Abstract: A method and system for the detection of microcalcifications in digital mammograms. Digital mammograms are obtained and regions-of-interest (ROIs) are selected therefrom which contain suspected microcalcifications, either individual or clustered microcalcifications. The suspect ROIs are background-trend corrected, followed by Fourier transformation and power spectrum calculation to perform detection in the frequency domain. Detection can also be carried out in the spatial domain by omitting the Fourier transformation and power spectrum calculation. The ROI is then scaled for input into a neural network trained to detect microcalcifications. The neural network outputs ROIs with detected microcalcifications. The method and system can also include normalizing the background-trend corrected ROIs and imputing the normalized ROI to a shift-invariant neural network trained to detect microcalcifications.

Abstract: A method and system for computer-aided differential diagnosis of diseases, and in particular, computer-aided differential diagnosis using neural networks. A first embodiment of the neural network distinguishes between a plurality of interstitial lung diseases on the basis of inputted clinical parameters and radiographic information. A second embodiment distinguishes between malignant and benign mammographic cases based upon similar inputted clinical and radiographic information. The neural networks were first trained using a hypothetical data base made up of hypothetical cases for each of the interstitial lung diseases and for malignant and benign cases. The performance of the neural network was evaluated using receiver operating characteristics (ROC) analysis. The decision performance of the neural network was compared to experienced radiologists and achieved a high performance comparable to that of the experienced radiologists.

Abstract: A computerized scheme for the analysis of digitized medical images which provides enhancement of interval changes occurring in a pair of temporally sequential images. In the method and apparatus of the invention, a pair of images are digitized and then are subjected to image registration including a nonlinear warping of one of the images so that corresponding locations in the two images are aligned with each other. Subsequent to image registration, a subtraction process is performed in order to generate a difference between the warped and unwarped images. In this manner, slight opacities which are only present in the later image may be detected based on the subtraction of the registered images.

Abstract: An automated method and system for discriminating between normal lungs and abnormal lungs having interstitial disease and/or septal lines, wherein a large number of adjacent regions of interest (ROIs) are selected, corresponding to an area on a digital image of a patient's lungs. The ROIs each contain a number of square or rectangular pixel arrays and are selected to sequentially fill in the total selected area of the lungs to be analyzed. A background trend is removed from each individual ROI and the ROIs are then analyzed to determine those exhibiting sharp edges, i.e., high edge gradients. A percentage of these sharp-edged ROIs are removed from the original sample based on the edge gradient analysis, a majority of which correspond to rib-edge containing ROIs. After removal of the sharp-edged ROIs, texture measurements are taken on the remaining sample in order to compare such data with predetermined data for normal and abnormal lungs.

Abstract: A computerized method and system based on quantitative analysis of geometric features of various infiltrate patterns in chest images for the detection and categorization of abnormalities related to the infiltrate patterns. Chest images are digitized and a lung texture analysis is performed on a number of small regions of interest (ROIs) in order to determine a classification of normal or abnormal of the particular patient's lungs. If the lungs are determined as being abnormal, large ROIs with a 128.times.128 matrix are selected in order to cover the detected areas of abnormality. Overall background trend correction is then performed in these large ROIs using a 2D-surface fitting technique for isolation of the fluctuating patterns of the underlying lung texture. Opacities of interstitial infiltrates are identified from two processed images which are obtained by employing thresholding with a morphological filter and a line enhancement filter.

Abstract: A computerized method and system for reducing the number of false-positive detections of nodule candidates in the detection of abnormalities in digital chest radiography. The image is initially subjected to an image difference technique where the detection sensitivity is increased so as to avoid missing small nodules which might otherwise go undetected. Such a technique tends to increase the number of false-positives, however, leading to possible incorrect diagnoses of the radiographs. To reduce the number of false-positives, feature extraction techniques are applied to grown regions around the nodule candidates, in order to provide computer generated information concerning the candidates. A data base of parameters common to false-positives is compared to calculated parameters of a candidate of interest. The candidates with grown region parameters within the data base range common to false-positives are eliminated as being probable false-positive detections due to normal background anatomical features.

