title: Reaching 200-ps timing resolution in a time-of-flight and depth-of-interaction positron emission tomography detector using phosphor-coated crystals and high-density silicon photomultipliers.
abstract: Current research in the field of positron emission tomography (PET) focuses on improving the sensitivity of the scanner with thicker detectors, extended axial field-of-view, and time-of-flight (TOF) capability. These create the need for depth-of-interaction (DOI) encoding to correct parallax errors. We have proposed a method to encode DOI using phosphor-coated crystals. Our initial work using photomultiplier tubes (PMTs) demonstrated the possibilities of the proposed method, however, a major limitation of PMTs for this application is poor quantum efficiency in yellow light, corresponding to the wavelengths of the converted light by the phosphor coating. In contrast, the red-green-blue-high-density (RGB-HD) silicon photomultipliers (SiPMs) have a high photon detection efficiency across the visible spectrum. Excellent coincidence resolving time (CRT; [Formula: see text]) was obtained by coupling RGB-HD SiPMs and [Formula: see text] lutetium fine silicate crystals coated on a third of one of their lateral sides. Events were classified in three DOI bins ([Formula: see text] width) with an average sensitivity of 83.1%. A CRT of [Formula: see text] combined with robust DOI encoding is a marked improvement in the phosphor-coated approach that we pioneered. For the first time, we read out these crystals with SiPMs and clearly demonstrated the potential of the RGB-HD SiPMs for this TOF-DOI PET detector.
authors.affiliation: University of California Davis , Department of Biomedical Engineering, Davis, California 95616, United States.
authors.forename: Sun Il
authors.initials: SI
authors.lastname: Kwon
authors.affiliation: Fondazione Bruno Kessler , via Sommarive 18, Trento, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Ferri
authors.affiliation: Fondazione Bruno Kessler , via Sommarive 18, Trento, Italy.
authors.forename: Alberto
authors.initials: A
authors.lastname: Gola
authors.affiliation: University of California Davis , Department of Biomedical Engineering, Davis, California 95616, United States.
authors.forename: Eric
authors.initials: E
authors.lastname: Berg
authors.affiliation: Fondazione Bruno Kessler , via Sommarive 18, Trento, Italy.
authors.forename: Claudio
authors.initials: C
authors.lastname: Piemonte
authors.affiliation: University of California Davis , Department of Biomedical Engineering, Davis, California 95616, United States.
authors.forename: Simon R
authors.initials: SR
authors.lastname: Cherry
authors.affiliation: University of California Davis , Department of Biomedical Engineering, Davis, California 95616, United States.
authors.forename: Emilie
authors.initials: E
authors.lastname: Roncali
keywords: coincidence timing resolution; depth-of-interaction; phosphor coating; positron emission tomography; silicon photomultiplier; time-of-flight