The Detector Design For TOF-PET

Positron Emission Tomography (PET) is a noninvasive imaging technique that can provide three-dimensional (3-D) tomographic images of radiotracer distribution as well as both spatial and temporal measurements of the distribution of biomolecules within a living subject.At present, the largest challenge for PET is how to optimize imaging system, improve sensitivity and image resolution, reduce significantly interference from detection. It's proved preliminary that TOF-PET(Time-of-Flight PET) can deal with challenges above .This thesis discusses the detector design and performance evaluation for TOF-PET aimed at the time resolution of 30-100ps, also time resolution and energy resolution of scintillator in traditional PET detector based on scintillator and photo-detector. The thesis points out the limits to traditional design, and shows tentatively the direction of scintillator in TOF-PET detector. At the part of front-end electronics, the differences between traditional mixed-signal processing and all-digital signal processing on time resolution and energy resolution are compared. The simulation results indicates that time resolution is poor(~130ps) using traditional method, though energy resolution is better, while ~40ps's time resolution can be achieved using all-digital processing, the latter has material advantage on determining event time. Further more, this thesis indicates that data acquisition system for all-digital PET is a potential approach, thereby an implementation for structure and sampling unit of all-digital PET is proposed, thus the detector design and performance evaluation for TOF-PET from science meaning are accomplished preliminary. The great difficulty which the project above facing is high-cost for fast analog-to-digital converters (ADCs). And then a new approach for pulse processing is validated, which the basic properties of the pulse that are relevant for PET event detection, including the pulse amplitude, the event time, and the decaytime constant, can be calculated from a trigger time and four time intervals measured on the pulse. These calculations can be easily implemented in electronics and the required measurements can be generated by using high-speed clocks, comparators, and registers that are relatively inexpensive, therefore eliminates the use of ADCs, and constant fraction discriminators (CFDs) from PET front-end electronics. Simplification in PET front-end electronics achieved with the new design can also lead to reduced power consumption. The results of experiment show that this new front-end electronics can help realize the front-end electronics for TOF-PET at the low cost.