摘要:
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.
摘要:
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.
摘要:
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. In this manner, the magnet is subject to a net force toward an axially balanced position, such that the force does not change sign during ramp up and ramp down.
摘要:
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). The movement of the slidable sheet (5) can be effected by a pulling device which consists of a slide (8) travelling on a rotatable shaft (7) and the movement of the slide is effected with the aid of ball bearings mounted against the shaft at a pitch angle. The reciprocating path of the slide (8) is preferably adjusted so that the slidable sheet (5) comes only partially out of the cassette (2) which thus continuously acts as a guide for the sheet.
摘要:
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. The apparatus includes a gradient coil system for generating a time-dependent magnetic field gradient necessary for imaging, as well as a coil system for producing an electromagnetic radio-frequency excitation signal to be linked with the nuclei or paramagnetic electrons of an imaged object as well as for registering the response of the nuclei or electrons to said signal. A control unit is used to control the above coils and to receive the information therefrom for producing an image or some other representation thereof.
摘要:
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.
摘要:
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. Said collimating means comprise a collimation unit (3) including at least two separate, narrow, contiguous, substantially parallel collimating slots (5) for producing narrow, fan-shaped beams, said slots being arranged preferably in alignment with the longitudinal axis of the object to be radiographed. The installation also includes means (11, 13) for displacing said collimating slots and the object to be radiographed in relation to each other at least substantially in alignment with the normal of said collimating slots, those parts of the object selected to be radiographed being arranged to be exposed to radiation by said narrow fan-shaped beams from a number of different directions. The information obtained from the object to be radiographed is stored preferably in digital form and processed for visualization.
摘要:
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).
摘要:
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. The vibration analyzer (62) controls one or more of a shim coil (70) which produces a field equal and opposite to the main field fluctuations, a reconstruction processor (52) to compensate for magnetic field resonance frequency fluctuations attributable to the main field fluctuations, and gradient magnetic fields applied by gradient field coils (22, 24).
摘要:
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. The pole pieces are positioned relative to each other and the ferrous flux return path such that the attraction between the pole pieces is balanced by the attraction between each pole piece and its magnetically mirrored image in the adjacent ferrous material of the flux return path. Optionally, the magnets are selectively extinguished and one or both pole pieces are moved for better access to the patient.