Abstract: An NMR radio-frequency (RF) coil is made up, in the preferred embodiment, of upper and lower coil assemblies. Each coil assembly includes a tuned circuit. In operation, only one of the tuned circuits is energized, while the other is mutually inductively coupled such that they resonate together as one circuit at substantially the same frequency. A first set of latches is provided to fasten the lower coil assembly to a patient cradle. A second set of latches is utilized to fasten the upper coil assembly to the lower while permitting relative longitudinal motion between the two assemblies.In another embodiment, which does not utilize mutual inductance, the tuned circuits on each assembly are electrically connected to form a complete coil by means of, for example, an electrical plug-and-jack arrangement.

Abstract: Apparatus for reducing heat leakage into the interior of a liquid cryogen-holding vessel from the sealed well through which the vessel is accessed. An actively cooled heat sink in the well transfers heat to low temperature cryogen vapor venting from this vessel to the external environment.

Abstract: An x-ray tube rotor controller uses the main high voltage inverters for acceleration and speed maintenance. The rotor controller includes a DC voltage source, and a rotary anode drive circuit including a rotary anode motor designed as a two-winding induction motor. The rotor controller comprises first and second inverter circuits which may be either half bridge or full bridge arrangements, the first and second inverter circuits for accelerating the anode, and further for generating high voltage for the x-ray tube. Electronic switching means allow for instantaneous electronic switching of the output of the first and second inverter circuits between the high voltage power supply and the anode motor. A phase switching capacitor may be used to provide the other phase of the motor.

Abstract: A method of forming a long 100-inch low resistance lap joint suitable for joining magnet coils in a superconducting magnet assembly on the magnet drum, which is accomplished by forming a flat solder sandwich within a groove on the drum and moving a heat source along the lap joint with controlled temperature, pressure and rotational speed of the drum.

Abstract: A cantilevered trapezoidal-toroidal structure is provided in an active magnetic shielding system for a superconducting magnet to support the bucking magnet coils in spaced relationship to the main magnet coils.

Abstract: An assembly is provided for improving operation of a radiation detection system which comprises a scintillation crystal 1, a photomultiplier tube 5 having a cathode maintained at a high negative voltage, a glass wall 3 positioned between the crystal and the tube, and structure 7 supporting the tube to receive a light signal from the crystal representing radiation received thereby. The assembly includes structure 4, 11 for applying the same high negative voltage to the crystal 1, and further includes structure 10 for electrically isolating the supporting structure 7 from the crystal 1 and glass wall 3, the supporting structure 7 being maintained at ground potential.

Abstract: A system for Write Once Read Many (WORM) optical storage devices to appear rewritable uses magnetic disk storage and optical WORM storage subsystem. All new write operations are made to a magnetic cache storage which resides on the magnetic disk subsystem. A Least Recently Written (LRW) technique is used to determine which valid data in cache storage is the oldest and must be transfered to optical storage to make room for new data. In this manner all new write operations are performed to the magnetic cache storage and only the oldest valid data is transferred to optical disk, optimizing its use.

Abstract: A method and apparatus for improving skin line viewing in a medical X-ray diagnostic system having an X-ray source for generating a scanning X-ray beam to image a target. In one form, the apparatus includes a first collimator positioned in the X-ray beam and having a rectangular shaped slit for passing the beam. A second collimator is positioned adjacent the first collimator and includes a plurality of spaced attenuation plates which can be moved over the slit in the first collimator. The attenuation plates are angles and tapered with respect to the slit. Control means is provided for locating the target within the slit and continuously driving the second collimator attenuation plates so as to intersect the edge of the target aligned with the slit.

Abstract: In an X-ray tube having a stationary anode stem, a shaft joined to the tube anode, and a rotary bearing to support the shaft and anode for rotation relative to the stem, a preloading element is positioned in a bore formed in the stem and is axially displaceable to apply a selected preload to the bearing. The preloading element has a cylindrical outer surface provided with longitudinal spaced-apart grooves in parallel relationship with the bore axis. A locking ball positioned in each groove extends through a complementary hole formed through the stem to oppose rotational displacement of the preloading element with respect to the stem, while allowing axial displacement to take place. An annular retaining ring positioned around the anode stem engages the locking balls to urge them in toward the bore, and to oppose radial displacement of the preloading element.

Abstract: A system is provided for controllably venting cryogen of extremely low temperature from a cryostat, wherein a conduit formed of selected metal provides a path of flow for the cryogen from the cryostat to an exhaust system. A gauge is coupled to the conduit, along the path of flow, by means of a bushing which thermally isolates the gauge from the metallic conduit, which is at an extremely low temperature. Thus, the gauge, which is used to continually monitor cryogen pressure, does not become unreadable due to icing or frosting as a result of heat loss from the gauge to the conduit. The bushing is formed from a material such as GC-10, and includes an intermediate portion for spacing the bushing away from the metallic conduit, and also for enclosing a dead space which substantially reduces heat transfer directly between the gauge and cryogen in the conduit.

