Photon Pulse Segmentation for PET Time-Walk Correction
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Solution Overview
Problem
Time-walk errors in positron emission tomography (PET) detectors due to variability in the response time of photon detectors limit the accuracy of timing information, which affects the reconstruction of images.
Innovation Solution
A device and method for determining photon detection times using multiple energy measurements, involving circuits to measure different parts of an electrical pulse and applying a time-walk correction based on these measurements, accounting for variations in fast and slow components of the pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional single-energy time-walk correction is used, then the device complexity is low, but the measurement precision of time-of-flight is insufficient
Solution Approach 1:
The electrical pulse is divided into multiple parts (first part and second part) with different time windows. Separate measurement circuits are used for each part to obtain different energy measurements, enabling more accurate time-walk correction through multiple parameters rather than a single energy measurement.
Solution Approach 2:
The correction approach transitions from single-dimensional (one energy measurement) to multi-dimensional (multiple energy measurements from different pulse parts). This adds temporal dimension by measuring different time windows of the pulse, providing more information for accurate time-walk correction.
2Measurement precision
If multiple energy measurements are used for time-walk correction, then the measurement precision improves, but the quantity of measurements and processing increases
Solution Approach 1:
Instead of taking multiple measurements of the entire pulse, the pulse is segmented into different parts (first part and second part), each measured by dedicated circuits. This segmentation allows parallel measurement of different pulse characteristics, obtaining multiple energy values without proportionally increasing total measurement time.
Solution Approach 2:
The patent measures only specific parts of the electrical pulse rather than the entire pulse waveform. By selecting representative time windows (first and second parts), sufficient information is obtained for time-walk correction without the need for complete pulse characterization, reducing measurement 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
Improves the accuracy of time-of-flight measurements by correcting for time-walk errors, enhancing the spatial and temporal resolution of PET imaging.
Implementation Method 1
a photodetector that converts a photon to a photocurrent
Implementation Method 2
the photodetector comprises a conversion material that is a scintillator configured to convert the gamma-ray photon to the plurality of photoelectrons
Data Source
AI summary
An apparatus and method are provided to correct for time-walk errors during photon detections (e.g., detecting gamma rays). A time-walk correction is determined using measurements of energy (or charge) that apply different time windows, enabling corrections accounting for variations in the ratio between fast and slow components in the detected pulse. For example, one time window can be used to integrate the leading end of the pulse, thereby predominantly measuring the fast component, while a second window is used to integrate a trailing end of the pulse to predominantly measure the slow component. Alternatively or additionally, low-pass and high-pass filters may select the slow and fast components, respectively. The time-walk correction is a function of multiple measurements representing different components (e.g., fast and slow) of the pulse shape.