies, respectively, with an opposing magnetic polarity, the fringe field is shaped and controlled reducing a distance (d) of the 5 Gauss line above the scanner to about 2 meters and reducing an amount of ferrous material in a ferrous flux return path (24).

Abstract: In an open magnetic resonance system, pole pieces (16, 18) on opposite sides of an imaging region (10) are supported by a ferrous flux return path (20). During normal operation, environmental disturbances that cause low frequency vertical vibrations in the floor cause corresponding fluctuations in the main field of the magnet. A spacing between the pole pieces (16, 18) expands and contracts with the vibration causing a strength of the main field to fluctuate. A force transducer (60) under the magnet assembly measures the magnitude of the vibrations. A vibration analyzer (62) analyzes the vibrations waveform and calculates compensation for the changes in the interpole spacing.

Abstract: A pair of pole assemblies (12, 14) are disposed on opposite sides of an examination region (10). A ferrous flux return path includes an overhead ferrous structure (18) above the upper pole assembly and a lower ferrous structure (20) adjacent to the lower pole assembly. The pole assemblies include a Rose ring assembly (34) having axially spaced segments (40, 42) with an axial gap (44) in between. Magnetic attractive forces between an annular magnet (30) and the Rose ring urge the Rose ring and the magnet into an axially centered alignment. The magnet of the upper pole piece assembly (12) is attracted toward the overhead ferrous structure (18) and toward the lower pole piece assembly (14), as well as toward the Rose ring. The magnet is also positioned such that the magnetic attractive forces between the magnet and the Rose ring dominate magnetic attractive forces between the overhead ferrous structure and the magnet.

Abstract: A pair of annular magnets (10) generate a vertical magnetic flux field through an imaging volume (12). The flux is focused by a pair of Rose rings (26) of high cobalt steel. A high order shim set includes a plurality of permanently magnetized or magnetized iron rings (32a, 32b, 32c, 32d) which cooperatively interact with the magnet assembly to optimize the homogeneity of the magnetic flux through the imaging volume. One of the permanent magnetic rings (32d), is mounted with an opposite polarity relative to the others. The magnetized rings are mounted in a non-ferrous, electrically insulating support structure (34) such that gradient coils (50) can be positioned behind the permanent magnet rings. A flux return path (14, 16, 18, 20, 22, 24) provides a low flux resistant path from adjacent the Rose ring at one side of the imaging volume remotely around the imaging volume to a position adjacent the Rose ring at the other side of the imaging volume.

Abstract: A magnetic resonance imaging suite is sheathed with plates (32, 34, 36) of iron or other ferrous material. The plates define projections (42, 44, 54, 54', 68) in alignment with each other on opposite ceiling and floor or wall surfaces. A pair of magnetic pole pieces (10, 10'; 50, 50'; 60, 60') are surrounded by superconducting electromagnetic coils (12, 12'; 52, 52'; 62, 62'). The pole pieces are positioned between the ferrous plates in axial alignment. When current flows through the electromagnetic coils, magnetic flux flows between the pole pieces. The ferrous wall sheathing or other ferrous constructions define a flux return path. The pole pieces are magnetically attracted toward each other and are each magnetically mirrored in and attracted toward the adjacent ferrous flux return path.

Abstract: A magnetic resonance imaging suite is sheathed with plates (32, 34, 36) of iron or other ferrous material. The plates define projections (42, 44, 54, 54', 68) in alignment with each other on opposite ceiling and floor or wall surfaces. A pair of magnetic pole pieces (10, 10'; 50, 50'; 60, 60') are surrounded by superconducting electromagnetic coils (12, 12'; 52, 52'; 62, 62'). The pole pieces are positioned between the ferrous plates in axial alignment. When current flows through the electromagnetic coils, magnetic flux flows between the pole pieces. The ferrous wall sheathing or other ferrous constructions define a flux return path. The pole pieces are magnetically attracted toward each other and are each magnetically mirrored in and attracted toward the adjacent ferrous flux return path.

