title: Improved EMCCD gamma camera performance by SiPM pre-localization.
abstract: High spatial resolution γ-imaging can be achieved with scintillator readout by low-noise, fast, electron-multiplying charge-coupled devices (EMCCDs). Previously we have shown that false-positive events due to EMCCD noise can be rejected by using the sum signal from silicon photomultipliers (SiPMs) mounted on the sides of the scintillator. Here we launch a next generation hybrid CCD-SiPM camera that utilizes the individual SiPM signals and maximum likelihood estimation (MLE) pre-localization of events to discriminate between true and false events in CCD frames. In addition, SiPM signals are utilized for improved energy discrimination. The performance of this hybrid detector was tested for a continuous CsI:Tl crystal at 140 keV. With a pre-localization accuracy of 1.06 mm (full-width-at-half-maximum) attained with MLE the signal-to-background ratio (SBR) was improved by a factor of 5.9, 4.0 or 2.2 compared to the EMCCD-only readout, at the cost of rejecting, respectively, 47%, 9% or 4% of the events. Combining the pre-localization and SiPM energy estimation improved the energy resolution from 50% to (19 ± 3)% while maintaining the spatial resolution at 180 µm.
authors.affiliation: Department of Radiation Radionuclides and Reactors, Applied Sciences, Delft University of Technology, JB Delft, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Salvador
authors.forename: M A N
authors.initials: MA
authors.lastname: Korevaar
authors.forename: J W T
authors.initials: JW
authors.lastname: Heemskerk
authors.forename: R
authors.initials: R
authors.lastname: Kreuger
authors.forename: J
authors.initials: J
authors.lastname: Huizenga
authors.forename: S
authors.initials: S
authors.lastname: Seifert
authors.forename: D R
authors.initials: DR
authors.lastname: Schaart
authors.forename: F J
authors.initials: FJ
authors.lastname: Beekman
mesh_terms: D055615:Electrical Equipment and Supplies; D015902:Gamma Cameras; D011877:Radionuclide Imaging / Q000295:instrumentation*; D012825:Silicon
chemical_list: D012825:Silicon