Abstract: A computerized tomography system including an X-ray source for emitting X-rays in a cone-beam shape, a two-dimensional X-ray image acquirer which is arranged so as to face the X-ray source and acquires an image of an object by using the X-rays; and rotator for rotating the X-ray source and the two-dimensional x-ray image acquirer around the object, wherein a three-dimensional reconstructed image is formed from the projection images acquired by the two-dimensional X-ray image acquirer while rotating the rotator. An iterative reconstruction calculator for forming the three-dimensional reconstructed image from the projection images is provided. The three-dimensional reconstructed image without artifacts can be acquired from a small amount of projection data.

Abstract: A high-energy photon imaging system including an imaging head, a signal processor, a data acquisition system and an image processing computer. The imaging head includes a detector comprising a plurality of closely-packed detection modules. Each detection module comprises a plurality of detection elements mounted to a circuit carrier. The detection elements produce electrical pulses having amplitudes indicative of the magnitude of radiation absorbed by the detection elements. The circuit carrier includes channels for conditioning and processing the signals generated by corresponding detection elements and for preparing the processed signals for further processing by a signal processor. Each conditioning and processing channel stores the amplitudes of the detection element electrical pulses exceeding a predetermined threshold. The detection modules employ a fall-through circuit which automatically finds only those detection elements that have a stored pulse amplitude exceeding the threshold.

Abstract: The object of the invention is to provide a bonding method for brazing an amorphous carbon (AC) material to a metal material or a ceramic material, and to provide an electron tube device having an input/output window made of the amorphous carbon material. The surface of the amorphous carbon (AC) material is roughened to form an irregularity. A brazing material is sandwiched between the amorphous carbon material and a metal material or ceramic material. The resultant structure is heated to braze the amorphous carbon material to the metal material or ceramic material. The electron tube device includes a sealed vessel having an opening portion, a peripheral portion of which is made of a metal material or a ceramic material. The electron tube device further includes a window, made of an amorphous carbon material and bonded to the peripheral portion of the opening portion with a brazing material, and having irregularity on a surface around the opening portion.

Abstract: The invention is a three-dimensional computed tomography method for inspecting and comparing actual geometry to predetermined geometry of an object. The method includes the following steps: A) three-dimensionally scanning the object using computed tomography to produce multiple slices of actual geometrical data of the object; B) processing the multiple slices of actual geometrical data into actual boundary data which defines internal and external boundaries of the object; and C) producing actual point cloud data from the actual boundary data. The method further includes comparing the actual point cloud data to object geometry predetermined data. The comparing may include outputting an image comparing the point cloud data to the predetermined data and the image may represent the geometry of non-conformance between the point cloud data and the predetermined data. The image may be rotated to present the non-conformance from different viewpoints around the feature.

Abstract: A method and apparatus for halfscan reconstruction in a CT scanning system using an asymmetric detector system are described. In halfscan asymmetric (HSA) reconstruction, a halfscan reconstruction approach is used for data acquired by the symmetric portion of the array, and a fullscan reconstruction approach is used to reconstruct data acquired by the asymmetric portion of the array. When scanning oversized subjects which extend beyond the symmetric field of view of the array, a halfscan reconstruction approach is used which applies a zero weighting to data acquired by the asymmetric portion of the array and ramps data acquired by the asymmetric portion to zero.

Abstract: An image processing apparatus includes a temporary memory for two-dimensionally mapping and temporarily storing image data containing image data regions corresponding to at least two image regions having similar shape and stored in an image data storing section, a CRT for reproducing an image based on the image data stored in the temporary memory, a pixel specifying section for specifying pixels corresponding to at least two equivalent points in at least two image regions having similar shape in the image displayed on the CRT, a data correcting section for effecting, between micro region image data corresponding to micro regions including coordinates of the at least two pixels specified by the pixel specifying section as center coordinates, rotation and movement correction and enlargement/reduction magnification correction on the micro region image data in the image data corresponding to one image region so that a rotation angle and an enlargement/reduction magnification of the one image region coincide with

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: A radiation source which generates a radiation cone-beam (14) and a two-dimensional radiation detector are spiralled continuously around and longitudinally relative to an imaging volume. Image data from the two-dimensional display is reconstructed (30.sub.1, 30.sub.2, . . . 30.sub.n) into a volumetric, physiological image stored in a subject memory (32). During an interventional surgical procedure with a surgical instrument (42), the x-ray source is gated to operate intermittently, e.g., at 60.degree. angular intervals, at a reduced radiation intensity by an x-ray tube control (40). The additional data is reconstructed into a three-dimensional image representation of the surgical instrument and stored in an instrument memory (34). An operator image selection processor (60) causes data retrieval circuits (62a, 62b) to retrieve like slices or other image representations from the subject and instrument memories.

Abstract: An improved data acquisition system filter, optimized for the time domain and for use in a computed tomography scanner of the type using x-ray focal spot wobble, includes a filter time response F(t) which is a function of the waveform w(t) used to drive the focal spot from one position to the other.

Abstract: A method of determining a trace gas concentration in a gas sample utilizing Fourier Transform Infrared Spectroscopy. The method includes the steps of(i) synthetically calibrating a spectrometer, and(ii) determining a spectral window within which to fit a calculated spectral trace to an experimental spectral trace by(a) choosing a series of candidate windows;(b) determining the likely error measure associated with a fitting of the spectral trace for each of the series of candidate windows;(c) utilizing the likely error measure associated with each of the fitting to determine a final window having substantially the lowest likely error measure; and(d) utilizing the final window as the spectral window.The calibration and the spectral window is then utilized to fit a calculated spectral trace to a spectral trace measured by the spectrometer and to determine the concentrations of constituent gases.

