Anti-Scatter Grid Layout for Uniform Sub-Pixel Shielding
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Solution Overview
Problem
Existing photon counting radiation detectors suffer from non-uniform shielding by anti-scatter grids, leading to lensing effects and sub-optimal count stability due to unequal shielding of sub-pixels, which affects the accuracy and reliability of photon detection.
Innovation Solution
The detector structure incorporates an anti-scatter grid with a reduced pitch between adjacent septa of less than 800 μm, ensuring equal shielding of peripheral edges of each sub-pixel, thereby mitigating lensing effects and improving count stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional anti-scatter grids with larger pitch are used, then device complexity is reduced and ease of manufacture is improved, but non-uniform shielding occurs leading to lensing effects and sub-optimal count stability
Solution Approach 1:
The anti-scatter grid is segmented into multiple septa with different vertical height dimensions. First septa have a first vertical height dimension while second septa have a second vertical height dimension that is less than the first. This segmentation allows different regions of the grid to provide different levels of shielding, achieving uniform sub-pixel shielding while managing structural complexity through functional differentiation.
Solution Approach 2:
Different regions of the anti-scatter grid are assigned different shielding properties. The first septa with greater vertical height provide stronger shielding in certain regions, while the second septa with lesser vertical height provide appropriate shielding in other regions. This local differentiation of shielding quality ensures that each sub-pixel receives equal shielding without requiring uniform structure throughout the entire grid.
2Reliability
If anti-scatter grids with non-uniform septa are used, then sub-pixel shielding uniformity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The grid structure is segmented into two types of septa (first and second septa) with different vertical heights. This segmentation transforms the complex requirement of precise uniform shielding across all septa into a more manageable task of controlling two distinct height dimensions, reducing overall manufacturing precision requirements while maintaining shielding uniformity.
3Measurement precision
If pitch between septa is reduced to less than 800 μm, then sub-pixel shielding uniformity is improved and lensing effects are mitigated, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The reduced pitch structure is segmented into first and second septa with different vertical heights arranged in a specific pattern. This segmentation allows the tight spacing to be managed through functional differentiation, where each septum type serves a specific shielding role, making the complex reduced-pitch configuration more manageable and manufacturable.
Solution Approach 2:
At the reduced pitch scale of less than 800 μm, local quality differentiation through varying septa heights becomes essential for achieving uniform sub-pixel shielding. The first and second septa provide locally optimized shielding properties that collectively ensure uniform protection across all sub-pixels despite the tight spacing constraints.
4Reliability
If uniform sub-pixel shielding is achieved through multi-height septa, then count stability is improved, but manufacturing process complexity increases
Solution Approach 1:
The manufacturing process is segmented into sequential patterning steps that first form the first septa with greater vertical height, then form the second septa with lesser vertical height. This segmentation of the manufacturing process into distinct stages simplifies each individual step compared to attempting to create all septa in a single complex operation, making the overall multi-height structure more manufacturable.
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 design enhances the stability and accuracy of photon counting by reducing non-uniform shielding, minimizing pile-up and charge sharing effects, and maintaining detector quantum efficiency.
Implementation Method 1
a pitch between adjacent septa of the anti-scatter grid along a first horizontal direction is less than 800 μm, and the septa of the anti-scatter grid shield an equal number of peripheral edges of each sub-pixel
Implementation Method 2
Room temperature pixelated radiation detectors made of semiconductors, such as cadmium zinc telluride (Cd1-xZnxTe where 0
Data Source
AI summary
Detector structures and methods of fabrication of detector structures that include a radiation sensor having a plurality of macropixels, each including a plurality of sub-pixels, and an anti-scatter grid (ASG) located over the radiation sensor, where the ASG has a pitch between adjacent septa of the ASG along at least one dimension that is less than 800μm, and the septa of the ASG partially shield an equal number of peripheral edges of each sub-pixel of each of the macropixels. In various embodiments, the ASG includes a plurality of first septa having a first vertical height dimension and a plurality of second septa having a second vertical height dimension different from the first vertical height dimension.