Sub-pixel Calibration for Radiation Detector Inhomogeneity
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Solution Overview
Problem
In nuclear medicine imaging, radiation detectors face inhomogeneity issues that lead to degradation in energy resolution and gain stability due to variations in detected energy across different locations on the detector surface, causing non-uniform signal distribution and spectral broadening.
Innovation Solution
A radiation detector assembly with semiconductor detectors and pixelated anodes is used, where a processor defines sub-pixels for each anode, acquires signals, determines sub-pixel locations, and applies calibration parameters on a per-sub-pixel basis to adjust energy spectra, improving energy resolution and gain stability by correcting inhomogeneous charge collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If per-pixel calibration is applied, then gain stability is improved, but inhomogeneity within pixels persists causing energy resolution degradation
Solution Approach 1:
Each pixelated anode is divided into multiple sub-pixels (e.g., 3x3 grid), allowing independent calibration for each sub-pixel region. This segmentation enables correction of inhomogeneity within pixels by applying location-specific calibration parameters to different sub-pixel regions, thereby improving energy resolution while maintaining gain stability.
Solution Approach 2:
The patent implements location-dependent calibration by determining sub-pixel locations for each acquisition event and applying calibration parameters specific to that sub-pixel location. This local quality approach ensures that each region within a pixel is calibrated according to its specific characteristics, correcting the inhomogeneity that persists with uniform per-pixel calibration.
2Measurement precision
If sub-pixel calibration is implemented, then energy resolution is improved, but device complexity increases
Solution Approach 1:
The patent introduces an intermediary computational layer that determines sub-pixel locations based on signals from pixelated anodes and applies appropriate calibration parameters. This intermediary processing step manages the complexity by systematically handling sub-pixel classification and calibration parameter application, rather than requiring complex hardware modifications.
Solution Approach 2:
The patent adds a sub-pixel dimension to the traditional pixel-based calibration approach. By dividing each pixel into multiple sub-pixels and applying calibration in this additional dimensional granularity, the system improves energy resolution while managing complexity through systematic organization of calibration data across the sub-pixel grid.
3Manufacturing precision
If sub-pixel division is applied, then inhomogeneity correction is improved, but processing time increases
Solution Approach 1:
The patent performs sub-pixel calibration parameter determination in advance during a calibration phase using a radiation source with known energy characteristics. By pre-calculating and storing calibration parameters for each sub-pixel location before actual imaging, the system avoids real-time computational overhead during data acquisition, thus improving inhomogeneity correction without significantly increasing processing time during operation.
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 enhances image quality by correcting inhomogeneous charge collection, improves energy resolution, and stabilizes gain, allowing detectors that initially do not meet specifications to be calibrated for better performance.
Implementation Method 1
Each pixelated anode is configured to generate a primary signal responsive to reception of a photon by the pixelated anode
Implementation Method 2
Each pixelated anode is configured to generate at least one secondary signal responsive to an induced charge caused by reception of a photon by at least one adjacent anode
Data Source
AI summary
A radiation detector assembly is provided that includes a semiconductor detector having a surface, plural pixelated anodes, and at least one processor. The pixelated anodes are disposed on the surface. Each pixelated anode is configured to generate a primary signal responsive to reception of a photon by the pixelated anode and to generate at least one secondary signal responsive to an induced charge caused by reception of a photon by at least one adjacent anode. The at least one processor is operably coupled to the pixelated anodes. The at least one processor configured to define sub-pixels for each pixelated anode; acquire signals corresponding to acquisition events from the pixelated anodes; determine sub-pixel locations for the acquisition events using the signals; and apply at least one calibration parameter on a per sub-pixel basis for the acquisition events based on the determined sub-pixel locations.