Development of diode-based row–column multiplexing boards with the TOFPET2 ASIC for clinical TOF-PET systems

<i>Objective.</i>A multiplexing technique is essential to reduce the cost and signal processing complexity of clinical time-of-flight positron emission tomography (TOF-PET). One critical issue in multiplexing is the degradation of coincidence timing resolution (CTR). In this study, we developed diode-based row-column (RC) summing multiplexing boards that can minimize the CTR degradation.<i>Methods.</i>We used fast-LGSO crystals (3.1 × 3.1 × 20 mm³) and an 8 × 8 silicon photomultiplier (SiPM) array. The SiPM signals were multiplexed by using RC summing multiplexing circuits. For data acquisition, a TOFPET2 ASIC evaluation kit was used. The effects of multiplexing on the detector performance were evaluated with three different diode models and a resistor.<i>Main results.</i>The CTR was degraded by 8.0% and 19.4% with the diode-based and resistor-based multiplexing, respectively. We achieved an average CTR of 326 ± 8 ps with the expanded multiplexing boards employing an optimal diode model in terms of CTR and cost.<i>Significance.</i>The developed diode-based multiplexing boards will offer a cost-effective solution for clinical TOF-PET development.