Method of reconstructing tomographic images
First Claim
1. A method of reconstructing a tomographic image of an object from incomplete projection data using a limited angle tomography technique, the method including the steps of:
- using the projection data to obtain a first reconstruction of the image;
creating an intermediate image in which each pixel represents the probability that a corresponding pixel of the first reconstruction of the image resembles the corresponding pixel of a final reconstruction of the image;
based on the intermediate image, identifying regions in the first reconstruction of the image that resemble their final reconstruction;
applying prior knowledge only to said regions in the first reconstruction of the image that resemble their final reconstruction, to obtain a second reconstruction of the image which is more accurate than the first reconstruction;
applying the projection data to projections of the second reconstruction of the image by constraining the projections of the second reconstruction of the image to the projection data, to obtain a third reconstruction of the image which is more accurate than the second reconstruction; and
iteratively creating intermediate images, identifying regions in the third reconstruction of the image and subsequent reconstructions of the image, that resemble their final reconstruction and applying the prior knowledge and the projection data in the same way to the third reconstruction of the image and subsequent reconstructions thereof until a final reconstruction is achieved.
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Accused Products
Abstract
A method of reconstructing a tomographic image of an object from incomplete projection data using a limited angle tomography technique. The method includes using the protection data to obtain a first reconstruction of the image. Thereafter, regions in the first reconstruction that can be predicted with an acceptable degree of certainty in a final reconstruction, are identified. Prior knowledge in the form of possible density levels and piece-wise smoothness that regions in an image can assume, are applied to those regions of acceptable certainty in the first reconstruction so as to obtain a second reconstruction. The projection data is then applied to projections of the second reconstruction using a constraining method to obtain a third reconstruction. In the same way regions of acceptable certainty are identified and the prior knowledge and the projection data are applied to the third reconstruction and subsequent reconstructions until a final reconstruction is achieved.
35 Citations
9 Claims
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1. A method of reconstructing a tomographic image of an object from incomplete projection data using a limited angle tomography technique, the method including the steps of:
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using the projection data to obtain a first reconstruction of the image;
creating an intermediate image in which each pixel represents the probability that a corresponding pixel of the first reconstruction of the image resembles the corresponding pixel of a final reconstruction of the image;
based on the intermediate image, identifying regions in the first reconstruction of the image that resemble their final reconstruction;
applying prior knowledge only to said regions in the first reconstruction of the image that resemble their final reconstruction, to obtain a second reconstruction of the image which is more accurate than the first reconstruction;
applying the projection data to projections of the second reconstruction of the image by constraining the projections of the second reconstruction of the image to the projection data, to obtain a third reconstruction of the image which is more accurate than the second reconstruction; and
iteratively creating intermediate images, identifying regions in the third reconstruction of the image and subsequent reconstructions of the image, that resemble their final reconstruction and applying the prior knowledge and the projection data in the same way to the third reconstruction of the image and subsequent reconstructions thereof until a final reconstruction is achieved. - View Dependent Claims (2, 3)
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4. A computer program product for reconstructing a tomographic image of an object from incomplete projection data using a limited angle tomography technique, the computer program product including program instructions for:
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using the projection data to obtain a first reconstruction of the image;
creating an intermediate image in which each pixel represents the probability that a corresponding pixel of the first reconstruction of the image resembles the corresponding pixel of a final reconstruction of the image;
based on the intermediate image, identifying regions in the first reconstruction of the image that resemble their final reconstruction;
applying prior knowledge only to said regions in the first reconstruction of the image that resemble their final reconstruction, to obtain a second reconstruction of the image which is more accurate than the first reconstruction;
applying the projection data to projections of the second reconstruction of the image by constraining the projections of the second reconstruction of the image to the projection data, to obtain a third reconstruction of the image which is more accurate than the second reconstruction; and
iteratively creating intermediate images, identifying regions in the third reconstruction of the image and subsequent reconstructions of the image, that resemble their final reconstruction and applying the prior knowledge and the projection data in the same way to the third reconstruction of the image and subsequent reconstructions thereof until a final reconstruction is achieved. - View Dependent Claims (5, 6)
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7. Processing means having software executable thereon for reconstructing a tomographic image of an object from incomplete projection data using a limited angle tomography technique, the software being configured to:
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use the projection data to obtain a first reconstruction of the image;
create an intermediate image in which each pixel represents the probability that a corresponding pixel of the first reconstruction of the image resembles the corresponding pixel of a final reconstruction of the image;
based on the intermediate image, identify regions in the first reconstruction of the image that resemble their final reconstruction;
apply prior knowledge only to said regions in the first reconstruction of the image that resemble their final reconstruction, to obtain a second reconstruction of the image which is more accurate than the first reconstruction;
apply the projection data to projections of the second reconstruction of the image by constraining the projections of the second reconstruction of the image to the projection data, to obtain a third reconstruction of the image which is more accurate than the second reconstruction; and
iteratively create intermediate images, identify regions in the third reconstruction of the image and subsequent reconstructions of the image, that resemble their final reconstruction and apply the prior knowledge and the projection data in the same way to the third reconstruction of the image and subsequent reconstructions thereof until a final reconstruction is achieved. - View Dependent Claims (8, 9)
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Specification