Small-Angle Scatter Detection for Wide-Field Material Characterization
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Solution Overview
Problem
Existing radiation scatter analysis systems face challenges in collecting small-angle X-ray scatter over wide fields of view, leading to incomplete material characterization due to blind spots and noise from Compton large-angle scatter, which limits the ability to accurately identify materials in scanned objects.
Innovation Solution
Implementing a system with multiple X-ray detector modules positioned on one side of the fan beam, each shielded by angular limiting elements to receive small-angle scatter, combined with a coded aperture to filter out Compton scatter, allowing for coherent scatter data collection over a wide field of view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single X-ray detector module is used to capture scatter, then the device complexity is low, but the field of view is limited and blind spots occur
Solution Approach 1:
The system divides the detection task into multiple detector modules (first, second, third, and fourth detector modules) positioned at different locations relative to the fan beam. Each detector module captures scatter from specific angular ranges, and the scattered radiation signals are combined to achieve comprehensive wide-field coverage without blind spots.
Solution Approach 2:
The patent combines signals from multiple detector modules to form a complete scatter pattern. By merging the detected scatter data from detectors positioned at different angles and locations, the system achieves a unified wide-field view that covers the entire scanned object cross-section.
2Area of stationary object
If the detector module is positioned to capture wide-angle scatter, then the field of view increases, but Compton scatter noise increases
Solution Approach 1:
Each detector module is assigned a specific angular acceptance range through strategic positioning relative to the fan beam. The first and second detector modules capture scatter at different angular ranges than the third and fourth modules. This local specialization allows each detector to operate in an optimized angular window that maximizes coherent scatter while minimizing Compton scatter contamination.
Solution Approach 2:
The system uses the inherent angular distribution differences between coherent scatter and Compton scatter to its advantage. By positioning detectors to capture specific angular ranges where coherent scatter dominates, the system converts the angular separation characteristic into a noise filtering mechanism, effectively using geometry to reject Compton scatter noise.
3Reliability
If multiple detector modules are used to cover wide fields of view, then blind spots are reduced, but the device complexity increases
Solution Approach 1:
The detector modules are positioned asymmetrically relative to the fan beam rather than in symmetric arrangements. The first and second detector modules are positioned on one side of the fan beam while the third and fourth are positioned on the other side, creating an asymmetric configuration that optimizes coverage of the scanned object cross-section and eliminates blind spots in specific regions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances material characterization by reducing blind spots and noise, enabling accurate estimation of material type through coherent scatter form factors, even in complex objects like suitcases, thereby improving security scanning efficiency.
Implementation Method 1
Frequently collecting only small angle (less than approximately 15 degrees) X-ray scatter allows collection of the useful information from coherent scatter without the noise from large-angle scatter such as Compton large-angle scatter
Implementation Method 2
The type of interaction of interest in this disclosure is coherent X-ray scatter, sometimes subdivided into small-angle X-ray scatter, which is often abbreviated as SAXS
Implementation Method 3
each X-ray detector module limited to a small-angle field of view by at least one detector side angle limiting element
Implementation Method 4
Coherent scatter is also referred to as X-ray diffraction, especially in the case when the scattering material has some degree of crystallinity
Data Source
AI summary
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.