Abstract: A method is provided for generating an image of a three-dimensional (3D) volume from a plurality of slices corresponding to a scan of the 3D volume, each of the plurality of slices comprising slice data for sample points within an image plane, each of the sample points being stored sequentially in rows of scan lines, the method comprising the steps of: selecting a permutation matrix such that each of the sample points stored in the scan lines of all of the plurality of slices can be projected in a sequential order without requiring the slice data to be transposed for two out of three dominant viewing directions respectively corresponding to two of out of three dimensions; and rendering the image by accessing the sample points in a voxel-by-voxel, row-by-row, and slice-by-slice sequence.

Abstract: A method of correcting aberrations caused by target x-ray scatter in three-dimensional images generated by a volumetric computed tomographic system is disclosed. The method uses a Monte Carlo simulation to determine the distribution of scattered radiation reaching the detector plane. The geometry for the scatter calculation is determined using the uncorrected three-dimensional tomographic image. The calculated scatter is used to correct the primary projection data which is then processed routinely to provide the corrected image.

Abstract: Sheet-shaped objects can be detected by analyzing a neighborhood of voxels surrounding a test voxel. If the density is sufficiently different, then the voxel is associated with a sheet object. Sheet objects can also be detected by eroding the CT data so as to eliminate voxels associated with thin objects. Remaining objects are then subtracted from the original data, leaving only thin sheet-shaped objects. If the number of voxels having densities below a predetermined threshold exceeds a predetermined number, then it is assumed that the test voxel is a surface voxel and is removed from the object. A connectivity process can be applied to voxels to combine them into objects after sheets are detected. A dilation function can then be performed to replace surface voxels. A corrected mass can be compared to mass thresholds. Bulk objects can be detected by a modified morphological connected components labeling (CCL) approach. A merging process can be used to reconnect related items.

Abstract: Sheet explosives can be detected by analyzing voxels surrounding a test voxel. If the density is sufficiently different, it is concluded that the test voxel is associated with a sheet object. Sheet objects can also be detected by eroding the CT data then subtracting from the original data, leaving only thin sheet-shaped objects. A connectivity process can be applied to voxels to combine them into objects after sheets are detected. A dilation function can then be performed to replace surface voxels. A corrected mass can be computed and compared to mass thresholds to classify the object as to whether it poses a threat. Multiple mass thresholds can be used. Bulk objects can be detected by a modified morphological connected components labeling (CCL) approach which performs a series of erosion and dilation steps to separate adjacent objects in the data such that they can be individually labeled and analyzed.

Abstract: A source applies imaging energy that passes through an object being imaged and is then detected by a detector. A scanning trajectory causes the detector to provide a Cauchy data set of measured cone beam data to a processor. The processor extrapolates by use of John's equation such that missing cone beam data is determined. The measured cone beam data and the determined cone beam data together provide a complete data set for exact image reconstruction.

Abstract: An apparatus and method is provided for coordinating two fluoroscope images, which permits accurate computer-based planning of the insertion point and angle of approach of a needle, drill, screw, nail, wire or other surgical instrumentation into the body of a patient, and subsequently guides the surgeon in performing the insertion in accordance with the plan.

Abstract: An image reconstructing method in relation to an X-ray CT apparatus for shifting, sequentially by a predetermined angle, a reconstructed image for a projection angle in a predetermined range so as to obtain a continuous reconstructed image, in which one normal reconstructed image is obtained as follows: First, 180.degree. amount of parallel beam projection data, which is obtained by converting fan beam measurement data into parallel beam data, is divided at a predetermined angle so as to obtain each partial reconstructed image for each partial segment. Then, weight-imposing is performed on the plurality of partial reconstructed images obtained, and the weight-imposed images are superposed, thus obtaining the one sheet of normal reconstructed image. At that time, concerning partial reconstructed images the view angles of which are in an opposing relationship to each other, a weighted average thereof is determined.

Abstract: A portable and preferably hand-held X-ray generator for use in intraoral and other X-ray applications, and a new process of dental image acquisition which utilizes a novel receptor holder physically linked to the lightweight, portable generator, and a unique, articulating arm and cradle which allows one generator to be used in multiple operatories. The system's generator has a reduced X-ray output and much smaller focal spot area than conventional dental X-ray generators. This reduced X-ray output reduces the overall patient X-ray burden. The smaller focal spot also allows for improved resolution in the final image.

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: A method and apparatus for determining an optimized radiation beam arrangement for applying radiation to a tumor target volume while minimizing radiation of a structure volume in a patient, which uses an iterative cost function based on a comparison of desired partial volume data, which may be represented by cumulative dose volume histograms and proposed partial volume data, which may be represented by cumulative dose volume histograms for target tumors and tissue structures for delivery of the optimized radiation beam arrangement to the patient by a conformal radiation therapy apparatus.

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 method for point reconstruction and metric measurement on radiographic images comprises the following steps: positioning a fluoroscope for producing a fluoroscopic image, in a position where an operator, such as a physician, can observe points inside a patient's body on which points at least one of reconstruction and metric measurement are to be carried out; positioning a positioning device on the patient's body at an arbitrarily selected point F visible in a radiographic image, designating target points T.sup.i, being points to be reconstructed, by the operator on the radiographic image; finding planes .pi..sup.i passing through the X-ray source and a line FT.sup.i as describe in the step I and II in the invention disclosure; rotating the fluoroscope to a new position and taking a new radiographic image from this new viewpoint, designating target points T.sup.i, being points to be reconstructed, by the operator the physician on the new radiographic image; computing first the orientation of vectors Ft.sup.

