Abstract: Process and installation making it possible to reconstitute precise images of an area of interest (2) of an object (1) by reducing the errors produced by the contribution of the compliment of the object. A first series of measurements is carried out, where a conical beam (10) only takes in the area of interest of the object (2) and this is followed by a second series of measurements in which the beam takes in the entire object. A combination of the measurements of the two series is carried out in order to make them compatible and obtain a more accurate image of the area of interest (2).

Abstract: An x-ray CT system acquires a series of views during a scan and reconstructs a slice image by backprojecting the filtered projection data from each acquired view. Backprojection is facilitated by employing a Cordic processor that produces the angle (.gamma.) and distance (L) of each pixel location from the x-ray source. The angle (.gamma.) selects the proper value from the filtered projection data, and this value is divided by the square of the distance (L) to arrive at a value used to update the slice image pixel value.

Abstract: A cone beam scanning apparatus reduces image artifacts incident to cone beam geometry by decomposing an acquired image into soft tissue and bone and air images based on the density of the pixels in that image The soft tissue image is filtered to remove image artifacts caused by zones of incomplete frequency space data in the original projection image and is recombined with the bone and air image. The filtering applied is dependent on the location of the reconstructed image along the z-axis.

Abstract: In a computer tomography apparatus which conducts a spiral scan, many images can be calculated quickly from spiral data, because data from the region of only one slice thickness are required. From an initial image I.sub.lr (x) in the plane of a reference projection l.sub.r at a specific location along the system longitudinal axis and from an auxiliary image I.sup.d.sub.lr+1 (x) the computer recursively calculates a new image I.sub.lr+1 (x) at the distance d/N.sub.2.pi. from the initial image I.sub.lr (x) according to the equation:I.sub.lr+1 (x)=I.sub.lr (x)-I.sup.d.sub.lr+1 (x)whereby d is the slice thickness and N.sub.2.pi. is the number of projections on the circumferential angle 2.pi.. The auxiliary image I.sup.d.sub.lr+1 (x) was in turn also recursively acquired from its predecessor I.sup.d.sub.lr (x).

Abstract: An x-ray computed tomography system for helically scanning a patient translates the patient as projections of the patient at various beam angles are obtained. The projection data are weighted prior to reconstruction to account for multiply measured projection data and the deviation of the cone beam from a parallel beam approximation.

Abstract: A method of producing a tomographic image from x-ray projection data acquired during a helical scan with two fan beams, includes weighting selected data in each projection data array to account for data redundancy and distance from the image plane. Each weighted array of projection data is back projected and combined to form the desired slice image.

Abstract: An optical recording disk system, which has a light-activated silicon controlled rectifier (LASCR), a resistor, and a recording film in each pixel, is used to record the optical information form the write beam. The write beam triggers the LASCR, which behaves as an optical switch, and lets an electric current pass the LASCR to generate either a thermal effect or an electro-optical effect on the recording film.

Abstract: Noise reduction for use in an x-ray examination apparatus is provided for performing weighted temporally averaging in dependence on an amount of motion in parts of successive x-ray images. Further noise reduction is performed by combining temporal averaging with spatial filtering and motion detection. This reduces both noise breakthrough and the occurrence of trailers. In particular, noise breakthrough is appropriately reduced by hi-temporal filtering. Threshold-values for discriminating between noise and motion are computed on the basis of images generated by the x-ray detector.

Abstract: A first image collection memory collects two-dimensional image data within a predetermined energy window to constitute a fine matrix. A second image collection memory collects three-dimensional image data, including energy spectral information, to constitute a coarse matrix. Each pixel of the data collected in the second image collection memory is subjected to a scatter correction with energy weighted acquisition using a weight function. Correction coefficients are derived from a ratio between data before the correction and data after the correction, and by interpolation processing for each pixel in the fine matrix, and are applied to the image data collected in the first image collection memory. The data collected in the second image collection memory is subjected to two-dimensional low-pass filter processing.

Abstract: The present invention discloses a method and apparatus for generating Radon derivative data on locations proximate to a near uniformly spaced polar grid in a digitized Radon space for a cone beam computerized tomography (CT) implementation. Radon derivative data is determined for uniformly spaced coordinates in r, .theta. and .phi. directions.

Abstract: Imaging of a region of interest within a larger object is accomplished without the need for determining Radon derivatives of portions of the object outside a field of view which generally corresponds to the region of interest. The field of view and region of interest may be relatively large compared to a relatively small area detector used for the imaging. In order to provide a complete data set satisfying Radon completeness requirements with little or no collection of data from outside the region of interest, a source scanning trajectory uses a first circle, a second circle, and a helical portion connecting the first and second circles. The first and second circle and helical portion define a cylinder which is outside and surrounding the field of view, which is likewise a cylinder.

Abstract: A pulse transmission scintigraphic imaging system for providing image data for attenuation correction and fiducial alignment. The system includes a shuttered photon flood transmission source, secured opposite an Anger gamma scintillation camera by an adjustable armature, a motorized photon-occluding shutter mechanism for producing photon pulses from the photons emitted by the flood source and a gating system for providing a signal to the gamma camera indicative of the presence of a photon pulse (shutter mechanism open) or the absence of a photon pulse (shutter mechanism closed).

