Abstract: A film thickness measuring method comprises the steps of measuring reflectances of X-rays on a film, extracting interference oscillations from the measured X-ray reflectances, and Fourier transforming the interference oscillations to compute a film thickness of the film, an average reflectance being given by fitting the measured X-ray reflectances to an analysis formula including a term of a product of a power function of an incident angle, which expresses attenuation of reflectances on a smooth surface of the film and an exponent function which expresses influence of roughness of the surface of the film, and a constant term expressing a background added to the product; the interference oscillations being given by using the measured X-ray reflectances and the average reflectance. The film thickness measuring method can extract interference oscillations of a reflectance curve by a method including arbitrariness and by a simple procedure.

Abstract: A plurality of axial images covering a region of interest in a subject to be treated are scanned and voxel data of the subject are produced from the axial images. The provisional location of an isocenter and the direction of radiation are determined over the axial images. A DRR of the subject viewed from the source of radiation is developed in accordance with the provisional isocenter location, the radiating direction, and the distance between the isocenter and the radiation source. The DRR is displayed together with three cross section images which represent an isocenter plane including the isocenter and arranged vertical to a line extending between the isocenter and the radiation source, a gantry rotation plane including the isocenter, and a plane including the isocenter and arranged vertical to both the isocenter plane and the gantry rotation plane. Each of the three cross section images indicates cross-hair ROI representing the other two planes and a cross-hair ROI representing the direction of radiation.

Abstract: A method of performing image reconstruction in a gamma camera system comprises the steps of performing a transmission scan of an object about a number of rotation angles to collect transmission projection data and performing an emission scan of the object about numerous rotation angles to collect emission projection data. The outer boundary of the object is then located based on the transmission projection data. Information identifying the boundary is then either stored in a separate body contour map or embedded in an attenuation map. The information identifying the boundary can be in the form of flags indicating whether individual pixels are inside or outside the boundary of the object. The emission projection data is then reconstructed, using the attenuation map if desired, to generate transverse slice images.

Abstract: A computer is provided for calculating input data for an X-ray machine which is about to be used for making an X-ray of a body part. The computer has a multiplicity of input devices each dedicated to inputting particular information that should enter into the input information for an X-ray machine including a series of input devices each dedicated to one pathological disease that the body to be X-rayed may have, input devices dedicated to particular body parts, and an input device dedicated to body part thickness. A program causes the computer to compute the input data for the X-ray machine based on the information fed to the computer via the input devices.

Abstract: There is provided a radiotherapy system comprising: 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: Prospective abnormal patterns in a radiation image of an object are detected in accordance with an image signal representing the radiation image. A probability density function of the image signal, which corresponds to a region, that is inward from a contour of each of the prospective abnormal patterns having been detected, and a neighboring region, is formed. Probability density function information in accordance with the probability density function is obtained. A definite prospective abnormal pattern, which is among the prospective abnormal patterns having been detected and has a high level of probability that it will be the true abnormal pattern, is detected in accordance with the probability density function information.

Abstract: A data processing technique for X-ray computerized tomography (CT) calculates the difference of two pieces of data having a same X-ray trajectory and existing on both sides of a plane of concern, and accumulates the differential value in a coordinate-correspondent buffer of respective xy coordinates on the X-ray trajectory. It repeats the operation for raw data of at least one turn on one side of the plane of concern, and stores the accumulative values in the buffers together with the z-axis position of the plane of concern. It repeats the operation while varying the z-axis position within a prescribed range on the plane of concern, and infers, based on the distribution along z-axis positions of the accumulative values in the buffers of same xy coordinates, the z-axis position of sharp varying plane of X-ray absorption coefficients relevant to the xy coordinates.

Abstract: The present invention, in one form, is a system for obtaining data measurement signals for producing a tomographic image of an object in a multislice scan. More specifically, detector cells in at least one channel of a detector array are electrically coupled, or ganged, so that the ganged channel provides one data measurement signal to be transmitted through the gantry slip ring. The signal distribution in the z-direction for the ganged channel is then determined using signals obtained by adjacent non-ganged detector cells.

Abstract: An x-ray backscatter tomography system includes a collimated x-ray source for directing a collimated beam towards a target at a select position and orientation, a first detector array for measuring photons scattered at a selected first angle, and a second detector array for measuring photons scattered at a selected second angle different from the first angle. The system is also responsive to the first and second detectors for calculating the density and atomic number of the target.

Abstract: The present invention, in one form, is a method for improving image quality in Computed Tomography systems by using a partial volume artifact estimation algorithm. In accordance with one embodiment of the algorithm, an object of interest is scanned to generate image data. The image data is segmented into low attenuation data and high attenuation data. A gradient image is generated for two adjacent slices of the image data. The gradient image is then forward projected and squared. The squared gradient image is an estimation of partial volume artifacts in the image data, and therefore is removed from the image data.