Abstract: A computer system and method solve the problem of getting a useful three-dimensional representation of an object like the spine using a small amount of data. This is done by gathering three-dimensional data in the form of a set of 2D computer tomography (CT) slices of a patient's bones and a coaxial set of 2D CT scout images, which are digital two-dimensional X-ray images that can be produced by a CT scanner; extracting from each of these three-dimensional data sets a corresponding stack of 2D contours; and constructing a 3D geometric model of the object. The main features of spinal deformation are captured by integrating these two sets of three-dimensional data, and constructing from them a three-dimensional geometric model of the spine. Scouts are usually used to monitor CT scan acquisition. Here, they are also used as an essential source of data.

Abstract: A method and system for the correction of artifacts in computed tomography ages. Artifacts may occur at a crossover channel in computed tomography images. Sets of interpolation data about the crossover channel and extended interpolation data are generated as extensions of the interpolation data. The extended interpolation data overlaps with a portion of the interpolation data. The overlapping portion includes the crossover channel where the artifact may occur. The overlapping portion is determined by threshold channels which may be automatically selected by the system according to the invention. In this overlapping portion, feathering weights are applied to the interpolated data and the extended interpolated data. New data values are defined to using the feathering weights which eliminate the crossover artifact and produce continuous data. The feathering weights are chosen to meet certain criteria.

Abstract: A system and method extracts object boundaries in computed tomography images that have been corrupted by noise. The system and method find object boundaries in tomography images by finding edges in sinogram data, thereby providing a segmentation method that is insensitive to the image noise introduced by the process of image reconstruction from projections. The boundary-detection system uses projection data, and optionally tomographic image data, to detect the boundaries of objects in tomographic images. The system is of particular value for boundary-detection in images corrupted by reconstruction artifacts, such as CT scans of hospital patients who have implanted metal prostheses. The system is applicable to recovering the boundaries of convex objects, and the convex segments of the boundaries of concave objects (though not the complete boundaries of the concave objects themselves).

Abstract: Sheet-shaped objects can be detected by analyzing voxels surrounding a test voxel. If the density different from the mean density then the test voxel is associated with a sheet object. Sheet objects can also be detected by eroding the CT data. Remaining objects are then subtracted from the original data removing with surface voxels, being removed. A connectivity process combines voxels into objects after sheets are detected A dilation function replaces surface voxels removed by erosion. A corrected mass can be compared to mass thresholds to classify the object. Multiple mass thresholds can be used, each of which is associated with a particular density range based on the density of an expected threat object. Bulk objects can be detected by a modified morphological connected components labeling (CCL) approach. A merging process can be used to reconnect related items, The system can also identify objects that contain liquids.

Abstract: A computer system and method solve the problem of getting a useful three-dimensional representation of an object like the spine using a small amount of data. This is done by gathering and combining three-dimensional data in the form of (a) a set of 2D computer tomography (CT) slices of a patient's bones with (b) a set of 2D CT scout images, which are digital two-dimensional X-ray images that can be produced by a CT scanner. The main features of spinal deformation are captured by integrating these two sets of three-dimensional data, and constructing from them a three-dimensional geometric model of the spinal. Scouts are usually used to monitor CT scan acquisition. Here, they are also used as an essential source of data.

Abstract: A scanning and data acquisition method and apparatus for three dimensional (3D) computerized tomographic (CT) imaging of a region-of-interest (ROI) in an object, wherein image reconstruction processing is applied to a plurality of sets of 2D cone beam projection data, each set being acquired on a 2D detector at a corresponding plurality of scan path source positions. A first image reconstruction processing step comprises applying a mask to each set of the projection data so that data inside the boundaries of each mask form a corresponding plurality of masked 2D data sets. The next step comprises ramp filtering of each masked 2D data set along a plurality of parallel lines formed therein, to generate a corresponding plurality of filtered 2D data sets. Each filtered 2D data set is a calculation of a first estimate of Radon derivative data determined from a given set of the 2D cone beam projection data.

Abstract: An x-ray imaging system provides automatic adjustment of x-ray tube voltage and current based on an identification and removal of background pixels in the image and a calculation of the functional relationship between voltage and current and dose for the particular imaged object as deduced from two exposures at different voltages. Real-time image distortion removal and image rotation are accomplished by computer processing using a generalized image transformation polynomial. Scatter in the image is reduced by calculating a scatter map based on a blurring of the received image and normalizing the scatter map to point scatter measurements made with an x-ray occluder eliminating direct exposure of certain areas of the image. Improved signal to noise ratio in a moving x-ray image is provided by averaging stationary portions of the image over a longer time than the moving portions of the image.

Abstract: A system and method to improve the quality of noisy computer tomography (CT) images that have been generated by a CT scanner running on low-power. The image noise is 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 remote sites with limited access to electric power, and relies only on data that are available from standard medical CT scanners.