摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
An X-ray tube for a CT apparatus comprises a ring-shaped vacuum tube containing a fixed cathode having a thermion emitting surface, a ring-shaped fixed anode, and a ring-shaped rotatable cathode interposed between the fixed cathode and fixed anode. The rotatable cathode defines a thermion receiving surface opposed to the thermion emitting surface, and a thermion emitting portion opposed to the fixed anode. Thermions are emitted from the thermion emitting portion toward the fixed anode while the rotatable cathode is suspended to non-contact state and rotated at high speed. With the thermions being accelerated and colliding on the fixed anode, an X-ray is generated toward the center of the vacuum tube. The X-ray generating position moves at high speed along a circumferential surface of the fixed anode with rotation of the rotatable cathode.
摘要:
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.
摘要:
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.
摘要:
A nondestructive test apparatus for testing a work is formed of a fixed radiation generating device; a rotatable work holding device situated near the radiation generating device; and a rotatable radiation image taking device situated near the work holding device at a side opposite to the radiation generating device. The radiation image taking device rotates or swings in accordance with rotation or swinging of the work holding device at a same angle thereto. The radiation image taking device receives and accumulates images of the work held on the work holding device and radiated by the radiation generating device while the work is being rotated or swung. It is possible to quickly obtain a sectional image with the relatively simple and compact structure. The test or inspection efficiency can be improved.
摘要:
A two-dimensional radiation detector for obtaining a radiographic image as converted into electric signals. The detector has a multi-layer structure including a scintilator, a translucent electrode film, a photoconductive film and a scan switch layer. The scan switch layer includes conductors arranged in matrix form and in contact with the photoconductive film, a plurality of FETs corresponding to the conductors arranged in matrix form, and a uniformly planar conductor for successively applying a bias voltage through the FETs to the matrix conductors row by row. Each FET has a drain electrode connected to one of the matrix conductors, a source electrode connected to the uniformly planar conductor, and a gate electrode connected to the drive circuit. The translucent electrode film includes column conductors corresponding to columns of the matrix conductors, each of the column conductors being connected to a signal reading line.