Abstract: An emission tomographic system which includes a gantry and a detector is described. The system automatically adjusts the detector attitude to maintain the detector at a desired orientation with respect to a patient during a scan. The system includes a tilt drive and processor coupled to the gantry and the detector. The processor receives signals indicative of changes in the gantry pitch angle, and uses such signals to determine appropriate changes in detector tilt. For each change in gantry pitch angle, the processor executes an algorithm relating gantry pitch angle to detector tilt angle, and determines an appropriate responsive change in detector tilt angle. The tilt drive then tilts the detector in accordance with the appropriate responsive change.

Abstract: A train control system is for a train comprising at least first and second train segments including a brake pipe being separated between adjacent train segments. The train control system preferably comprises a first control subsystem for installation in a locomotive of the first train segment and a second control subsystem for installation in a locomotive of the second train segment. The first and second control subsystems communicate with one another for controlling train braking. The system also preferably includes a third control subsystem for installation in a railcar adjacent an end of the first train segment. This third control subsystem preferably includes at least one pressure transducer for sensing brake pipe pressure adjacent the end of the first train segment, and at least one control valve for controlling brake pipe pressure adjacent the end of the first train segment.

Abstract: The present invention, in one form, is a system for performing image reconstruction from projection data acquired in a helical scan. More specifically, the system implements an incremental reconstruction algorithm for helical scan projection data which does not require filtering, weighting and backprojecting such projection data for generating each image. Particularly, a segmentation algorithm divides the projection into a plurality of segments so that subsequent images are generated by generating image data only for those segments that have changed from the base image.

Abstract: The present invention, in one form, is a method for correcting for artifacts caused by highly attenuating objects in a CT image data using a correction algorithm. In accordance with one embodiment of the algorithm, the highly attenuating objects are identified in the image data using the CT numbers from the image data. The segmented image data for each highly attenuating material are used to produce separate component images for each material. The component image data for each material is then separately forward projected to generate projection data for each material. The projection data for each material is then adjusted for the attenuation characteristic of the material to generate projection error data for each material. The resulting projection error data are then filtered and backprojected to produce error-only image data. The error-only image data are then scaled and combined with the original image data to remove the highly attenuating object artifacts.

Abstract: A correction algorithm for substantially eliminating "stair case" type artifacts in dental scans is described. In one specific embodiment, all high density object boundaries in the reformatted images are identified. To identify high density object boundaries, structures in the reformatted image are separated into two classes, namely, structure containing teeth and structure not containing teeth. Then, within each class, fuzzy logic is used to define the membership grade of each pixel. Particularly, linear interpolation is utilized to determine the boundary, and to reduce the probability that spike noise will be erroneously considered as high density objects, the N by N neighbors of the boundary candidate are searched to ensure that the number of pixels that belong to the high density object exceeds a certain predefined threshold. Such searching can be performed by summing the N by N neighbors of the membership function, .xi., and comparing the summation against a pre-defined threshold.

Abstract: Methods and apparatus for dose reduction in a computed tomography (CT) system are described. In one embodiment, the CT system includes a configurable multislice detector array and an adjustable source collimator. The detector array includes a photodiode cell array optically coupled to a scintillator array. The photodiode array includes a plurality of photodiodes arranged in rows and columns that may be combined to collect slice data from a number of inner and outer slices. The CT system also includes an x-ray source and a collimator. The x-ray source generates an x-ray beam that is collimated by the collimator to define the thickness of each outer slice. In operation, an operator determines the quantity and thickness of inner slices and the thickness of each outer slice. After altering the detector and collimator configuration, as defined by an operator, slice data for each inner slice and each outer slice is gathered.

Abstract: A combination of double and triple cell ganging which resolves any incompatibility between the number of detector channels and the lower number of DAS channels without requiring any significant hardware and software changes is described. In one specific embodiment, at least some detector cells on one side of the detector outside the FOV are wired in pairs, i.e., ganged, to form a set of 2 mm channels, and on the other side of the detector outside the FOV, at least some detector cells are wired together, i.e., ganged, to form a set of 3 mm channels. Such ganging of detector cells avoids having to make any significant hardware and software changes to known multislice CT systems.

Abstract: The present invention, in one form, is a method for performing image reconstruction from projection data acquired in a multislice helical scan. More specifically, helical weighting factors are generated and then applied to the collected data. The helical weighting algorithm provides a high quality image with a low level or number of artifacts is described. Such algorithm also reduces the total time required to reconstruct such an image.

Abstract: A CT system having an adjustable pre-patient collimator and a partial volume artifact reduction algorithm is described. In one embodiment, a scout scan is performed to collect scout scan data. Utilizing the scout scan data, the algorithm identified the boundaries and radius of a partial volume artifact producing object. The algorithm then determines an average attenuation coefficient and an attenuation index of the object. The object radius, the attenuation coefficient and attenuation index are then graded to identify the object. A collimator aperture index is then determined based upon a variation of the attenuation characteristic along the z axis for the identified object. Utilizing the collimator aperture index, the CT system computer adjusts the collimator aperture for the appropriate size to eliminate, or significantly reduce, partial volume artifacts.

Abstract: Filtering algorithms which offer tradeoffs between slice profile widening and the noise and mAs, reduction are described. In one embodiment, the FWHM is adjusted based on the helical pitch to provide a constant reduction of noise. The percentage increase of FWHM is a function of helical pitch as described below in more detail. The amount of projection data used to reconstruct an image is fixed, independent of the helical pitch. In another embodiment, a roughly constant percentage increase of FWHM is maintained while the amount of reduction of mAs or noise decreases as helical pitch increases. The amount of projection data used to reconstruct an image is also a function of helical pitches. The above described filters provide that for various helical pitches, the filter maintains the same amount of mAs or noise reduction, or maintains the same percentage increase of FWHM. Such filters can be implemented without significantly increasing the processing time.

