Abstract: Light spots are irradiated onto an optical disk and are detected as signals. A selection is made to receive as an input one of the detected signals from the light spots. The use of two light spots in a signal processing system permits writing information with one light spot and then reading it with the other to confirm the write state or erase state of the information.

Abstract: During acquisition of X-ray attenuation measurements of a patient being imaged, the measurements are processed to determine error factors for each detector in the system. In doing so, an average value is calculated for each detector from the X-ray attenuation measurements acquired during a scan of the patient. The set of average values should increase and decrease monotonically going toward and away from the value in the set for center detector. Deviation from such monotonic variation indicates a calibration error and is used to change a calibration factor in the signal processing circuit for the corresponding detector.

Abstract: A method and apparatus for identifying an unknown gas by generating an infrared spectrum of the unknown gas using an infrared spectrophotometer that includes a circular variable interference filter, compressing the infrared spectrum of the unknown gas, and comparing the compressed infrared spectrum of the unknown gas to a library of compressed infrared spectra of reference compounds. After comparison, the compressed spectra that most closely match the unknown gas are decompressed and displayed. Because frequency characteristics of circular variable interference filters vary from filter to filter, information designating these frequency characteristics for the particular filter employed are used in generating the infrared spectrum of the unknown gas.

Abstract: Computerized tomography provides three-dimensional imaging by applying cone beam energy to an object to be imaged. The energy passes through the object and is detected. The resulting cone beam data is efficiently processed to provide Radon data on polar grid points on a series of vertical planes. The Radon data is calculated by initially defining a Radon circle on each of the coaxial vertical planes. Radon derivative data is calculated at intersection points between the Radon circle and the radial lines. The values of Radon derivative data are binned according to the nearest grid point or nearest two grid points. Values are stored in the bins for each point in a particular plane until values for all of the planes have been supplied. The values for all the points are recalculated with each of a series of source positions, corresponding to the relative positioning of the source of cone beam energy and the object being imaged.

Abstract: An x-ray generator has a power rectifier connected to a high-frequency inverse rectifier and having a high-voltage transformer supplied by the rectifier. In order to achieve low losses in the operation of the high-voltage transformer with a low internal capacitance, the electrical windings of the high-voltage transformer are provided with an insulation having a thickness which is greater than the thickness which would be required solely to accommodate the maximum voltage load.

Abstract: A limited number of views or projections, e.g., two, are used to generated a reconstructed image of an object. In order to improve the quality of the image, terracing and smoothing functions are implemented. In addition, the reconstructed image may be divided into objects and background prior to terracing and smothing and the object and background can be reconstructed separately. Further, after the reconstructed image is generated threat and texture analyses of the reconstructed image may be performed.

Abstract: Measurements are made on a sample (1) to obtain an experimental profile (2) having structural features (3, 4) determined at least in part by the given characteristic and an expected profile (5) calculated for the sample using selected parameters. A degree of smoothing is applied to the experimental profile (2) to reduce the structural features (3,4) thereby producing a smoothed experimental profile (21 a) and the same degree of smoothing is applied to the calculated profile (5) to produce a smoothed calculated profile 51 a. The smoothed calculated profile (51 a) is compared with the smoothed experimental profile (21 a) to determine the difference between the smoothed profiles. The calculated profile is then modified by varying at least one of the parameters until the smoothed modified profile fits the smoothed experimental profile.

Abstract: Compensating for vignetting (loss of brightness at the edge of an image) is achieved by electronically multiplying the pixel-values of the vignetted image by a gain characteristic so as to obtain an unperturbed image. A gain characteristic pertaining to a particular vignetting effect is formed by a set of correction factors for all pixels. These correction factors are obtained from the image of an object having a spatially homogeneous brightness distribution. Various gain characteristics can be stored so that vignetting is compensated for even when the adjustments of the imaging system are varied. When, in order to improve spatial resolution, the image formed on the output screen of an image intensifier in an x-ray examination apparatus is split into two sub-images which are subsequently recombined, the vignetting effects in either of the sub-images are inevitably different due to the use of a beam splitter.

Abstract: A system for recording fewer of the events that are caused either by Compton scatter photons or by gamma radiation interacting with lead. The system locally determines the energy spectrum and fits the determined energy spectrum with a trial function composed of a photopeak component of known energy shape, but unknown magnitude and a Compton scatter component having a theoretically derived energy shape and an unknown magnitude for each pixel of the image. The trial function is locally fitted to the measured energy spectrum to obtain the values of both the Compton Coefficient and the gamma radiation interacting with lead. This enables removal of Compton contamination and also the contamination caused by interaction of the gamma photons with lead components.

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. A cone beam reconstruction method, which accounts for the divergence of the rays of a fan beam of x-rays, is used to reconstruct multiple narrow slices which are combined to provide a larger slice with an improved slice profile. The conical shape of the fan beam causes some voxels to be scanned more than once for a given beam angle and this extra data is weighted and combined with its counterpart data to improve the quality of the image.

Abstract: Element identification and concentration calculation can be conducted with precision by correcting waveform distortion caused by the energy resolution of a detection system. A smoothing process is effected on a measured waveform of fluorescent X-rays obtained from an object to be measured. A device function of the detection system is obtained for each analytic element, based on the energy resolution of the detection system for a fluorescent X-ray energy value of each analytic element. A deconvolution process is effected on the measured waveform thus smoothed, by using the device functions of the detection system. Analytic elements are identified and concentrations of the analytic elements are obtained from the waveform data after the deconvolution process. The measured waveform is compensated for absorption in a beryllium window prior to smoothing.

