Abstract: Method and apparatus for scatter-glare correction in x-ray diagnostic images from a patient. A reference object placed between the x-ray source and the subject is imaged in superposition with the subject without completely blocking any area of the subject image. The density distribution of the reference object is designed to have very small spatial correlation with the density distribution of the subject. The scatter-glare component is modeled by convoluting the primary component with a parameterized response function. During post-processing of the digital image, the unknown parameters of the response function are adjusted to minimize a cost function based on the expectation that the correlation between the reference object and the subject should be small and that the values of the parameters not deviate significantly from the estimated values for a typical patient.

Abstract: A high speed, digitally based, signal processing system which accepts directly coupled input data from a detector with a continuous discharge type preamplifier and produces a spectral analysis of the x-rays illuminating the detector. The system's principal elements are an analog signal conditioning section, a combinatorial logic section which implements digital triangular filtering and pileup inspection, and a microprocessor which accepts values captured by the logic section and uses them to compute x-ray energy values. Operating without pole-zero correction, the system achieves high resolution by capturing, in conjunction with each peak value from the digital filter, an associated value of the unfiltered signal, and using this latter signal to correct the former for errors which arise from its local slope terms. This correction greatly reduces both energy resolution degradation and peak centroid shifting in the output spectrum as a function of input count rate.

Abstract: In an improved CT scanner calibration method and apparatus, a radiation beam, for example an x-ray beam, is directed at a plurality of radiation detectors. The beam is attenuated by a phantom of known attenuation characteristics. The detectors generate measured attenuation data from the attenuated beam. The measured attenuation data is back-projected to generate a measured phantom image. The measured phantom image is converted to an ideal phantom image. The ideal phantom image is forward projected to generate ideal attenuation data. Calibration values for each detector channel in the scanner are generated by cross-referencing the ideal and measured attenuation data. In a preferred embodiment, this cross-referenced data is compressed and stored in a look-up table for referencing during later interrogation of subjects.

Abstract: A computer-implemented method of identifying suspect masses in digital radiologic images and a system for computer-aided diagnosis of such images in which the images are thresholded at a large number of threshold levels to discriminate spots and a two stage classifier is applied to the spots. The first classification stage applies multiple rules predetermined from a training set of images, to a relatively computationally inexpensive set of initial features, namely area, compactness, eccentricity, contrast, and intensity variance for each spot. More computationally expensive features, namely edge orientation distribution and texture features, are computed only for spots that are accepted by the first classification stage to points for these spots in an expanded feature space.

Abstract: The method comprises the following stages: first the attenuation function of at least three reference materials are determined across a wide x-ray spectrum and projection functions (F.sub.p1, F.sub.p2, F.sub.p3, F.sub.p4) forming a base are derived therefrom, then the attenuation function in said x-ray spectrum of at least one target material is determined and the attenuation function of each target material is projected onto said base; further, for each point of the object (1), the attenuation function of the object (1) is determined in said x-ray spectrum and projected onto said base, and the projections so obtained are compared with the projection from each target material and from this comparison an inference is made whether at least one target material enters the constitution of the object (1) at the point of inspection.Application: luggage inspection and control.

Abstract: A method of resampling of a sinogram from a fan beam SPECT includes the steps of angular resampling of the sinogram using frequency modulation, and thence transfers resampling of the sinogram using linear interpolation. This permits the use of parallel geometry algorithms in quantitative work without the expected degradation of resolution or the introduction of artifacts.

Abstract: This invention relates to an anode for use in an X-ray tube and a method of manufacturing the anode, and to a stationary anode X-ray tube. An anode base formed of copper or the like includes a recess formed in an end surface thereof and having an upwardly diverging inner peripheral wall. An anode target material such as tungsten is directly deposited in the recess by chemical vapor deposition.

Abstract: An X-ray tube has an anode and a photocathode inside a vacuum envelope and an electron multiplier is disposed between them. Such an electron multiplier may be a plurality of sequentially disposed dynodes or a microchannel plate. Because of the secondary electron emission from such an electron multiplier, a higher-power radiation is obtained without requiring a high optical power level to generate photoelectrons. The vacuum envelope may be of a rotary type with the anode and photocathode having annular regions.

Abstract: The present invention, in one embodiment, is a system for performing image reconstruction from raw projection data acquired in a tomographic scan. More specifically, the system implements an estimation algorithm for raw projection data which does not require fully pre-processing all raw projection data for image reconstruction. Particularly, raw projection for a base view is pre-processed to generate pre-processed projection data for the base view. A linear calibration algorithm generates a linearization vector using at least a portion of the fully pre-processed projection data for the base view. The linearization vector is then applied to raw projection data for subsequent views to generate estimated pre-processed projection data for such subsequent views.

Abstract: A device and a process for producing tomograms by means of an X-ray diagnostic device which has a C-frame-like mount (7) on which a radiation transmitter (5) and a planar detector as radiation receiver (6) are arranged at opposite ends facing each other. Various signals stored in memory (17, 18, 19, 27) are used by a signal processing device (4) in the calculation of processed image signals. These signals include signals (I.sub.P) relating to the central point of rotation (31) for the scanning operation, and signals (.DELTA.S, .DELTA.U) for correction geometric distortions and/or vignetting effects and/or the film-focus distance.

Abstract: A method of manufacturing an X-ray optical element. The element consists of a body of a material having a shape memory. At a high temperature, i.e. a temperature beyond the transition temperature of the material, the body is pressed so as to impart a first, desired shape. A surface of the body is thus shaped for example, as a logarithmic spiral or as another curved shape. After cooling to a low temperature, i.e. a temperature below the transition temperature of the material, a second, machinable shape is imparted to the body, preferably a flat surface. A number of precision operations can be performed on this second, machinable shape, for example polishing to a surface roughness of 0.5 nm RMS. Subsequent to this precision operation, the body is heated and resumes its first, desired shape which is retained after cooling. The body can be provided, if desired, with a comparatively thin surface layer which is also polished in the flat shape and which bends when the body resumes the desired shape.

