Nuclear Medicine Diagnosis Apparatus Laser Pulse Synchronization
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Solution Overview
Problem
Nuclear medicine diagnosis apparatuses face challenges in achieving high time resolution and accurate clock synchronization for PET image acquisition due to the complexity and cost of clock synchronization mechanisms, as well as the need for frequent timing calibration to account for varying photodetector response times.
Innovation Solution
The apparatus employs a laser pulse generator to create pseudo events, using the time difference between gamma and pseudo event detection times as a relative timestamp to cancel out response time differences between photodetectors, eliminating the need for clock synchronization and reducing the burden of timing calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-accuracy clock synchronization is implemented to achieve 10 psec time resolution, then measurement precision is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent introduces a laser pulse as an intermediary signal to synchronize the response timing of multiple photodetectors. The laser pulse simultaneously excites all photodetectors, creating a common reference point that eliminates the need for complex clock synchronization mechanisms. This intermediary approach achieves precise time resolution by using the laser-induced response as a universal time marker across all detectors.
Solution Approach 2:
The patent replaces the mechanical/electronic clock synchronization system with an optical synchronization method using laser pulses. Instead of relying on complex electronic clock distribution and synchronization circuits, the system uses the optical response of photodetectors to a simultaneous laser excitation as the synchronization mechanism, thereby reducing device complexity while maintaining measurement precision.
2Measurement precision
If timing calibration is performed frequently to account for photodetector response time variations, then measurement precision is maintained, but loss of time and user burden increase
Solution Approach 1:
The laser pulse serves as a real-time calibration reference that continuously monitors and compensates for photodetector response time variations. By incorporating the laser synchronization signal into the ongoing measurement process, the system maintains measurement precision without requiring separate, time-consuming calibration procedures. The laser-induced response provides an ongoing reference that automatically accounts for temporal drifts.
Solution Approach 2:
The patent implements continuous timing calibration by using the laser pulse as an ongoing reference signal throughout the measurement process. Instead of performing discrete, periodic calibration steps that interrupt measurements, the system continuously uses the laser-synchronized photodetector responses to maintain accurate timing, thereby eliminating loss of time while preserving measurement precision.
3Measurement precision
If response time equalization is achieved through calibration data, then measurement precision is improved, but device complexity and operational burden increase due to frequent recalibration requirements
Solution Approach 1:
The laser pulse acts as a universal intermediary that simultaneously calibrates all photodetectors in the system. By using the laser-induced response as a common reference, the system achieves response time equalization across all detectors without requiring individual calibration procedures. This eliminates the operational burden of managing multiple calibration data sets and simplifies the calibration process to a single, system-wide laser synchronization step.
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 enhances time resolution and accuracy in PET image reconstruction, reduces manufacturing costs, and simplifies the calibration process, thereby increasing user efficiency and image quality.
Implementation Method 1
a laser pulse generator 40 which repeatedly generates light signals
Implementation Method 2
each detector block 31 includes a photodetector 335 and a front end circuit 35
Data Source
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AI summary
According to one embodiment, a nuclear medicine diagnosis includes a light signal generating unit (40), photodetection unit (31), measurement unit (355), calculation unit (55), and storage unit (57). The light signal generating unit (40) repeatedly generates light signals. The photodetection unit (31) repeatedly generates first output signals corresponding to intensities of the light signals, repeatedly generates second output signals corresponding to intensities of gamma rays emitted from a subject. The measurement unit (355) repeatedly measures light signal detection times and repeatedly measures gamma ray detection times. The calculation unit (55) calculates a difference between a target gamma ray detection time and a target light signal detection time of the light signal detection times for each of the gamma ray detection times. The target light signal detection time is measured before the target gamma ray detection time. The storage unit (57) stores the calculated difference in association with a target second output signal of the second output signals.