Abstract: Emission tomography enables locations and values of internal isotope density distributions to be determined from radiation emitted from the whole object. In the method for locating the values of discontinuities, the intensities of radiation emitted from either the whole object or a region of the object containing the discontinuities are inputted to a local tomography function .function..sub..LAMBDA..sup.(.PHI.) to define the location S of the isotope density discontinuity. The asymptotic behavior of .function..sub..LAMBDA..sup.(.PHI.) is determined in a neighborhood of S, and the value for the discontinuity is estimated from the asymptotic behavior of .function..sub..LAMBDA..sup.(.PHI.) knowing pointwise values of the attenuation coefficient within the object. In the method for determining the location of the discontinuity, the intensities of radiation emitted from an object are inputted to a local tomography function .function..sub..LAMBDA..sup.(.PHI.

Abstract: A stimulable phosphor sheet, on which a radiation image of an object has been stored, is exposed to stimulating rays, which cause the stimulable phosphor sheet to emit light in proportion to the amount of energy stored thereon during its exposure to radiation. The emitted light is detected by a photoelectric read-out device, and an image signal representing the radiation image is thereby obtained. Threshold value processing is carried out in accordance with the obtained image signal, and a prospective abnormal pattern is thereby detected from the radiation image. A predetermined threshold value, which is used in the threshold value processing for detecting the prospective abnormal pattern, is set to be a small value as the amount of change in the image signal corresponding to the region in the vicinity of the prospective abnormal pattern becomes large.

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, an overscan weighting algorithm generates weighting factors to be applied to projection data to generate base image projection data. An update weighting algorithm generates update weighting factors to be applied to the base image projection data to generate subsequent image projection data.

Abstract: A computed tomography method and system where a voxel of a subject irradiated with x-rays is divided into an plurality of sub-voxels, and backprojection data is obtained for the sub-voxels. Projection data for the sub-voxels can be weighted before backprojecting, or the projection data can be backprojected and then weighted. With the method according to the invention, instead of backprojecting data on a straight line passing through the center of a voxel, the beam passing through the entire voxel is backprojected. Also, the method and system weights the sub-voxels using a space-variant function. The weighting can be applied to discrete sub-voxels or integration can be used with infinitely thin sub-voxels. The present invention is a more accurate method and can take into account of spreading of the x-ray beam.

Abstract: An image processing method includes multi-resolution decomposition to decompose an input image into frequency-band images, which are subsequently filtered according to an order statistics filtering. Preferably, a finite impulse response median hybrid is employed. The filtered frequency-band images are synthesized to form the filtered output image.

Abstract: In an x-ray computed tomography apparatus with low radiation exposure to the patient, marks are additionally imaged during scanning of the patient, by which the geometry of the image can be determined. The marks are arranged above and/or below a region of interest in the measurement field on rings and are imaged by the x-ray beam.

Abstract: A primary object of the invention is to provide a method and system for detecting humans present in a restricted space, particularly, in a commuter train, a building, etc., by using an infrared sensor capable of detecting the presence of humans, and for judging the ratio of human occupancy in that space. To accomplish this object, according to the invention, the infrared sensor is installed, for example, on a ceiling near the center of a room, and the whole room space is scanned by the infrared sensor to detect in which region of the room a human is present. The proportion of human presence regions thus detected to the whole detection region is determined as the ratio of human occupancy. More specifically, a designated space is detected by the infrared sensor, and only human presence regions are extracted from that space; then, the ratio of human occupancy in the room is estimated from the ratio of the area of the extracted human presence regions to the area of the whole detection area.

Abstract: A computed tomography apparatus which generates an image of an examined subject using Fourier reconstruction with a gridding algorithm operates so that this algorithm is efficiently implemented by employing a hardware unit in the form of an ASIC, which produces the additional formation of contributions in the Cartesian frequency matrix, derived from the polar support points.

Abstract: A method of automatically segmenting the bone regions in a digital radiograph of a body extremity comprising the steps of: providing a digital radiographic image of a body extremity having one or more digits; estimating the upper and lower threshold values of the provided image; binarizing the provided image by a binarization system which uses the estimated upper and lower threshold values to produce a bi-tonal image; removing noise from the binarized image by a noise removal system; processing the noise removed binary image by a skeletonization technique in order to form an initial estimate of the central axis of each body extremity digit; approximating the locus of points generated by the processing step by a linear fit system; joining lines with near end points with a line linking system which results in a piece wise linear approximation of the central axis for each body extremity digit; for each point along the axes, generating perpendicular projections which extend a fixed pixel distance; for each perpen

Abstract: Frequency signals of a plurality of different frequency bands are obtained by transforming each of image signals into a multi-resolution space. Each image signal represents one of radiation images of a single object, which have been formed respectively with a plurality of kinds of radiation having different energy distributions and in which different images of at least part of the object are embedded. Signal components of the frequency signals, which are of an identical frequency band and correspond to different image signals, are weighted with weight factors, which are set in accordance with the frequency band, the signal components representing corresponding picture elements in frequency images represented by the frequency signals. The weighted signal components of the frequency signals are subtracted from one another. Difference signals are thus obtained for the plurality of the different frequency bands.