Abstract: An apparatus, article of manufacture and method of creating an image of uncompressed matter from compressed matter are disclosed, such as a method of creating an image of uncompressed human breast tissue from an x-ray image of breast tissue compressed in the mammography process. The method embodiment includes the steps of dividing the compressed matter into a plurality of volumetric cells; collecting intensity data from the compressed matter, for each volumetric cell of the plurality of volumetric cells, to form volumetric cell data; and utilizing a deformation state lens and the volumetric cell data, creating the image of uncompressed matter.

Abstract: A density distribution of an object to be examined is obtained, for example by X-ray computed tomography or magnetic resonance imaging, and an accurate dimension of a detail of the object is derived from density values of a corresponding relevant detail of the density distribution and density values outside the relevant detail. Preferably, a reduction of a maximum density value of the relevant detail is compensated on the basis of density values outside the relevant detail.

Abstract: In an X-ray apparatus, an X-ray film is placed in an closed space formed by front and rear sensitizer screen supports and a closing member fixed to one of the sensitizer screen supports so that a part of the X-ray film projects outside the closed space. The closed space is evacuated so that the sensitizer screens are brought into close contact with opposite sides of the X-ray film under vacuum. The front and rear sensitizer screen supports are movable between the X-raying position and a retracted position shifted from the X-raying position and are movable relative to each other in the retracted position between a closing position where the supports form the closed space together with the closing member and an open position where the supports form therebetween a wedge-shaped space flaring upward to permit insertion and removal of the X-ray film into and from the space.

Abstract: There is provided a radiotherapy system comprising: a radiotherapy planning CT system integratedly having an X-ray scanner member for acquiring image data of a diagnostic portion of a subject by irradiating X-rays to the subject, said diagnostic portion including a lesion, a radiotherapy planner member for displaying the image data and producing radiotherapy plan data including a position data of an isocenter and a contour data of a radiation field limiting radiations from a virtual radiation source irradiated into the diagnostic portion, and a positioning member for automatically pointing a marking position on the subject based on the position data of the isocenter; and a radiotherapy apparatus for carrying out radiotherapy on the basis of the therapy plan data.

Abstract: In accordance with the principles of the present invention, image reconstruction errors which occur when using an area detector having a plurality of rows of detector elements defining a height for the detector that is smaller than the cone beam image, can be avoided by correlating an amount of orthogonal translation applied to line segments L extending across the detector towards top and bottom edges thereof that are used for calculating Radon derivative data, with the spacing between adjacent rows of the detector elements that are at the top and bottom edges of the detector. In a preferred embodiment the detector comprises a plurality of M rows of detector elements centered between the top and bottom edges of the detector, and an additional N rows of detector elements adjacent the M rows, at both of the top and bottom edges of the detector (where N may equal 1).

Abstract: A method of reconstructing an image in a medical imaging system comprises the steps of detecting transverse rays and oblique rays using a limited range of projection angles. The limited range of projection angles is achieved by either limiting the range of rotation of the detectors at each position along the z axis, or by causing the detectors to trace a continuous-motion helical path along the z axis. Data is then rebinned to create a stack of partially-complete sinograms corresponding to individual transverse slice images corresponding to, in the aggregate, a three-dimensional image. Because of the limited projection angles, each sinogram represents an incomplete data set. The rebinning includes, for each oblique ray, identifying among the sinograms the images intersected by the ray, and, applying to each of the sinograms associated with the images intersected by the ray an increment that is representative of the ray.

Abstract: A computed tomography (CT) system utilizes a ring suppression filter for suppressing ring artifacts in a CT image. The system generates projections at a plurality of projection angles, and each projection includes one measurement of a plurality of projection data signals. The ring suppression filter includes a high pass filter, a histogram generator, and a combiner. The high pass filter generates a measurement of an error signal corresponding to each of the measurements of one of the projection data signals, and each of the error signal measurements is representative of the high frequency components in a portion of one of the projections. The histogram generator generates a histogram signal representative of a relationship between the measurements of the error signal and the measurements of the projection data signal. The combiner combines the measurements of the error signal and the histogram signal to generate a plurality of measurements of a ring corrected signal.

Abstract: The invention provides a system for and method of precalibrating the position of the focal spot of an X-ray tube before its installation in a CT scanner system so that the focal spot of the tube is properly aligned with the off-focal aperture, slice-defining aperture and detectors of the scanner system. The precalibration is performed using an interface registration support that receives the X-ray tube and supports the X-ray tube on a mount provided in either the precalibration system or the scanner system. The mount of the precalibration system duplicates the mount of the scanner system, so that desired position of the focal spot in the scanner system relative to the scanner system mount is duplicated in the precalibration system relative to the precalibration system mount.

Abstract: The method of the present invention combines an ensemble of truncated partial cone beam projections to synthesize a complete virtual projection. The individual partial projections are obtained with CT scanners, where for each partial projection the investigated object is positioned at precise locations specified by formulas described in the present application (e.g., formulas (3), (4), (6) and (18) for linear cone beam synthetic scanner arrays or formulas (9)-(13), (20), (21) and (25)-(27) for circular cone beam synthetic scanner arrays). Prior to the actual reconstruction, the partial cone beam projections are combined to form a complete virtual projection, equivalent to a projection one would obtain by using a sufficiently large detector.