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内容記述 |
Signal multiplexing is important to reduce the complexity and cost of clinical positron emission tomography (PET) systems. In addition, good coincidence timing resolution (CTR) is also required to improve the image quality of PET by using the time-of-flight (TOF) information. Here, we report a diode-based row-column multiplexing (RC mux) circuit for clinical TOF-PET applications. A TOF detector consists of fast-LGSO crystal 8×8 array (crystal pitch=3.2 mm, thickness=20 mm) and Hamamatsu SiPM 8×8 array (S14160-3050HS, pixel pitch=3.2 mm) with one-to-one coupling (Fig. 1(a)). Custom-made RC mux circuits were developed to reduce the SiPM channels from 64 into 16 (8 x-position + 8 y-position) with diode and resistor materials, respectively (Fig. 1(b-c)). The timing information was obtained from the meantime of the x and y signals. The multiplexed analog signals were digitized by using PETsys TOFPET2 ASIC modules with an energy window of 440-560 keV (Fig. 2(a)). The effects of the RC mux circuits on the CTR were evaluated with the same crystal and SiPM arrays (Fig. 2(b)). The CTR with the diode-multiplexing was 339 ps, which was 4.3% worse and 34.5% better than the case without multiplexing (325 ps) and with resistor-based multiplexing (456 ps). In conclusion, the diode-based RC multiplexing is a cost-effective solution for the development of clinical TOF-PET systems. |
