The Design, Realization And Evaluation Of Digital PET Module Based On SiPM

Positron emission tomography(PET) is a quantitative, non-invasive, real-time imaging equipment for biological function. The metabolism, functional activities and biochemical reactions of organs are evaluated by detecting the distribution of the tracer in vivo. PET plays an important role in the diagnosis and evaluation of cancer, angiocardiopathy, nervous system, it can also be used in biopharmaceutical industry. PET system built with digital methods is a hot spot for research, because it has strong anti-interference ability and can be easily calibrated and optimized. The Multi-voltage threshold(MVT) is an efficient digitizing method, which can replace high sampling rate ADC in high performance PET system.The main content of this paper is the building of digital PET detector module using silicon photomultiplier(SiPM) and MVT digitizing method. SiPM is novel, compact photodetector with high gain, and can be used in magnetic fields, The PET detector with SiPM has the unique advantage. However, when using SiPM, PET detector has lots of channels to be read out, which reduces its work efficiency. This paper will show a new and efficient channel multiplexing method for SiPM array using two-dimensional transmission-line. In the module design, MVT is used in the digitization of the SiPM pulse, and innovatively, it is used to achieve the position information of transmission-line. With MVT method, the two-dimensional timing difference histogram from the two-dimensional-transmission-line can distinguish the SiPM position very well. The digital PET detector module is compact with a total detection sensitive area of 7.5 cm×5 cm, and can expediently assemble and expansion with digital interface. In this paper, we build the experimental platform using a pair of detector module placed face-to-face to evaluate the performance of the detector module. We obtain legible position spectrum and energy resolution of 16.8%@511 keV, and obtain coincidence resolving timing of 1.67 ns with 450 keV to 650 keV energy window(do not deteriorate much compared with the 1.42 ns without multiplexing method). With a Derenzo, we get the preliminary imaging which successfully resolves 1.6 mm-diameter rods separated by 3.2 mm.