Abstract: A programmable, medical imaging system which incorporates algorithms for enhancing the usability of the system for clinicians is described. With respect to programmability, and in one aspect, the present invention relates to a programmable system which includes a learn mode usable for script generation. In the learn mode, a user can rehearse a sequence of actions and save those actions to be replayed later. In another aspect, the present invention is directed to an algorithm which provides a non-blocking, synchronous interface to an underlying asynchronous architecture. Generally, the algorithm decouples the client-server portion of the application from the synchronous development environment. Using this algorithm, a programmer can develop a non-blocking, highly interactive, client-server application without having to resort to asynchronous programming techniques.

Abstract: A programmable, medical imaging system which incorporates algorithms for enhancing the usability of the system for clinicians is described. With respect to programmability, and in one aspect, the present invention relates to a programmable system which includes a learn mode usable for script generation. In the learn mode, a user can rehearse a sequence of actions and save those actions to be replayed later. In another aspect, the present invention is directed to an algorithm which provides a non-blocking, synchronous interface to an underlying asynchronous architecture. Generally, the algorithm decouples the client-server portion of the application from the synchronous development environment. Using this algorithm, a programmer can develop a non-blocking, highly interactive, client-server application without having to resort to asynchronous programming techniques.

Abstract: A nuclear imaging radiation system including a gamma camera which, in one embodiment, includes a scintillation crystal, a collimator and an array of photomultiplier tubes, is described. The collimator is positioned adjacent a face of the crystal, and defines a field of view. The array of photomultiplier tubes is positioned adjacent an opposite face of the crystal, and selected tubes outside the field of view are disabled so that light events outside of the field of view are not processed.

Abstract: A reduced field of view collimator for a nuclear imaging gamma camera is described. In one form, the collimator includes a gamma ray attenuating plate, several core plates, and a ramp member. The gamma ray attenuating plate is sized to substantially cover a scintillation crystal face, and includes an opening. The core plates extend from the attenuating plate at a periphery of the plate opening and define an outer periphery of a collimator core. The ramp member includes a ramp having a sloped surface, and is formed of gamma ray attenuating material. The ramp member is secured adjacent to at least one of the core plates so that the sloped surface extends substantially angularly with respect to the attenuating plate and the core plate.

Abstract: Cathode cup assemblies for an x-ray tube are described. In one embodiment, the cathode cup assembly includes a cathode cup, and a cathode insulator assembly. The cathode insulator assembly includes a filament lead tube, an insulator, and a nickel eyelet. The filament lead tube is inserted within the ceramic insulator so that a portion of the tube extends from the insulator. The nickel eyelet is brazed at a first end to the insulator. An outer surface of the nickel eyelet is brazed to the cathode cup to secure the cathode insulator assembly to the cathode cup. The brazed nickel eyelet enables filament leads to be positioned at a filament set height with respect to the cathode cup.

Abstract: A CT Fluoro system having an architecture and algorithms which facilitate increasing the frame rate and providing acceptable image quality is described. Generally, and in one embodiment, the system includes apparatus and algorithms that speed-up image reconstruction and reduce image artifacts that may result from such fast reconstruction. The fast reconstruction is achieved by performing, for example, view compression, channel compression, backprojection with reduced delay, and parallel processing.

Abstract: An emission tomographic system for imaging an object of interest is described. The system, in one form, includes a gantry and a patient table. A detector including a collimator is secured to the gantry, and a computer is coupled to the gantry and to the detector to detect and control the position of the detector relative to the table. The system is configured to determine a transmission measurement and generate a scatter fraction utilizing the transmission measurement. A dual energy window data acquisition algorithm then determines non-scatter photons in a primary energy window utilizing the scatter fraction.

Abstract: An electric motor for an x-ray tube of a medical imaging system is described herein. The electric motor includes a stator and a substantially cylindrical rotor. The stator includes stator winding slots and stator windings injected into the stator winding slots. The stator also has a stator bore. The rotor is rotatably mounted within a stator bore so that the rotor is coaxial with the stator bore. The rotor includes a rotor core, a plurality of rotor bars, and end rings. The rotor bars are at located in rotor bar openings at a periphery of the rotor. At least one of the rotor bars has a different cross-sectional area than one of the other rotor bars.

Abstract: The present invention, in one form, is a system for generating a high resolution image of an object from projection data acquired during a computed tomography scan. The system includes a gantry having an x-ray source which rotates around the object. The x-ray source emits an x-ray beam which is collimated with a collimator having a collimator aperture to define an x-ray beam width, or slice thickness. The projection data is reconstructed to generate image data for adjacent image slices. A deconvolution algorithm is applied to the image data to generate a deconvolved image having a finer, i.e., smaller, resolution than the collimator aperture.

Abstract: The present invention, in one form, is a system for generating a high resolution image of an object from projection data acquired during a computed tomography scan. The system includes a gantry having an x-ray source which rotates around the object and emits an x-ray beam toward a detector. The system identifies a region of x-ray beam movement and divides the region into subregions. Linear Q-CAL vectors are then generated for each subregion so that each vector is representative of detector gain in one of the subregions. These Q-CAL vectors are then applied to projection data to generate image data.