IMAGE RECONSTRUCTING METHOD AND X-RAY CT APPARATUS
First Claim
1. An image reconstructing method for reconstructing a tomogram based on projection data collected by a multi-row X-ray detector for detecting X-rays radiated from the X-ray generating device, the image reconstructing method comprising:
- a first step of convolving row-directional filter on said projection data;
a second step of convolving a reconstructing function on said data obtained by said first step; and
a third step of reconstructing by performing three-dimensional back-projection process based on data obtained by said second step.
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Accused Products
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.
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Citations
22 Claims
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1. An image reconstructing method for reconstructing a tomogram based on projection data collected by a multi-row X-ray detector for detecting X-rays radiated from the X-ray generating device, the image reconstructing method comprising:
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a first step of convolving row-directional filter on said projection data;
a second step of convolving a reconstructing function on said data obtained by said first step; and
a third step of reconstructing by performing three-dimensional back-projection process based on data obtained by said second step.
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2. An image reconstructing method for reconstructing a tomogram based on projection data collected by a multi-row X-ray detector for detecting X-rays radiated from the X-ray generating device, the image reconstructing method comprising:
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a first step of convolving a reconstructing function on said projection data;
a second step of convolving row-directional filter on the data obtained by said first step; and
a third step of reconstructing by performing three-dimensional back-projection process based on the data obtained by said second step.
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3. An X-ray CT apparatus comprising:
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X-ray generating device;
a multi-row X-ray detector which detects X-rays radiated from said X-ray generating device;
data collecting device which collects projection data by rotating said X-ray generating device and said multi-row X-ray detector around a center of rotation between the X-ray generating device and the multi-row X-ray detector;
row-directional filtering device for convolving row-directional filter on the projection data collected by said data collecting device;
reconstruction convolving device for convolving a reconstructing function on the projection data obtained said row-directional filtering device; and
back-projecting device for reconstructing a tomogramic view by three-dimensional back projecting the projection data obtained processing by said reconstruction convoluting device. - View Dependent Claims (5, 7, 9, 11, 13, 15, 17, 19, 21)
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4. An X-ray CT apparatus comprising:
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X-ray generating device;
a multi-row X-ray detector which detects X-rays radiated from said X-ray generating device;
data collecting device which collects projection data by rotating said X-ray generating device and said multi-row X-ray detector around a center of rotation between the X-ray generating device and the multi-row X-ray detector;
reconstruction convolving device for convolving a reconstructing function on the projection data collected by said data collecting device;
row-directional filtering device for convolving row-directional filter in the row direction based on the projected data obtained by said reconstruction convoluting device; and
back-projecting device for reconstructing a tomogramic view by three-dimensional back projecting the projection data obtained processing by said row-directional filtering device. - View Dependent Claims (6, 8, 10, 12, 14, 16, 18, 20, 22)
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Specification