Freight Screening Detector Array for Material Classification
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Solution Overview
Problem
Current freight and baggage screening systems face challenges in accurately identifying materials due to high false alarm rates and limited resolution, requiring skilled operators to distinguish between contraband and non-contraband items.
Innovation Solution
The system employs a detector array with scintillation material and silicon photomultipliers to generate high-resolution energy spectra of X-rays, allowing for the computation of effective atomic numbers and improved material classification through advanced processing algorithms, including pileup recovery, gain calibration, and Fourier transform techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional detectors are arranged in a 1xN array to capture integrated density images, then the device complexity is reduced and ease of manufacture is improved, but measurement precision and material classification accuracy deteriorate due to high false alarm rates
Solution Approach 1:
The detector array is segmented into multiple independent detector elements arranged in a 2D grid pattern rather than a single linear array. Each detector element independently measures X-ray intensity at its specific position, enabling spatial resolution and detailed material classification while maintaining manufacturing feasibility through modular assembly
Solution Approach 2:
The detector array transitions from a 1D linear arrangement to a 2D spatial configuration, adding a spatial dimension to the measurements. This enables the system to capture not only integrated density but also spatial distribution of materials, significantly improving classification accuracy and reducing false alarms
2Measurement precision
If two different detector arrays are used to generate high energy and low energy images separately, then measurement precision for density estimation is improved, but device complexity increases
Solution Approach 1:
Each detector element in the 2D array is designed to be multi-functional, capable of measuring X-ray intensity across a broad energy spectrum. By using a single universal detector array instead of separate specialized arrays, the system achieves both high and low energy image generation while reducing overall device complexity
Solution Approach 2:
The system achieves energy differentiation by processing signals from the same detector array under different operating conditions or using signal processing techniques to separate energy components, rather than requiring physically separate detector arrays for each energy range
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
This approach significantly enhances material classification accuracy, reducing false alarms and enabling more effective identification of materials, including contraband, with improved operator efficiency.
Implementation Method 1
each detector being configured to produce an electrical pulse caused by the detected packets having a characteristic size or shape dependent on an energy of the packets; The scintillation material may be lutetium-yttrium oxyorthosilicate (LYSO)
Implementation Method 2
The photon-sensitive material may be a silicon photomultiplier (SiPM)
Data Source
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AI summary
The invention provides a device (100) for screening one or more items (101,1806) of freight or baggage for one or more types of target material, the device comprising: a source (200, 201,1800) of incident radiation (204,206,1804) configured to irradiate the one or more items (101,1806); a plurality of detectors (202,209,1807, 301) adapted to detect packets of radiation (205,207,1700) emanating from within or passing through the one or more items (101, 1806) as a result of the irradiation by the incident radiation (204, 206, 1804), each detector being configured to produce an electrical pulse (312) caused by the detected packets having a characteristic size or shape dependent on an energy of the packets; one or more digital processors (203, 210, 303, 304, 306, 305) configured to process each electrical pulse to determine the characteristic size or shape and to thereby generate a detector energy spectrum for each detector of the energies of the packets detected, and characterise a material associated with the one or more items based on the energy spectrum.