Abstract: A magnet having a yoke and a pair of poles coupled to the yoke in a spaced apart relationship includes a pair of energization coils in proximity to each of the poles for creating a magnetic field of a desired strength. A pair of prepolarization coils are also disposed in proximity to each of the poles to vary the strength of the magnetic field during a nuclear magnetic resonance prepolarization procedure. In order to minimize the amount of eddy currents introduced to the yoke during the prepolarization procedure the poles are comprised of magnetically effective and substantially non-electrically conductive material. Magnetically effective material includes material having a low hystresis. To further reduce the amount of eddy currents introduced to yoke, a flux is created having a sense substantially opposite of that produced by the energization coil. Such opposing flux may be produced by the prepolarization coils and/or by a shield winding placed in proximity of the poles for that purpose.

Abstract: An object (22) is positioned on a patient support (25) between an x-ray source (10) and an x-ray detector assembly (15). The x-ray source (10) is selectively activated to transmit an x-ray beam (20) through an imaging region (32) to the x-ray detector assembly (15). Positioning of the object (22) on the patient support (25) is such that a gap 33 exists in the imaging region (32) through which x-rays may pass unattenuated. An x-ray equalization filter (30) is introduced into the gap 33 and substantially conforms to its shape. The equalization filter (30) comprises a fluid medium disposed in a flexible receptacle. The fluid medium contains x-ray attenuating material suspended in a gel base. Placement of the equalization filter (30) in the gap reduces the number of unattenuated x-rays reaching the x-ray detector assembly (15) thereby enhancing image quality.

Abstract: A microscope calibrator includes a housing supporting a series of focusing targets each situated at a predetermined distance from one another. Attributes of the microscope are determined by focusing the microscope on one ore more of the focusing targetrs and determining a location of the microscope with respect to the focusing targets focused upon. The position of the focusing targets are determinable by virtue of a local reference frame target attached to the microscope calibrator or by using a tracked probe to communicate the location of each point focused upon by the microscope on each of the focusing targets.

Abstract: An apparatus (1) for supporting a surgical instrument in the operative environment of an imaging device comprises components all made of a material compatible for use in the operative environment of the imaging device. The components of the apparatus (1), made of such a material, include a member (32) that has a spherical surface and includes a bore (50) extending through the member along its diameter. A grip (26) has a grip surface (40) defining an aperture that is adapted to receive the member for rotatable movement within the aperture. The grip (26) extends around the member (32) in a circumferential path and has a gap (42) therein. A fastener (30) is operatively connected to the grip (26). The fastener (30) is adjustable to change the size of the gap (42) and adjust the compressive force applied to the received member (32) in the grip.

Abstract: In an x-ray imaging system, an x-ray detector assembly includes an x-ray detector and a support assembly secured to the x-ray detector for supporting an antiscatter grid assembly. The x-ray detector preferably includes a matrix of crystal detectors. The support assembly includes a foam bezel having one or more magnets disposed therein. The antiscatter grid assembly includes an antiscatter grid secured to a metal frame. The one or more magnets disposed in the bezel are situated so as to align with the metal frame of the antiscatter grid assembly when the antiscatter grid assembly is coupled to the x-ray detector assembly. The strengths of the one or more magnets are such as to allow the antiscatter grid assembly to be removably secured to the x-ray detector assembly. Alternatively, the one or more magnets may be secured to the metal frame of the antiscatter grid assembly and corresponding metal plates may be placed in the support assembly.

Abstract: A gamma camera system includes two or more radiation detector heads and which are mounted opposite each other to a gantry for rotation about a subject. A transmission radiation source assembly is mounted to the front face of at least one of the detectors and can be moved across the face of the detector. The source assembly includes a radiation attenuating housing, a leaded bronze source holder, and a radionuclide source. The radionuclide source is retained in a longitudinal groove disposed in the source holder. The source holder may be rotated into open, closed, and access positions. The transmission radiation emitted by the source assembly is directed across the examination region, attenuated by the subject, and detected by the opposed detector. The gamma camera system also includes a filter which selectively attenuates the transmission radiation to obtain a desired attenuation profile which prevents saturation of the opposed detector.

Abstract: An x-ray tube includes an anode, a cathode, and an electrode disposed in an evacuated envelope. The electrode is positioned such that the electrode is remote from an area in immediate proximity to the envelope. An electric field defined by electrode is of sufficient strength such that arcing preferentially occurs between the electrode and the anode as opposed to occurring between the cathode and anode. The electrode is further situated such that metal sputtered from the electrode substantially falls in a define region on the anode and serves as an active getter for pumping gas from the envelope. The electrode is composed of an active metal which, upon being passively heated by the anode, also acts as a getter material to aid in pumping gas from the envelope.

Abstract: An x-ray tube is disposed within an x-ray tube housing defining a chamber filled with oil or other cooling medium for cooling the x-ray tube. The x-ray tube includes an envelope enclosing an evacuated chamber in which an anode assembly is rotatably mounted to a bearing assembly and interacts with a cathode assembly for production of x-rays. The bearing assembly includes a bearing housing and a plurality of bearings disposed on a surface of the bearing housing. A heat sink is coupled to the bearing assembly and provides a thermally conductive path between the bearing assembly and the cooling medium in the x-ray tube housing for providing direct cooling of the bearing assembly during operation.

Abstract: An x-ray tube includes an envelope defining an evacuated chamber in which an anode assembly is rotatably mounted to a bearing assembly and interacts with a cathode assembly for production of x-rays. The bearing assembly includes a bearing housing and a plurality of bearings disposed on an outer surface of the bearing housing. A cooling channel is defined within the bearing assembly and directs cooling fluid such as oil across an inner surface of the bearing housing. As the cooling fluid flows adjacent the inner surface of the bearing housing, heat from the bearing housing is absorbed by the cooling fluid thereby reducing the heat transferred to the bearings.

