Abstract: A system and method reduce the noise, and hence improve the usefulness, of computer tomography (CT) images that have been corrupted by metal-induced reconstruction artifacts. Metal-induced reconstruction artifacts in CT images are reduced by restoring crucial quantitative image information. The system does not fail when applied to sparsely-sampled and/or low-resolution projection data and is clinically viable in that it is a method that can be embodied in a practical, real-world system that can be used routinely in hospitals and medical clinics, and relies only on data that are available from standard medical CT scanners.

Abstract: An object to be imaged is positioned between an x-ray source and an x-ray imager. The x-ray source is operated to direct x-rays through and around the object. Electrical signals representative of the intensity of the x-rays impinging on the x-ray imager are used to locate a boundary of the object, and an x-ray image is generated using this boundary. Alternatively or additionally, an x-ray image is generated using the highest frequency magnitude in the set of electrical signals.

Abstract: A method for the detection and localization of a surgical tool in a radiographic image, including an image of a surgical device and an anatomical background image, includes the steps of generating a radiographic reference image, including an image of a surgical device and an anatomical background image and applying an oscillating movement to the device. The method further includes the steps of generating a number k of radiographic images during the oscillating movement; subtracting each image from the reference image, so as to generate a difference image; and deriving the mathematical intersection of all of the reference images, whereby a resulting image results including only the image of the device on the radiographic reference image and substantially without the anatomical background image.

Abstract: A scanning and data acquisition method and apparatus for three dimensional (3D) computerized tomography (CT) imaging of an object, wherein a plurality of line integral derivatives for a respective plurality of line segments L formed in cone beam projection data acquired on a detector at a plurality of source positions, are calculated. The extent of line segments L in the data acquired at each of the source positions is determined by a mask formed by cone beam projections onto the plane of the detector of portions of the source scan path that are above and below the source position that acquired the cone beam data in which the line integral derivatives for line segments L are being calculated. The line integral derivatives calculated for a plurality of the line segments L are then backprojected onto a 2D space corresponding to the plane of the detector. Finally, the results of the 2D backprojecting step are 3D backprojected into a 3D space, thereby reconstructing a 3D image of the object.

Abstract: An apparatus and method for determining the orientation of a device with respect to an x-ray source. In one embodiment, the present invention is coupled to a medical device in order to determine the rotational orientation of the medical device with respect to the x-ray source. In such an embodiment, the present invention is comprised of a scintillator portion which is adapted to emit photons upon the absorption of x-rays emitted from the x-ray source. An x-ray blocking portion is coupled to the scintillator portion. The x-ray blocking portion is disposed so as to vary the quantity of x-rays which penetrate the scintillator portion based upon the particular rotational orientation of the medical device with respect to the x-ray source. A photon transport mechanism is also coupled to the scintillator portion. The photon transport mechanism is adapted to pass the photons emitted from the scintillator portion to an electronics portion.

Abstract: A nutating slice CT image reconstruction apparatus and method generates a set of projection data using helical cone-beam scanning. The three-dimensional projection data is used to reconstruct a series of planar image slices. The slices are selected such that they define a tilt angle and a rotation angle with respect to the longitudinal axes of the object being scanned. Successive slices have equal tilt angles but changing rotation angles such that normal axes of successive slices define a nutation and precession about the longitudinal axis of the object. Projection data for the tilted slices are formed of selected one-dimensional fan-beam data. As such, the projection data can be applied to conventional two-dimensional reconstruction approaches to generate an image. The projection data can also be used to generate two-dimensional projection images at one or more stationary projection angles through an object being scanned.

Abstract: In the present invention, an iterative process is provided for cone-beam tomography (parallel-beam and fan-beam geometries are considered as its special cases), and applied to metal artifact reduction and local reconstruction from truncated data, as well as image noise reduction. In different embodiments, these iterative processes may be based upon the emission computerized tomography (CT) expectation maximization (EM) formula and/or the algebraic reconstruction technique (ART). In one embodiment, generation of a projection mask and computation of a 3D spatially varying relaxation factor are utilized to compensate for beam divergence, data inconsistence and incompleteness.