Abstract: A method and apparatus for recording the information from the slidable sheet (5) of a RIM cassette (2). The information included on the sheet, used especially in X-ray photography, is read from the sheet surface drawn out of the cassette with the aid of a laser beam focused on it, after which the sheet is emptied of information with the aid of a powerful light and returned to the cassette. According to the invention, the reading is effected during the linear withdrawal of the slidable sheet (5) in the reading position (9) past which the sheet surface including the information is guided, and the removal of the information is effected during the linear return travel of the slidable sheet in the emptying position (10) past which the sheet surface travels while the sheet is being pushed back into the cassette (2).

Abstract: The invention relates to a novel magnetic resonance imaging apparatus. The nuclei, protons or the paramagnetic electrons of an imaged object are cyclically polarized during a period of about one second with a permanent magnet which is then quickly shifted away from the imaged object in a permanent magnet carrier tube, so that the field of the permanent magnet would not have an interfering effect on the immediately following signal-collection for MRI-imaging. The permanent magnet can be manipulated or shifted back and forth in the tube either magnetically, pneumatically, hydraulically or mechanically. The apparatus also includes another permanent magnet or a resistive magnet coil couple, which is located in the tube near the opposite end of the tube, and which generates a homogeneous magnetic field within the imaged area.

Abstract: The invention relates to a supporting system of a sliding plate of a magazine comprising a magazine case and a sliding plate which travels in a linear direction inside the magazine case. The system is comprised of a guide bar that is secured to the lower cover of the magazine, parallel to the longitudinal axis of the lower cover. The sliding plate rests upon the guide bar and upon support screws arranged on the end part of the magazine case against the front portion of the sliding plate.

Abstract: A method and an apparatus for the radiographic recording of a patient's dentition, jaws, and skull regions invalues seating a patient in a patient chair (9) so as localize the patient in the coordinate system of the radiographic apparatus in an unequivocal position before taking the exposure for a radiograph (87). Furthermore, in accordance with the invention, the radiograph (87) is used for measuring the coordinates of a desired object (95) by a coordinate locator (88), after which the desired partial area (94 or 96) is selected on the basis of the coordinates, and the exposure direction is changed in relation to the first exposure in the horizontal plane and/or the vertical plane before executing the exposure program for the desired partial area (94 or 96).

Abstract: An apparatus for the implementation of a vertical movement for a chair, especially a patient chair is disclosed. This apparatus comprises a lift column (1) with an upper end suitable for mounting a chair, a tubular shell construction (2) against which the lift column (1) is telescopically supported, a threaded member (5) whose rotation enables elevation and lowering of the lift column (1), and a motor (4) for rotating the threaded member (5). In the apparatus according the lift column (1) has a polygonal cross section, and it receives for each of its sides a support incorporating a spring action and sliding bearing contact by support braces (3) mounted to the inner surface of the shell construction (2). The apparatus achieves a vibration-free lift movement.

Abstract: A friction planetary transmission has a sun roller planetary roller and an elastically deformable outer periphery. The planetary rollers are attached to shafts which have a limited amount of radial movement. The outer periphery deforms to exert a frictional contact pressure on the planetary rollers such that a torque can be transmitted. The torque is adjustable by a circular disk which fits inside the outer periphery to regulate the amount of deformation. The circular disk can be moved axially to adjust the torque.

Abstract: The purpose of the invention is to create a mechanically uncomplicated installation for producing radiographic layer images, making it possible to use small radiation dosages and, however, to collect sufficiently information on the object by one exposure, whereby separation of the superimposed layers from each other in a desired way for visualization can be accomplished by means of tomosynthesis. The installation includes radiation generating means (1, 2), collimating means for confining the radiation and focusing it on an object (4) to be radiographed, e.g. a patient, means (10) for detecting the radiation passed through the object and means for storing and processing the information contained in said detection.

Abstract: A slit collimator for use in a panoramic X-ray apparatus for the collimation of X-rays into a narrow fan-like beam. The collimation is achieved by means of a collimator slit formed in a trunion which is rotatable about its longitudinal axis and by rotating the trunion the effective radiation-penetrable size of the slit is varied.

Abstract: Lumber is classified in terms of knots. The method used employs high frequency radio energy and a detector responsive to phase to detect the energy passing through the lumber. The knots exhibit a different dielectric constant, the real part of which is different from normal wood, and the difference in phase of the radiation detected effects the measurement. Preferably, the frequency radiation is near 10 GHz.