Asymmetric 3D X-ray Detector with Overlap Region Filter
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Solution Overview
Problem
Existing 3D X-ray devices irradiate an overlap region twice during rotations exceeding 180°, leading to uneven X-ray dose distribution within the object volume, which increases the dose burden for patients.
Innovation Solution
A 3D X-ray device with an asymmetrical X-ray detector and strategically placed X-ray filters between the X-ray source and the object volume, specifically within the overlap region, to attenuate the X-ray dose uniformly across the object volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the X-ray device rotates more than 180° to capture projection images from multiple directions, then the completeness of 3D image reconstruction is improved, but the X-ray dose to the overlap region increases due to double irradiation
Solution Approach 1:
The patent applies local quality by placing X-ray filters specifically in the overlap region where double irradiation occurs. The filters have different attenuation properties in different angular ranges, creating locally optimized dose distribution. This allows the system to maintain complete 3D reconstruction while reducing the harmful dose effect in the specific overlap region where it occurs.
Solution Approach 2:
The X-ray filters act as intermediaries between the X-ray source and the object volume. By introducing these filtering elements in the beam path, particularly in the overlap region, the system mediates the excessive radiation dose while preserving the necessary projection data for complete 3D reconstruction. The filters selectively attenuate rays in the overlap region without preventing the acquisition of necessary angular views.
2Illumination intensity
If no X-ray filter is used to maintain beam intensity, then the signal quality for image reconstruction is improved, but the X-ray dose burden on patients increases
Solution Approach 1:
The patent implements local quality by applying X-ray filters with spatially varying attenuation properties. The filters are designed to provide different levels of attenuation in different angular ranges, with stronger attenuation in the overlap region and weaker or no attenuation in non-overlap regions. This maintains adequate beam intensity for image quality while locally reducing the dose burden in regions where it is excessive.
Solution Approach 2:
The patent applies parameter changes by varying the attenuation parameters of the X-ray filters across different angular ranges. The filters are configured with different material compositions or thicknesses to achieve specific attenuation characteristics for different projection angles. This allows optimization of the balance between beam intensity for image quality and dose reduction for patient safety.
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 solution achieves a homogeneous X-ray dose distribution within the entire object volume, reducing the dose burden for patients and preventing over-irradiation in the overlap region.
Implementation Method 1
At least one X-ray filter is disposed between the X-ray source and the object volume for attenuating an X-ray dose inside the overlap region
Data Source
AI summary
A 3D X-ray device including an X-ray detector, an X-ray source and a computer. The X-ray detector and the X-ray source are moved about an object volume to be recorded on movement paths with a rotation of at least 185°. A number of X-ray projection images are recorded from different directions. X-rays irradiate the object volume in one of the irradiation directions and are captured by the detector. A 3D X-ray image of the object volume is calculated from the recorded X-ray projection images by a reconstruction method. The X-ray detector is arranged asymmetrically relative to a central axis through a center of rotation of the 3D X-ray device. A first fan beam and an opposite second fan beam rotated 180° form an overlap region. At least one X-ray filter is placed between the X-ray source and the object volume for attenuating an X-ray dose inside the overlap region.