X-ray Detector Defective Element Interpolation Using Weighted Signal Addition
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Solution Overview
Problem
Photon-counting X-ray detectors with a high number of minute detection elements experience increased processing time, number of processing circuits, and interpolation data volume due to a higher percentage of defective elements, leading to decreased processing speed, increased device cost, and longer man-hours.
Innovation Solution
An X-ray detector with a detection section, addition rate determination section, and position information storage section, where detection elements are grouped into arrays corresponding to pixels, and addition rates are determined to calculate pixel signal values, with defective element positions identified to adjust addition rates for accurate interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a photon-counting detector with many minute detection elements is used, then measurement precision and energy-specific imaging capability are improved, but processing time and device complexity increase due to higher percentage of defective elements
Solution Approach 1:
The detection element group corresponding to one pixel is segmented into multiple detection elements, where at least one is identified as defective. The signal processing is then segmented to exclude defective elements and weight-only use normal elements, reducing the processing burden while maintaining imaging capability.
Solution Approach 2:
Defective detection elements are extracted and identified from the detection element group using stored position information. These defective elements are then excluded from signal processing, removing the source of complexity and error while preserving the functionality of normal elements.
2Reliability
If conventional defect interpolation is applied to photon-counting detectors, then pixel defects are corrected, but processing time and interpolation data volume increase significantly
Solution Approach 1:
Position information indicating the locations of defective detection elements is stored in advance in a storage section. This preliminary action allows the system to quickly identify and exclude defective elements during signal processing without performing time-consuming defect detection and interpolation calculations at imaging time.
Solution Approach 2:
The defective detection elements are extracted from the signal processing chain using the pre-stored position information. By removing defective elements beforehand, the system avoids the need for complex real-time interpolation, significantly reducing processing time while maintaining reliability.
3Productivity
If all detection elements including defective ones are used for signal calculation, then processing speed is maintained, but artifacts occur in projection images
Solution Approach 1:
Different weighting is applied to different detection elements within the same pixel group based on their quality. Normal detection elements are assigned a weight of 1 and are fully used in signal calculation, while defective detection elements are assigned a weight of 0 and excluded. This local quality differentiation maintains processing speed while eliminating artifacts caused by defective elements.
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 reduces processing time, processing circuits, and interpolation data, enhances interpolation accuracy, and suppresses artifacts effectively.
Implementation Method 1
An integrated X-ray detector applied to such an X-ray CT device includes a plurality of detection elements, converts X-ray energy transmitted through the test subject to an electrical signal on an individual detection element basis
Implementation Method 2
An X-ray CT device having a photon-counting X-ray detector for measuring the number of X-ray photons has been developed in recent years
Data Source
AI summary
There is disclosed an X-ray detector that includes a detection section, an addition rate determination section, an addition section, and a position information storage section in order to enhance the accuracy of interpolation of an output signal from a defective element and suppress artifacts with ease without increasing, for example, the length of processing time, the number of processing circuits, and the amount of interpolation data. The detection section includes a plurality of arrays of detection element groups that are each formed of a plurality of detection elements in correspondence with one pixel. The addition rate determination section determines addition rates for output signals of the detection elements. The addition section calculates the signal value of each pixel of a projection image by adding the output signals of the detection elements belonging to the detection element groups in accordance with the addition rates. The position information storage section stores pixel position information and defective element position information. The pixel position information indicates the positional relationship between the pixel and the detection elements. The defective element position information indicates the position of a defective element. Based on the pixel position information and the defective element position information, the addition rate determination section determines the addition rate for the output signal of the defective element and the addition rate for the output signal of a diagonal detection element positioned symmetrically with respect to the defective element in such a manner that the addition rates are equal and lower than the addition rates for the other detection elements and that the addition rates for the other detection elements are substantially equal.