Calibration method for a spectral computerized tomography system
| DWPI Title: Calibration method for x-ray computerized tomography system, involves measuring point spread function at each of multiple points, and compressing point spread functions in grid of calibration points in field of view of system |
| Abstract: A calibration method for an x-ray computerized tomography system and a method of tomographic reconstruction are provided. The calibration method includes steps of measuring at least one point spread function (PSF) at each of a plurality of points, compressing each PSF, and in one or more storing operations, storing the compressed PSFs in a computer-accessible storage medium. The PSF measurements are made in a grid of calibration points in a field of view (FOV) of the system. In the measuring step, an absorber is positioned at each of the calibration points, and an x-ray projection is taken at least once at each of those absorber positions. In the method of tomographic image reconstruction, projection data from an x-ray tomographic projection system are input to an iterative image reconstruction algorithm. The algorithm retrieves and utilizes a priori system information (APSI) The APSI comprises comprising point spread functions (PSFs) of all voxels in a voxelization of the field of view that are compressed in the form of vectors of parameters. For utilization, each retrieved vector of parameters is decompressed so as to generate a discretized PSF. |
| Use: Calibration method for an x-ray computerized tomography system for reconstructing three-dimensional visualizations of objects from scans obtained using x-rays or other penetrating radiation. |
| Advantage: The method effectively reconstructs the three-dimensional visualizations of objects from scans obtained using x-rays or other penetrating radiation, and estimates the nonlinear system operator of the computerized tomography (CT) system as a sequence of linear operators. The method reduces the number of scans needed for full system characterization, and preserves essential information in the compression of the system operator to reconstruct the object from a sinogram. |
| Novelty: The calibration method involves measuring a point spread function (PSF) at each set of points. A PSF is compressed by fitting an ellipse spline. The compressed PSF is stored in a computer-accessible storage medium. The PSF measurement made in a grid of calibration points in a field of view (FOV) of the system. An absorber is positioned at each calibration point and an x-ray projection is taken once at each absorber position. The PSF at each point of the grid is measured in a number of X-ray energy bins. An imputed PSF for points in the FOV is calculated by interpolation of measured PSF. |
| Filed: 12/23/2019 |
| Application Number: US16725549A |
| Tech ID: SD 14833.0 |
| This invention was made with Government support under Contract No. DE-NA0003525 awarded by the United States Department of Energy/National Nuclear Security Administration. The Government has certain rights in the invention. |
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