Abstract: The device is provided for detachably coupling a power source to a lead pin of the superconducting magnet, the magnet being located in a cryostat using helium and the lead pin being in the region of helium vapor. Device includes a split connector formed to engage the pin, an elongated rod joined to the connector in conductive relationship, and a torque tube positioned around the rod in rotatable relationship. The tube is rotated, a nut joined to the tube and positioned around split connector causes the connector to tightly grip the pin. The device is configured to direct a flow of helium vapor along a path which is proximate to the interface between the connector and pin, to remove heat from the interface and thereby reduce resistance to current flow across the interface.

Abstract: Apparatus located aboard a platform situated in an acoustic environment for racking a moving body when the body is proximate to the platform. The apparatus includes a selected number of acoustic sensor elements at selected locations around the platform, each of the elements for detecting acoustic information arriving at its selected location. The apparatus further includes signal conditioners coupled to the sensor elements, a given one of the signal conditioners providing a conditioned signal representing acoustic information which is emitted by the moving body when the body is proximate to the platform, and which arrives at the location of the acoustic sensor element to which the given signal conditioner is coupled.

Abstract: In a method and apparatus for searching a subsurface environment to detect he presence of a target therein, an electromagnetic field is emitted which comprises successive electromagnetic pulses of selected duty cycle, the time interval between pulses comprising a zero emission interval and a sampling interval, the sampling interval following the zero emission interval, and the polarity of the pulses of the emitted field alternating at a selected alternating frequency. The emitted field is projected into the environment from a selected location, and the electromagnetic field proximate to the selected location is sampled during each of the sampling intervals to provide a train of proximate field samples. The train of proximate field samples is spectrum analyzed to determine whether or not the field proximate to the selected location contains a component having a frequency which is equal to the alternating frequency.

Abstract: A shield is provided for a magnet of the type used in magnetic resonance imaging or spectroscopy to limit the fringe field of a superconducting magnet to specified boundaries when the magnet is generating a magnetic field having a strength required for normal magnet operation. The shield includes a number of steel rectangular plates position around the magnet to form respective sides of a shield, the shield having a cross section in the form of a polygon such as a octrahedron. End caps having the shape of such polygon are joined to the ends of the plates. Structure is provided for supporting the magnet for movement as an integral unit relative to the shield. The supporting structure includes a first set of adjusting mechanisms for moving the magnet vertically and a second set of adjusting mechanisms for moving the magnet laterally, relative to the shield, to move the axis of the magnet into alignment with the shield axis, to avoid magnet quenching and inhomogeneities in the field generated by the magnet.

Abstract: A method and apparatus for improving imaging in an X-ray mammography machine having a controllable X-ray source incorporates apparatus for directing the X-ray beam in a preselected configuration onto at least a portion of a target area. The creation intensity of the beam is detected in each of a plurality of substantially equal segments of the target area and a first segment of lowest radiation intensity is identified. The X-ray source is adjusted to establish a predetermined radiation intensity in the identified first segment. Second segments are then identified each having a radiation intensity greater than a predetermined percentage of the radiation intensity in the identified first segment. The radiation intensity directed toward the identified second segments is then automatically attenuated by a control system responsive to the radiation intensity detected in the second segments.

Abstract: Three-dimensional images are formed from tomographic data collected such that each two-dimensional slice is tilted with respect to the transverse slice direction. Geometric distortion in the reconstructed 3-D image caused by the slice tilt is removed either during extraction of the 3-D surface from the tomographic data or during rendering of the final surface using a matrix transformation.

Abstract: A graphical image display provides improved image presentation due to potential removal of background data which would otherwise degrade presentation of the region of interest and due to automatic adjustment of image brightness and contrast based on operator preference. Statistical analysis of the image data is employed. The invention is particularly useful in medical diagnostic imaging.

Abstract: Method and apparatus for minimizing scatter in an X-ray imaging system of the type including a controllable source of X-ray radiation and means for collimating the X-ray radiation into a fan-shaped beam and effecting scanning of the X-ray beam across a target area. The improved system includes a grid assembly extending in a transverse direction across the target area and having a relatively narrow width in the beam scanning direction. A drive is coupled to the grid removing the grid in synchronism with the X-ray beam and an X-ray impervious belt is coupled to the grid and extends in a transverse direction across the target area and is movable with the grid for covering the target area outside the grid to prevent scatter radiation from impinging on X-ray film located beneath the grid. In one form, the grid includes a plurality of air interspersed septa to allow reduced beam energy.

Abstract: An electrode assembly, particularly useful in nuclear magnetic resonance apparatus, for sensing a physical characteristic of a live study subject includes an electrode positioned in electrical contact with the subject for sensing the physical characteristic. The electrode assembly further includes a lead wire connected at one of its ends to the electrode and having an impedance selected to protect the study subject from heating. The impedance is also selected to have a low voltage coefficient of resistivity in order to prevent conversion of radio-frequency energy to ECG in-band energy.

Abstract: Three-dimensional representations of the surface of a structure located in a three-dimensional space are formed from tomographic data collected in a medical diagnostic imaging system. The images include structures of specific interest displayed at a high resolution and adjacent structures to improve the perception of the structures of interest displayed at a low resolution. Total examination time is reduced because the total number of slices needed to form the image is reduced. A plurality of slices of different spacings are obtained and divided into first and second space portions (associated with different slice spacings). An interpolation factor which varies as a function of slice spacing is used in the dividing step to establish selected dimensions of first and second three-dimensional elements.