Abstract: Techniques and system for pre-processing cone beam projection data for reconstructing substantially free of interpolation-induced artifacts a three-dimensional computerized tomography (CT) image of a portion of an object are provided. Such techniques include identifying first, second and third regions on a surface array detector such that only cone beam projection data acquired in the identified regions is retained for subsequent processing. The identified regions cooperate to eliminate interpolation effects upon lines of integration situated relatively close to boundaries on the array detector and thus allow for reconstructing the substantially free of interpolation-induced artifacts CT image.

Abstract: Computerized tomography (CT) reconstruction of images is accomplished for asymmetric grids. After initial data acquisition and normalization, the asymmetric projection data is distorted by a compression process which effectively converts the data into symmetric data. The data may then be processed using Radon reconstruction procedures which convert projection data into object density functions. The object density functions or data which are provided are then subject to a stretching or extension procedure which compensates or reverses the initial distortion or compression. Cone beam imaging with asymmetric grids may be two-dimensional or three dimensional when utilizing the technique.

Abstract: A noise reducing method and associated apparatus for use in a medical radiographic imaging system wherein an image represented by an array of pixels is processed and the processed image is recorded on a recording medium or visualized on a display monitor. The processing comprises the steps ofa) decomposing an original image into a sequence of detail images or into an array of coefficients representing detail strength at multiple resolution levels and a residual image,b) pixelwise attenuating the detail images or the coefficient arrays according to the locally estimated amount of relevant signal present and in accordance with an estimated noise level,c) reconstructing a processed image by accumulating detail obtained from the attenuated detail images or from the attenuated detail coefficients, and further adding the residual image.

Abstract: A high repetition-rate laser plasma target source system and lithography system is disclosed. The target source system comprises in a preferred embodiment a liquid tank source and freezer which freezes microscopic particles into crystal shapes which are projected by a nozzle jet from a high repetition rate liquid-droplet injector into the path of a flashing laser beam, which results in producing soft x-rays of approximately 13 nm. Uncollected and unshot target crystals are collected and reliquified by a heater source in order to be recycled back to the liquid tank source. Optionally an auxiliary source and detector system can be used to allow for instantaneous triggering of the laser beam. The target source system can be incorporated into well known EUV lithography systems for the production of wafer chips.

Abstract: In a CT imaging system a baseline image is acquired prior to the injection of a contrast agent into the subject and a series of monitoring images are acquired which enable the affects of the contrast agent to be observed in real time. Regions in the baseline image may be selected with a cursor and the contrast enhancement amounts in these regions are calculated and displayed in both graphic and numerical form. By observing the changes that occur in the displayed information, the operator can determine the moment to begin the image scan for optimal image contrast.

Abstract: Non-invasive measurements of physiological chemicals such as glucose are made using infrared radiation and a signal processing system that permits the construction of a device suited for home use. The level of a selected physiological chemical in a test subject is determined in a non-invasive and quantitative manner by a method comprising the steps of: (a) irradiating a portion of the test subject with near-infrared radiation such that the radiation is transmitted through or reflected from the test subject; (b) collecting data concerning the transmitted or reflected infrared radiation using a detector; (c) digitally filtering the collected data to isolate a portion of the data indicative of the physiological chemical; and (d) determining the amount of physiological chemical in the test subject by applying a defined mathematical model to the digitally filtered data. The data collected may be in the form of an absorbance spectrum, i.e.

Abstract: A device for processing a measured signal corresponding to the intensity reflected, as a function of the glancing angle (.theta.) at an X-ray wavelength (.lambda..sub.RX), by a real multi-layer structure stacked on a substrate (100), which layers exhibit small differences as regards refractive index at their interfaces, transforms the function (f(.theta.)), corresponding to the reflected intensity signal measured as a function of the glancing angle (.theta.) in a range of glancing angles which is bounded by minimum and maximum angular values .theta..sub.min -.theta..sub.max, into a function (F(d)) corresponding to the intensity signal formulated as a function of the depth (d) within the real multi-layer structure, the function (F(d)) obtained enabling a direct representation to be formed of the depth of each interface (d.sub.1, d.sub.2, . . . d.sub.n) of the real structure, and of the associated reflected intensities.

Abstract: A computed tomography system includes an image reconstruction data generator for generating image reconstruction data for a desired slice plane of an object in accordance with measuring projection data, the image reconstruction data being obtained from measuring projection data obtained at each of a plurality of rotation positions of a radiation source, and an image reconstructor for obtaining tomographic image data of the object for the desired slice plane in accordance with the image reconstruction data. The image reconstruction data generator has the capability of grouping the measuring projection data into a plurality of groups respectively corresponding to a plurality of desired slice planes of the object, the desired slice planes being spaced apart from each other by a distance corresponding to one rotation position of the radiation source, with each of the groups corresponding to a continuous rotation range of 360.degree.