Abstract: A method for cleaning the interior of a heat exchanger includes connecting the heat exchanger (25a-e) to a fluid supply (26) and fluid delivery system (24). Fluid flow is provided from the fluid supply (26) through the interior of the heat exchanger (25a) in a first direction. The fluid flow is pulsed a predetermined number of times to change the pressure within the heat exchanger. The fluid flow is then pulsed a plurality of times through the heat exchanger in a second direction.

Abstract: A gamma camera includes first and second detectors. The first detector is located beneath a patient receiving surface. The second detector is located above the patient receiving surface. The second detector is movable between operating and retracted positions. The second detector includes a plurality of discrete detector portions, each detector portion having a first radiation sensitive face which faces an examination region and a second radiation sensitive face. The patient receiving surface generates signals indicative of pressure applied to the patient receiving surface. A movable transmission radiation source provides transmission radiation, interactions between the transmission radiation and the second detector generating Compton scattered radiation at least a portion of which is received by the first detector, coincident radiation being used to generate a transmission attenuation map. The gamma camera also includes an ultrasound device.

Abstract: An x-ray tube apparatus includes a housing defining a chamber and an x-ray tube mounted therein. The x-ray tube includes an envelope defining an evacuated void in which an anode assembly is rotatably mounted to a bearing assembly. The anode assembly interacts with a cathode assembly for the production of x-rays. The bearing assembly includes a cooling channel that is defined within the bearing assembly to direct cooling fluid, such as oil, across an inner surface of the bearing housing. A flow director is located in a fluid input port in the housing and has a fluid input aperture for connecting the flow director to the heat removal system. A cavity is defined by the housing of the flow director and two fluid output apertures are in fluid communication with each other and the fluid input opening. One of the fluid output apertures supplies cooling fluid to the cooling channel in the bearing assembly and the other fluid output aperture supplies cooling fluid to the chamber in the housing.

Abstract: A high voltage low inductance resistor (120) includes a resistor body (122) having a perimeter and a center. A first terminal (126) is located away from the center of the resistor near the perimeter of the body (122). A serpentine resistance element (130) includes a first end (136). A conductive ring (124) is located near the perimeter and circumscribes the serpentine resistance element (130). The ring (124) is electrically connected to the first terminal (126). The first end (136) is electrically connected to the conductive ring (124). A first resistance segment (138a) of the resistance element (130) begins at the first end (136) and extends in a first direction generally around the perimeter of the body (122). An apex (142a) has an input portion (143) and an output portion (145). The apex (142a) redirects the resistance element in a generally opposite direction, the input portion (143) transitioning into the first resistance segment (138a).

Abstract: The present invention describes an apparatus for an improved patient support table for use in nuclear medical studies. The table provides regions, such as a slot or hole, where there is lowered radiation attenuation for particular regions of the body. By supporting and aligning the patient with these regions of lowered radiation attenuation, better image quality and/or lowered radiation dosage may be achieved.

Abstract: A system for exchanging and storing collimators for medical imaging devices includes a first frame having a first receptacle and a second frame having a first docking member. A collimator can be attached to and removed from the first receptacle. The first docking member can be positioned adjacent to the first receptacle such that the first docking member can contact the collimator to remove the collimator from the first receptacle. The collimator is coupled to the first docking member while the collimator is removed from the first receptacle.

Abstract: A method of correcting for deadtime and for emission contamination of a transmission scan in a nuclear camera system is provided. The transmission scan is used to correct positron emission tomography (PET) images for attenuation. The camera system includes two detectors and two corresponding single-photon point sources that are collimated to produce fanbeam illumination profiles. A transmission detection window and an emission contamination detection window is defined on each detector. Radiation from each source is scanned axially across the field of view of the corresponding detector in synchronization with the corresponding transmission detection window to acquire transmission projection data. The emission contamination detection windows are also scanned axially concurrently with, but offset from, the transmission detection windows to acquire emission data.

Abstract: A nuclear medicine imaging system includes the capability to correct for the deadtime, including the capability to correct for spatial variations in deadtime across the imaging surface of a detector. The imaging system includes one or more radiation detectors, each using a large, monolithic scintillation crystal. Each detector has deadtime associated with it. A given detector is used to acquire an energy profile of a patient based on emission radiation. The detector includes a number of timing channels. The energy profile is used to select a zone influence map indicating the extent of spatial overlap in response between the various timing channels. Emission data of the patient is then acquired during an emission scan. During acquisition of the emission data, a rate meter assigned to each timing channel samples the number of counts associated with each timing channel to acquire deadtime data.

Abstract: In a magnetic resonance imaging apparatus in which excitation pulses are applied to a restricted region 5 of a magnetic resonance imaging magnet bore, in which the field is uniform, and the data samples collected are Fourier transformed to form a volumetric image of the restricted region, a motor 6 continuously moves a patient couch 3 so that a region of interest passes through the region of good field, and the data samples collected are corrected to compensate for the motion so that a volumetric image is formed of greater length than that of the restricted region.

Abstract: An x-ray tube (20) comprising a cathode (23) and an anode (24) in operative relationship with the cathode (23). The anode (24) is mounted on a stem (32). The x-ray tube includes at least one bearing (58) rotatably receiving the stem (32). The at least one bearing (58) has an outer bearing race (66) in an outer race member, an inner bearing race (62) and a plurality of bearing members (64) operatively disposed between the inner and outer bearing races. The x-ray tube (20) also includes an evacuated envelope (78) which encloses the tube components and receives the outer race member of the at least one bearing (58) in thermally conductive contact along an inner surface (79).

