Abstract: Embodiments and processes of computer tomography perform tasks associated with denoising a reconstructed image using an anisotropic diffusion filter and adaptively weighting an iterative instance of the diffused image based upon the product of a weight value and a difference between the iterative instance of the diffused image and the original image. In general, the adaptive weighting is a negative feedback in the iterative steps.

Abstract: A CT imaging apparatus has processing circuitry that is configured to obtain projection data collected by a CT detector during a scan of an object. The processing circuitry is also configured to perform iterative reconstruction of the projection data to generate a current image. The iterative reconstruction includes filtering forward-projected data during backprojection or filtering image data prior to forward projection to model system optics. The processing circuitry is also configured to combine the current image with a previously-obtained image to generate an updated image.

Abstract: A computed tomography (CT) imaging apparatus that reduces metal artifacts for digital subtraction angiography by, in circuitry, obtaining mask frames and contrast frames generated during scans of an object; performing a first reconstruction of the mask frames to generate metal volume data; identifying metal voxels in the metal volume data; re-projecting the metal voxels into the mask frames to generate metal-mask frames; defining a region of interest in each of the mask frames, each region of interest including metal regions; re-projecting the contrast frames; blending the mask frames with the re-projected contrast frames; registering the contrast frames with respect to the blended mask frames performing a cross-correlation analysis of the mask frames and the contrast frames, frame-pair-by-frame-pair; subtracting the registered contrast image from the corresponding mask image, frame-pair-by-frame-pair, to generate subtracted frames; and performing a second reconstruction on the subtracted frames.

Abstract: A method and apparatus to correct for scatter in projection data by successive approximations of a primary-beam estimate and a scatter estimate. The scatter estimate is calculated by convolving a scattering function, which is a function of the primary-beam estimate, with a smoothing function that includes Rayleigh scattering and Compton scattering terms. The scattering function is greater than zero in the limit that the primary-beam estimate goes to zero. The projection data can be X-ray computed tomography projection data, and the choice of scattering function has the benefit of reducing dark-band artefacts in reconstructed computed tomography images.

Abstract: A computed tomography (CT) imaging apparatus that reduces metal artifacts for digital subtraction angiography by, in circuitry, obtaining mask frames and contrast frames generated during scans of an object; performing a first reconstruction of the mask frames to generate metal volume data; identifying metal voxels in the metal volume data; re-projecting the metal voxels into the mask frames to generate metal-mask frames; defining a region of interest in each of the mask frames, each region of interest including metal regions; re-projecting the contrast frames; blending the mask frames with the re-projected contrast frames; registering the contrast frames with respect to the blended mask frames performing a cross-correlation analysis of the mask frames and the contrast frames, frame-pair-by-frame-pair; subtracting the registered contrast image from the corresponding mask image, frame-pair-by-frame-pair, to generate subtracted frames; and performing a second reconstruction on the subtracted frames.

Abstract: A method and apparatus to correct for scatter in projection data by successive approximations of a primary-beam estimate and a scatter estimate. The scatter estimate is calculated by convolving a scattering function, which is a function of the primary-beam estimate, with a smoothing function that includes Rayleigh scattering and Compton scattering terms. The scattering function is greater than zero in the limit that the primary-beam estimate goes to zero. The projection data can be X-ray computed tomography projection data, and the choice of scattering function has the benefit of reducing dark-band artefacts in reconstructed computed tomography images.

Abstract: A CT imaging apparatus has processing circuitry that is configured to obtain projection data collected by a CT detector during a scan of an object. The processing circuitry is also configured to perform iterative reconstruction of the projection data to generate a current image. The iterative reconstruction includes filtering forward-projected data during backprojection or filtering image data prior to forward projection to model system optics. The processing circuitry is also configured to combine the current image with a previously-obtained image to generate an updated image.

Abstract: The methods and systems of the present invention is an algorithm which estimates motion inside objects that change during the scan. The algorithm is flexible and can be used for solving the misalignment correction problem and, more generally, for finding scan parameters that are not accurately known. The algorithm is based on Local Tomography so it is faster and is not limited to a source trajectory for which accurate and efficient inversion formulas exist.

Abstract: Embodiments and processes of computer tomography perform tasks associated with denoising a reconstructed image using an anisotropic diffusion filter and adaptively weighting an iterative instance of the diffused image based upon the product of a weight value and a difference between the iterative instance of the diffused image and the original image. In general, the adaptive weighting is a negative feedback in the iterative steps.

