Segmented X-Ray Beamshaper for CT Scatter Reduction
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Solution Overview
Problem
Conventional bow-tie filters in CT scanners preferentially filter lower energy x-rays, leading to beam hardening and image quality degradation, while also producing undesired scatter and increasing patient dose.
Innovation Solution
A beamshaper with interleaved x-ray attenuating elements and material-free regions is used, translating to shape the x-ray flux profile uniformly across the detector array, reducing beam scatter and mitigating shading artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional bow-tie filter is used to shape the x-ray beam transmission profile, then the flux intensity distribution is improved, but beam hardening occurs and image quality degrades
Solution Approach 1:
The beamshaper is divided into multiple discrete attenuating elements arranged in a pattern of interleaved attenuating and non-attenuating regions. This segmentation allows selective attenuation of specific beam paths without the continuous filtering that causes beam hardening in conventional bow-tie filters.
Solution Approach 2:
Different regions of the beamshaper provide different attenuation characteristics - central regions have lower attenuation while peripheral regions have higher attenuation. This local variation in quality achieves flux shaping while preserving the x-ray spectrum by avoiding uniform energy filtering.
2Illumination intensity
If a conventional bow-tie filter is used to shape the x-ray beam, then transmission profile is improved, but undesired scatter is produced and patient dose increases
Solution Approach 1:
The segmented structure with discrete attenuating elements creates well-defined beam paths through material-free regions. This segmentation reduces scatter by eliminating the continuous filtering interface that generates scatter in conventional filters, while maintaining precise flux profile control.
3Illumination intensity
If the beamshaper is translated during acquisition, then flux uniformity across the detector array is improved, but device complexity increases
Solution Approach 1:
The beamshaper is made movable rather than fixed, allowing dynamic adjustment of its position during the acquisition interval. This dynamic capability enables flux uniformity across the detector array by translating the beamshaper to compensate for detector element variations, while the simple translation mechanism adds minimal complexity.
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 smoother flux intensity profile, reduces beam scatter, and improves image quality by maintaining optimal x-ray spectrum and minimizing patient dose.
Implementation Method 1
A beamshaper, located between the radiation source and the examination region, defines a flux intensity profile of the radiation beam traversing the examination region. The beamshaper includes a plurality of x-ray attenuating elements, which attenuate x-rays incident thereon
Implementation Method 2
A beamshaper mover translates the beamshaper during the at least one acquisition interval of the scan. The beamshaper mover translates the beamshaper a distance approximately equal to a width of an attenuating element during the at least one acquisition interval
Data Source
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AI summary
An imaging system (300) includes a radiation source (308) that emits radiation that traverses in a direction of an examination region (306) during a scan and a detector array (316) located opposite the radiation source, across the examination region, which detects radiation traversing the examination region during the scan and produces a signal indicative thereof. A beamshaper (318), located between the radiation source and the examination region, defines a flux intensity profile of the radiation beam traversing the examination region. The beamshaper includes a plurality of x-ray attenuating elements(326), which attenuate x-rays incident thereon, interleaved with a plurality of material free regions, which pass x-ray unattenuated. A transmittance of the x-rays is greater nearer a center region of the beamshaper relative to ends regions of the beamshaper. A beamshaper mover (328) translates the beamshaper during at least one acquisition interval of the scan.