Abstract: Magnetic resonance imaging apparatus uses magnetic field gradients X, Y, Z to spatially encode the magnetic signals arising from a patient on a couch 2 in bore 1 of a main magnet. Thermal stresses arising from aggressive gradients during multiple acquisitions result in imperfectly repeated gradients and resulting image artefacts. The invention uses a probe 4 provided with a gradient coil set similar to that for imaging, and fed by currents derived from the imaging gradient coils, connected so as to produce an opposing gradient surrounding an MR active substance in the probe. This enables a probe with a sufficiently large amount of MR active substance to produce a useful signal to be used to monitor the gradient, while overcoming the de-phasing problem. which would otherwise occur. Closed loop control of gradients thereby becomes possible.

Abstract: An RF coil structure for intra-cavity use includes a pair of conductors (7, 8) separated by a support such as a web (9) which come together at positions separated along the length of the coil structure such as (A, B). Previous coils have included two parallel conductors. If the conductors (7) and (8) were parallel, while the structure could be flexed transverse to the plane of the web (9) about the arrow (10), it could not be flexed in the plane of the web (9) about arrows (12, 13). Because the conductors come together at points (A) and (B), it can be so flexed. A second coil may be provided including conductors (4, 5) and flexing about the same points as for the first coil is still possible because the points of closest approach for one pair come between those for the other pair.

Abstract: A patient bed (1) of an MR imaging apparatus is provided with a tube (17) through which pre-polarised fluid can be injected into a patient in order to improve contrast when imaging veins, arteries or other vessels in the body. Fluid is delivered from pump (2) into a high field polarising magnet (3) and along a tube (4) to the patient. Valve (5) is provided so that fluid in the tube (4) downstream of the pre-polarised fluid can be discarded rather than being injected in the patient, and is associated with a reservoir into which the fluid to be discarded and the pre-polarised fluid can be rapidly injected. Then, when the pre-polarised fluid is injected into the patient, its magnetisation has not deteriorated by as much as it would have done if the tube (4) had been directly connected into the patient.

Abstract: A transmission radiation source assembly suitable for use in both SPECT and PET imaging includes a line source assembly having a medium energy transmission source. The line source assembly includes a primary collimator rotatably disposed about the medium energy transmission source. The primary collimator includes one or more beam limiting slots for shaping the width of a transmission beam emitted from the line source. An on/off collimator is rotatably disposed about the primary collimator and serves to control the on/off state of the line source. The on/off collimator includes a beam exit slot which, when aligned with one of the beam limiting slots allows the transmission beam to exit the line source. In order to sweep the transmission beam across an opposing detector head, the primary collimator and on/off collimator are synchronously rotated about an axis of rotation of the line source with the on/off collimator in the “on” position.

Abstract: An evacuated tube (24) includes an envelope (50) and an electrode (78) in the tube envelope (50). The electrode (78) is electrically connected to conductors (74a, 74b) that extend through the tube envelope (50). A getter (72) is included in the tube envelope (50) and is electrically connected to the conductors (74a, 74b) extending through the tube envelope (50). Diodes (82a, 82b) are connected to the electrode (78) and the getter (72) for selectively providing electrical energy through the conductors (74a, 74b) extending through the tube envelope (50) to one of the electrode (78) and the getter (72).

Abstract: A gamma camera system includes a rotatable gantry supporting multiple detector heads each capable of receiving radiation from a region of interest of a subject disposed in an examination region. Each of the detector heads include a collimator which substantially defines the resolution and sensitivity of the respective detector head. At least two of the detector heads include collimators providing different resolution. Preferably, one of the collimators provides a detector head with substantially high resolution and another provides a detector head with substantially high sensitivity. An operator selectively combines image data detected by each of the multiple detector heads. If desired, the operator combine the image data from the multiple detector heads in a variety of manners to obtain images of various resolution and sensitivity from a single imaging procedure. The operator may also selectively weight the contribution that the image data from each of the detector heads has in the overall image.

Abstract: A gamma camera includes detector heads disposed about an examination region. A high energy collimator collimates the radiation received by each of the detector heads. Either a positron emitting radionuclide or a positron emitting radionuclide and a single photon emitting radionuclide is introduced into an object to be imaged. Radiation which is received by the detectors within a coincidence time interval and radiation which is received by either of the detectors but having an energy characteristic of a positron annihilation are used to generate coincidence data. Radiation which is not indicative of coincidence radiation but which has an energy characteristic of the single photon emitting radionuclide is used to generate single photon data. The data is processed and used to generate one or more images of the object.

Abstract: The configuration of a multi-head gamma camera requires coordination between tangential and radial motions so that the detectors maintain a desired orientation, either corner to corner or overlapping. Based on the radial and angular positions of the detectors, desired tangential positions are determined. The desired tangential positions are compared with the actual tangential positions, to generate position error signals. Tangential motion is initiated to reduce the position errors. If the required tangential motion exceeds the capability of the tangential drive or cannot be achieved, the radial motion is slowed or stopped.

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 x-ray tube further includes a heat shield disposed in the envelope. The heat shield serves to reduce heat radiating from the anode assembly which is transferred to the bearing assembly or otherwise serves to insulate the bearing assembly from such radiated heat. The heat shield is brazed or otherwise bonded to the anode assembly and is comprised of a material having a low emissivity so that a minimum amount of heat radiates through the heat shield.

Abstract: A transformable gamma camera includes detectors mounted for circumferential movement with respect to a rotating gantry. The rotating gantry includes radial bores at desired angular positions about the rotating gantry. The stationary gantry includes a docking station such as a bore. A coupling mechanism allows the detectors to be coupled to the bores in the rotating gantry or to the docking station. Each of the detectors is movable radially with respect to the rotating gantry's axis of rotation and tangentially to the imaging region. The gamma camera is readily transformable between 120 degree, orthogonal, and opposed detector configurations; a plurality of aperture sizes can also be defined.