Non-Orthogonal Signal Traces in PET Light Sensors
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Solution Overview
Problem
Conventional Silicon photomultiplier (SIPM) systems in Positron Emission Tomography (PET) detectors face reduced timing performance due to long signal path lengths caused by orthogonal 'zig-zag' signal paths, which affect the accuracy of coincidence detection and image generation in PET systems.
Innovation Solution
The implementation of a light sensor with a micro-cell array featuring non-orthogonal signal paths defined by signal traces that electrically couple micro-cells to a pin-out, allowing for reduced transit time spread and improved timing resolution, using micro-cells shaped as hexagons, triangles, or other non-rectangular forms to optimize signal trace configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If orthogonal zig-zag signal paths are used in conventional SIPM, then manufacturing is simplified, but signal path length increases reducing timing performance
Solution Approach 1:
The patent applies curvature by replacing orthogonal zig-zag signal paths with curved or non-orthogonal signal paths that directly connect micro-cells to the through via. This eliminates the 90-degree bends characteristic of conventional orthogonal routing, reducing the overall signal path length and improving timing performance while remaining manufacturable using standard PCB routing techniques.
Solution Approach 2:
The patent utilizes the third dimension (vertical depth) by implementing a through via that extends through the entire thickness of the SIPM substrate. This allows signal paths to transition from a two-dimensional orthogonal plane to a three-dimensional configuration, enabling direct vertical connections that significantly reduce signal path length compared to conventional planar orthogonal routing.
2Ease of manufacture
If rectangular micro-cells are used, then manufacturing is easier, but signal path length increases affecting timing resolution
Solution Approach 1:
The patent replaces the rectangular micro-cell geometry with hexagonal micro-cells. This geometric change allows for optimized signal trace routing that reduces path length while maintaining ease of manufacture. The hexagonal shape provides more favorable angles for signal traces to reach the through via, eliminating the need for long orthogonal paths required by rectangular cells.
Solution Approach 2:
The patent introduces asymmetry in the micro-cell geometry by using hexagons instead of symmetric rectangles. This asymmetric shape optimization enables shorter signal paths to the through via while maintaining manufacturability, thereby improving timing resolution without significantly increasing manufacturing complexity.
3Loss of time
If through via with non-orthogonal signal paths is implemented, then timing performance improves, but device complexity increases
Solution Approach 1:
The through via serves multiple functions simultaneously: it acts as a ground reference, a signal return path, and a timing optimization element. By integrating these multiple functions into a single structural element, the patent reduces overall device complexity while achieving improved timing performance through the non-orthogonal signal paths.
Solution Approach 2:
The patent merges the signal path optimization with the existing through via structure. Instead of adding separate components or complex routing layers, the non-orthogonal signal paths are integrated directly into the through via configuration, combining timing improvement functionality with the existing device architecture and minimizing additional 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
This configuration enhances the timing performance of SIPM systems by reducing signal path lengths, thereby improving the accuracy of coincidence detection and image generation in PET systems, leading to better localization of gamma ray sources and increased signal-to-noise ratio in imaging.
Implementation Method 1
Each microcell contains avalanche photo diode and quenching circuitry
Implementation Method 2
The photons are emitted in opposite directions along a line of response
Data Source
AI summary
Methods and systems for a light sensor for a gamma ray detector of a positron emission tomography (PET) imaging system is provided. The methods and systems include a plurality of micro-cells forming a micro-cell array. The methods and systems include a set of signal traces electrically coupling the plurality of micro-cells to the pin-out. The set of signal traces are configured to define a non-orthogonal signal path from each of the micro-cells to the pin-out.