Abstract: In an improved method and apparatus for cone-beam reconstruction, a technique for mitigating reconstruction error, referred to herein as successive approximation, incrementally improves the quality of the resultant image, with an exponential decrease in error at each succession. Projection data are collected and reconstructed to form a first reconstructed image containing error due to imprecision in reconstruction. The first reconstructed image is forward projected to generate intermediate projection data which are in turn compared to the collected projection data to generate error projection data. The error projection data are reconstructed to form an error image which is, in turn, used to correct the first reconstructed image . The result is a second image which is improved in image quality. The invention is applicable to a range of computed tomography applications, including medical scanning, baggage scanning, and industrial product scanning applications.

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: The device is an apparatus for infrared spectroscopy. A succession of collimated light beams throughout the middle and near infrared spectrum are impinged against a sample or samples and the diffuse component of the reflected light is measured throughout the spectrum. This diffuse component is analyzed by a neural network to determine such characteristics as content of the sample.

Abstract: A method and apparatus for reconstructing an image of an object using a three dimensional (3D) computerized tomographic (CT) imager having a cone beam radiation source and detector arrangement for acquiring measurement data. The source and detector arrangement is operated at a plurality of source positions along a spiral scan path so as to acquire a corresponding plurality of sets of measurement data representative of radiation attenuation caused by the object. Image reconstruction processing information required for processing of the acquired measurement data in a Radon space partitioned by plurality of vertically oriented coaxial .phi.-planes for reconstructing the image, is pre-calculated and stored in a hitlist. The stored information is pre-calculated on less that all of the .phi.-planes, but due to a symmetry that is induced in the reconstruction processing, the stored information can be used for calculating Radon data for all of the .phi.-planes that partition the Radon space.

Abstract: A method and apparatus for performing CT scans of baggage being carried or loaded onto commercial aircraft are described. The CT baggage scanner of the invention includes numerous features which provide the system with high baggage throughput on the order of seven hundred bags per hour as well as improved image quality and accurate target detection. In one aspect, the scanner includes an adaptive image reconstruction window which identifies data collected from the field of view that are not related to the baggage being scanned. These unrelated data are excluded from the image reconstruction process, resulting in greatly reduced reconstruction time and increased baggage throughput. The invention also includes the capability of performing calibration "air scans" with objects such as the system conveyor in the field of view.

Abstract: This invention describes a method for aligning radiation therapy beams with a treatment target of a patient. Diagnostic computer tomography scanning is used to map the treatment target in the patient's anatomy and to aid physicians in deciding where to aim the radiation therapy beams. Digitally reconstructed radiographs are generated from an intermediate 3-D image produced from the CT scans. These DRRs are compared with x-ray images taken of the treatment target's position taken at the time of treatment. A transformation equation is used to compare the DRRs and the x-ray images. A minimization equation is used to determine the similarity between the two sets of images. If the difference between the two sets fall below a determined minimum value, then the position of the treatment target is deemed correct and the radiation therapy begins. If the difference does not fall below the determined minimum value, then either the radiation beams or the treatment target is adjusted and the process is repeated.

Abstract: A two-step 3D Radon inversion processor for processing Radon data on a set of vertically oriented co-axial .phi.-planes that partition Radon space, wherein each of the .phi.-planes is sampled during the processing so as to have its own independent local Radon origin. In accordance with further principles of the present invention, a 3D Radon data generator generates Radon data on a set of vertically oriented co-axial .phi.-planes that partition Radon space, wherein each of the .phi.-planes is sampled so as to have its own independent local Radon origin, and a two-step 3D Radon inversion processor independently processes each of the .phi.-planes. Any shift of the local Radon origins with respect to a global coordinate system is compensated for during the 3D Radon inversion processing. Compensation for the origin shift may be made during or after a first step of the Radon inversion processing.

