Volumetric X-ray Reconstruction via Direct and Iterative Techniques
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Solution Overview
Problem
Conventional X-ray imaging systems, particularly those used in security inspection scenarios, face challenges in reliably detecting and characterizing objects with thin dimensions due to limitations in projection imaging, which can result in incomplete or inaccurate representation of such objects in volumetric images.
Innovation Solution
A computational method combining direct and iterative reconstruction techniques to derive a full-volume volumetric image of an object, where an initial estimate is generated using direct reconstruction and iteratively improved using an iterative method, allowing for accurate imaging even with less rigid geometry constraints on X-ray sources and detectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If projection imaging is used to image objects, then the imaging system is simple and fast, but thin objects cannot be reliably detected or characterized
Solution Approach 1:
The patent transitions from two-dimensional projection imaging to three-dimensional volumetric imaging by adding the temporal dimension through sequential rotation. The object is rotated through multiple angles and imaged at each angle, creating a volumetric representation that provides depth information and enables reliable detection of thin objects that are invisible in single-angle projections.
Solution Approach 2:
The imaging system employs periodic rotation of the object through a defined angular range, with detectors capturing images at multiple discrete angles. This periodic sampling of the object from different orientations enables reconstruction of three-dimensional structure while maintaining imaging speed through efficient rotational mechanics.
2Reliability
If multiple projection images from different angles are obtained to improve detection of thin objects, then detection reliability improves, but the complexity of the imaging system increases
Solution Approach 1:
A single rotating object stage serves multiple functions: it provides mechanical rotation for multi-angle imaging, acts as the sample holder, and enables consistent positioning throughout the measurement sequence. This multi-functionality reduces the need for separate complex subsystems while achieving reliable detection through angular sampling.
Solution Approach 2:
The system creates multiple copies of the object's appearance from different angular perspectives by rotating the object and capturing images at each angle. These angular copies are then computationally combined to form a volumetric representation, distributing the imaging complexity across multiple simpler single-angle measurements rather than requiring a single complex system.
3Productivity
If conventional direct reconstruction methods are used, then the imaging process is fast, but the geometry constraints on X-ray sources and detectors must be stringent
Solution Approach 1:
The iterative reconstruction process incorporates feedback by repeatedly comparing the reconstructed volumetric image against the original projection images and adjusting the reconstruction until convergence is achieved. This feedback mechanism allows the system to work with relaxed geometry constraints while maintaining reconstruction accuracy, as the iterative process adapts to the actual measurement geometry rather than requiring pre-specified strict geometric conditions.
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 enables the production of accurate and cost-effective volumetric images of objects, improving detection capabilities for thin objects and reducing the need for stringent geometric constraints, thus enhancing the efficiency and effectiveness of imaging systems.
Implementation Method 1
X-rays from a source passing through the object interact with the internal structures of the object and are altered according to various characteristics of the material (e.g., transmission, scattering and diffraction characteristics, etc.)
Implementation Method 2
X-rays from a source passing through the object interact with the internal structures of the object and are altered according to various characteristics of the material (e.g., transmission, scattering and diffraction characteristics, etc.)
Implementation Method 3
X-rays from a source passing through the object interact with the internal structures of the object and are altered according to various characteristics of the material (e.g., transmission, scattering and diffraction characteristics, etc.)
Implementation Method 4
an array of detectors responsive to X-ray radiation typically is arranged on one side of the object opposite a radiation source. The magnitude of the radiation, measured by any detector in the array, represents the density of material along a ray from the X-ray source to the X-ray detector
Data Source
AI summary
A system and method for forming volumetric images of an imaged object based on multiple radiation measurements of the object taken from different angles. A first volumetric image of the object may be calculated using a direct reconstruction method from a plurality of radiation measurements of the object. At least one iteration of an iterative reconstruction method may be performed to compute a second volumetric image of the object. The iterative reconstruction method may be initialized with the first volumetric image of the object.