Method and system for noise reduction in low dose computed tomography
First Claim
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1. A method, comprising:
- de-noising projection data from a lower dose scan in the projection domain, wherein the lower dose scan corresponds to a scan which produces image data with a noise level that is higher than a predetermined target image data noise level;
reconstructing the de-noised projection data to generate volumetric image data;
determining a noise level of the image data;
estimating a noise level for the image data of the higher dose scan;
determining a ratio of the noise level of the higher dose scan to the noise level of the image of the lower dose scan; and
de-noising the volumetric image data in the image domain based on the ratio.
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Abstract
A method includes de-noising projection data from a lower dose scan in the projection domain, reconstructing the de-noised projection data to generate volumetric image data, and de-noising the volumetric image data in the image domain. A system includes a projection domain processor (116) that de-noises projection data from a lower dose scan, a reconstructor (118) that reconstructs the de-noised projection data and generates image data, and an image domain processor (120) that de-noises the image data such that a noise level of the de-noise image data is substantially the same as an estimated image data noise level of image data for a higher dose scan.
22 Citations
20 Claims
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1. A method, comprising:
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de-noising projection data from a lower dose scan in the projection domain, wherein the lower dose scan corresponds to a scan which produces image data with a noise level that is higher than a predetermined target image data noise level; reconstructing the de-noised projection data to generate volumetric image data; determining a noise level of the image data; estimating a noise level for the image data of the higher dose scan; determining a ratio of the noise level of the higher dose scan to the noise level of the image of the lower dose scan; and de-noising the volumetric image data in the image domain based on the ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system, comprising:
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a first parameter determiner that determines a noise variance of projection data from a lower dose scan; a second parameter determiner that determines a variation of the projection data, wherein the variation is estimated based on a gradient scalar product; a projection domain processor that de-noises the projection data based on the noise variance and the variation; a reconstructor that reconstructs the de-noised projection data and generates image data; and an image domain processor that de-noises the image data. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16)
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17. A non-transitory computer readable storage medium encoded with computer executable instructions, which, when executed by a processor of a computer, cause the processor to:
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estimate a noise variance of projection data for a lower dose scan; de-noise the projection data in the projection domain; determine a decrease in noise variance of the projection data for the lower dose scan due to the de-noising; determine a de-noising factor from a subset of the projection data; estimate a projection variance for the lower dose scan based on the noise variance and the de-noising factor; estimates a projection variance for a higher dose scan; reconstruct the de-noised projection data and generate image data; estimate an image noise variance for the projection de-noised lower dose scan and for the higher dose scan; and de-noise the image data based on the image noise variances for the lower and higher dose scans. - View Dependent Claims (18, 19, 20)
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Specification