Nano-material Imaging Detector with Integral Pixel Border
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Solution Overview
Problem
Direct converter spectral CT detectors face issues with cross-talk, leading to signal measurement errors and reduced spatial resolution in reconstructed images, which existing software and hardware corrections struggle to fully address, especially under high pulse rates and threshold differences between pixels.
Innovation Solution
A radiation detector array with detector modules featuring a plurality of pixels, each having an integral pixel border and direct conversion active area, utilizing a combination of materials like porous silicon, lead sulphide, and lead or titanium to directly convert X-ray photons into electrical signals, reducing cross-talk through an integral pixel border that interacts to produce electron-hole pairs and minimize electrical crosstalk between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct conversion material is used to convert X-ray photons into electrical signals, then detection efficiency is improved, but cross-talk between pixels occurs leading to signal measurement errors
Solution Approach 1:
The detector is divided into discrete pixel elements with clear boundaries. Each pixel is separated from adjacent pixels by isolation structures that prevent electrical signal leakage between neighboring detection elements, thereby eliminating cross-talk while maintaining high detection efficiency.
Solution Approach 2:
An intermediary material or structure is introduced between adjacent pixels to prevent direct electrical interaction. This intermediary layer acts as an electrical barrier that blocks charge carrier migration between pixels, thus preventing cross-talk without interfering with X-ray detection in the active regions.
2Measurement precision
If pixel size is reduced to improve spatial resolution, then image quality is improved, but signal strength per pixel decreases
Solution Approach 1:
Multiple small pixel signals are electronically combined or summed to reconstruct the original high-resolution image. This merging process at the signal processing stage allows maintenance of fine spatial resolution while recovering sufficient signal strength through coherent addition of adjacent pixel data.
Solution Approach 2:
The signal processing parameters are optimized to enhance the weak signals from small pixels. This includes adjusting amplification gains, integration times, and digital filtering parameters to maximize signal strength while preserving the fine spatial details provided by the small pixel size.
3Productivity
If high pulse rates are used to improve productivity, then scanning speed is improved, but correction errors increase due to threshold differences between pixels
Solution Approach 1:
Pixel threshold variations are characterized and corrected in advance during a calibration phase before actual scanning. This preliminary correction establishes individual pixel offset values that are applied during high-speed scanning, eliminating the need for real-time corrections and preventing errors even at high pulse rates.
Solution Approach 2:
Hardware-based correction mechanisms are replaced with software-based digital correction algorithms. This substitution allows for flexible, programmable correction of pixel threshold differences that can be applied rapidly without mechanical adjustment, enabling accurate corrections even at high scanning speeds.
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 enhances detection efficiency and resolution while minimizing artifacts and improving geometric efficiency, effectively addressing cross-talk issues and providing accurate image reconstruction.
Implementation Method 1
The direct conversion material directly converts X-ray photons incident thereon into electrical currents or pulses
Implementation Method 2
Each of the plurality of detector pixels includes an integral pixel border and a direct conversion active area within the integral pixel border
Data Source
AI summary
A radiation detector array (112) of an imaging system (100) comprises a plurality of detector modules (114). Each of the plurality of detector modules includes a plurality of detector pixel (116). Each of the plurality of detector pixels includes an integral pixel border (202, 204, 206, 208) and a direct conversion active area within the integral pixel border. A method comprises receiving radiation with a nano-material detector pixel that includes an integral pixel border, generating, with the detector pixel, a signal indicative of an energy of the received radiation, while reducing pixel signal crosstalk, and reconstructing the signal to construct an image. An imaging system (100) comprises a source of X-ray radiation configured to emit X-ray radiation that traverses an examination region, a nano-material imaging detector with an integral pixel border, wherein the nano-material imaging detector is configured to detect X-ray radiation, and a reconstructor configured to reconstruct an output of the nano-material imaging detector to produce a CT image.