42 results about "Ordered subsets" patented technology

A method and system for image reconstruction of data acquired by a device such as computed tomography is provided. The method and system use a multi-stage statistical iterative reconstruction techniques to provide a three dimensional representation of the scanned object. In one embodiment, the first stage uses a projection-based reconstruction technique, such as Ordered Subset (OS) to converge on a solution for low frequency portion of the image. A subsequent stage uses a voxel-based reconstruction technique, such as Iterative Coordinate Descent (ICD), to converge on a solution for high frequency portions of the image. Systems and methods for reconstructing images from incomplete or partial projection data is also provided.

The CT imaging system optimizes its image generation by adaptively weighting certain parameters during the iterations in an iterative reconstruction algorithm. The projection data is grouped into N subsets, and after each of the N subsets is processed by the ordered subsets simultaneous algebraic reconstruction technique (OSSART), the image undergoes total variation (TV) minimization process. During the iterative reconstruction algorithm, a combination of the parameters such as a total variation, a relaxation parameter and a step size parameter is assigned a respective value based upon the current value of the iteration.

The CT imaging system optimizes its image generation by adaptively changing parameters in an iterative reconstruction algorithm based upon certain information such as statistical information. The coefficients for the parameters include at least a first coefficient for a predetermined data fidelity process and a second coefficient for a predetermined regularization process in an iterative reconstruction algorithm. The iterative reconstruction algorithm includes the ordered subsets simultaneous algebraic reconstruction technique (OSSART) and the simultaneous algebraic reconstruction technique (SART). The first coefficient and the second coefficient are independently determined using some predetermined statistical information such as noise and or error in matching the real data.

Methods, systems, and non-transitory computer readable media for image reconstruction are presented. Measured data corresponding to a subject is received. A preliminary image update in a particular iteration is determined based on one or more image variables computed using at least a subset of the measured data in the particular iteration. Additionally, at least one momentum term is determined based on the one or more image variables computed in the particular iteration and / or one or more further image variables computed in one or more iterations preceding the particular iteration. Further, a subsequent image update is determined using the preliminary image update and the momentum term. The preliminary image update and / or the subsequent image update are iteratively computed for a plurality of iterations until one or more termination criteria are satisfied.

A method, computer program product, and a data processing system for determining an edge for inversion in a cyclic compound directed graph. A plurality of graph nodes of a graph are evaluated for generation of a first node order subset pair. A determination that the graph requires a recursive evaluation for completing node ordering of the plurality of graph nodes is made. The graph is divided into a plurality of graph partitions, and respective node order subset pairs are generated for the graph partitions.

The CT imaging system optimizes its image generation by updating an image with the current application of a data fidelity update and a regularization update together in a single step in an iterative reconstruction algorithm. The iterative reconstruction algorithm includes the ordered subsets simultaneous algebraic reconstruction technique (OSSART) and the simultaneous algebraic reconstruction technique (SART). The data fidelity update and the regularization update are independently obtained using some predetermined statistical information such as noise and or error in matching the real data.

The invention discloses a CT (Computed Tomography) iterative image reconstruction method, which can be applied to precise sectional image reconstruction in incomplete projection data situations such as low X-ray tube current, under-sampling or limited angle. The method comprises steps of projection-driven iterative calculation, adaptively-determined ordered subset number, adaptive weight, and distance-driven orthographic projection and back projection calculation. A set of all projection data processed by each time of iterative calculation at each projection angle is firstly divided into a plurality of ordered subsets and each subset undergoes the following steps of distance-driven orthographic projection, subtraction with real projection data and weighting, distance-driven back projection and to-be-reconstructed image correction. In the scanning modes of low X-ray tube current, under-sampling or limited angle, a reconstructed image which can fully meet imaging clinical diagnosis demands can be obtained, the method can be self-sufficiently applied to CT imaging aiming at reducing the X-ray radiation dose or can be used for front-end processing of other CT image reconstruction algorithm.

A framework for an iterative reconstruction algorithm is described which combines two or more of an ordered subset method, a preconditioner method, and a nested loop method. In one type of implementation a nested loop (NL) structure is employed where the inner loop sub-problems are solved using ordered subset (OS) methods. The inner loop may be solved using OS and a preconditioner method. In other implementations, the inner loop problems are created by augmented Lagrangian methods and then solved using OS method.

A method, system and unit for controlling the configuration of a transmission path coupling a first unit and a second unit is disclosed. The first unit and the second unit are configurable to support the transfer of information items over the transmission path in time-slots of successive transmission frames in accordance with a plurality of modes, each of the plurality of modes allocating differing numbers of time-slots within each frame to different types of information items. The method comprises the steps of: programming control logic of the first unit and the second unit with an indication of an ordered subset of the plurality of modes to be supported by the first unit and the second unit; configuring the first unit and the second unit to support the transfer the information items over the transmission path using a default one of the plurality of modes; and responsive to an indication requesting that a different mode be selected, causing the first unit and the second unit to be configured to support the next in the ordered subset of the plurality of modes indicated by the control logic. By providing within each unit a predetermined ordered list of modes to be supported by those units, it is only necessary to provide an indication that some change is required and the mode which needs to be changed to can be determined simply by referring to the ordered list. It will be appreciated that this provides a mechanism to switch efficiently between modes, significantly reduces the amount of data required to indicate the new mode and may improve the efficiency of total data transaction.