Abstract: An end mounting (2) for pivotally mounting a housing (5) of a ram (1) to a structure (3) is formed from a single solid piece of material. The end mounting (2) comprises a mounting block (9) which is secured to the structure (3), an end cap (10) which is sealably secured to the housing (5), and a connecting portion (14) which extends between the mounting block (9) and the end cap (10). The connecting portion (14) is of hour-glass shape, cross-section and extends the width of the mounting block (9) to form a plastic hinge. The connection portion (14) defines a pivot axis (18) at the waist (19) of the hour-glass shape about which the end cap (10) and the mounting block (9) are pivotal relative to each other.

Abstract: A feature detection apparatus includes a reflective imaging system, a transmissive imaging system, and memory for generating an image of a workpiece. The reflective imaging system generates a first bit image of a surface of the workpiece. The transmissive imaging system generates a second, different bit image of the density of the workpiece. The two images are then combined in memory into a more complete image that contains data describing the surface and interior of the workpiece. The apparatus also includes a filter for enhancing the combined bit image so that physical features of the workpiece are accurately detected. The filter is constructed to perform the following steps. For detecting a feature of interest, the filter determines a mean, standard deviation, and normal distribution of the image's pixel intensities.

Abstract: An x-ray computed tomography device and method where backprojection is performed with pixels each having their own back projection range. The range is determined using a two-dimensional completeness condition such that every line through a reconstructed slice must intercept the projection of the source orbit onto the plane of the slice. The completeness condition provides an adequate amount of data for the back projection to maintain quality of the reconstructed image while allowing a higher helical pitch ratio. This is advantageous in situations where fast scanning is desired, such as patient screening and CT-angiography. The method and device are preferably applied to a helical cone beam system. The backprojection can be performed using cone-beam projection data obtained with a helical scan or after sorting the projection data into parallel-beam ray-sums in the transverse plane while maintaining the cone angle.

Abstract: A nutating slice CT image reconstruction apparatus and method generates a set of projection data using helical cone-beam scanning. The three-dimensional projection data is used to reconstruct a series of planar image slices. The slices are selected such that they define a tilt angle and a rotation angle with respect to the longitudinal axes of the object being scanned. Successive slices have equal tilt angles but changing rotation angles such that normal axes of successive slices define a nutation and precession about the longitudinal axis of the object. Projection data for the tilted slices are formed of selected one-dimensional fan-beam data. As such, the projection data can be applied to conventional two-dimensional reconstruction approaches to generate an image. The projection data can also be used to generate two-dimensional projection images at one or more stationary projection angles through an object being scanned.

Abstract: A three-dimensional image is displayed on a display in a central projection method based upon a viewpoint which is placed at the inside of an object and a line of sight. In this case, a plurality of tomographic images interposed between the viewpoint and a projection plane are sequentially arranged and displayed on a display screen. Polygon visual field frames are formed at points of intersection of projection lines forming a polygon pyramid and each tomographic image, and the visual field frames are displayed on the display screen. Thereby, the position of the viewpoint and the line of sight with respect to the currently-displayed three-dimensional image showing the inside of the object can be easily detected, and the part of the object which is being displayed can be easily recognized.

Abstract: A nutating slice CT image reconstruction apparatus and method generates a set of projection data using helical cone-beam scanning. The three-dimensional projection data is used to reconstruct a series of planar image slices. The slices are selected such that they define a tilt angle and a rotation angle with respect to the longitudinal axes of the object being scanned. Successive slices have equal tilt angles but changing rotation angles such that normal axes of successive slices define a nutation and precession about the longitudinal axis of the object. Projection data for the tilted slices are formed of selected one-dimensional fan-beam data. As such, the projection data can be applied to conventional two-dimensional reconstruction approaches to generate an image. The projection data can also be used to generate two-dimensional projection images at one or more stationary projection angles through an object being scanned.