Abstract: A first and a second accumulated value calculating units are provided which, in a location where foil shadows by grid foil strips straddle pixels, identify this location based on geometry, and calculate straddle accumulated values of the foil shadows in the identified location. Even when the foil shadows by the grid foil strips straddle the pixels due to twisting and bending of the grid foil strips, such location is identified based on geometry and the straddle accumulated values of the foil shadows in the identified location are calculated. Therefore, even when changes are made in the pitches or pixel sizes of an X-ray grid and a flat panel X-ray detector (FPD), the foil shadows will be removed based on the straddle accumulated values. As a result, the foil shadows can be removed taking twisting and bending of the grid foil strips into consideration, and in a way to accommodate X-ray grids and FPDs of various sizes.

Abstract: A first and a second accumulated value calculating units re provided which, in a location where foil shadows by grid foil strips straddle pixels, identify this location based on geometry, and calculate straddle accumulated values of the foil shadows in the identified location. Even when the foil shadows by the grid foil strips straddle the pixels due to twisting and bending of the grid foil strips, such location is identified based on geometry and the straddle accumulated values of the foil shadows in the identified location are calculated. Therefore, even when changes are made in the pitches or pixel sizes of an X-ray grid and a flat panel X-ray detector (FPD), the foil shadows will be removed based on the straddle accumulated values. As a result, the foil shadows can be removed taking twisting and bending of the grid foil strips into consideration, and in a way to accommodate X-ray grids and FPDs of various sizes.

Abstract: A radiographic apparatus includes a radiation source for emitting radiation, a radiation detecting device for detecting the radiation, a radiation grid placed to cover a radiation detecting plane of the radiation detecting device, a pattern storage device for storing a plurality of patterns of shadows of the radiation grid falling on the radiation detecting device, an image generating device for generating an original image showing the object under examination and the shadows of the radiation grid, based on detection signals outputted from the radiation detecting device, a grid shadow estimating device for estimating a pattern of superimposed grid shadows, which are the shadows of the radiation grid appearing on the original image, from the patterns of shadows stored in the pattern storage device, and a removing device for removing the shadows of the radiation grid from the original image based on the superimposed grid shadows estimated.

Abstract: A radiographic apparatus includes a radiation source for emitting radiation, a radiation detecting device for detecting the radiation, a radiation grid placed to cover a radiation detecting plane of the radiation detecting device, a pattern storage device for storing a plurality of patterns of shadows of the radiation grid falling on the radiation detecting device, an image generating device for generating an original image showing the object under examination and the shadows of the radiation grid, based on detection signals outputted from the radiation detecting device, a grid shadow estimating device for estimating a pattern of superimposed grid shadows, which are the shadows of the radiation grid appearing on the original image, from the patterns of shadows stored in the pattern storage device, and a removing device for removing the shadows of the radiation grid from the original image based on the superimposed grid shadows estimated.

Abstract: A grid 3 arranged with a scattered radiation shielding plate 31 for each column is arranged at a front face of a radiation detector 2. The distance between the grid 3 and the radiation detector 2 is desirably a integral multiple of the height of the scattered radiation shielding plate 31. A true image signal of the pixel column including the shade is estimated from the image signal of the pixel column adjacent to the pixel column including the shade 41. The scattered radiation distribution is estimated from the image signals of the pixel column including the shade of the scattered radiation shielding plate and the image signals when considering that the shielding plate is not included in the shielded pixel. A clear diagnosis image without influence of scattered radiation is obtained by subtracting the estimated scattered radiation distribution from the estimated image signal distribution.

Abstract: A grid 3 arranged with a scattered radiation shielding plate 31 for each column is arranged at a front face of a radiation detector 2. The distance between the grid 3 and the radiation detector 2 is desirably a integral multiple of the height of the scattered radiation shielding plate 31. A true image signal of the pixel column including the shade is estimated from the image signal of the pixel column adjacent to the pixel column including the shade 41. The scattered radiation distribution is estimated from the image signals of the pixel column including the shade of the scattered radiation shielding plate and the image signals when considering that the shielding plate is not included in the shielded pixel. A clear diagnosis image without influence of scattered radiation is obtained by subtracting the estimated scattered radiation distribution from the estimated image signal distribution.

