TDC Modules for PET SPECT Continuous Data Acquisition
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Solution Overview
Problem
Current positron emission tomography (PET) and single-photon emission computed tomography (SPECT) systems rely on triggering systems to pre-select signals, leading to information loss and limitations in temporal and spatial resolution, especially with large scintillator blocks where resolutions below 100 ps are difficult to achieve.
Innovation Solution
A system using a front-end electronic assembly with time-to-digital converter (TDC) modules and a field-programmable gate array (FPGA) controller for continuous data acquisition, eliminating the need for triggering and allowing synchronized time measurements across multiple TDC circuits, enabling lossless recording of all events with improved calibration and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a triggering system is used to pre-select signals in PET/SPECT systems, then device complexity is reduced and processing load is minimized, but information loss occurs and temporal/spatial resolution deteriorates
Solution Approach 1:
The patent removes the triggering system from the signal processing chain entirely. By extracting this selective filtering component, all measurement signals are recorded without pre-selection, eliminating information loss while maintaining manageable complexity through continuous recording architecture
Solution Approach 2:
The system performs preliminary continuous recording of all signals before any processing or analysis occurs. This preliminary action ensures no information is lost during acquisition, and subsequent processing can selectively analyze recorded data without having discarded potentially valuable signals
2Productivity
If a triggering system pre-selects signals, then data processing volume is reduced, but temporal resolution and dead time performance worsen
Solution Approach 1:
The system implements continuous recording of all measurement signals without interruption or selective filtering. This continuous action eliminates dead time associated with triggering decisions and signal rejection, maintaining constant data acquisition capability while reducing overall processing requirements through efficient continuous processing architecture
3Measurement precision
If triggering systems are used for signal pre-selection, then system complexity is reduced, but measurement accuracy and calibration precision deteriorate
Solution Approach 1:
The triggering system is completely extracted from the measurement chain. This removal eliminates the complexity of trigger logic, threshold setting, and signal selection algorithms, while calibration accuracy improves because all signals including low-amplitude calibration events are recorded and processed without discrimination
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 facilitates continuous, lossless data acquisition during PET or SPECT imaging, enhancing temporal and spatial resolution by minimizing dead times and allowing for real-time analysis and accurate calibration of detection modules, particularly beneficial in polymer scintillator-based systems.
Implementation Method 1
A gamma quantum enters the scintillator, which absorbs its energy to re-emit it in the form of light (a stream of photons)
Implementation Method 2
Light pulses reaching the scintillator can be converted into electric pulses by means of photomultipliers or photodiodes
Implementation Method 3
The coordinates of annihilation place are obtained from the difference in times of arrival of two gamma quanta to the detectors located at both ends of the LOR. In the prior art literature, this technique is referred to as the time of flight (TOF) technique
Data Source
AI summary
A system for acquisition of tomographic measurement data from measurement signals (S) of positron emission tomography (PET) or single-photon emission computed tomography (SPECT) detectors, the system comprising: a front-end electronic assembly (2) configured to convert the measurement signals (S) into digital and analog signals (DAS); a measurement electronics assembly (3) comprising time to digital converter (TDC) modules (31) configured to determine times (T) of pulses in digital signals (DS). The measurement electronics assembly (30) comprises: a series (TDCa-TDCd) of TDC modules (31), each module comprising a series (TDC1-TDC4) of TDC circuits (311-314); a module controller (315) configured to transmit a clock signal (CLK), input to the module controller (315) from a system controller (40), to each of the TDC circuits (311-314); wherein each of the TDC circuits (311-314) is configured to execute measurements in a measurement window delimited by the neighboring edges of the clock signal (CLK) which is common for all TDC circuits (311-314).