Abstract: Apparatus and methods for Compton scattering tomography employ a source of monoenergetic gamma rays and a detector capable of detecting the energy of scattered photons and determining the detector location both disposed on one side of an object to be imaged. Based on analysis of the measurement of the energy of the detected photons and the detector locations, a circle of possible scattering locations is determined as to each scattering event. By performance of a number of experiments as a function of detector location and energy, the density of the object can be reconstructed by filtering and back-projecting the data to yield an image responsive to variation in the density of the material of the object to be imaged.

Abstract: The position, size, structure, and the like of each particle can be accurately detected. Gray image data of a tomographic image group having a clear positional correlation in a sample where particles are distributed is obtained to obtain three-dimensional gray image data of each particle. Binarization of a density of each pixel data of the three-dimensional gray image data is performed to obtain three-dimensional binary image data of each particle. Three-dimensional shrinkage of the three-dimensional binary image data is performed to convert binary image data of each particle to binary image data of only a central point thereof, thereby the position of each particle is three-dimensionally confirmed.

Abstract: An image processing technique especially useful in processing digital radiographic images. A method for finding a histogram region of interest for improved tone scale reproduction of digital radiographic images includes the following steps. A digital radiographic image is randomly sampled with a sample having an appropriate size to delineate an object of interest. Each sample is processed using texture analysis techniques to extract a plurality of texture features. Using the extracted texture features, each sample is classified with a previously trained neural network classifier to determine its class. Last, the pixel values belonging to the same class are accumulated to form separate histograms for each class. Each of the histograms are then used to optimize tone scale reproduction.

Abstract: An artificial intelligence system is used with a conglomeration of fluorescence data to provide a method of improving recognition of an unknown from its spectral pattern. Customized neural network systems allow the ultimate organization and resourceful use of assumption-free variables already existing in a total scanning fluorescence database for a much more comprehensive, discrete and accurate differentiation and matching of spectra than is possible with human memory. The invention provides increased speed of fingerprinting analysis, accuracy and reliability together with a decreased learning curve and heightened objectivity for the analysis.

Abstract: A contaminating-element analyzing method and an apparatus of the same are disclosed. Differential smoothing process is performed for a measured waveform of a fluorescent X-ray obtained from an object to be measured so as to detect a peak of the measured waveform, the object containing a contaminating element. A model function with variables which are initial parameters with respect to each peak of the measured waveform is provided so as to constitute a model waveform. A nonlinear optimizing process is performed using the method of least squares of the model waveform and the measured waveform so as to decide initial parameters of each model function and to obtain discriminated waveforms. A contaminating element is identified corresponding to each of the discriminated waveforms and obtaining an integrated intensity of a discrete waveform of each of the identified contaminating elements.

Abstract: A scanning method and apparatus for providing a geometrically corrected large angle whiskbroom scan of a portion of the earth's surface using a linear array of radiation-sensitive detectors mounted in a low earth orbiting satellite contemplate: scanning a portion of the earth's surface with the array to define an irregularly-shaped swath on the surface which represents a field of view of the array, defining a regularly-shaped ground area of interest within the field of view of the array, dividing the area of interest into a number of pixel lines fewer in number than the number of detectors in the array and extending generally perpendicularly to the array, subdividing each pixel line into a plurality of pixels, each of which encompasses at least a portion of the field of view, selectively combining outputs from the detectors to provide a data signal representative of each pixel, and reconstructing a representation of the ground area of interest from the data signal.

Abstract: A method of image processing is provided for generating an image of an object in a computer X-ray tomography apparatus having an X-ray source and a detector. The method desirably permits relatively coarse spacing between adjacent detector views and correspondingly lowers exposure to X-ray radiation while maintaining a high resolution image. The method includes the step of acquiring actual detector data for multiple views of the object. After actual detector data is acquired for adjacent views of the object, the actual detector data from these adjacent views is interpolated to obtain virtual detector data between the adjacent views as though a virtual detector had been placed therebetween. The actual detector data and the resultant virtual detector data is then mapped into Radon space. The process is repeated until Radon space is sufficiently filled with actual detector data and virtual detector data to permit image reconstruction.

Abstract: A radiation therapy apparatus, for a radiation therapy machine providing an irradiation of a tumor at 360.degree. about the tumor within a plane, determines a distribution of charges in a conductor that would produce a potential energy field matching the desired dose to the tumor in the plane. The fluence of any given ray through the tumor may be determined by summing the charges along the ray's path. The distribution may include areas of no irradiation which may require negative fluences. Physically realizable non-negative fluences are obtained by an iterative process of adjusting an input dose map in light of the actual dose produced by the calculated fluences.

Abstract: Streaking artifacts in a computed tomography x-ray image are reduced by adaptively filtering each set of projection data. The adaptive filter produces an error vector (.theta.) by low-pass filtering the projection data (P) and subtracting the error vector (.theta.) from the projection data (P) prior to image reconstruction. A window function generator controls the low-pass filter as a function of x-ray detector readings.