title: Evaluation of Matrix9 silicon photomultiplier array for small-animal PET.
abstract: OBJECTIVE
  The MatrixSL-9-30035-OEM (Matrix9) from SensL is a large-area silicon photomultiplier (SiPM) photodetector module consisting of a 3 × 3 array of 4 × 4 element SiPM arrays (total of 144 SiPM pixels) and incorporates SensL's front-end electronics board and coincidence board. Each SiPM pixel measures 3.16 × 3.16 mm(2) and the total size of the detector head is 47.8 × 46.3 mm(2). Using 8 × 8 polished LSO/LYSO arrays (pitch 1.5 mm) the performance of this detector system (SiPM array and readout electronics) was evaluated with a view for its eventual use in small-animal positron emission tomography (PET).
  
  
  METHODS
  Measurements of noise, signal, signal-to-noise ratio, energy resolution, flood histogram quality, timing resolution, and array trigger error were obtained at different bias voltages (28.0-32.5 V in 0.5 V intervals) and at different temperatures (5 °C-25 °C in 5 °C degree steps) to find the optimal operating conditions.
  
  
  RESULTS
  The best measured signal-to-noise ratio and flood histogram quality for 511 keV gamma photons were obtained at a bias voltage of 30.0 V and a temperature of 5 °C. The energy resolution and timing resolution under these conditions were 14.2% ± 0.1% and 4.2 ± 0.1 ns, respectively. The flood histograms show that all the crystals in the 1.5 mm pitch LSO array can be clearly identified and that smaller crystal pitches can also be resolved. Flood histogram quality was also calculated using different center of gravity based positioning algorithms. Improved and more robust results were achieved using the local 9 pixels for positioning along with an energy offset calibration. To evaluate the front-end detector readout, and multiplexing efficiency, an array trigger error metric is introduced and measured at different lower energy thresholds. Using a lower energy threshold greater than 150 keV effectively eliminates any mispositioning between SiPM arrays.
  
  
  CONCLUSIONS
  In summary, the Matrix9 detector system can resolve high-resolution scintillator arrays common in small-animal PET with adequate energy resolution and timing resolution over a large detector area. The modular design of the Matrix9 detector allows it to be used as a building block for simple, low channel-count, yet high performance, small animal PET or PET/MRI systems.
authors: Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616.
authors: Junwei
authors: J
authors: Du
authors: Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616.
authors: Jeffrey P
authors: JP
authors: Schmall
authors: Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616.
authors: Yongfeng
authors: Y
authors: Yang
authors: Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616.
authors: Kun
authors: K
authors: Di
authors: Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616.
authors: Emilie
authors: E
authors: Roncali
authors: Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California 95616.
authors: Gregory S
authors: GS
authors: Mitchell
authors: SensL Technologies Ltd., 6800 Airport Business Park, Cork, Ireland.
authors: Steve
authors: S
authors: Buckley
authors: SensL Technologies Ltd., 6800 Airport Business Park, Cork, Ireland.
authors: Carl
authors: C
authors: Jackson
authors: Department of Biomedical Engineering, University of California-Davis, One Shields Avenue, Davis, California, 95616.
authors: Simon R
authors: SR
authors: Cherry
mesh_terms: D000818:Animals; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D059629:Signal-To-Noise Ratio; D012825:Silicon; D013696:Temperature
chemical_list: D012825:Silicon
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