Abstract: A tomographic image at a given slice position is normally reconstructed by executing convolution and back projection calculations of virtual view data obtained by interpolating projection data in a range of 360.degree.+a double fan angle before and after the slice position, and their reflection beam data. A tomographic image at a slice position adjacent to the given position is calculated in such a manner that the convolution and back projection calculations of the difference between data used in reconstruction of the tomographic image at the first slice position, and data necessary for normally reconstructing a tomographic image to be reconstructed at a current slice position are executed, and the calculation result is added to the already reconstructed tomographic image.

Abstract: An ultrasonic diagnostic apparatus comprising unit for collecting echo signals by scanning a three-dimensional area of a subject with an ultrasonic beam, unit for making a three-dimensional bloodstream information based on the echo signals, unit for producing a plurality of projection images with different projecting directions based on the three-dimensional bloodstream information, and unit for displaying the plurality of projection images in specified sequence.

Abstract: In a helical scanning X-ray CT apparatus, views at an m-th slice position are obtained by interpolating 360.degree. views in a range next to the slice position in a forward direction in which the slice position number increases and 360.degree. views in a range next to the slice position in the backward direction, and m-th tomographic image is reconstructed based on the interpolated views at the m-th slice position. An m-th backward image (mBI) is reconstructed based on the 360.degree. views in the range next to the m-th slice position in the backward direction without interpolation and an m-th forward image (mFI) is reconstructed based on the 360.degree. views in the range next to the m-th slice position in the forward direction without interpolation. An (m+1)BI is obtained by BP [CONV (a-b)] on the mBI and (m+1)FI is obtained by BP [CONV (c-a)] on the mFI. Here, BP: back projection, CONV: convolution, a: a view at the m-th slice position, b: a view which is separated from "a" by 360.degree.

Abstract: A digital image display apparatus for converting a pixel value of medical digital image data such as MRI image data or CT image data into brightness in accordance with a display window including a window level and a window width of a display unit, determines the optimum window level and width for each image as follows. The apparatus obtains a histogram of pixel values from the digital image data and calculates brightness data of a pixel value having a highest frequency, brightness data of a pixel value at a boundary between a background and an image, area data of a portion having middle brightness within a display brightness range, area data of a portion having maximum brightness, and data indicating a ratio between an area of a portion having higher brightness than the middle brightness and an area of a portion having lower brightness than that obtained, when the digital image is to be displayed by a given display window on the basis of the histogram.

Abstract: A stereoscopic image display apparatus comprises a CT scanner, a data processing device, and a stereoscopic image display device. The data processing device processes projection data obtained from the CT scanner to remove data corresponding to portions unnecessary for stereoscopic display. Specifically, the data processing device forms a sinogram which represents the level of projection data for each portion as the locus of brightness with the ordinates denoting projection angles and the abscissas denoting detecting positions. In the projection angles from 0.degree. through 360.degree., the projection data obtained at the detecting positions from 1 to a predetermined number is removed from the locus of that detecting position so that the loci of outside portions of a circle of a predetermined radius corresponding to a predetermined detecting position are removed.

Abstract: A computed tomography device comprising a subtraction unit which obtains differential data strings representing the difference between each time-serial projection data string of a group of projection data strings corresponding to a prospective reconstruction image generated by projection data strings acquired by a data acquisition system, a convolution unit which convolves each time-serial projection data string of the group of projection data strings corresponding to the prospective reconstruction image, and a back-projection unit which back-projects the convolved data strings.