Abstract: A cathode assembly (18) for an x-ray tube (1) includes a base (60) to which a filament (70) is mounted. A pair of deflectors (82, 84) are carried by the base for deflecting a beam (A) of electrons generated by the filament. Metal tubes (130, 132) are mounted in bores (106) of insulator blocks (104, 105). Metalized ends (150) of the insulator blocks are brazed into bores (122) in the base. A rod (130, 132) attached to the deflector is slid into the tube and the deflector's position and alignment are gauged and accurately set. The rod and tube are crimped to set the deflector position then welded.

Abstract: A multi-channel RF cable trap (70) blocks stray RF current from flowing on shield conductors (114) of coaxial RF cables (60) of a magnetic resonance apparatus. An inductor (116) is formed by a curved semi-rigid trough (80) constructed of an insulating material coated with an electrically conducting layer. Preferably, the inductor (116) and the cable follow an “S”-shaped path to facilitate good electromagnetic coupling therebetween. The RF cables (60) are laid in the trough (80) and the shield conductors inductively couple with the inductor (116). A capacitor (82) and optional trim capacitor (83) are connected across the the trough of the inductor (116) to form a resonant LC circuit tuned to the resonance frequency. The LC circuit inductively couples with the shield conductors (114) to present a high, signal attenuating impedance at the resonance frequency. The resonant circuit is preferably contained in an RF-shielding box (84) with removable lid.

Abstract: A diagnostic medical imaging system (10) includes an imaging apparatus (100) having an examination region (112) in which a subject (20) being examined is portioned. The imaging apparatus (100) obtains, at first resolution, a plurality of first image slices of the subject (20). The first image slices are loaded into a storage device, and a data processor combines subsets of first image slices to generate a plurality of second image slices having a second resolution lower than the first resolution. The subsets each includes a number n of contiguous first image slices. A display (152) having a plurality of view ports including a first view port which depicts one or more selected second image slices and a second view port which depicts one or more first image slices which are constituents of one of the second image slices depicted in the first view port.

Abstract: A three-dimensional fast spin echo (FSE) scan is performed by stepping (220) through a plurality of phase encode k-space views from a computed view list (210). The view list is computed such that (i) magnetic resonance echoes having a selected image contrast are encoded in the center of k-space, (ii) adjacent data lines in k-space have similar contrast, and (iii) common planes of data lines in k-space are completed at regular intervals. As each data line is read, it is Fourier transformed (230) and stored (240) within a fast-access memory (52). Once a plane of data lines is acquired, it is Fourier transformed (250) along a second direction using a plurality of parallel processors (54). The twice-transformed data is stored (260) in conventional memory (56). Once all of the phase encode views on the view list are acquired, a final Fourier transform (60) along a third direction is performed (270), rendering a volumetric image representation.

Abstract: A non-rectangular central kernel (200, 400, 500) of magnetic resonance image data is collected and stored in an acquired data memory (44). A non-rectangular peripheral portion (210, 410, 510) of magnetic resonance image data adjacent the central kernel (200) is collected and stored in the acquired data memory (44). A phase correction data value set (54) is generated from at least a portion of the central and peripheral data value sets. A synthetic conjugately symmetric data set (220, 420, 520) is generated (60) from the peripheral data set and phase corrected (60) using the phase correction data value set (54). Unsampled corners of k-space are zero filled. The central, peripheral, and conjugately symmetric data sets are combined (80) to form a combined data set. The combined data'set is Fourier transformed (82) to form an intermediate image representation (84), which may be exported for display (90) or used for a further iteration.

Abstract: A CT scanner (10) for obtaining a medical diagnostic image of a subject includes a stationary gantry (12), and a rotating gantry (14) rotatably supported on the stationary gantry (12) for rotation about the subject. A fluid bearing is interposed between the stationary gantry (12) and the rotating gantry (14) by means of radial and axial fluid bearing pads, (100) and (102) respectively. The fluid bearing provides a fluid barrier which separates the rotating gantry (14) from the stationary gantry (12). In a preferred embodiment, the fluid bearing provides for quieter CT scanner operation at high rotational speeds. Moreover, eliminating the physical contact between the gantries minimizes wear and optimizes longevity.

