Abstract: A magnetic imaging apparatus includes an RF coil (F) in electrical communication with an RF signal generator (C) and a receiver (G) through an interface circuit (E). The signal generator transmits resonance excitation signals at one of at least two resonance frequencies, e.g. the resonance frequencies of hydrogen helium 3, fluorine, phosphorous, carbon, or xenon. During the transmit cycle, PIN diode (30) is forward biased forming a filter at a first resonance frequency, electrically isolating the receiver from first frequency excitation signals. Simultaneously during the transmit cycle, PIN diode (32) is forward biased forming a filter at a second resonance frequency electrically isolating the receiver from second frequency excitation signals. During a receive cycle, the diodes are reverse biased turning both filters into low impedance circuits around the first and second resonance frequencies allowing a received magnetic resonance signal to pass unimpeded from the RF coil to the receiver.

Abstract: A diagnostic imaging apparatus such as a magnetic resonance imaging (MRI) device includes a gradient coil assembly (34) and an RF coil (36) disposed proximate pole faces (30, 32). An interventional head coil assembly (40) includes a base (90), a head frame housing (96) including at least one first conductor (130) associated therewith, a first mount (94) that connects the head frame housing (96) to the base (90), a bridge housing (98) including at least one second conductor (142) associated therewith, and a second mount (100) that connects the bridge housing (98) to the head frame housing (96) thereby coupling the at least one first conductor (130) to the at least one second conductor (142) to form a surface coil for use in imaging an object attached to the head frame housing (96).

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: A radio frequency coil (12, 19) adapted for use in interventional magnetic resonance imaging consists of a loop of an elongated electric conductor arranged to form a twisted wire pair (12, 19) and means associated with it for operating the coil both in transmit and receive mode, in order that the coil does not image anything but tracks its own path on an MR image, without affecting the magnetization in the main bulk of the body being imaged.

Abstract: A diagnostic imaging system includes oppositely disposed radiation detectors (32, 34) configured to detect coincidence radiation events caused by a substance injected into a subject which generates positron emissions. A coincidence data processor (40) collects and processes the radiation detected by the detectors (32, 34) and a coincidence circuitry (44) matches and compares the detected events to determine coincidence. Coincidence data is generated and stored in a coincidence data memory (46). A collimated radiation detector (50) is disposed at an angle to the coincidence radiation detectors (32, 34) and is configured to detect single photon radiation traveling along a selected projection path determined by a collimator (52) mounted on a front face of the collimated radiation detector (50). A single photon data processor (60) generates collimated data (74) based on the radiation detected by the collimated radiation detector (50).

Abstract: A magnetic imaging apparatus generates a main magnetic field longitudinally through an image region and excites magnetic resonance in selected nuclei in a patient or subject disposed in the image area. The resonating nuclei generate radio frequency magnetic resonance signals which are received by a quadrature highpass ladder surface coil (D). The highpass ladder coil includes a central leg 34 having a capacitive element Cv disposed symmetrically about a midpoint 44. A like number of additional legs 30, 32, 36, 38 are disposed parallel to and symmetrically on opposite side of the central leg. Side elements 40, 42 include capacitive elements CA which interconnect adjacent ends of each of the legs. The capacitive elements are disposed symmetrically about the midpoint 44 and are selected such that the coil supports at least two intrinsic resonant modes including an odd mode 50 and an even mode 52.

Abstract: A method of diagnostic image reconstruction from projection data is provided. It includes generating projection data followed by a convolution of the same. The convolved projection data is then scaled into unsigned, fixed precision words of a predetermined number of bits. The words are then split into a predetermined number of color channels corresponding to color channels of a multi-color rendering engine (150). Simultaneously and independently, the split words are backprojected along each of the color channels to obtain backprojected views for each color channel. The backprojected views for each color channel are accumulated to produce separate color images corresponding to each color channel. Finally, the separate color images are recombined to produce an output image. In a preferred embodiment, prior to the convolution of the projection data, a rebinning operation is performed to ensure that the projection data is in a parallel format.

Abstract: A cardiac gated spiral CT scanner (10) has a source of penetrating radiation (20) arranged for rotation about an examination region (14) having a central axis extending in a z direction. The source (20) emits a beam of radiation (22) that passes through the examination region (14) as the source (20) rotates. A patient support (30) holds a patient within the examination region (14) and translates the patient through the examination region (14) in the z direction while this source (20) is rotated such that the source (20) follows a helical path relative to the patient. A control processor (90) implements a patient-specific scan protocol in response to measured patient characteristics (for example, the patient's heart rate, the patient's breath hold time, and/or the range of coverage in the z direction based on the patient's anatomy) and scanner characteristics (for example, the number of detector rings, and/or the scan rate).

Abstract: An x-ray tube (10) includes an anode (14) connected to a mechanical drive (36). The mechanical drive oscillates the anode in a gyrating motion relative to a body of the x-ray tube. The mechanical drive is operatively connected to the anode via a bellows assembly (16) and is capable of rocking the anode in two axes simultaneously. The preferred anode is shaped in a shperical section (28) providing a fixed focal distance between the anode and a cathode (20) regardless of relative position of the anode within the body. An electron shield (40) is disposed between the cathode and the anode and has an opening along a preferred path for electron travel. Improved heat exchange is provided by applying a heat transfer agent to an obverse side of the anode which is preferably located outside of a vacuum envelope (18) defined by the x-ray tube body, the anode, and the bellows.

