Method for capture of small-angle scatter over wide fields of view
Inventors
Greenberg, Joel Alter • Gehm, Michael Eric • Kapadia, Anuj Jawahar • Coccarelli, David Scott
Assignees
Quadridox Inc • Duke University
Publication Number
US-12360064-B1
Publication Date
2025-07-15
Expiration Date
2044-03-11
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Abstract
Estimate material coherent scatter form factors for voxels within a scan object by exposing a series of slices of the scan object to an X-ray fan beam within a coherent scatter scanner. Capturing coherent scatter data at a least two X-ray detector modules that are limited to a small-angle field of view by at least one detector-side angle limiting element to provide for capture of small-angle scatter over a wide field of view. Combining the coherent scatter data from the at least two X-ray detector modules to generate an aggregated collection of estimated material coherent scatter form factors for at least some voxels. Combining the aggregated collection of estimated material coherent scatter form factors with a model of aggregate items that clusters voxels in the scan object into model items. Using the aggregated collection of estimated material coherent scatter form factors to estimate a material type for individual model items.
Core Innovation
The invention provides a method and system for estimating material coherent scatter form factors for voxels within a scan object by exposing slices of the scan object to an X-ray fan beam within a coherent scatter scanner. The method captures coherent scatter data at least two X-ray detector modules, each limited to a small-angle field of view by detector-side angle limiting elements, to capture small-angle scatter over a wide field of view. The coherent scatter data from these modules is combined to generate aggregated estimated material coherent scatter form factors for voxels.
The aggregated collection of coherent scatter form factors is then combined with a model of aggregate items that clusters voxels into model items. This combined information is used to estimate material types for individual model items within the scanned object. The system includes angle limiting elements such as collimators, blinders, or blocking plates to limit the X-rays reaching detector modules to primarily small-angle coherent scatter and exclude noise such as Compton large-angle scatter.
A key problem addressed is the difficulty in capturing coherent small-angle X-ray scatter over wide fields of view when using immobile X-ray source and detector systems. Small-angle scatter collection is limited by detector geometry and the need to exclude large-angle scatter noise, which creates blind spots and limits the effective spatial coverage of conventional systems. By positioning multiple X-ray detector modules on the same side of the fan beam and limiting each detector to a specific angular portion via angle limiting elements, the invention enables greater coverage of scan object slices while maintaining small-angle scatter detection and reducing noise.
Claims Coverage
The patent contains two independent claims focused on methods for determining estimated coherent scatter form factors using multiple detector modules with small-angle field of view limitations and combining this data with voxel clustering models.
Using multiple fixed X-ray detector modules each limited to a small-angle field of view
Capturing coherent scatter data at a set of at least two X-ray detector modules in fixed positions, each limited by detector-side angle limiting elements to small-angle fields of view not exceeding 15 degrees parallel to the fan beam plane, positioned on the same side of the X-ray fan beam to detect coherent scatter from different angular portions.
Combining coherent scatter data with a separate voxel clustering model to estimate material form factors
Aggregating coherent scatter data from multiple detectors and combining it with a separate model clustering sets of voxels into model items to map estimated material coherent scatter form factors to model items or individual voxels within model items.
Creating voxel clustering model using CT scanner or alternative property estimates
Generating the separate model that clusters voxels based on properties estimated by a CT scanner or alternative sources such as ultrasound or a manifest, grouping contiguous voxels with substantially identical property estimates into model items.
Using angle limiting elements that allow broader angle acceptance than traditional collimators
Employing detector-side angle limiting elements such as X-ray absorbing blinders or blocking plates with single openings sized to absorb substantially all X-rays from angles beyond the small-angle field of view, enabling angular acceptance up to about 15 degrees.
Assuming voxels in blind spots share form factors with neighboring visible voxels
For voxels within blind spot zones that do not receive coherent scatter data from the detectors, assuming those voxels have the same coherent scatter form factors as other voxels not in blind spots within the same clustered model item.
Using polychromatic or partially monochromatic X-ray fan beams with energy-resolving detectors
Exposing the scan object to X-ray fan beams that are polychromatic or partially monochromatic and using energy-resolving X-ray detector modules to segregate data by X-ray energy to improve form factor estimation.
Assigning estimated material identities based on derived form factors
Using a subsequent processing step to determine estimated material identity for at least some model items based on the mapped estimated material coherent scatter form factors.
The claims cover methods for capturing small-angle coherent X-ray scatter data from multiple fixed detector modules with limited angular fields of view covering different portions of the fan beam, integrating that scatter data with voxel clustering models to estimate material form factors, and assigning material types while addressing blind spots through assumptions about voxel materials.
Stated Advantages
Capture of small-angle coherent scatter over wide fields of view is improved by using multiple detector modules each limited to a small-angle field, thus increasing coverage and reducing blind spots.
Use of detector-side angle limiting elements reduces noise from Compton large-angle scatter without significantly diminishing coherent scatter signal.
Modular arrangement of detector modules and angular limiting elements allows flexibility in system configuration, potentially reducing cost compared to a single large detector.
Combining scatter data with voxel clustering from CT or other sources enhances accuracy of material identification by leveraging structural side information to resolve ambiguities.
Documented Applications
Security screening of scan objects such as suitcases or parcels moving on conveyor belts through tunnels using coherent scatter scanners combined with CT scanners for threat detection.
Material identification within complex scan objects by estimating the coherent scatter form factors of voxels clustered into model items.
Use in baggage inspection systems at security checkpoints where wide field of view coherent scatter imaging is required.
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