Abstract: An X-ray CT apparatus includes an X-ray irradiation unit for applying X-rays based on a first X-ray tube voltage and X-rays based on a second X-ray tube voltage to a subject by being switched every one view, a projection data acquisition unit for acquiring projection data by which X-ray tube voltage information about the applied X-rays are identified, and an image reconstruction unit for identifying first energy projection data based on the first X-ray tube voltage, second energy projection data based on the second X-ray tube voltage, and transient energy projection data acquired upon switching between the first and second X-ray tube voltages based on the X-ray tube voltage information, the image reconstruction unit including a conversion processor that converts the transient energy projection data to another data using the transient energy projection data and performs image reconstruction using the data subsequent to the conversion process.

Abstract: The present invention provides an X-ray CT apparatus capable of improving image quality of a dual energy image. The X-ray CT apparatus comprises an X-ray tube for applying X rays having a first energy spectrum and X rays having a second energy spectrum different from the first energy spectrum to a subject, an X-ray data acquisition unit for acquiring X-ray projection data of the first energy spectrum projected onto the subject and X-ray projection data of the second energy spectrum projected thereonto, dual energy image reconstructing unit for image-reconstructing tomographic images indicative of X-ray tube voltage-dependent information at X-ray absorption coefficients related to a distribution of atoms, based on the X-ray projection data of the first energy spectrum and the X-ray projection data of the second energy spectrum, and adjusting unit for adjusting conditions for the image reconstruction in order to optimize the tomographic images indicative of the X-ray tube voltage-dependent information.

Abstract: With the objective of evaluating whether a dose is excessive for a subject, such a dose that image noise reaches less than or equal to a predetermined value is estimated upon an axial scan on the basis of projection data acquired by a scout scan. The dose is set as a maximum dose. An area other than air, of an image obtained by the axial scan is partitioned into a plurality of small areas i. Image noises N(i) at the respective small areas i are calculated. A warning image G1 in which all of pixel values of pixels in small areas in which the image noises N(i) are less than or equal to a predetermined value, are substituted with pixel values expressed in black level, is created and displayed.

Abstract: To provide an X-ray CT apparatus capable of acquiring information on energy of X-rays generated by an X-ray generating apparatus, an X-ray CT apparatus (100) comprises: an X-ray generating apparatus for generating X-rays and emitting the X-rays toward a subject; a first X-ray detector having a plurality of X-ray detection channels for detecting the X-rays emitted from the X-ray generating apparatus; a second X-ray detector for detecting the X-rays emitted from the X-ray generating apparatus in order to acquire information on energy of the X-rays emitted from the X-ray generating apparatus; and an X-ray energy information identifying section for identifying information on energy of the X-rays emitted from the X-ray generating apparatus based on the information detected by the second X-ray detector.

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: To provide an X-ray CT apparatus capable of acquiring information on energy of X-rays generated by an X-ray generating apparatus, an X-ray CT apparatus (100) comprises: an X-ray generating apparatus for generating X-rays and emitting the X-rays toward a subject; a first X-ray detector having a plurality of X-ray detection channels for detecting the X-rays emitted from the X-ray generating apparatus; a second X-ray detector for detecting the X-rays emitted from the X-ray generating apparatus in order to acquire information on energy of the X-rays emitted from the X-ray generating apparatus; and an X-ray energy information identifying section for identifying information on energy of the X-rays emitted from the X-ray generating apparatus based on the information detected by the second X-ray detector.

Abstract: A CT image reconstruction method includes substituting other projection data, which has a predetermined positional relationship to projection data that is found defective during scanning, for the defective data, and interpolating back projection data using a value and information on a scanned position that are contained in the substitute data.

Abstract: An X-ray CT apparatus includes an X-ray irradiation unit for applying X-rays based on a first X-ray tube voltage and X-rays based on a second X-ray tube voltage to a subject by being switched every one view, a projection data acquisition unit for acquiring projection data by which X-ray tube voltage information about the applied X-rays are identified, and an image reconstruction unit for identifying first energy projection data based on the first X-ray tube voltage, second energy projection data based on the second X-ray tube voltage, and transient energy projection data acquired upon switching between the first and second X-ray tube voltages based on the X-ray tube voltage information, the image reconstruction unit including a conversion processor that converts the transient energy projection data to another data using the transient energy projection data and performs image reconstruction using the data subsequent to the conversion process.

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: An apparatus for improving the tomographic image quality by preventing the tomographic image contrast from degrading and preventing artifact from occurring even if many scattered radiations occur. An X-ray detection array obtains first detection data using the X-ray detection elements corresponding to an area not shielded by a collimator. Further, the X-ray detection array obtains second detection data using the X-ray detection elements corresponding to an area shielded by the collimator. A central processing unit corrects the first detection data based on the detection data including the first and second detection data. Finally, the central processing unit generates a tomographic image for an imaging area of the imaging object.

Abstract: The present invention provides an X-ray CT apparatus capable of improving image quality of a dual energy image. The X-ray CT apparatus comprises an X-ray tube for applying X rays having a first energy spectrum and X rays having a second energy spectrum different from the first energy spectrum to a subject, an X-ray data acquisition unit for acquiring X-ray projection data of the first energy spectrum projected onto the subject and X-ray projection data of the second energy spectrum projected thereonto, dual energy image reconstructing unit for image-reconstructing tomographic images indicative of X-ray tube voltage-dependent information at X-ray absorption coefficients related to a distribution of atoms, based on the X-ray projection data of the first energy spectrum and the X-ray projection data of the second energy spectrum, and adjusting unit for adjusting conditions for the image reconstruction in order to optimize the tomographic images indicative of the X-ray tube voltage-dependent information.

Abstract: With the object of enhancing operability and executing imaging efficiently, a moving speed adjustment unit adjusts a speed at which a table section is moved within an imaging space of a scanning gantry, on the basis of a command from an operator when the scanning gantry scans a subject.

Abstract: A method of measuring a modulation transfer function (MTF) includes detecting the center of a line spread function (LSF) image in order to calculate an MTF. For this purpose, an enlarged image of a portion of an image containing the LSF image is created, and binary-coded based on a threshold. A morphological operation is performed on the binary-coded image. Coordinates representing points that define the contour of the resultant image are sampled, and used to work out coordinates representing the center of a circle through Hough transform. The coordinates representing the center are transformed into coordinates representing a point in an original image.

Abstract: A method and apparatus for reducing the contrast of a tomographic image due to crosstalk and the occurrence of artifacts and improve the quality of the tomographic image. Detection data are subjected to fitting processing in such a manner that, of the data generated by an X-ray detected by X-ray detection elements disposed in array form in a plurality of X-ray detection modules disposed adjacent to one another, first detection data generated by the X-ray detected by X-ray detection elements adjacent to a boundary between the plurality of X-ray detection modules are adapted to waveform data based on second detection data generated by the X-ray detected by X-ray detection elements lying around the adjacent X-ray detection elements.

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: 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: Tomography or X-ray CT fluoroscopy reduced in exposure to radiation in an X-ray CT apparatus or an X-ray CT fluoroscopic apparatus is to be substantialized. A channel-direction X-ray collimator or a beam forming X-ray filter is positionally controlled in the channel direction to carry out X-ray data acquisition while irradiation with X-rays limited to only the region of interest. Either the profile area of the whole subject is obtained or the profile area of the whole subject is predicted from views or scout images of irradiation of the whole subject out of X-ray projection data. Image reconstruction of views not irradiating the whole subject out of the collected X-ray projection data is carried out by predicting lacking parts from the profile area of the whole subject and making corrections accordingly.

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: 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.