Abstract: A patient supported on a patient support (12) is moved into a bore (22) of a planning imaging device, such as a CT scanner (20). A three-dimensional diagnostic image in three-dimensional diagnostic image space is generated and stored in a memory (130). The patient is repositioned outside of the bore with a region of interest in alignment with a real time imaging device, such as a fluoroscopic imaging device (40). A surgical planning instrument (60), such as a pointer or biopsy needle (62), is mounted on an articulated arm (64). As the instrument is inserted into the region of interest, fluoroscopic images are generated and stored in a memory (140). The coordinate systems of the CT scanner, the fluoroscopic device, and the surgical instrument are correlated (102, 104, 112, 120) such that the instrument is displayed on both the CT images (134) and the fluoroscopic images (50), such that cursors move concurrently along the fluoroscopic and CT images, and the like.

Abstract: A gamma camera includes first and second detectors which face an examination region. The detectors are rotatable about the examination region and translatable in a direction tangential to the examination region. Translation of the detectors is coordinated with the rotation of the detectors about the examination so as to increase the effective field of view of the detectors. In a first embodiment, the detectors are translated in the transverse direction when the detectors are located at each of a plurality of positions about the examination region. In a second embodiment, translation of the detectors is coordinated such that, for a given projection angle, the first detector is used to detect radiation data from a subset of the region of interest.

Abstract: A magnetic resonance imaging scanner includes a pair of opposing pole pieces (20, 20') disposed symmetrically about an imaging volume (24) facing one another. The pair of opposing pole pieces (20, 20') includes a first ferrous pole piece (20) which has a front side (22) facing the imaging volume (24) and a back side (28). Also included is a second ferrous pole piece (20') which also has a front side (22) facing the imaging volume (24) and a back side (28). A magnetic flux return path (30) extends, remotely from the imaging volume (24), between a point adjacent the back side 28 of the first pole piece (20) and a point adjacent the back side 28' of the second pole piece (20)'. A source of magnetic flux generates a magnetic flux through the imaging volume (24), the pair of opposing pole pieces (20, 20'), and the magnetic flux return path (30). An array of annular hoops (40) and (40') are integrated with the pair of opposing pole pieces (20, 20') for homogenizing the magnetic flux through the imaging volume (24).

Abstract: A high energy x-ray tube includes an evacuated chamber (12) containing a rotor (34) which rotates an anode (10) in the path of a stream of electrons (A) to generate an x-ray beam (B) and heat. The rotor includes an armature (36) which rotates around a stationary rotor support (40). An emissive coating is formed on the rotor by depositing an iron Fe.sub.3 O.sub.4 oxide plasma onto the surface of the armature. Heat generated in the anode during the production of x-rays is conducted through the anode and the rotor to the emissive coating which irradiates the heat across vacuum, thereby increasing the lifetime of the tube. A stator (32) generates an oscillating magnetic field which induces opposing fields in the Fe.sub.3 O.sub.4 coating to create the rotational forces to rotate the anode.

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: A camera for use in coincidence imaging includes detector heads (10a, 10b) disposed about an examination region (12). The detector heads (10a, 10b) include septa (36) for absorbing radiation having a relatively large axial angle. The septa, however, cause the sensitivity of the detectors (10a, 10b) to vary as a function of axial position along their face. The relative positions of the detectors (10a, 10b) and the patient are varied so as to reduce septal artifacts. In particular, artifacts arising from second and fourth harmonics may be reduced.

Abstract: A method of calibrating pre-emphasis gradient pulse conditioning for long term eddy current compensation in an MRI system is provided. It includes positioning an object in the MRI system for imaging therewith. A long term eddy current generating pre-scan gradient pulse is applied, and after a delay, an EPI sequence is run such that a resulting image of the object is acquired. This process of applying the pre-scan gradient pulse followed by the EPI sequence is repeated while varying the delay therebetween. Size variations in the resulting images of the object are observed, and these size variations are fit to an exponential curve to obtain one or more time constants for the long term eddy currents. Next, a reference EPI sequence is run without applying the long term eddy current generating pre-scan gradient pulse such that a reference image of the object is acquired.

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: An x-ray tube (10) includes a body (16) defining a vacuum envelope. A plurality of anode elements (18) each defining a target face are rotatably disposed within the vacuum envelope. Mounted within the vacuum envelope, a plurality of cathode assemblies (22) are each capable of generating an electron stream (36) toward an associated target face. A filament current supply (32) applies a current to each of the cathode assemblies, and is selectively controlled by a cathode controller (34) which powers sets of the cathodes based on thermal loading conditions and a desired imaging profile. A collimator (C) is adjacent to the body and defines a series of alternating openings (42) and septa (44) for forming a corresponding series of parallel, fan-shaped x-ray beams or slices (46).