Abstract: An FPD has a detecting plane with detecting elements arranged in rows (u-axis) and columns (v-axis) extending in two intersecting axial directions. In time of primary scanning, the FPD is moved about a sectional axis to maintain the u-axis parallel to a body axis constantly. Consequently, in a reconstruction process, a set of projection points on the detecting plane of X rays having passed through lattice points in one row along the body axis A of an imaginary three-dimensional lattice, is parallel to the u-axis. It is therefore possible to derive all projection data that should be projected back to the lattice points in one row, only from detection signals acquired from the detecting elements in two lines having the set of projection points in between. Thus, the quantity of detection signals required for obtaining the projection data is reduced to perform the reconstruction process at high speed.

Abstract: Projection images of a calibration phantom are picked up and stored. Three-dimensional position information on an X-ray tube and an area detector is obtained from the projection images and three-dimensional arrangement information on markers inside the calibration phantom. Three-dimensional position information is obtained for all projection images, and stored in a three-dimensional position information storage unit. Projection images of an object under examination are picked up by following the same tracks and the same sequence as when radiographing the calibration phantom. Radiographic data of the projection images is read. A reconstructing calculation is carried out for the object based on the three-dimensional position information on the X-ray tube and area detector relative to the calibration phantom, to create slice images or three-dimensional volume data of a selected site of the object.

Abstract: An FPD has a detecting plane with detecting elements arranged in rows (u-axis) and columns (v-axis) extending in two intersecting axial directions. In time of primary scanning, the FPD is moved about a sectional axis to maintain the u-axis parallel to a body axis constantly. Consequently, in a reconstruction process, a set of projection points on the detecting plane of X rays having passed through lattice points in one row along the body axis A of an imaginary three-dimensional lattice, is parallel to the u-axis. It is therefore possible to derive all projection data that should be projected back to the lattice points in one row, only from detection signals acquired from the detecting elements in two lines having the set of projection points in between. Thus, the quantity of detection signals required for obtaining the projection data is reduced to perform the reconstruction process at high speed.

Abstract: The radiographic apparatus according to this invention has a scan frame with an X-ray tube frame and a flat panel type detector (FPD) frame arranged therein. The X-ray tube frame surrounds an X-ray tube, and the FPD frame surrounds an FPD. The X-ray tube frame and FPD frame are rotatable together about a sectional axis. Thus, the X-ray tube and FPD rotate on the respective frames together directly about the sectional axis (for a main scan). Further, the X-ray tube and FPD are rotatable together about a scan center axis (for an auxiliary scan). The main scan and auxiliary scan are combined to achieve a high-speed scan and improves resolution in the direction of the sectional axis, thereby obtaining a three-dimensional sectional image with isotropic spatial resolution.

Abstract: Projection images of a calibration phantom are picked up and stored. Three-dimensional position information on an X-ray tube and an area detector is obtained from the projection images and three-dimensional arrangement information on markers inside the calibration phantom. Three-dimensional position information is obtained for all projection images, and stored in a three-dimensional position information storage unit. Projection images of an object under examination are picked up by following the same tracks and the same sequence as when radiographing the calibration phantom. Radiographic data of the projection images is read. A reconstructing calculation is carried out for the object based on the three-dimensional position information on the X-ray tube and area detector relative to the calibration phantom, to create slice images or three-dimensional volume data of a selected site of the object.

Abstract: A radiographic apparatus according to this invention rotates, together about a sectional axis, an X-ray tube on an X-ray tube frame surrounding the X-ray tube, and a flat panel type detector (FPD) on an FPD frame surrounding the FPD. The X-ray tube and FPD may thereby be rotated safely and at high speed. Thus, a dynamic sectional image may be obtained of a moving site of interest such as the heart.

Abstract: In a radiation tomography device, in case a wide photographing area is required, even if a resolution capability in a depth direction of a section of a subject including an intersection of a rotation axis and a radiation irradiating axis is low, a small Laminographic angle &agr;1 is set. In case a high resolution capability is required in the depth direction, even if the photographing area is narrow, a large Laminographic angle &agr;2 is set. Since a balance between the resolution capability in the depth direction of the subject and the photographing area can be adjusted by varying the Laminographic angle, the photographing modes can be freely selected to thereby carry out the tomography suitable for the photographing requirement.

