Multi-functional Radiation ASIC for Photon Counting and Energy Resolution
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Solution Overview
Problem
Conventional digital radiation imaging systems face challenges in calibrating photon counting devices due to loss of photon energy information when converting it to digital counts, limiting their flexibility and effectiveness in applications requiring diverse photon event treatment.
Innovation Solution
A multi-functional radiation identifying and processing ASIC with pixel cell circuits that include preamplifiers, peak hold circuits, comparators, multi-functional counters, and logic units for mode selection, enabling photon counting, analog to digital conversion, and timing measurements, allowing for versatile photon processing and imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If photon counting imaging is used to improve image signal to noise ratio and contrast, then imaging quality is improved, but device complexity increases due to requirements for preamplifier and comparator-counter circuitry
Solution Approach 1:
The pixel circuit is designed to perform multiple functions including photon counting, energy measurement, and timing operations using shared circuitry. The same pixel circuit can operate in different modes (counting mode, energy measurement mode, timing mode) by reconfiguring the preamplifier, comparator, and counter resources, thereby achieving high measurement precision without proportionally increasing device complexity.
2Measurement precision
If conventional scintillator-photo multiplier gamma cameras are used, then imaging capability is achieved, but spatial and energy resolution are limited
Solution Approach 1:
The patent replaces the mechanical/optical system of scintillator-photo multiplier tubes with a solid-state semiconductor detector system. The semiconductor detector directly converts incident photons into electrical signals, eliminating the need for scintillation conversion and photomultiplier amplification, thereby achieving superior spatial and energy resolution while reducing device complexity.
3Ease of operation
If photon energy information is converted to digital counts, then counting operation is simplified, but photon energy information is lost reducing calibration flexibility
Solution Approach 1:
The pixel circuit incorporates dynamic reconfiguration capability that allows it to operate in different modes depending on the application requirements. The circuit can dynamically switch between counting mode (for simplified operation) and energy measurement mode (for preserving energy information), with the ability to adjust threshold levels and measurement parameters on-the-fly, thereby maintaining ease of operation while preventing information loss.
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
Enables the construction of flexible x/gamma ray imaging devices capable of identifying and processing each radiation event, offering improved spatial and energy resolution, and allowing for various operational modes to suit different imaging applications.
Implementation Method 1
each said imaging cell generating a charge in response to incident radiation events
Data Source
Figure 1
Figure 2~3(a)
Figure 3(b)~3(c)
AI summary
A radiation device includes a detector connected to a multi-functional radiation identifying and processing application specific integrated circuit. The detector includes a plurality of individual imaging cells, each imaging cell generating a charge in response to incident radiation events and outputting the generated charge at an imaging cell output. The application specific integrated circuit includes a different circuit connected respectively to a corresponding one of the imaging cell outputs, each circuit receiving and processing the generated charge received from the corresponding one imaging cell output. Each circuit includes a preamplifier for generating a voltage or current amplitude in response to the received charge, a counter, and a mode logic configured for setting the counter to perform, selectively, at least two of a) photon counting, b) analog to digital conversion of the one of the voltage amplitude and the current amplitude, and c) timing measurement of incident radiation events.