A silicon photo-multiplier signal readout using strip-line and waveform sampling for Positron Emission Tomography

Abstract

A strip-line and waveform sampling based readout is a signal multiplexing method that can efficiently reduce the readout channels while fully exploiting the fast time characteristics of photo-detectors such as the SiPM. We have applied this readout method for SiPM-based time-of-flight (TOF) positron emission tomography (PET) detectors. We have prototyped strip-line boards in which 8 SiPMs (pitch 5.2 mm) are connected by using a single strip-line, and the signals appearing at the ends of the strip-line are acquired by using the DRS4 waveform sampler at a nominal sampling frequency of 1–5 GS/s. Experimental tests using laser and LYSO scintillator are carried out to assess the performance of the strip-line board. Each SiPM position, which is inferred from the arrival time difference of the two signals at the ends of the strip-line, is well identified with 2.6 mm FWHM resolution when the SiPMs are coupled to LYSO crystals and irradiated by a 22Na source. The average energy and coincidence time resolution responding to 511 keV photons are measured to be ~32% and ~510 ps FWHM, respectively, at a 5.0 GS/s DRS4 sampling rate. The results show that the sampling rate can be lowered to 1.5 GS/s without performance degradation. These encouraging initial test results indicate that the strip-line and waveform sampling readout method is applicable for SiPM-based TOF PET development.

Physics and technology of time-of-flight PET detectors

“…Compact and affordable digitizers with sampling rates >1 GHz exist that facilitate multichannel implementation of this approach (Cho et al 2011, Ronzhin et al 2013, Ashmanskas et al 2014, Park et al 2018. Time-multiplexing can be used to reduce costs, but leads to an increased DCR on the multiplexed channel (Grant and Levin 2015, Kim et al 2016, Bieniosek et al 2016a, Won et al 2016a. At the time of writing, waveform sampling of individual events is mostly used in research setups.…”

Modularized compact positron emission tomography detector for rapid system development

“…[16][17][18] For SiPM-based PET systems, readout/data-acquisition (DAQ) is a significant issue as a system can employ a vast number of SiPM pixels. To address the issue, multiplexing readouts that can substantially reduce channel number [19][20][21][22][23] and applicationspecific integrated circuits that can provide many readout channels on a small chip [24][25][26][27][28] have been reported and remain active topics of research. Generally, devising an efficient readout/DAQ that can support high spatial resolution and time resolution is still a major challenge.…”

“…Previously to address the readout challenge, we proposed the use of striplines (SL) for multiplexing readout 23,32,33 and developed a sampling-based DAQ called the multivoltage threshold (MVT) method. [34][35][36][37] SL readout is easy to implement and can maintain fast-time characteristics to support TOF detection.…”

Note: Rapid measurement of fluorescence lifetimes using SiPM detection and waveform sampling

“…In the present work, we demonstrate, for the first time, the feasibility of making fluorescence lifetime measurements using off-the-shelf analog silicon photomultipliers (SiPMs) 4 and switched-capacitor array based waveform sampling techniques. 5,6 Comparison of the fluorescence lifetimes derived from this simple cost-effective system to those made on a much larger and more elaborate commercial instrument revealed a surprisingly high degree of correlation and reproducibility.…”

“…4, Paul Scherrer Institute-PSI) evaluation board using a method previously reported by us for precise timing correction, with up to 30 ps timing resolution. 5,6 The DRS4 chip has 8 sampling channels, each 1024 cells deep, that can be daisy-chained to attain virtually unlimited sampling depth at frequencies ranging from 0.7 GS/s (giga-samples per second) to 5 GS/s. On-chip phase locked loop (PLL) is used to stabilize the sampling frequency with a jitter of less than 30 ps.…”