title: Development of brain PET using GAPD arrays.
abstract: OBJECTIVE
  In recent times, there has been great interest in the use of Geiger-mode avalanche photodiodes (GAPDs) as scintillator readout in positron emission tomography (PET) detectors because of their advantages, such as high gain, compact size, low power consumption, and magnetic field insensitivity. The purpose of this study was to develop a novel PET system based on GAPD arrays for brain imaging.
  
  
  METHODS
  The PET consisted of 72 detector modules arranged in a ring of 330 mm diameter. Each PET module was composed of a 4 × 4 matrix of 3 × 3 × 20 mm(3) cerium-doped lutetium yttrium orthosilicate (LYSO) crystals coupled with a 4 × 4 array three-side tileable GAPD. The signals from each PET module were fed into preamplifiers using a 3 m long flat cable and then sent to a position decoder circuit (PDC), which output a digital address and an analog pulse of the interacted channel among 64 preamplifier signals transmitted from four PET detector modules. The PDC outputs were fed into field programmable gate array (FPGA)-embedded data acquisition (DAQ) boards. The analog signal was then digitized, and arrival time and energy of the signal were calculated and stored.
  
  
  RESULTS
  The energy and coincidence timing resolutions measured for 511 keV gamma rays were 18.4 ± 3.1% and 2.6 ns, respectively. The transaxial spatial resolution and sensitivity in the center of field of view (FOV) were 3.1 mm and 0.32% cps/Bq, respectively. The rods down to a diameter of 2.5 mm were resolved in a hot-rod phantom image, and activity distribution patterns between the white and gray matters in the Hoffman brain phantom were well imaged.
  
  
  CONCLUSIONS
  Experimental results indicate that a PET system can be developed using GAPD arrays and the GAPD-based PET system can provide high-quality PET imaging.
authors.affiliation: Department of Electronic Engineering, Sogang University, Mapo-Gu, Seoul, Korea.
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Jung
authors.forename: Yong
authors.initials: Y
authors.lastname: Choi
authors.forename: Key Jo
authors.initials: KJ
authors.lastname: Hong
authors.forename: Jihoon
authors.initials: J
authors.lastname: Kang
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.forename: Hyun Keong
authors.initials: HK
authors.lastname: Lim
authors.forename: Yoonsuk
authors.initials: Y
authors.lastname: Huh
authors.forename: Sangsu
authors.initials: S
authors.lastname: Kim
authors.forename: Jiwoong
authors.initials: J
authors.lastname: Jung
authors.forename: Kyu Bom
authors.initials: KB
authors.lastname: Kim
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging*; D006801:Humans; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation*; D012588:Scintillation Counting / Q000295:instrumentation*; D013997:Time Factors