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An 8 16 pixel array based on CMOS small-area silicon photomultipliers (mini-SiPMs) detectors for PET applications is reported. Each pixel is 570 610 m in size and contains four digital mini-SiPMs, for a total of 720 SPADs, resulting in a full chip fill-factor of 35.7%. For each gamma detection, the pixel provides the total detected energy and a timestamp, obtained through two 7-b counters and two 12-b 64-ps TDCs. An adder tree overlaid on top of the pixel array sums the sensor total counts at up to 100 Msamples/s, which are then used for detecting the asynchronous gamma events on-chip, while also being output in realtime. Characterization of gamma detection performance with an 3 3 5 mm LYSO scintillator at 20 C is reported, showing a 511-keV gamma energy resolution of 10.9% and a coincidence timing resolution of 399 ps.

Abstract.A high-speed and hardware-only algorithm using a center of mass method has been proposed for singledetector fluorescence lifetime sensing applications. This algorithm is now implemented on a field programmable gate array to provide fast lifetime estimates from a 32 × 32 low dark count 0.13 μm complementary metaloxide-semiconductor single-photon avalanche diode (SPAD) plus time-to-digital converter array. A simple look-up table is included to enhance the lifetime resolvability range and photon economics, making it comparable to the commonly used least-square method and maximum-likelihood estimation based software. To demonstrate its performance, a widefield microscope was adapted to accommodate the SPAD array and image different test samples. Fluorescence lifetime imaging microscopy on fluorescent beads in Rhodamine 6G at a frame rate of 50 fps is also shown. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).