Abstract: A method and system for correcting a non-linear characteristic of an image, wherein an input image is digitized to produce digital image data representative of the image and a histogram of the digital image data is produced. At least a first pixel value characteristic of a variable under which the image was derived is extracted from the histogram. A plurality of non-linear correction curves relating original pixel values to corrected pixel values for different degrees of the variable are stored in a memory, and a particular one of the correction curves is selected based at least in part on the first extracted pixel value and a predetermined corrected pixel value. Corrected image data are then formed utilizing the selected correction curve by correcting each original pixel value of the image to a respective corrected pixel value based on the relationship therebetween defined by the selected correction curve, and a non-linearity corrected image is produced based on the corrected image data.

Abstract: A method and system for quantitation of blood flow rates by using digital subtraction angiographic (DSA) images, wherein the spatial shift of the distribution of contrast material injected into an opacified vessel in the acquired angiographic images is analyzed as a bolus of the contrast material proceeds through the vessel. In order to determine the distance that the bolus travels between image acquisitions, there is obtained from the DSA images the distribution of vessel contrast along the length of the vessel, called and "distance-density" curve. The distance that the contrast material travels during the time between two images acquisitions is determined by means of cross correlation of the two respective distance-density curves. The flow rate between the image acquisitions is calculated by multiplying this distance by the frame rate and the vessel cross-sectional area which is estimated from the vessel size assuming a circular cross section.

Abstract: A method for automated analysis of abnormalities in the form of lesions and parenchymal distortions using digital images, including generating image data from respective of digital images derived from at least one selected portion of an object, for example, from mammographical digital images of the left and right breasts. The image data from each of the digital images are then correlated to produce correlated data in which normal anatomical structured background is removed. The correlated data is then searched using one or more predetermined criteria to identify in at least one of the digital images an abnormal region represented by a portion of the correlated data which meets the predetermined criteria. The location of the abnormal region is then indicated, and the indicated location is then subjected to classification processing to determine whether or not the abnormal region is benign or malignant. Classification is performed based on the degree of spiculations of the identified abnormal region.

Abstract: An automated method and system to determine a number of parameters related to the size and shape of the heart as well as parameters related to the lungs from data derived from digital chest radiographs. A cardiac rectangle enclosing the heart and portions of the surrounding lung tissue is determined, and within the cardiac rectangle, horizontal and vertical profiles, and the first derivatives thereof, are determined. Based on these derivatives, cardiac boundary points on the left and right sides of the cardiac contour are determined, as well as diaphragm edge points. A predetermined model function is then fitted to selected of the determined cardiac boundary points to determine the cardiac contour. Tests are performed to determine whether or not the heart has an abnormal size or is a "tall" heart, and if so, corrective measures are taken. In a preferred embodiment, a shift-variant cosine function is used as a model function fitted to the selected cardiac boundary points.

Abstract: An optical image processing method and system in a radiographic system, wherein an image of an object is produced by an image intensifier and converted to video signal by a television (TV) camera system. A liquid crystal display (LCD) is placed bewteen the image intensifier and the T.V. camera system at a location shifted from a focal plane of the T.V. camera system. The liquid crystal display defines plural pixels which are controllable so that light produced by the image intensifier and impinging on the plural LCD pixels can be selectively attenuated by application of selected control signals to the LCD. Control signals are generated selectively based on predetermined parameters of the radiographic system and the image. These control signals are applied to the LCD to perform selective attenuation and corresponding dynamic range compression of light passing through respective LCD pixels, thereby to perform unsharp masking of the image produced by the image intensifier using the LCD.

Abstract: A method and system for detecting and displaying abnormal anatomic regions existing in a digital X-ray image, wherein a single projection digital X-ray image is processed to obtain signal-enhanced image data with a maximum signal-to-noise ratio (SNR) and is also processed to obtain signal-suppressed image data with a suppressed SNR. Then, difference image data are formed by subtraction of the signal-suppressed image data from the signal-enhanced image data to remove low-frequency structured anatomic background, which is basically the same in both the signal-suppressed and signal-enhanced image data. Once the structured background is removed, feature extraction, is performed. For the detection of lung nodules, pixel thresholding is performed, followed by circularity and/or size testing of contiguous pixels surviving thresholding. Threshold levels are varied, and the effect of varying the threshold on circularity and size is used to detect nodules.

