Inesc Id Institute Of Engineering Of Sistemas E Computadores

Lisbon, Portugal

Inesc Id Institute Of Engineering Of Sistemas E Computadores

Lisbon, Portugal
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Rolo M.D.,Lip Laboratory Instrumentacao E Fisica Experimental Of Particulas | Rolo M.D.,University of Turin | Bugalho R.,Lip Laboratory Instrumentacao E Fisica Experimental Of Particulas | Bugalho R.,University of Lisbon | And 7 more authors.
Journal of Instrumentation | Year: 2013

A 64-channel ASIC for Time-of-Flight Positron Emission Tomography (TOF PET) imaging has been designed and simulated. The circuit is optimized for the readout of signals produced by the scintillation of a L(Y)SO crystal optically coupled to a silicon photomultiplier (SiPM). Developed in the framework of the EndoTOFPET-US collaboration [1], the ASIC is integrated in the external PET plate and performs timing, digitization and data transmission for 511 keV and lower-energy events due to Compton scattering. Multi-event buffering capability allows event rates up to 100 kHz per channel. The channel cell includes a low input impedance low-noise current conveyor and two trans-impedance amplifier branches separately optimized for energy and time resolution. Two voltage mode discriminators generate respectively a fast trigger for accurate timing and a signal for time-over-threshold calculation, used for charge measurement. The digitization of these signals is done by two low-power TDCs, providing coarse and fine time stamps that are saved into a local register and later managed by a global controller, which builds-up the 40-bit event data and runs the interface with the data acquisition back-end. Running at 160 MHz the chip yields a 50 ps time binning and dissipates 7 mW per channel (simulated for 40 kHz event rate p/channel) for high capacitance photodetectors (9 mm2 active area Silicon Photomultiplier with 320 pF terminal capacitance). The minimum SNR of 23.5 dB expected with this capacitance should allow triggering on the first photoelectron to achieve the envisaged timing performance for a TOF-PET system. © 2013 IOP Publishing Ltd and Sissa Medialab srl.


Rolo M.D.,Lip Laboratory Instrumentac Ao E Fisica Experimental Of Particulas | Bugalho R.,Lip Laboratory Instrumentac Ao E Fisica Experimental Of Particulas | Goncalves F.,Inesc Id Institute Of Engineering Of Sistemas E Computadores | Rivetti A.,National Institute of Nuclear Physics, Italy | And 4 more authors.
IEEE Nuclear Science Symposium Conference Record | Year: 2012

A 64-channel ASIC for TOF PET imaging is presented. The circuit provides time and energy measurements of events produced by a SiPM coupled to a L(Y)SO fast scintillator. This ASIC is developed in the framework of the EndoTOFPETUS collaboration as an option for the readout of external 200×200 mm plate detector, which consists of 3×3×15 mm crystals and 3×3 mm (active area) SiPMs. Using the chip with non-segmented and/or higher light yield crystals is possible. The same applies for photodetectors with different gain, polarity, or even higher dark count rate. The targeted 200 ps timing resolution for the system and the need for a low power consumption have driven the choice of a closed-loop amplifier input stage and a 50 ps time binning TDC based on analogue interpolation. A power consumption between 5 to 10 mW per channel is expected to guarantee a SNR of at least 20 dB for the single photon, using a SiPM with 320 pF terminal capacitance. © 2012 IEEE.

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