Accelerated fast iterative shrinkage thresholding algorithms for sparsity‐regularized cone‐beam CT image reconstruction. Issue 4 (23rd March 2016)

• Record Type: Journal Article
• Authors: Xu, Qiaofeng; Yang, Deshan; Tan, Jun; Sawatzky, Alex; Anastasio, Mark A.
• Is Part Of: Medical physics. Volume 43:Issue 4(2016)
• Page Start: 1849
• Page End: 1872
• Publication Date: 2016-03-23
• Subjects: computerised tomography -- graphics processing units -- image reconstruction -- iterative methods -- medical image processing; Computed tomography; Computerised tomographs -- Biological material, e.g. blood, urine; Haemocytometers -- Digital computing or data processing equipment or methods, specially adapted for specific applications -- Image data processing or generation, in general -- Processor architectures; Processor configuration, e.g. pipelining; computed tomographic image reconstruction -- x‐ray cone‐beam computed tomography -- sparsity‐regularized inverse problems; Image reconstruction -- Medical image reconstruction -- Cone beam computed tomography -- Medical image quality -- Image guided radiation therapy -- Medical X‐ray imaging -- Three dimensional image processing -- Computer modeling; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4942812
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: The development of iterative image reconstruction algorithms for cone‐beam computed tomography (CBCT) remains an active and important research area. Even with hardware acceleration, the overwhelming majority of the available 3D iterative algorithms that implement nonsmooth regularizers remain computationally burdensome and have not been translated for routine use in time‐sensitive applications such as image‐guided radiation therapy (IGRT). In this work, two variants of the fast iterative shrinkage thresholding algorithm (FISTA) are proposed and investigated for accelerated iterative image reconstruction in CBCT. Methods: Algorithm acceleration was achieved by replacing the original gradient‐descent step in the FISTAs by a subproblem that is solved by use of the ordered subset simultaneous algebraic reconstruction technique (OS‐SART). Due to the preconditioning matrix adopted in the OS‐SART method, two new weighted proximal problems were introduced and corresponding fast gradient projection‐type algorithms were developed for solving them. We also provided efficient numerical implementations of the proposed algorithms that exploit the massive data parallelism of multiple graphics processing units. Results: The improved rates of convergence of the proposed algorithms were quantified in computer‐simulation studies and by use of clinical projection data corresponding to an IGRT study. The accelerated FISTAs were shown to possess dramatically improved convergence properties as compared to the standard FISTAs. For example, the number of iterations to achieve a specified reconstruction error could be reduced by an order of magnitude. Volumetric images reconstructed from clinical data were produced in under 4 min. Conclusions: The FISTA achieves a quadratic convergence rate and can therefore potentially reduce the number of iterations required to produce an image of a specified image quality as compared to first‐order methods. We have proposed and investigated accelerated FISTAs for use with two nonsmooth penalty functions that will lead to further reductions in image reconstruction times while preserving image quality. Moreover, with the help of a mixed sparsity‐regularization, better preservation of soft‐tissue structures can be potentially obtained. The algorithms were systematically evaluated by use of computer‐simulated and clinical data sets.