Abstract: A quadrature RF coil assembly (48) is employed for quadrature excitation and/or reception in an open or vertical field magnetic resonance apparatus. The quadrature RF coil (48) includes a plurality of parallel rung elements (70, 72, 74, 76, 78). A pair of electrical conductive end segments (80, 82) connect the plurality of rung elements. Capacitive elements (CV, CA) interrupt a central rung element and the end segments. Preferably, the capacitive elements (CV, CA) are arranged in a high-pass configuration such that the two highest resonant modes, an odd mode (90) and an even mode (92), are tuned to have peak responsivity to a common imaging frequency. The odd mode (90) is responsive to magnetic fields which are normal to the coil (48), while the even mode is responsive to magnetic fields which are parallel to the coil (48) and perpendicular to the main magnetic field.

Abstract: A tunable radio frequency birdcage coil (26, 34) has an improved tuning range for use with a magnetic resonance apparatus. The coil includes a pair of end ring conductors (60, 62) which are connected by a plurality of spaced leg conductors (L2, L4, . . ., L26) to form a generally cylindrical volume. Both the end rings and the leg conductors contain reactive elements, preferably capacitors (C2, C4, . . ., C124). The radio frequency coil also includes a pair of tuning rings (100, 120) for tuning the reactive elements (C2, C4, . . ., C124), which each include a non-conductive support cylinder (110, 130) and a plurality of tuning bands (120, 122, . . ., 142 and 150, 152, . . ., 172) which extend axially along the outer surface of the support cylinder (110, 130). The tuning rings (100, 120) are rotated or translated with respect to the leg conductors (L2, L4, . . ., L26) in order to vary capacitance and inductance of the coil (26, 34) to tune the (26, 34) coil to the desired resonant frequency.

Abstract: A black blood magnetic resonance angiogram is produced by exciting dipoles (52) and repeatedly inverting the resonance (541, 542, . . . ) to produce a series of magnetic resonance echoes (561, 562, . . . ). Early echoes (e.g., (561, . . . , 568)) are more heavily proton density weighted than later echoes (e.g., (569, . . . , 5616)), which are more heavily T2 weighted. The magnetic resonance echoes are received and demodulated (38) into a series of data lines. The data lines are sorted (60) between the more heavily proton density weighted data lines and T2 weighted data lines which are reconstructed into a proton density weighted image representation and a T2 weighted image representation. The proton density weighted and T2 weighted image representations are combined (90) to emphasize the black blood from the T2 weighted images and the static tissue from the proton density weighted image. The combination processor (90) scales (92) the PDW and T2W images to a common maximum intensity level.

Abstract: A nuclear gamma camera employs a virtual contouring technique in order to maximize the portion of transmission radiation fan beams (32a, 32b) which pass through a subject (12). A plurality of radiation detector heads (20a-20c) having radiation receiving faces and a plurality of radiation sources (30a, 30b) are mounted to a gantry (16). An orbit memory (42) stores clearance offset orbit (45) around the subject and a subject support (10). A tangent calculator (46) calculates virtual lines (48a, 48b) between the radiation sources (30a, 30b) and the corresponding radiation detector heads (20a, 20b). The virtual lines (48a, 48b) correspond to edge rays of the transmission radiation fans (32a, 32b). A shift calculator (50) calculates and sends shift commands to a motor orbit controller (52) which controls rotational and translational drives attached to the detector heads (20a-20c).

Abstract: An asymmetric sampling scheme for use with a nuclear medicine gamma camera facilitates collection of a full set of higher resolution emission data and lower resolution transmission data with one complete 360° rotation of the gantry. The gantry (16) contains a plurality of radiation detectors (20a-20c) and at least one adjustably mounted radiation source (30a). During a scan, the gantry (16) is incrementally rotated about a subject receiving aperture (18) by a predetermined step size throughout a first 180° of a rotation (P1, . . . , P6). The gantry (16) is then rotated about the subject receiving aperture (18) by one-half the predetermined step size (P7 or P8). The gantry (16) is then incrementally rotated about the subject receiving aperture (18) by the predetermined step size throughout the remaining 180° of the scan (P8, . . . , P2). Emission data collected during the second half of the scan (P8, . . . , P12) is interleaved into the data from the first half of the scan.

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. Heat is carried away from the anode to a bearing shaft (54) which rotates relative to a stationary rotor (42) on forward and rear lubricated bearings (44P, 44R). The heat is directed away from the forward bearings (44F), by a core (70) of a thermally conductive material, such as copper, disposed in a central cavity (60) within the shaft. Annular insulating regions (74,76) are optionally defined between the core and the bearing shaft adjacent the races to increase the thermal path between the anode and the races. The reduction in temperature of the forward bearings results in a decrease in the evaporation rate of the lubricant (46) and a corresponding increase in the lifetime of the x-ray tube.

