Imaging Detector Signal Summing Without Timing Coincidence
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Solution Overview
Problem
Existing diagnostic imaging systems, such as SPECT and CT, face inefficiencies in processing charge-sharing events due to inaccurate timing measurements and high noise levels in semiconductor detectors, leading to the rejection of valid imaging events.
Innovation Solution
A system and method that processes event information from pixelated detectors by comparing energy levels and pixel locations in real-time, combining energies of adjacent events without relying on time-coincidence measurements, and assigning pixel locations to charge-sharing events, enabling efficient image reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If neighbor summing is performed using time-coincidence verification, then charge-sharing events can be identified, but timing accuracy deteriorates due to depth-of-interaction dependence
Solution Approach 1:
The patent extracts the timing verification step from the neighbor summing process by removing time-coincidence checks. Instead of verifying timing coincidence between adjacent pixels, the system directly sums signals from adjacent pixels based on spatial proximity alone, eliminating the timing accuracy problem caused by depth-of-interaction variations
Solution Approach 2:
The patent segments the event identification process into two independent stages: first identifying charge-sharing events through spatial adjacency of pixel signals, then summing those signals without timing verification. This segmentation allows the system to handle charge-sharing events reliably without being constrained by timing precision limitations
2Speed
If trigger signal is derived from cathode contact, then timing signal is obtained immediately upon photon absorption, but noise level increases requiring high threshold levels
Solution Approach 1:
The patent converts the harmful noise from cathode contact into a beneficial feature by using the high threshold level required to filter noise as the selection criterion for charge-sharing event identification. Events exceeding the threshold are automatically identified as potential charge-sharing events, turning the noise-filtering requirement into a positive event detection mechanism
Solution Approach 2:
The patent introduces an intermediary processing stage that receives signals from the cathode contact and applies threshold-based filtering before further processing. This intermediary threshold mechanism separates the noise (signals below threshold) from valid events (signals above threshold), allowing the system to use cathode-derived triggers without being overwhelmed by noise
3Object-affected harmful factors
If high threshold level is used to filter cathode noise, then noise propagation is prevented, but valid low-energy events are rejected
Solution Approach 1:
The patent applies dynamic, adaptive threshold levels rather than fixed high thresholds. The threshold is adjusted based on local signal characteristics and pixel adjacency patterns, allowing the system to maintain high noise rejection in most cases while preserving valid low-energy events that exhibit spatial coherence with neighboring pixels
Solution Approach 2:
The patent applies different threshold criteria to different spatial contexts. Isolated low-energy signals are rejected to filter noise, while low-energy signals that are spatially adjacent to other signals are preserved as potential charge-sharing events. This local quality approach allows context-dependent threshold application
4Reliability
If conventional neighbor summing with time-coincidence verification is used, then charge-sharing events can be identified, but processing complexity and cost increase
Solution Approach 1:
The patent extracts and removes the time-coincidence verification hardware from the neighbor summing system. By eliminating the timing verification stage entirely, the system reduces hardware complexity and cost while maintaining charge-sharing event identification capability through purely spatial signal summation methods
Solution Approach 2:
The patent replaces the mechanical/electronic timing verification system with a computational spatial analysis approach. Instead of using hardware timers and coincidence circuits, the system uses software-based spatial adjacency algorithms to identify and sum charge-sharing events, reducing hardware 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 approach improves image quality, reduces processing time, and enhances the accuracy of imaging scans by effectively identifying and counting charge-sharing events, while reducing complexity and cost in imaging procedures.
Implementation Method 1
Photons absorbed in the detector may be absorbed by one step including photo-electric absorption
Implementation Method 2
Compton Scattering may occur in the detector, with the amount of Compton Scattering inside the detector increasing with photon energy
Data Source
AI summary
A system includes a detector and a main processing unit having an event processing module. The detector includes pixels to detect an event corresponding to photon absorption. The event processing module is configured to read event information for each event detected by each pixel of the detector in order of receipt from the detector and to compare an energy level value in the event information for each event to a predetermined range of energy level values. An event is counted when the energy level value is within the predetermined range of energy level values. For each event having an energy level below the predetermined range, the energy level value for a next consecutive event in the received event information is read and a combined energy level value of the event and the next consecutive event is determined as well as the pixel locations of the event and the next consecutive event. The combined energy level is counted as a single event when the combined energy level value is within a predetermined range of energy level values and when the pixel location for the event is near a pixel location for the next consecutive event. At least one pixel location is assigned to the single event.