Abstract: A radiation CT apparatus comprises a radiation source for irradiating a subject with radiations, detection section having at least two detector columns to detect radiations allowed to pass through the subject, section for obtaining data to be backprojected in accordance with data detected by the detection section, and image reconstruction section for reconstructing a transmitted image of the subject, wherein the image reconstructing section includes first backprojection section for backprojecting detected data to a predetermined centering plane, and second backprojection section for backprojecting data backprojected to the centering plane to the voxels corresponding to backprojected data.

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.

Abstract: Method of correcting a radiation image for defects in the recording member. Defects in a member for recording a radiation image are corrected by generating a calibration matrix comprising for each pixel a correction value and by applying corresponding elements of the calibration matrix to the pixels of a recorded image. The values of the calibration matrix represent in each pixel the deviation of the value that is effectively obtained in a pixel when the recording member is subjected to a flat field exposure and the value that would be expected in the pixel. Different methods are described for determining the expected value in a pixel. Further, an overlay image is generated wherein local defects are visualised.

Abstract: An image forming apparatus includes an image data memory for storing image data, a temporary memory for two-dimensionally mapping and temporarily storing the image data stored in the image data memory, an image data selecting section for selecting image data from among the image data stored in the temporary memory, an image data enlarging/reducing section for enlarging or reducing the selected image data, an enlarged/reduced image data memory for two-dimensionally mapping and temporarily storing the enlarged or reduced image data, a graphic data memory for storing graphic data to be displayed on a CRT together with the image data, a data synthesizing section for selecting graphic data to be displayed from among graphic data stored in the graphic data memory and synthesizing them and the image data stored in the enlarged/reduced image data memory, a synthesized data memory for two-dimensionally mapping and temporarily storing the synthesized image data and graphic data, a data area selecting section for select

Abstract: An X-ray tube has a vacuum housing that accepts a cathode and an anode and that is provided with an electrically conductive beam exit window. During operation of the X-ray tube, the beam exit window lies at a negative potential and is electrically conductively connected via a resistance to a potential that is positive relative to the negative potential, this resistance being dimensioned such that, during operation of the X-ray tube, the difference in potential between the negative potential of the beam exit window and the positive potential lies on the order of magnitude of a few kilovolts.

Abstract: A system for and method of generating a reconstructed tomographic image is described using an asymmetric detector array during a helical scan. An improved helical weighting system applies a helical halfscan technique to data collected by a symmetric portion of an asymmetric detector system and applies a helical fullscan technique to data collected by an asymmetric portion of the asymmetric detector system. The preferred system comprises an equi-angle interpolator, a streak artifact suppression filter, and an isocenter interpolator that preserve the distinction between even and odd data points in parallel beam projection data.

Abstract: A method and apparatus for processing images received on an image sensor of rectangular configuration bounded by four outer edges and including a plurality of pixel elements arranged in a rectangular matrix includes the following operations: A. locating an initial rectangular-matrix region consisting of pixel elements determined to be free of an artifact; B. sequentially testing each pixel element along two contiguous outer edges of the image sensor, starting from the initial rectangular-matrix region, to determine whether the pixel value of the tested pixel element is sufficiently large to indicate the probability of an artifact, and for each such pixel element found to have such a pixel value, replacing its pixel value with another having a relation to the pixel value of its closest neighbours found to be free of an artifact, thereby cleaning the respective pixel element; and C. cleaning in a similar manner each of the remaining pixel elements.

Abstract: A computer tomography device is provided with a reconstruction unit (1) for deriving brightness values of an image from density values. An image processing system (2) for deriving corrected brightness values from the brightness values of the image is arranged to calculate the variation of brightness values of the image in the radial direction and in the tangential direction. The image processing system is also arranged to calculate the deviation between the variation in the radial direction and the variation in the tangential direction and to derive corrected brightness values from brightness values of the image and the deviation.

Abstract: An x-ray computed tomography system and method having a reconstruction processing circuit that interpolates projection data for an x-ray beam path from 2N detector elements in a detector array proximate to a point where the x-ray beam path intersects the detector array. The system and method can also extrapolate data from 2N detector elements when the x-ray path intersects the detector array in an uppermost or lowermost detector row. The system and method determines an overlap region between two x-ray beams and can perform backprojection in the overlap region based upon both of the overlapping beams. The system can also determine a border region in the overlap region and perform backprojection in the border region based upon the two overlapping beams and in the remainder of the overlap area based upon cone angles of the x-ray beams. The system can also cancel or attenuate image artifacts by varying the helical scanning pitch, and can apply position-dependent and/or angular-dependent weighting.

Abstract: In a method of processing an image the image is divided in one or more blocks. Separate blocks are spatially frequency transformed in that pixel-values of the blocks are transformed into spectral coefficients. A noise level of the image is estimated and reduced spectral coefficients are derived from spectral coefficients and the estimated noise level. Pixel-values for a processed block are synthesized from the reduced spectral coefficients and the processed blocks are assembled into a processed image. The noise level is estimated from the image information within the image. Preferably, a few parameters relating to the circumstances under which the image was acquired are also taken into account for estimating the noise level.