Pixelated K-edge coded aperture system for compressive spectral X-ray imaging
Inventors
Cuadros, Angela • Arce, Gonzalo
Assignees
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Publication Number
US-10874361-B2
Publication Date
2020-12-29
Expiration Date
Abstract
Aspects of the invention are directed to systems and methods for generating spectral computed tomography data for spectral X-ray image reconstruction using of pixelated k-edge apertures. A method is provided for generating a spectral computed tomography. The method includes the steps of generating a plurality of X-ray beams; encoding the plurality of X-ray beams by transmitting the plurality of beams through a pixelated K-edge coded aperture structure; detecting the encoded plurality of X-ray beams; and reconstructing a spectral CT image from the encoded plurality of X-ray beams.
Core Innovation
The patent describes spectral computed tomography (SCT) data generation for spectral X-ray image reconstruction by positioning an X-ray beam generator along a scanning pathway that includes a plurality of discharge positions. The X-ray beam generator generates an X-ray beam at each discharge position, at least one K-edge filter is assigned to each discharge position, and filtered X-ray beams are detected and their intensities are measured for spectral CT image reconstruction.
The core approach encodes X-ray beams using a pixelated K-edge coded aperture structure that delineates a plurality of openings, where the openings contain at least one K-edge filter. The patent also describes reconstruction using measured intensities associated with coded filtration, including quasi-monochromatic spectrum generation by subtraction of balanced K-edge/Ross filter pairs, and encoding pattern design choices such as random versus non-random coding patterns and filter assignment forming patterns.
For compressive spectral X-ray imaging (CSXI), the patent describes reconstructing spectral X-ray images from encoded measurements using joint sparse and low-rank optimization formulated with tensor modeling and solved with ADMM, including sparsity regularization and a low-rank constraint via nuclear norm regularization. The document contrasts CSXI with a comparative multi-shot balanced K-edge filtering approach and reports improved reconstruction of fine phantom features under limited angles/sub-sampling, along with fewer artifacts.
Claims Coverage
The partial content includes three independent claims. Across them, the inventive coverage focuses on generating spectral CT data using a scanning pathway with multiple discharge positions combined with coded K-edge filtration/encoding via pixelated aperture structures, detection and intensity measurement of the encoded/filtered beams, and spectral CT image reconstruction from those measured intensities, with claim-specific constraints on the coded aperture/pixel/material relationships and scanning/beam geometry.
Scan-path positioning with multiple discharge positions and K-edge filtering assignment
Positioning an X-ray beam generator along a scanning pathway comprising a plurality of discharge positions, generating an X-ray beam at each discharge position, assigning at least one K-edge filter to each discharge position so that the X-ray beam generated at each discharge position is filtered by at least one K-edge filter, detecting the filtered X-ray beams generated at each discharge position, measuring an intensity of the detected filtered X-ray beams generated at each discharge position, and reconstructing a spectral CT image from the measured intensities of the detected filtered X-ray beams.
Pixelated K-edge coded aperture encoding for spectral X-ray tomography
Scanning a target with a plurality of X-ray beams generated at a plurality of discharge positions along a scanning pathway, encoding the X-ray beams by transmitting the X-ray beams through a pixelated K-edge coded aperture structure that delineates a plurality of openings containing at least one K-edge filter, detecting an intensity of the encoded plurality of X-ray beams, measuring an intensity of the detected filtered X-ray beams generated at each discharge position, and reconstructing a spectral CT image from the measured intensities of the detected filtered X-ray beams.
Pixelated coded aperture with different pixel thickness/material for spectral CT data generation
Positioning an X-ray beam generator along a scanning pathway comprising a plurality of discharge positions, generating an X-ray beam at each discharge position, filtering at least one of the X-ray beams generated at each discharge position with a pixelated coded aperture where at least one of a plurality of pixels contains a material having a different thickness than at least another one of the plurality of pixels, detecting the at least one filtered X-ray beams generated at each discharge position, measuring an intensity of at least the detected filtered X-ray beams generated at each discharge position, and reconstructing a spectral CT image from the measured intensities of at least the detected filtered X-ray beams.
Collectively, the independent claims cover spectral CT data generation and reconstruction based on multi-discharge scanning with coded K-edge filtration. They specify encoding through pixelated K-edge coded aperture structures with openings containing K-edge filters, and an alternative formulation using a pixelated coded aperture with pixels having materials of different thicknesses, followed by detection, intensity measurement, and spectral CT image reconstruction.
Stated Advantages
Reduces scan time/dose.
Yields higher PSNR and fewer artifacts than a comparative multi-shot balanced K-edge filtering approach.
Better reconstruction of fine phantom features under limited angles/sub-sampling.
Documented Applications
Simulation examples for compressive spectral X-ray imaging (CSXI) using Ross filters and reconstruction under limited angles/sub-sampling, including a Modified Forbild thorax phantom.
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