Abstract: The present invention is intended to improve the quality of a three-dimensional display image, an MPR display image, or an MIP display image presented by an X-ray CT system that performs a conventional (axial) scan, a cine scan, or a helical scan. The X-ray CT system includes an image reconstruction unit or an image display unit. The image reconstruction unit or image display unit measures deviations of tomographic images in an x direction that is a horizontal direction and deviations thereof in a y direction that is a vertical direction according to the continuity in a z direction of an object that exhibits high CT numbers and that is visualized as a reference in the tomographic images; such as, a cradle, a head holder, the surface of a subject's body, or a bone. The image reconstruction unit or image display unit then compensates the deviations.

Abstract: The slice thickness of tomograms of an X-ray CT apparatus is to be kept as constant as practicable within an xy plane. In projected data before three-dimensional back-projection, after convolving row-directional filter of an X-ray detector whose filter coefficient is adjusted channel by channel, three-dimensional back-projection is performed to achieve image reconstruction thereby to control the slice thickness of tomograms according to the distance from the center of the xy plane. The slice thickness is controlled to keep it as constant as practicable independent of the distance from that center to regulate the picture quality of tomograms. Further, the relative density of distances on the reconstruction plane of X-ray detector data or projection data projected on the reconstruction plane is controlled by creating virtual projection data thereby to improve the picture quality of tomograms.

Abstract: A computed tomography (CT) imaging system for improving the image quality of a tomographic image at a predefined image production position in a subject's axis direction in tomographic image reconstruction by axial scanning. The CT system includes an X-ray tube and a detector array configured to conduct a plurality of scans for detecting X-rays passing through a region to be examined around an axis AX of the region to be examined at different positions along the subject's axis Ax direction; and for each of the plurality of scans, and a reconstructing section configured to calculate and reconstruct data for tomographic images of the region to be examined at a position corresponding to a detector row in the axis direction based on detected data acquired in that scan, and combine the data for the plurality of reconstructed tomographic images to generate data for a combined tomographic image at the position corresponding to the detector row.

Abstract: Improvement of the picture quality of tomograms in an X-ray CT apparatus using a multi-row x-ray detector is to be realized. When conventional scanning (axial scanning) or cine-scanning is to be performed in consecutive different scanning positions in the z-axis direction, the width of the X-ray beam at scanning positions at both ends is kept at exactly or approximately D/2 relative to the multi-row x-ray detector. Alternatively, the interval between one scanning position and another is kept at not more than D. Unevenness of picture quality dependent on positions on the z-axis on a reconstructed plane can be improved.

Abstract: A scan control method for an X-ray CT apparatus wherein a subject with a contrast agent injected therein is helically scanned with an X-ray beam and image reconstruction is performed based on projection data obtained through an X-ray detector. The method includes controlling a velocity of a helical scan following motion of the contrast agent in the subject.

Abstract: X-ray CT apparatus includes an x-ray data collecting device for collecting x-ray projection data transmitted by a subject positioned between an x-ray generating device and a multi-row x-ray detector, while rotating said x-ray generating device and said multi-row x-ray detector around a rotation center positioned in-between, an image reconstructing device for performing image reconstruction from the projection data collected from the x-ray data collecting device, an image display device for displaying a tomogram obtained by image reconstruction, and a scanning condition setting device for setting various scanning conditions of tomography scanning.

Abstract: A method for producing a CT image by applying Z-filtering to axial scan data collected using a multi-row detector, wherein second axial scan data is collected at a second position Z2 to which an X-ray tube and a multi-row detector are rectilinearly moved relative to a subject to be imaged from a first position Z1 toward an end of the multi-row detector, projection data corresponding to a central portion a2 of a reconstruction field P3 near the end of the multi-row detector is extracted from the second axial scan data, and Z-filtering is applied based on the projection data of reconstruction fields P1, P2 and P3 to produce one CT image.

Abstract: The slice thickness of tomograms of an X-ray CT apparatus is to be kept as constant as practicable within an xy plane. In projected data before three-dimensional back-projection, after convolving row-directional filter of an X-ray detector whose filter coefficient is adjusted channel by channel, three-dimensional back-projection is performed to achieve image reconstruction thereby to control the slice thickness of tomograms according to the distance from the center of the xy plane. The slice thickness is controlled to keep it as constant as practicable independent of the distance from that center to regulate the picture quality of tomograms. Further, the relative density of distances on the reconstruction plane of X-ray detector data or projection data projected on the reconstruction plane is controlled by creating virtual projection data thereby to improve the picture quality of tomograms.