Abstract: An X-ray tube and an X-ray area detector are driven synchronously in scanning action to revolve about a scan axis extending substantially through the center of a region of interest of an object under examination. An image processor performs a predetermined image processing on projection data detected in each scan position. In the image processing, a low-pass filtering is applied to projection data in each row of pixels of the area detector perpendicular to a direction corresponding to the scan axis, the low-pass filtering being in accordance with a location on the scan axis to which each row of pixels is projected. This filtering reduces artifacts due to a volume scan mode appearing in three-dimensional volume data of the region of interest generated by projecting the projection data after the low-pass filtering back to a virtual three-dimensional lattice.

Abstract: In a radiation tomography device, in case a wide photographing area is required, even if a resolution capability in a depth direction of a section of a subject including an intersection of a rotation axis and a radiation irradiating axis is low, a small Laminographic angle &agr;1 is set. In case a high resolution capability is required in the depth direction, even if the photographing area is narrow, a large Laminographic angle &agr;2 is set. Since a balance between the resolution capability in the depth direction of the subject and the photographing area can be adjusted by varying the Laminographic angle, the photographing modes can be freely selected to thereby carry out the tomography suitable for the photographing requirement.

Abstract: In a radiation tomography device, in case a wide photographing area is required, even if a resolution capability in a depth direction of a section of a subject including an intersection of a rotation axis and a radiation irradiating axis is low, a small Laminographic angle &agr;1 is set. In case a high resolution capability is required in the depth direction, even if the photographing area is narrow, a large Laminographic angle &agr;2 is set. Since a balance between the resolution capability in the depth direction of the subject and the photographing area can be adjusted by varying the Laminographic angle, the photographing modes can be freely selected to thereby carry out the tomography suitable for the photographing requirement.

Abstract: A radiation source and an area detector are arranged across sectional planes of an object are driven to scan and pick up images of the sectional planes. A back projection unit performs an the image reconstruction to generate three-dimensional volume data of a region of interest of the object by projecting projection data detected in varied scan positions back to predetermined lattice points of a three-dimensional lattice virtually set to the region of interest. The back projection unit generates the three-dimensional volume data, with lattice spacing along a sectional axis extending substantially through the center of the region of interest and perpendicular to the sectional planes, among the three orthogonal axes of the three-dimensional lattice, made larger than lattice spacing in the two other directions. This reduces the amount of data back-projected, and shortens the processing time for the image reconstruction.

Abstract: An X-ray tube and an X-ray area detector are driven synchronously in scanning action to revolve about a scan axis extending substantially through the center of a region of interest of an object under examination. An image processor performs a predetermined image processing on projection data detected in each scan position. In the image processing, a low-pass filtering is applied to projection data in each row of pixels of the area detector perpendicular to a direction corresponding to the scan axis, the low-pass filtering being in accordance with a location on the scan axis to which each row of pixels is projected. This filtering reduces artifacts due to a volume scan mode appearing in three-dimensional volume data of the region of interest generated by projecting the projection data after the low-pass filtering back to a virtual three-dimensional lattice.

Abstract: A radiation source and an area detector are arranged across sectional planes of an object are driven to scan and pick up images of the sectional planes. A back projection unit performs an the image reconstruction to generate three-dimensional volume data of a region of interest of the object by projecting projection data detected in varied scan positions back to predetermined lattice points of a three-dimensional lattice virtually set to the region of interest. The back projection unit generates the three-dimensional volume data, with lattice spacing along a sectional axis extending substantially through the center of the region of interest and perpendicular to the sectional planes, among the three orthogonal axes of the three-dimensional lattice, made larger than lattice spacing in the two other directions. This reduces the amount of data back-projected, and shortens the processing time for the image reconstruction.

Abstract: In a CT apparatus, e.g. an X-ray CT apparatus, according to this invention, a plural scan executing unit executes a first and a second helical scans successively, with an X-ray tube and an X-ray detector each advancing along helical paths having a 180° phase difference (bisectional phase difference) therebetween. Consequently, CT image composing data is acquired from opposite directions for each point in an area of interest. That is, the CT image composing data obtained, as a whole, covers a scanning range corresponding to 360°. Then, an image reconstructing unit performs an image reconstructing process properly based on the CT image composing data collected through all the helical scans and covering the 360° scanning range. As a result, artifacts are restrained from appearing in CT images ultimately obtained.