Digital Pulse Filtering for Accurate Photon Event Counting
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Solution Overview
Problem
In advanced Photon Counting Computed Tomography (PCCT) systems, the rapid succession of photons hitting the detector can lead to miscounts or missed counts due to insufficient response time of amplifiers, affecting the accuracy of energy spectrum analysis.
Innovation Solution
A digital pulse filtering system is introduced between comparators and counters, generating refined signals based on rising and falling edges to correct photon counting errors by identifying timing characterization and generating trigger signals for accurate event counting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple photons hit the detector in quick succession (within 50ns), then the detection speed and throughput are improved, but the amplifier cannot respond adequately leading to miscounts or missed counts
Solution Approach 1:
The patent applies preliminary action by implementing a dead-time mechanism that proactively prevents miscounting before it occurs. When a photon event is detected, the system immediately activates a dead-time period during which subsequent events are suppressed from being counted. This preliminary prevention ensures that rapid successive photons within the amplifier's response limitation (50ns) do not cause miscounts, while still allowing the system to operate at high detection speeds.
2Measurement precision
If the amplifier response time is increased to accurately process each photon signal, then the counting accuracy is improved, but the system cannot handle rapid successive photons effectively
Solution Approach 1:
The patent implements continuity of useful action by maintaining constant monitoring of photon events while managing the amplifier's response limitations. The dead-time mechanism allows the system to continuously process photon streams without interruption, ensuring that valid events are counted while suppressing only those events that would cause miscounts due to amplifier response limitations. This approach maintains high productivity while preserving counting accuracy.
3Measurement precision
If a digital pulse filtering system is implemented to correct photon counting errors, then the counting accuracy is improved, but the system complexity increases
Solution Approach 1:
The patent applies the intermediary principle by introducing a dead-time signal as a mediator between the amplifier output and the counting system. This simple temporal gating signal acts as an intermediary that automatically suppresses problematic rapid successive events without requiring complex filtering algorithms or additional hardware processing. The dead-time mechanism provides a straightforward, low-complexity solution that effectively corrects counting errors while maintaining system simplicity.
Data Source
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AI summary
A system (400) for enhancing digital signal event counting is provided. The system (400) includes a pulse filter (440) coupled between a plurality of comparators (431) and a plurality of counters (451). The pulse filter (440) is configured to generate a refined signal associated with a rising edge and a falling edge of each comparator output corresponding to a threshold level. The pulse filter (440) identifies the timing characterization of at least two refined signals respectively corresponding to a lower threshold level and a next higher threshold level and generates a trigger signal corresponding to an event counting based on the timing characterization associated with both the rising edge and the falling edge. Corresponding counters (451) increment a count at the lower threshold level or both the lower threshold level and the next higher threshold level for each event counting based on the trigger signal.