Tomographic Imaging for Thin Object Detection
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Solution Overview
Problem
Conventional x-ray inspection systems struggle to reliably detect thin objects, as projection imaging methods fail to recognize objects with thin dimensions parallel to the radiation path, leading to incomplete detection of contraband items.
Innovation Solution
The system employs a method where an item under inspection is moved relative to radiation sources and detectors, with ray paths forming acute angles exceeding three degrees, allowing for the accumulation and processing of transmission data to form a three-dimensional tomographic image, enabling detection of objects regardless of orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If projection imaging is used to inspect items, then the inspection system is simple and fast, but thin objects with dimensions parallel to the radiation path cannot be reliably detected
Solution Approach 1:
The patent transitions from two-dimensional projection imaging to three-dimensional tomographic imaging by acquiring data from multiple angles. The conveyor moves the item through a fan beam, and by accumulating data at different positions, the system reconstructs a 3D representation of the item's contents, enabling detection of thin objects regardless of their orientation relative to the radiation path.
2Productivity
If conventional x-ray projection imaging is used, then the inspection process is rapid, but objects with thin dimensions parallel to the radiation path are not detected
Solution Approach 1:
The system maintains continuous inspection capability by moving the item through the fan beam along the conveyor, continuously accumulating transmission data at multiple positions. This continuous data collection enables 3D reconstruction while maintaining inspection throughput, allowing rapid detection of objects in any orientation without sacrificing speed.
3Adaptability or versatility
If a linear array of detectors is used with a fan beam, then the system is suitable for baggage inspection, but it cannot detect thin objects oriented parallel to the beam direction
Solution Approach 1:
The patent enhances the linear array detector system by moving it through multiple positions along the conveyor, effectively adding a third dimension to the detection geometry. This allows the system to reconstruct 3D images where thin objects in any orientation produce measurable signal variations, significantly improving detection precision for previously undetectable objects.
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 enhances the detection of thin objects by creating a three-dimensional image that can identify contraband items more accurately, improving the reliability of security inspections by accounting for all possible orientations of the object.
Implementation Method 1
penetrating radiation (such as x-rays) may be used to characterize the contents of parcels, luggage, etc.
Implementation Method 2
The contents of an item may be characterized by placing an array of x-ray 'detectors' on the opposite side of the item from the x-ray source and collimator, and causing the beam of x-rays to pass through the item before impinging upon the detectors
Data Source
AI summary
A method for operating an inspection system is disclosed in which an item under inspection may be moved between radiation sources and detectors illuminated by the sources. The radiation sources may be positioned such that radiation from at least some of the sources impinge on the radiation detectors, forming acute angles with respect to a plane having a normal direction coinciding with the first direction that are substantially in excess of three degrees. Data accumulated by the radiation detectors may be processed to form a three-dimensional tomographic data image of at least a portion of the item under inspection. The processing may be performed using an algebraic reconstruction technique using an inverse system matrix. The inverse matrix can be derived without first computing a transpose of the system matrix.