Abstract: Photon starvation causes streaks and noise and seriously impairs the diagnostic value of the CT imaging. To reduce streaks and noise, a new scheme of adaptive Gaussian filtering relies on the diffusion-derived scale-space concept in one embodiment of the current invention. In scale-space view, filtering by Gaussians of different sizes is similar to decompose the data into a sequence of scales. As the scale measure, the variance of the filter linearly relates to the noise standard deviation of a predetermined noise model in the new filtering method. The new filter has only one optional parameter that remains stable once tuned. Although single-pass processing using the new filter generally achieves desired results, iterations are optionally performed.

Abstract: Embodiments and processes of computer tomography perform tasks associated with denoising a reconstructed image using an anistropic diffusion filter and adaptively weighting an iterative instance of the diffused image based upon the product of a weight value and a difference between the iterative instance of the diffused image and the original image. In general, the adaptive weighting is a negative feedback in the iterative steps.

Abstract: The current invention is generally related to an image processing method and system for substantially reducing ring artifacts. Using the attenuation data, the ring artifacts are substantially prevented based upon two-step process, and the second ring artifact reduction step removes the undesirable rings based upon previously determined statistical data including mean and standard deviation.

Abstract: Spatial resolution is substantially improved by simulating a system blur kernel including an angle variable in the forward projection during a predetermined iterative reconstruction technique. The iterative reconstruction acts as a deconvolution, which overcomes certain restrictions of system optics. In general, resolution is substantially improved with cone beam and helical data without a large increase in noise.

Abstract: The methods and systems of the present invention is an algorithm which estimates motion inside objects that change during the scan. The algorithm is flexible and can be used for solving the misalignment correction problem and, more generally, for finding scan parameters that are not accurately known. The algorithm is based on Local Tomography so it is faster and is not limited to a source trajectory for which accurate and efficient inversion formulas exist.

Abstract: Photon starvation causes streaks and noise and seriously impairs the diagnostic value of the CT imaging. To reduce streaks and noise, a new scheme of adaptive Gaussian filtering relies on the diffusion-derived scale-space concept in one embodiment of the current invention. In scale-space view, filtering by Gaussians of different sizes is similar to decompose the data into a sequence of scales. As the scale measure, the variance of the filter linearly relates to the noise standard deviation of a predetermined noise model in the new filtering method. The new filter has only one optional parameter that remains stable once tuned. Although single-pass processing using the new filter generally achieves desired results, iterations are optionally performed.

Abstract: Photon starvation causes streaks and noise and seriously impairs the diagnostic value of the CT imaging. To reduce streaks and noise, a new scheme of adaptive Gaussian filtering relies on the diffusion-derived scale-space concept in one embodiment of the current invention. In scale-space view, filtering by Gaussians of different sizes is similar to decompose the data into a sequence of scales. As the scale measure, the variance of the filter linearly relates to the noise standard deviation of a predetermined noise model in the new filtering method. The new filter has only one optional parameter that remains stable once tuned. Although single-pass processing using the new filter generally achieves desired results, iterations are optionally performed.

Abstract: Spatial resolution is substantially improved by simulating a system blur kernel including an angle variable in the forward projection during a predetermined iterative reconstruction technique. The iterative reconstruction acts as a deconvolution, which overcomes certain restrictions of system optics. In general, resolution is substantially improved with cone beam and helical data without a large increase in noise.

Abstract: The current invention is generally related to an image processing method and system for substantially reducing ring artifacts. Using the attenuation data, the ring artifacts are substantially prevented based upon two-step process, and the second ring artifact reduction step removes the undesirable rings based upon previously determined statistical data including mean and standard deviation.

Abstract: A computed tomography apparatus and method where data is upsampled with shifting to produce upsampled data. The data is shifted up and down in the same amount in the z-direction, and then upsampled through interpolation. An image is reconstructed using the upsampled data. The process is preferably performed column-by-column. An upsampling shift and interpolation kernel size can be adaptive to the data z-gradient.

Abstract: A three dimensional image processing apparatus includes a region-of-interest setting unit to obtain a moving image of an area of movement of the subject radiographed from a predetermined direction, the moving image including a sequence of frames, to obtain a first feature region in a first frame of the sequence, to search each subsequent frame in the sequence to identify corresponding feature regions most similar to the first feature region so as to identify a sequence of feature regions, and to set a region of interest on the first frame as a rectangular region that just covers all of the identified feature regions in the sequence of feature regions.