Forward-Offset Hoop for High-Speed X-Ray Vehicle Scanning
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Solution Overview
Problem
Existing beam chopping apparatuses with rearward offset x-ray sources have limited fields of view and slow image acquisition rates, making them inadequate for scanning vehicles moving at high speeds, as they are constrained by the maximum rotation speed of the hoop and result in low-resolution images due to larger beam sizes.
Innovation Solution
A forward-offset x-ray source relative to the axis of rotation of the rotating hoop, allowing for increased number of apertures and scan lines per rotation, maintaining a sufficient field of view while enhancing scan speed, and optionally using moveable shielding devices for adjustable fan beam angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the source is offset rearward from the axis of rotation to increase collimation distance, then beam divergence is reduced and image resolution is improved, but the field of view is limited and scan speed is reduced
Solution Approach 1:
The patent inverts the conventional rearward offset configuration by positioning the x-ray source forward of the hoop's axis of rotation. This forward offset allows the beam to originate closer to the object being scanned, increasing the effective collimation distance while maintaining a large field of view and enabling high scan speeds. The inversion resolves the contradiction by achieving high resolution without sacrificing productivity.
Solution Approach 2:
The patent introduces a new spatial dimension by allowing the source to be positioned at any offset distance and angle relative to the hoop's axis of rotation, not just on the axis or rearward offset. This dimensional freedom enables optimization of both collimation distance and field of view simultaneously, resolving the trade-off between resolution and scan speed.
2Length of stationary object
If the source is offset rearward from the axis of rotation, then collimation distance is increased, but the field of view is limited
Solution Approach 1:
The patent inverts the conventional rearward offset by positioning the source forward of the axis of rotation. This forward offset configuration allows the beam to traverse a larger angular range while maintaining adequate collimation distance, thereby increasing the field of view without sacrificing resolution.
Solution Approach 2:
The patent employs a variable offset mechanism that allows the source-to-axis distance to be adjusted dynamically. This enables the system to optimize the balance between collimation distance and field of view based on specific scanning requirements, resolving the fixed trade-off in conventional designs.
3Productivity
If the hoop rotation speed is increased to improve scan rate, then image acquisition rate is improved, but beam size increases and resolution decreases
Solution Approach 1:
The forward offset configuration changes the geometric relationship between source, hoop, and object, allowing high rotation speeds to be achieved without proportionally increasing beam size. The forward positioning creates a more favorable geometry that maintains collimation effectiveness even at high scan rates.
Solution Approach 2:
The patent changes the fundamental geometric parameter of source offset direction (from rearward to forward), which alters the relationship between rotation speed and beam divergence. This parameter change enables high acquisition rates while maintaining resolution by creating a geometry where beam size increases more slowly with rotation speed.
4Measurement precision
If the distance between source and aperture is increased to minimize beam divergence, then image resolution is improved, but the hoop size and moment of inertia increase
Solution Approach 1:
The forward offset configuration reduces the required distance between source and aperture for achieving adequate collimation, compared to rearward offset designs. This is because the forward positioning creates a more efficient geometric arrangement where the beam naturally diverges less over the available distance, allowing a smaller hoop while maintaining resolution.
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 forward-offset configuration enables faster scan rates with a larger field of view, capable of imaging entire vehicles, and maintains high image resolution by reducing beam divergence and increasing collimation distance, thus overcoming the limitations of prior art.
Implementation Method 1
a rotating structure which attenuates the beam other than when it emanates from one or more apertures within the structure during a portion of the rotation of the structure
Implementation Method 2
A first collimator is disposed proximate to the source itself, to collimate the beam substantially into a plane (or into a fan beam with a small divergence parallel to the fan)
Implementation Method 3
The distance between the focal spot of the source and the aperture is ideally as large as possible in order to minimize the divergence of the beam with increasing distance
Data Source
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AI summary
An apparatus for forming a beam of energetic particles and for scanning the beam of particles with respect to an inspected object. The apparatus has a source of energetic particles characterized by an effective beam origin and a rotating hoop having at least one aperture, such that the effective beam origin of the source is closer to the inspected object than the axis of rotation of the rotating hoop. A collimating structure disposed interior to the rotating hoop collimates emission by the source into a fan beam prior to impinging on the rotating hoop. In some embodiments, the effective beam origin may be moved with respect to the axis of rotation of the hoop.