Systems and a method of improved material classification using energy-integrated backscatter detectors
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Solution Overview
Problem
Existing backscatter inspection systems using energy-integrating detectors lack the capability to discriminate between different organic materials due to the loss of spectral information, leading to numerous false positive alarms.
Innovation Solution
An X-ray inspection system with a detector panel comprising spatially distributed, independent detector assemblies and filters of varying thicknesses operates in energy-integration mode, reconstructing an energy spectrum to extract unique material characteristics for classification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If energy-integrating detectors are used, then detection efficiency and response time are improved, but spectral information is lost and material classification capability deteriorates
Solution Approach 1:
The detector panel is segmented into multiple detector assemblies, each with filters of different thicknesses. This segmentation allows the system to simultaneously capture multiple energy bins by dividing the detection function across separate detector units, each sensitive to different energy ranges, thereby recovering spectral information while maintaining the speed advantage of energy-integrating detectors.
Solution Approach 2:
The patent introduces a new dimension to the detection system by adding filters of varying thicknesses in front of detector assemblies. This creates a multi-dimensional detection space where each detector assembly measures intensity at a specific energy bin, transforming the single-dimensional energy-integrated measurement into a multi-dimensional spectral measurement without sacrificing temporal resolution.
2Power
If energy-integrating detectors are used, then detection efficiency is improved, but material identification capability deteriorates
Solution Approach 1:
Each detector assembly is equipped with a specific filter of predetermined thickness that is optimized for detecting a particular energy bin. This local quality differentiation allows each detector to be tuned for its specific energy range, improving the overall material identification capability while maintaining high detection efficiency through the energy-integrating operation mode.
Solution Approach 2:
The patent changes the parameter of filter thickness to differentiate between energy bins. By varying the filter thickness across different detector assemblies, the system creates distinct detection channels for different energy ranges, enabling material classification based on spectral shape while preserving the high efficiency of energy-integrating detection.
3Loss of information
If filters of different thicknesses are added to detector assemblies, then spectral information is recovered, but device complexity increases
Solution Approach 1:
The patent merges the filter elements directly with the detector assemblies in a unified detector panel structure. This integration combines the spectral filtering function with the detection function in a single compact unit, recovering spectral information while minimizing the increase in device complexity through modular assembly.
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
The system effectively distinguishes between similar organic materials, reducing false positive alarms by utilizing spectral information to improve material identification.
Implementation Method 1
The optical signal generated through the scintillation process is converted to an electrical signal through a photodiode or PMT
Implementation Method 2
Typical backscatter detectors use inorganic scintillator phosphors with decay times in the order of microseconds (μs). The optical signal generated through the scintillation process is converted to an electrical signal
Implementation Method 3
an array of 'n' filters, wherein each of the 'n' filters has a thickness and is positioned over one of the 'm' spatially distributed and independent detector assemblies
Implementation Method 4
reconstruct an energy spectrum from the acquired scan data, wherein the reconstructed energy spectrum includes the required number of energy bins
Data Source
AI summary
The present specification describes a system of acquiring spectral information from backscatter scan data acquired using a detector panel having an array of ‘m’ spatially distributed, independent detector assemblies or modules an array of ‘n’ filters positioned over the array of detector assemblies or modules. In some embodiments, m=n. From the acquired set of detector response measurements, an energy spectrum is mathematically reconstructed or calculated by formulating and solving the energy reconstruction problem as an inverse problem.