Abstract: The present invention is intended to improve the quality of a three-dimensional display image, an MPR display image, or an MIP display image presented by an X-ray CT system that performs a conventional (axial) scan, a cine scan, or a helical scan. The X-ray CT system includes an image reconstruction unit or an image display unit. The image reconstruction unit or image display unit measures deviations of tomographic images in an x direction that is a horizontal direction and deviations thereof in a y direction that is a vertical direction according to the continuity in a z direction of an object that exhibits high CT numbers and that is visualized as a reference in the tomographic images; such as, a cradle, a head holder, the surface of a subject's body, or a bone. The image reconstruction unit or image display unit then compensates the deviations.

Abstract: The present invention is intended to improve the quality of a tomographic image to be produced by an X-ray CT apparatus including an X-ray area detector represented by a multi-array X-ray detector or a flat-panel detector. A conventional (axial) or cine scan is performed on the first and second scanned positions in the direction of a z axis. Projection data items produced by scanning the first scanned position and projection data items produced by scanning the second scanned position are used to reconstruct a tomographic image.

Abstract: An X-ray CT apparatus including an X-ray tube, a detector array including a plurality of detector rows along the axis of rotation, and a reconstructing section for calculating and reconstructing tomographic image data of a subject based on the acquired projection data. The CT apparatus also includes a collimator for adjusting the emission extent of the X-rays from the X-ray tube in response to a control command, and a control section for calculating detector rows required for acquiring the projection data for use in reconstruction of a certain portion of the tomographic image data based on parameters relating to reconstruction of the tomographic image data by the reconstructing section, and outputting the control command to the collimator for emitting the X-rays to impinge upon the calculated detector rows.

Abstract: A scan control method for an X-ray CT apparatus wherein a subject with a contrast agent injected therein is helically scanned with an X-ray beam and image reconstruction is performed based on projection data obtained through an X-ray detector. The method includes controlling a velocity of a helical scan following motion of the contrast agent in the subject.

Abstract: A method for producing a CT image by applying Z-filtering to axial scan data collected using a multi-row detector, wherein second axial scan data is collected at a second position Z2 to which an X-ray tube and a multi-row detector are rectilinearly moved relative to a subject to be imaged from a first position Z1 toward an end of the multi-row detector, projection data corresponding to a central portion a2 of a reconstruction field P3 near the end of the multi-row detector is extracted from the second axial scan data, and Z-filtering is applied based on the projection data of reconstruction fields P1, P2 and P3 to produce one CT image.

Abstract: An image reconstructing method includes upon reconstructing an image using a multi-row detector having a plurality of detector sequences and on the basis of projection data D0 collected by a helical scan with a scan surface being tilted effecting, on the projection data, a tilt correcting process for correcting variations on every view, in positions of respective channels of the detector sequences with respect to a linear travel axis due to the inclination of the scan surface, projecting respective pixels in an X-ray penetration direction along lines parallel to an X axis or a Y axis on a reconstruction plane to determine the corresponding projection data and defining the same as backprojected pixel data of respective pixels constituting the reconstruction plane, and adding the backprojected pixel data of all views used in image reconstruction in association with the pixels to determine backprojected data.

Abstract: An X-ray CT apparatus including an X-ray tube, a detector array including a plurality of detector rows along the axis of rotation, and a reconstructing section for calculating and reconstructing tomographic image data of a subject based on the acquired projection data. The CT apparatus also includes a collimator for adjusting the emission extent of the X-rays from the X-ray tube in response to a control command, and a control section for calculating detector rows required for acquiring the projection data for use in reconstruction of a certain portion of the tomographic image data based on parameters relating to reconstruction of the tomographic image data by the reconstructing section, and outputting the control command to the collimator for emitting the X-rays to impinge upon the calculated detector rows.

Abstract: A computed tomography (CT) imaging system for improving the image quality of a tomographic image at a predefined image production position in a subject's axis direction in tomographic image reconstruction by axial scanning. The CT system includes an X-ray tube and a detector array configured to conduct a plurality of scans for detecting X-rays passing through a region to be examined around an axis AX of the region to be examined at different positions along the subject's axis Ax direction; and for each of the plurality of scans, and a reconstructing section configured to calculate and reconstruct data for tomographic images of the region to be examined at a position corresponding to a detector row in the axis direction based on detected data acquired in that scan, and combine the data for the plurality of reconstructed tomographic images to generate data for a combined tomographic image at the position corresponding to the detector row.