Title :
Time Determination of BGO-APD Detectors by Digital Signal Processing for Positron Emission Tomography
Author :
Leroux, Jean-Daniel ; Martin, Jean-Pierre ; Rouleau, Daniel ; Pepin, Catherine M. ; Cadorette, Jules ; Fontaine, Réjean ; Lecomte, Roger
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Univ. de Sherbrooke, Sherbrooke, QC, Canada
Abstract :
Coincidence timing resolution in Positron Emission Tomography (PET) can be improved by replacing fast analog pulse shaping and Constant Fraction Discriminator (CFD) with fully digital signal processing. This can be achieved by digitizing the signal from individual detectors using 100-MHz, 8-bit Analog-to-Digital converters (ADC) and by processing the data on-the-fly in Field Programmable Gate Arrays (FPGA). Various digital filters and baseline restorers were implemented and combined with numerical least mean square fit to the data to extract the time of interaction and the energy deposited in BGO-APD detectors. An intrinsic time resolution of 7.2 ns was obtained with digital techniques. However, it is shown that bias in the timestamp estimation can be introduced by digital time discrimination techniques, which could affect the ability of digital methods to accurately estimate random event rates by the delayed time window method. Accordingly, the coincidence FWHM metric should not be the only figure of merit when comparing digital and analog time discrimination strategies.
Keywords :
analogue-digital conversion; coincidence techniques; digital filters; discriminators; field programmable gate arrays; nuclear electronics; positron emission tomography; pulse shaping; signal processing; solid scintillation detectors; 8-bit analog-to-digital converters; ADC; APD detectors; BGO detectors; CFD; FPGA; PET; coincidence timing resolution; constant fraction discriminator; digital filters; digital signal processing; digital techniques; fast analog pulse shaping; field programmable gate arrays; front-end processing electronics; numerical least mean square fit; positron emission tomography; time determination; Computational fluid dynamics; Delay estimation; Detectors; Digital signal processing; Field programmable gate arrays; Positron emission tomography; Pulse shaping methods; Signal processing; Signal resolution; Timing; Avalanche photodiodes; PET; digital circuits; digital signal processing; field-programmable gate arrays (FPGAs); numerical methods; time resolution;
Journal_Title :
Nuclear Science, IEEE Transactions on
DOI :
10.1109/TNS.2009.2023655