X-ray detector active area uniformity for artifact suppression
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Solution Overview
Problem
Conventional X-ray CT apparatuses face issues with detection efficiency and signal-to-noise ratios due to smaller active areas at the ends of photodiode arrays, leading to artifacts caused by degraded detection efficiency and SN ratios.
Innovation Solution
The X-ray detector is configured such that the widths of active areas are equal in at least one direction, with varying intervals between adjacent active areas, to maintain uniform detection efficiency and SN ratios across all photodiodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If active areas are arranged at regular intervals in the photodiode array, then uniform detection is achieved, but active areas at the end parts become smaller leading to degraded detection efficiency and SN ratios
Solution Approach 1:
The patent applies local quality by making the active-area formation prohibited areas larger at the end parts of the photodiode array compared to intermediate parts. This local variation compensates for the smaller active areas at the ends, ensuring that detection efficiency and SN ratios are uniform across all photodiodes regardless of position.
2Ease of manufacture
If active-area formation prohibited areas are present at end parts of the photodiode array, then manufacturing defects are avoided, but active areas become smaller causing detection efficiency degradation
Solution Approach 1:
The patent implements local quality by differentiating the size of active-area formation prohibited areas based on position: end parts have larger prohibited areas than intermediate parts. This approach maintains manufacturing quality by preventing defects at vulnerable end regions while compensating for the resulting smaller active areas through adjusted prohibited area dimensions, thereby preserving detection efficiency.
3Ease of manufacture
If active areas at end parts are smaller than other active areas, then manufacturing constraints are satisfied, but artifacts occur due to degraded SN ratios
Solution Approach 1:
The patent applies local quality by varying the size of active-area formation prohibited areas according to position, with larger prohibited areas at end parts. This local differentiation satisfies manufacturing constraints that necessitate smaller end active areas while compensating for the resulting SN ratio degradation, thereby preventing artifact formation in the detected images.
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 configuration suppresses the occurrence of artifacts by ensuring consistent detection efficiency and SN ratios among photodiodes, improving the overall performance of the X-ray detector.
Implementation Method 1
Each of the photodiodes has an active area configured to convert visible light emitted by the scintillator into an electrical signal
Data Source
AI summary
An X-ray detector according to an embodiment includes a scintillator array and a photodiode array. In the scintillator array, a plurality of scintillators are arranged in a first direction and a second direction intersecting the first direction. The photodiode array includes photodiodes each of which is installed for a different one of the scintillators and each of which has an active area configured to convert visible light emitted by the scintillator into an electrical signal. The photodiodes are arranged in such a manner that the widths of the active areas are equal to one another in the first direction.