A SiPM-Readout ASIC for SPECT Applications

摘要

In this paper, we present ANGUS, an application specific integrated circuit (ASIC) for silicon photomultiplier (SiPM) readout designed for low-energy gamma imaging (140 keV), specifically targeting clinical single photon emission computed tomography (SPECT) applications based on Anger-type detectors. The chip is composed of 36 channels, each featuring a current conveyor input followed by an RC filter with a time constant programmable from 200 ns up to 10n$mu text{s}$n, a baseline holder and a peak stretcher stage. Multichannel readout is performed with anpollingnstrategy thanks to two analog multiplexers. The chip has been designed to cope with input capacitance values of several nanofarad, like the ones featured by the large-sized SiPM pixels (8 mmn${times }$n8 mm) of the application. Despite being conceived for operation with slow scintillator crystals like cesium-iodide (CsI), this ASIC can successfully manage the readout of faster crystals like lutetium-yttrium oxyorthosilicate. Measurements of the ASIC carried out on a fully equipped SPECT detection module have shown an energy resolution of 13.7% at the 140-keV line ofn^{99mnTc, for a 5 cmn${times }$n5 cm gamma camera consisting of a continuous CsI crystal and a SiPM detection plane cooled at 0 °C.}