Abstract: A magnetic resonance apparatus includes a multi-mode receiver assembly which facilitates operation in both a quadrature combination mode and phased array mode. The multi-mode receiver assembly includes a receiver coil assembly (30) comprising a first RF coil assembly (32) and a second RF coil assembly (34). A signal combining circuit, which includes a switch means, performs at least one of combining and splitting magnetic resonance signals received by the first and second RF coil assemblies (30, 32). The application of a DC bias potential to the switch means switches the multi-mode receiver assembly into the quadrature combination mode in which the received magnetic resonance signals are phase shifted and combined into a quadrature signal and an anti-quadrature signal. The absence of a DC bias potential to the switch means switches the multi-mode receiver assembly into the phased array mode in which the received magnetic resonance signals are phase shifted and passed individually to corresponding receivers.

Abstract: An interactive virtual endoscopy system 10 includes a CT scanner 12 or other non-invasive examination apparatus which examines an interior region of a subject 14 in an examination region 16 and generates data indicative thereof. The data is stored in a volume image data memory 20. Using a sequence generating computer 22, a human operator 24 generates a sequence of sphere-mappable panoramic views of selected portions of the CT data along a viewpath in the patient 14. The sequence generating computer includes a view renderer 182 for rendering a plurality of views which in total cover the entire visual space about a viewpoint on the viewpath within the subject. A view compositer 240 combines the plurality of views into a full image covering the entire visual space about the viewpoint. The sequence is transferred to a server 26 which processes the data and makes it available for remote access.

Abstract: A tomographic scanner includes an imaging device for obtaining images of the anatomy of a patient. A localizer device such as an articulated arm includes a base portion mounted in a fixed relationship to the imaging device and a free end adapted for selective movement into varied positions near a patient body disposed on the imaging device. A guide device such as grid lattice is attached to the free end of the arm. A position transducer associated with the localizer device generates information as to the position of the localizer and hence the position of the guide device in scanner coordinates. The guide device contains a plurality of needle guides. The position of the guide device is displayed in relation to images of the anatomy of the patient. This information is used by the operator to guide the insertion of brachytherapy seeds in a desired pattern and location in relation to the anatomy of the patient.

Abstract: A frame (A) of a diagnostic imaging device such as a CT scanner or an MRI device has a bore defining a patient examination region (12). A first x-ray source (B) is mounted to a frame (C) for rotation around the examination region (12). An arc of first radiation detectors (14) detects x-rays which have traversed the examination region. A first image reconstruction processor (18) reconstructs a tomographic image representation from signals generated by the first radiation detectors. A fluoroscopy device (D) is mechanically coupled to the diagnostic scanner for generating and displaying at least substantially real-time fluoroscopic projection image representations on a display monitor (60). A second x-ray source (32) transmits x-rays to an amorphous silicon flat panel radiation detector (36). A second image reconstruction processor (58) reconstructs the fluoroscopic projection image representations from signals generated by the flat panel radiation detector (36).

Abstract: A magnetic resonance imaging system includes a patient couch (10) which selectively positions a patient relative to an examination region (14). An imaging coil (B) is disposed adjacent to a region of interest for receiving magnetic resonance signals emanating from the patient. A processor (48) both controls the imaging event and processes received signals from the imaging coil. A plug and socket assembly (24, 26) having a proximal component and a distal component relative to the imaging coil provides selective electrical connectivity between the imaging coil (B) and the processor (48). A non-volatile memory device (86), such as a 1-WIRE™ EEPROM, is affixed to the proximal component of the plug and socket assembly (24, 26) for storing a variety attributes associated with the imaging coil. The memory device is most conveniently mounted to a coaxial connector (110).

Abstract: Data collected from a cone beam scanner is reconstructed by defining a plurality of oblique surfaces (44) which are reconstructed into a reconstruction cylinder (C). An interpolator (52) identifies non-redundant rays that intersect a center point of each oblique surface (70) along with rays tangent to surface rings on each oblique surface (72, 74). Data from the non-redundant rays is weighted by a first data processor (54). A second data processor (56) convolves the weighted data and passes it to a backprojector (58) which backprojects the data into an image memory (60). The oblique surface reconstruction technique facilitates the use of conventional two-dimensional convolution and backprojection techniques that enjoy relative computational simplicity and efficiency as well as three-dimensional reconstruction techniques that use a minimum number of projections.