The Design And Verification Of Digital PET Detector Based On Sine MVT Method

PET is a nuclear medicine technology that can perform functional imaging in living animals non-invasively.PET images the biochemical reactions in the body and plays a key role in the early diagnosis and curative effect evaluation of many diseases,such as nervous diseases and tumors.The data acquisition system of PET extracts information from the scintillation pulse and obtains coincidence events,which has important effects on the quality of PET image.Due to the increasing size and complexity of the modern PET,the data acquisition system using the analog circuit cannot meet the requirements for higher stability and performance.So,the digital PET is a research hotspot and focus in PET.The main work of this thesis is the performance research of the Sine MVT digital method and the architecture design of the digital PET detector based on the Sine MVT method.Based on the traditional constant threshold MVT method,the Sine MVT method develops several constant thresholds into a Sine signal threshold,which can increase the dynamic range without increasing the number of comparators.First,the principle verification of the Sine MVT method is completed through simulation.Two methods to calculate the energy are proposed to study the energy performance of the Sine MVT method.After that,the Sine MVT method is implemented on the circuit.Comparators are used to digitize the scintillation pulses to evaluate the performance of the Sine MVT digital method.Finally,the basic architecture of the Sine MVT digital PET detector is designed.The architecture is mainly composed of the detector unit,the Sine MVT digitizer unit,and the digital signal processing unit.The specific implementation of each unit is also described.In the simulation test,the integration of samples acquired by an oscilloscope at the rate of6.25 GSps is considered as the benchmark.The simulation results show that the energy performance of the Sine MVT method,including the energy resolution and energy accuracy in the full spectrum,is close to the benchmark in theory,when the frequency of sine signal reaches50 MHz and amplitude is higher than the amplitude of the pulse.An oscilloscope is used to collect the samples from the Sine MVT digitizer.The similar results are obtained in the energy performance evaluation test,and the sine signal frequency required reaches 100 MHz.The coincidence time resolution obtained in the time performance test is 223 ps,while the time resolution obtained by directly sampling the pulses using the oscilloscope is 204ps.