Abstract: A novel method for determination of 3-D structure in biplane angiography, including determining the distance of a perpendicular line from the focal spots of respective x-ray sources to respective image planes and defining the origin of each biplane image as the point of intersection with the perpendicular line thereto, obtaining two biplane digital images at arbitrary orientations with respect to an object, identifying at least 8 points in both images which correspond to respective points in the object, determining the image coordinates of the 8 or more identified object points in the respective biplane images, constructing a set of linear equations in 8 unknowns based on the image coordinates of the object points and based on the known focal spot to image plane distances for the two biplane images; solving the linear equations to yield the 8 unknowns, which represent the fundamental geometric parameters of the biplane imaging system; using the fundamental parameters to calculate the 3-dimensional positions o

Abstract: A method and system for automated analysis of digital radiographic images in which regions-of-interest (ROI's) are first determined, and subsequently analyzed for abnormalities. To locate the ROI's, the outer ribcage and midline boundary locations of the chest image are determined from the digital image data. Vertical profiles are then selected and background trend is then removed from each vertical profile. A shift-variant sinusoidal function is fitted to each vertical profile and ROI's are selected based on the fitted functions. The non-uniform background trend is removed from the original image data of each selected ROI to obtain corrected data. The power spectrum of the lung texture is obtained from the 2D Fourier transform of the corrected data and is filtered by the human visual response.

Abstract: A method and system for reconstructing image data obtained from plural sequential exposures of an object by a radiation source through a multiple slit beam scanning assembly, wherein frames of original image data in the form of plural pixels are obtained for each discrete scanning step/exposure and a minimum pixel value of at least one frame is determined. Based on this determined minimum value, a cutoff value is determined. The pixel values of each frame are compared with the cutoff value, and the image is reconstructed by summation of all the pixel image data above the cutoff value for each respective pixel. In order to improve spatial resolution, the slit width of the scanning assembly is selected be the narrower than the pixel size. Pixel image data produced by exposure from radiation passing through the same slit of the scanning assembly in consecutive scanning steps are then assigned to adjacent pixels in a direction perpendicular to the scanning beam of an enlarged pixel matrix.

Abstract: A method and system for automated classification of distinction between normal lungs and abnormal lungs with interstitial disease, based on the analysis of predetermined physical texture measures and also on a data base for normal lungs of these texture measures. The texture measures selected are the RMS variation, R, and the first moment of power spectrum, M, for lung texture. These two texture measures are normalized by using the data base for normal lungs. A single texture index is determined from the two normalized texture measures by taking into account the distribution (or the data base) of texture measures obtained from abnormal lungs, in order to facilitate the automated classification of normal and abnormal lungs. A threshold texture index is then chosen for initial selection of "abnormal" regions of interest (ROIs), which contain a large texture index above the threshold level.

Abstract: An X-ray imaging apparatus comprising an X-ray generator having a cylindrical rotating target, a slit plate having a slit extending in a direction perpendicular to the direction in which an X-ray focal point moves on the target, the slit plate and rotating target being moved relatively in a direction perpendicular to the direction in which the slit extends, an X-ray detector arranged opposite to the slit plate with an object interposed between them and serving to convert X-ray beams passing through the slit and the object to electrical signals, a signal processor for picking up only those signals which relate to the object from these electrical signals obtained through the X-ray detector, and a display device for displaying an X-ray image which corresponds to the signals picked up by the signal processor.

Abstract: Rotary piston engine having a rotor housing applied with a pin-point type porous chromium plating having porosity of 10 to 60 percent and a hardness of 930 to 1200 in Vicker's scale. The engine also has a rotor having apex seals each constituted by cast iron based material. Each apex seal has a sliding surface including 50 to 70 volume percent of carbides and a hardness of 700 to 900 in Vicker's scale.