Investigation of the Power Consumption of the PETsys TOFPET2 ASIC

Abstract

In state-of-the-art positron emission (PET) tomography systems, application-specific integrated circuits (ASICs) are commonly used to precisely digitize the signals of analog silicon photo-multipliers (SiPMs). However, when operating PET electronics in a magnetic resonance (MR) system, one faces the challenge of mutual interference of these imaging techniques. To prevent signal deterioration along long analog signal lines, PET electronics with a low power consumption digitizing the signals close to the SiPMs are preferred. In this study, we evaluate the power consumption of the TOFPET2 ASIC. Its power consumption ranges from 3.6 mW/channel to 7.2 mW/channel as a function of the input stage impedance and discriminator noise settings. We present an analytical model allowing to compute the power consumption of a given ASIC configuration. The configured input stage impedance and discriminator noise have an impact on the coincidence resolution time, energy resolution, and dark count rate. Since TOFPET2 ASICs delivers state-ofthe art performance with a power consumption similar or even lower than other ASICs typically used for PET applications, it is a favorable candidate to digitize the signals of SiPMs in future simultaneous PET/MR systems.

Hybrid total-body pet scanners—current status and future perspectives

“…Directly after the analog detector block, applicationspecific integrated circuits (ASICs) are employed to trigger on the analog signal pulses created by SiPMs and PMTs (see Fig. 2) [18,72,91,96]. Alternatively, digital SiPMs are used which are combining the function of an analog SiPM and the ASIC [16,95].…”

Evaluation of the PETsys TOFPET2 ASIC in multi-channel coincidence experiments

“…In addition, when designing a PET system or a MR-compatible PET insert, one has to keep in mind other system requirements such as power supply limitations or interference problems [75]. The power consumption of the TOFPET2 ASIC and its influence on the ASIC performance were already evaluated in an additional study [59]. Regarding MR-compatibility tests, similar test protocols as in [28,76,77] need to be defined and executed.…”

“…The TOFPET2 ASIC is characterized by its compactness (14 mm × 14 mm chip size including bonding area [58]), 128 readout channels, low power consumption [49,59] and a high hit rate of up to 480 kcps per channel, which corresponds to a data rate of 640 Mbit/s [49,54]. The maximum output data rate of the ASIC, i.e., 64 channels, is specified as 2.8 Gbit/s [49].…”

“…The whole setup can be enclosed with a top cover featuring thermo-control and operated inside a climate chamber. Graphic reprinted from [59] Fig. 3 Assembly tools.…”

“…to 3 p.e. (photoelectron) as it is reported for the example of a Hamamatsu S14161-3050-HS-08 SiPM array in [59]. For each setting, raw data were acquired for 120 s at an overvoltage of 2.75 V to 7.75 V. Additionally, the crystal top-to-source distance was varied between 18 mm to 58 mm in steps of 20 mm.…”