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: The present invention provides a method for positively acquiring projection data for reconstructing a CT image at a slice position outside the linear movement range. When performing “projection data acquisition” with “rotating” and “linearly moving” the X-ray tube and the multidetector, a holding time is provided in which only the “rotation” is performed without “linear movement” at the starting point and the end point of the linear movement. By adjusting the holding time, the projection data in the view angle range required for image reconstruction of a CT at the slice position outside the linear movement range can be positively acquired, when the rotating velocity is slower or when the linear movement velocity is faster.

Abstract: The present invention aims to obtain a tomographic image similar in image quality to a tomographic image obtained by executing a scan at X-ray tube current value set by an X-ray automatic exposure function even when the X-ray tube current value set by the X-ray automatic exposure function are not within a standard range of the X-ray tube current values settable at the X-ray tube (21). X-ray tube current value supplied to the X-ray tube (21) are set by the X-ray automatic exposure function. Thereafter, when the X-ray tube current value set by the X-ray automatic exposure function is not within in the standard range of the X-ray tube current value settable at the X-ray tube, the X-ray tube current value at a portion not within the standard range are changed so as to be within the standard range, and the set value of helical pitch is changed so as to correspond to the ratio between the pre-changed x-ray tube current value and the post-changed X-ray tube current value.

Abstract: Embodiments of the present invention improve image quality by preventing artifacts from developing. From the projection data obtained by performing a scan for the imaging area of a subject, a tomographic image for a cross-sectional plane of the imaging area is reconstructed. Based on the tomographic image, the density distribution of the imaging area of the subject is then calculated. Thereafter, the scattered radiation beam data is calculated depending on the density distribution, and the projection data is corrected using the scattered radiation beam data. Finally the corrected image is reconstructed based on the corrected projection data.

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 present invention aims to realize an improvement in image quality of a two-dimensional display extracted from a three-dimensional display image such as continuous tomographic images which tomographic images at a conventional scan or the like of an X-ray CT apparatus having a two-dimensional X-ray area detector of a matrix structure typified by a multi-row X-ray detector or a flat panel X-ray detector are arranged in a z direction corresponding to an imaging table travel direction. For the purpose, an image display apparatus of the present invention comprises image filter processing device for preforming a image filter processing on the three-dimensional image, wherein said image filter process varies depending on a cross sectional direction of said two-dimensional image to be displayed.

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 provides the adjustment of CT value which is the pixel value of a tomographic image in the conventional scan (axial scan) or cinescan or helical scan by an X-ray CT apparatus incorporating a multi column X-ray detector or a two-dimensional X-ray detector of matrix arrangement represented by a flat panel X-ray detector. The gain and bias of the projection data of each row are adjusted prior to the three-dimensional back projection or prior to the reconstruction function convolution. Alternatively, the gain and bias are adjusted after determining the gain and bias value to adjust the CT value by taking into account the contribution rate of each row to the tomographic image after the three-dimensional back projection.

Abstract: A method to make a common procedure adaptable to reconstruction planes whose positions relative to a multi-channel detector are different from one another. A reference procedure required for construction of a CT image based on reference linear data representing one line or a plurality of lines formed on a reference reconstruction plane is preserved. Real data associated with a first reconstruction plane different from the reference reconstruction plane is used to produce virtual reference linear data equivalent to the reference linear data. A CT image is reconstructed based on the virtual reference linear data using the reference procedure.

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 image quality ensured by a conventional (axial) scan, a cine scan, or a helical scan performed by an X-ray CT apparatus including a two-dimensional area X-ray detector that has a matrix structure. In helical scan image reconstruction based in three-dimensional image reconstruction performed in an X-ray CT apparatus including a two-dimensional area X-ray detector that is represented by a multi-array X-ray detector or a flat-panel X-ray detector and that has a matrix structure, an image expressing a slice thickness larger than the width of one detector array included in a multi-array X-ray detector is reconstructed according to either of a method of convoluting a z-direction filter to projection data items in the direction of detector arrays (z direction) and a method of convoluting a filer to a tomographic image space in the z direction. The two methods are optimized in terms of a calculation time and tomographic image quality.

Abstract: A method for performing scattered radiation correction. The position of a collimator and the width of a slit are adjusted so that direct radiation will fall on one of a plurality of arrays of detectors. A predetermined phantom is scanned. The scan is performed relative to each of the plurality of arrays of detectors. Based on data detected during each scan, scattered radiation correction data is produced. The produced scattered radiation correction data is used to correct projection data acquired by scanning a subject.

Abstract: An X-ray CT apparatus capable of imaging a subject based on X-rays of multiple energy levels while using an ordinary X-ray detector includes an X-ray tube which generates X-rays from multiple focal points of different 3-dimensional positions sequentially on a time-division basis, a plurality of filters which implement the filtering individually for the X-rays generated individually from the focal points, a collimator which equalizes the irradiation range of the X-rays generated individually from the focal points, collection means which collects projection data of multiple views of a subject of imaging for the X-rays generated individually from the focal points, and reconstruction means which reconstructs an image based on the projection data. The anode of the X-ray tube has multiple impingement portions where electrons released by the cathode impinge at multiple positions on the trajectory of electrons sequentially on a time-division basis.

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: A method of reducing the distance of rectilinear motion in a helical scan includes defining a rectilinear motion start point La and a rectilinear motion end point Lb within a region of interest ROI for which a CT image is to be created, collecting projection data from the rectilinear motion start point La to the rectilinear motion end point Lb, and creating a CT image at a desired image position in the region of interest ROI using the collected projection data.

Abstract: The present invention is intended to improve the quality of a four-dimensional image that is a time-varying three-dimensional image. The four-dimensional image that is a time-varying three-dimensional image is spatially filtered in the direction of a time axis and the directions of spatial axes alike.

Abstract: When an X-ray CT apparatus including a two-dimensional X-ray area detector performs a conventional (axial) scan or a cine scan, a plurality of segments of projection data items detected synchronously with an external signal or a biomedical signal is sampled from projection data items acquired during one scan or a plurality of scans. Projection data items corresponding to those detected during a half scan of rotating an X-ray tube by an angle of 180° plus the angle of a fan beam falling on the detector or during a 360° full scan are used to reconstruct a three-dimensional image. Thus, a three-dimensional tomographic image enjoying a high temporal resolution is displayed. Moreover, successive three-dimensional display images showing states of a subject synchronized with respective phases of the external signal or biomedical signal may be displayed as a four-dimensional image.