Sub-pixel Calibration for Radiation Detector Inhomogeneity
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Solution Overview
Problem
Nuclear medicine imaging systems, such as SPECT and PET, face challenges due to inhomogeneity issues in radiation detectors, leading to degradation in energy resolution and gain stability caused by varying energy detection across different locations on the detector surface.
Innovation Solution
The implementation of a radiation detector assembly with semiconductor detectors and pixelated anodes, where a processor defines sub-pixels for each anode, acquires signals, determines sub-pixel locations, and applies calibration parameters to adjust energy spectra, improving energy resolution and gain stability by correcting inhomogeneous charge collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If detectors are manufactured with standard production processes, then production costs are reduced, but inhomogeneity issues cause degradation in energy resolution and gain stability
Solution Approach 1:
The system performs preliminary calibration by dividing each pixel into multiple sub-pixels and determining sub-pixel locations before actual imaging operations. Calibration parameters are pre-calculated for each sub-pixel based on their specific locations, allowing the detector to compensate for manufacturing inhomogeneities before they affect imaging quality.
Solution Approach 2:
The invention changes the calibration approach from uniform per-pixel calibration to location-specific sub-pixel calibration. By determining sub-pixel locations and applying different calibration parameters to each sub-pixel based on its position within a pixel, the system compensates for spatial variations in detector response without requiring higher manufacturing precision.
2Reliability
If per-pixel calibration is applied, then gain stability improves, but inhomogeneity within pixels remains uncorrected
Solution Approach 1:
Each pixel is segmented into multiple sub-pixels, and calibration is performed independently for each sub-pixel based on its location. This segmentation allows the system to address intra-pixel inhomogeneities that uniform per-pixel calibration cannot correct, improving energy detection uniformity across the entire pixel area.
Solution Approach 2:
The calibration approach transitions from uniform quality across a pixel to location-specific quality within each pixel. By determining sub-pixel locations and applying tailored calibration parameters to each sub-pixel, the system ensures that each region of the pixel is calibrated according to its specific characteristics, improving overall energy detection uniformity.
3Manufacturing precision
If sub-pixel calibration is implemented, then energy resolution and gain stability improve, but system complexity increases
Solution Approach 1:
The system performs self-calibration by automatically determining sub-pixel locations and calculating appropriate calibration parameters for each sub-pixel without requiring external intervention or complex manual calibration procedures. The processor autonomously divides pixels into sub-pixels, determines their locations, and applies the appropriate calibration parameters, simplifying the overall system operation despite the increased calibration granularity.
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, improves energy resolution, and stabilizes gain, allowing detectors that initially do not meet specifications to be calibrated for better performance, thereby reducing production costs and improving overall imaging accuracy.
Implementation Method 1
pixelated anodes...configured to generate a primary signal responsive to reception of a photon
Data Source
Figure 1~2
Figure 3~4A
Figure 4B~5
AI summary
A radiation detector assembly 100 is provided that includes a semiconductor detector 110 having a surface 112, plural pixelated anodes 114, and at least one processor 120. The pixelated anodes 114 are disposed on the surface 112. Each pixelated anode 114 is configured to generate a primary signal responsive to reception of a photon by the pixelated anode 114a 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 114b. The at least one processor 120 is operably coupled to the pixelated anodes 114. The at least one processor 120 configured to define sub-pixels for each pixelated anode 1302; acquire signals corresponding to acquisition events from the pixelated anodes 1304; determine sub-pixel locations for the acquisition events using the signals 1306; and apply at least one calibration parameter on a per sub-pixel basis for the acquisition events based on the determined sub-pixel locations 1308.