Hybrid Detector Array for CT Pulse Pileup Correction
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Solution Overview
Problem
Current imaging apparatuses using radiation technology face limitations with energy integrating cells, such as inability to provide photon number and energy feedback, and photon counting cells are not widely applied in CT systems due to cost and saturation issues like pulse pileup.
Innovation Solution
An imaging apparatus and method that combines energy integrating cells and photon counting cells in a detector array, allowing for simultaneous measurement of attenuation using both cell types during a helical scan, enabling the generation of images with combined data to correct for pulse pileup and derive energy information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photon counting cells are used, then radiation dose can be reduced and energy discrimination is enabled, but pulse pileup occurs at high flux rates and cost is higher
Solution Approach 1:
The detector array is segmented into multiple cell types - photon counting cells for low-dose/energy discrimination applications and energy integrating cells for high-flux applications. Each segment handles specific flux conditions optimally, preventing pulse pileup in photon counting cells while maintaining their counting accuracy.
Solution Approach 2:
The system dynamically adjusts operational parameters by switching between or combining photon counting and energy integrating modes based on detected flux rates. At high flux, energy integrating mode prevents saturation; at low flux, photon counting mode provides precise measurement and energy discrimination.
2Reliability
If energy integrating cells are used, then high flux rate saturation is avoided, but photon number and energy feedback cannot be provided and radiation dose must be increased
Solution Approach 1:
The patent merges both photon counting cells and energy integrating cells into a single detector array. This combination allows the system to leverage the saturation resistance of energy integrating cells at high flux while simultaneously obtaining photon number information from photon counting cells at lower flux levels.
Solution Approach 2:
The detector array performs multiple functions simultaneously - it can count photons, measure energy, and handle high flux rates all within the same system. The combined cell types enable the array to adapt to varying radiation conditions and provide both quantitative and spectral information.
3Loss of information
If photon counting cells are used, then energy discrimination is enabled, but pulse pileup occurs due to inability to return to normal state quickly enough
Solution Approach 1:
The detector array is segmented into photon counting cells and energy integrating cells, where energy integrating cells serve as a backup or complementary measurement channel when flux rates exceed the recovery capability of photon counting cells, ensuring continuous operational productivity.
Solution Approach 2:
The system employs periodic switching or alternating measurement modes between photon counting and energy integrating operations, allowing photon counting cells to recover between high-rate measurements while energy integrating cells provide continuous coverage during high-flux periods.
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 reduces radiation dose, corrects for pulse pileup, and provides energy discrimination, enhancing image quality and accuracy by leveraging the strengths of both cell types while addressing their individual limitations.
Implementation Method 1
Energy integrating cells are configured to convert energy into signals (e.g., current or voltage signals) that are proportional to an incoming photon flux rate and a photon energy
Implementation Method 2
Photon counting cells are configured to output signals for respective detection events and may be configured to convert energy into signals that are proportional to the energy of a detected photon
Data Source
AI summary
Among other things, one or more techniques and/or systems are described for measuring the attenuation of a line integral through an object via a photon counting cell (302) and via an energy integrating cell (304). That is, an imaging apparatus is provided that comprises a radiation source (208) and a detector array (210). The detector array is comprised of both photon counting cells (302) and energy integrating cells (304) arranged such that, during an examination of the object, attenuation of a line integral through the object is measured by at least one photon counting cell and at least one energy integrating cell. In this way, at least two substantially complete views of an object may be acquired, one from measurements yielded from the photon counting cell (and other photon counting cells) and one from measurements yielded from the energy integrating cell (and other energy integrating cells).