Photon Counting Detector Energy Windowing for Charge Sharing

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Solution Overview

Problem

Photon counting detector-based x-ray computed tomography (PCD-CT) systems suffer from charge sharing issues that lead to inaccurate photon counts, degraded image quality, and spectral distortion due to pulse pileup, especially at high count rates.

Innovation Solution

A multi-energy inter-pixel coincidence counter (MEICC) technique is employed, using energy-dependent coincidence counters to record charge sharing events during data acquisition, allowing for post-acquisition correction or compensation without interfering with the primary counting process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If event-based real-time charge sharing correction is implemented, then measurement precision is improved, but productivity deteriorates due to slower processing speed

Engineering Contradiction:

Improvephoton count accuracyVSAvoidprocessing speed

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by recording coincidence events and their energy information during data acquisition in parallel with the primary counting process, so that charge sharing correction can be performed efficiently after acquisition without slowing down the detector's counting capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the correction process into separate coincidence counters for different energy windows, allowing independent processing of charge sharing events in each energy window without interfering with the primary counting process

Inventive Principle:

Principle #1Segmentation

2Productivity

If reading-based post-acquisition charge sharing correction is implemented, then productivity is maintained, but measurement precision deteriorates due to loss of energy information

Engineering Contradiction:

Improvecounting speedVSAvoidcharge sharing correction accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The patent introduces an intermediary energy-dependent coincidence counter that records both the occurrence of coincidence events and their energy window information during data acquisition, serving as a mediator between the primary counting process and the post-acquisition correction process

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent performs preliminary recording of energy window information for coincidence events during data acquisition, so that accurate charge sharing correction can be applied after acquisition without degrading the detector's counting capability

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If analog charge sharing correction is implemented, then measurement precision is improved, but device complexity increases due to sophisticated circuitry

Engineering Contradiction:

Improvecharge sharing correction accuracyVSAvoidcircuitry complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the analog mechanical circuitry with a digital implementation, using digital coincidence counters and logic operations to detect and correct charge sharing events, thereby reducing circuitry complexity while maintaining correction accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Measurement precision

If event-based real-time charge sharing rejection is implemented, then measurement precision is improved, but loss of information increases due to discarded photons

Engineering Contradiction:

Improvephoton count accuracyVSAvoiddiscarded photon data

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The patent converts the harmful effect of charge sharing into beneficial information by using the coincidence event records to identify and correct charge sharing occurrences, thereby recovering information that would otherwise be lost and improving photon count accuracy

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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

The MEICC method maintains the speed of PCDs while significantly reducing noise variance and spectral distortion, achieving improved Cramér-Rao lower bounds and signal-to-noise ratios, particularly benefiting K-edge imaging.

Implementation Method 1

Photon counting detector-based x-ray computed tomography (PCD-CT) is a technique used to develop and produce CT images

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS12468050B2Direct energy windowing for photon counting detectors

Publication Date: 2025.11.11 JOHNS HOPKINS UNIVERSITY

AI summary

Techniques for counting respective photons having energy levels within at least a first energy window and a second energy window, where the first energy window is lower than the second energy window, are presented. The techniques include: receiving a first indication of a first photon detection, the first photon detection being of a photon having an energy of at least a lower end of the first energy window; receiving a second indication of a second photon detection, the second photon detection being of a photon having an energy of at least a lower end of the second energy window; within a predetermined time interval of the receiving the first indication, communicating locally the second indication to counter logic for the first energy window, where a counter for the first energy window is not incremented; and incrementing a counter for an energy window higher than the first energy window.