Investigation of Electronic Signal Processing Chains for a Prototype TOF-PET System With 100-ps Coincidence Time Resolution

Abstract

We have evaluated the coincidence time resolution (CTR) performance of four different mixed-signal front-end electronic readout configurations with the goal to achieve 100 picoseconds (ps) CTR. The proposed TOF-PET detector elements are based on two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3{\times } 3{\times }10$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> “fast LGSO” crystal segments, side coupled to linear arrays of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3{\times }3$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> silicon photomultipliers (SiPMs), to form a total crystal length of 20 mm. We studied multiple configurations and components for the front-end readout: 1) high speed radio frequency (RF) amplifiers; 2) an ASIC-based discriminator; 3) a combination of RF amplifier, balun transformer, and discriminator ASIC; and 4) combination of balun transformer and discriminator ASIC. Using two <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3{\times } 3{\times }10$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> fast LGSO crystals side coupled to a linear array of three SiPMs, coincidence data were experimentally acquired for each readout configuration in combination with a low jitter field-programmable gate array (FPGA)-based time-to-digital converter (TDC). After evaluating the timing performance of the three readout schemes, the best CTR value of 99.4 ± 1.9 ps FWHM was achieved for configuration (3), which is more than 20 ps better than the results achieved using configurations (1), (2), and (4).