Abstract: An x-ray tube includes an envelope defining an evacuated chamber and having a window transmissive to x-rays. An anode assembly and a cathode assembly operate within the envelope to produce x-rays which travel through the window transmissive to x-rays towards a patient or subject under examination. A shield transmissive to x-rays is coupled to the envelope and positioned such that x-rays traveling through the window transmissive to x-rays must first travel through the shield. The shield prevents substantially all secondary electrons created during the production of x-rays from coming into contact with the window transmissive to x-rays thereby preventing excessive heating of the window transmissive to x-rays. An electrode defined by the envelope in a region proximate the window transmissive to x-rays may additionally or alternatively be used to prevent secondary electrons from reaching the window transmissive to x-rays.

Abstract: An imaging apparatus includes a plurality of detector assemblies disposed for rotation about an imaging region. The detector assemblies may be adjusted between at least two relative angular orientations about the imaging region. The relative angular orientations are selected based on the size of an object within the imaging region. The center of the transverse fields of view of the detectors may be offset from the axis of rotation. Gamma radiation generated by positron annihilation events is detected and used to generate tomographic images.

Abstract: A microscope calibrator probe includes a handle, a tool head connected to the handle, a viewable target connected to an end of the tool head opposite the handle, and three or more position signaling devices disposed on the handle for tracking the probe in an image guided surgery system. The tool head includes a bend of approximately 90 degrees to provide easy placement of the viewable target on an object being viewed below a microscope. Other angles for the bend are also acceptable. A precise location of the object being viewed is determined by sensing a location the three or more position signaling devices disposed on the handle with respect to an operating room reference frame and knowing an offset between the position signaling devices and a bottom surface of the viewable target in contact with the object. Additionally, the viewable target includes a viewable aperture for calibrating a line of sight of the microscope and a means for indicating a rotational sense of the viewable target.

Abstract: A tool calibrator includes two portions shaped to slidably engage and secure a tool in a desired position. The tool is secured by a series of staggered V shaped grooves on each of the two portions having a known geometrical relationship with a diameter of a tool head of the tool. The tool calibrator further includes at least one position signaling device for communicating a location of the tool calibrator in an operating room or other area. A position and direction of a tip of the tool is determined by comparing a location of the tool secured within the tool calibrator to the location of each of the two portions. Further, based on the location of each of the two portions, the diameter of the tool head is calculated.

Abstract: A position signaling is usable in connection with an image guided surgery system. A plurality of infrared emitters are mounted on a reference object. The reference object is in turn attached to the rocker arm of a head clamp. The head clamp includes a frame and a first head engaging pin secured to one side of the frame. The rocker arm includes two head engaging pins and is movable in relation to the frame. The image guided surgery system uses the signals provided by the infrared emitters to determine and account for movement of the patient's head.

Abstract: A rotating assembly 79 includes an anode assembly 55 coupled to a shaft 70 and a rotor 75 including a rotor body 77. The anode assembly 55 includes an elongated neck portion 58 and is rotated via the shaft 70 about an axis of rotation 65 in an x-ray tube 12. The shaft 70 is mounted by a straddle bearing assembly 68 having a bearing housing 100. The bearing housing 100 includes a first elongated portion 101 and second elongated portion 102, and a base portion 103. The first elongated portion 101 and the second elongated portion 102 each pass through a center of mass C of the rotating assembly 79 and define an cooling duct 119 for removing heat from the anode assembly 55 during operations. A first bearing 90a and a second bearing 90b are disposed in the bearing housing 100 on opposite sides of the center of mass C of the rotating assembly 79.

Abstract: A surgical guide for use with an image guided surgery includes first and second surfaces. At least three signaling devices such as infrared emitters are disposed on the first surface, and a cylindrical mounting boss is disposed on the second surface. A guide aperture is perpendicular to the first and second surfaces and extends between them. The guide aperture is configured to support a surgical tool such as a biopsy needle. A sleeve may be placed in the aperture to support additional tools.

Abstract: A magnetic probe (1) for use with a magnetic resonance imaging apparatus comprises an electron spin resonance (ESR) magnetometer. The position of the probe (1) tracked by measuring the resonant frequency of an ESR sample (32) in the probe. The resonant frequency is measured in the presence of a gradient sequence which employs three orthogonal, linear gradients. By determining the resonant frequency of the ESR sample in the presence of each of the gradients, the position of the probe can be determined. The probe may be placed on or in an object, and the position of the probe may be displayed on a desired magnetic resonance image of the object.

Abstract: A method and coil arrangement for use in magnetic resonance imaging facilitates the examination of a localized region of the body. A plurality of substantially identical saddle coils are disposed about a former. The coils, which define a generally cylindrical volume, overlap one another in a circumferential direction. In one embodiment, a generally planar rectangular coil intersects the cylindrical volume. The method and coil arrangement are particularly well suited to imaging a region adjacent but outside the cylindrical volume. The coil arrangement is also well suited to insertion within the body, especially the rectum.

Abstract: An MR compatible endoscope 1 has associated MR saddle coil 10 mounted on a removeable former 9. The tip 2 of the endoscope has the usual service channels for imaging. The coil 10 provides an additional MR signal. To avoid the need to plug the coil 10 in, it is inductively couples to a pick-up coil 13 and, to enable this to be removable as will from the endoscope, this may be located in one of the service channels 7 of the endoscope. The removable nature of the coil permits easy repair and, more importantly, a range of coils to be fitted to the endoscope to accommodate different magnetic field strengths.