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 PETsystem based on GAPD arrays for brainimaging.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 mm3 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 tranmitted from four PETdetector 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 PETsystem can be developed using GAPD arrays and the GAPD-based PETsystem can provide high-quality PETimaging.
This research was supported by the Converging Research Center Program through the Ministry of Education, Science and Technology (Grant No. 2011K000715) and by the Technology Innovation Program funded by the Ministry of Knowledge Economy (Grant No. 10030029), Republic of Korea.
II. MATERIALS AND METHODS
II.A. BrainPET design and fabrication
II.A.1. PETdetector module
II.A.2. Analog signal processing
II.A.3. Digital signal processing
II.A.4. BrainPET using GAPD arrays
II.B. Performance measurement of the prototype PET
II.B.1. Energy and timing resolutions
II.B.3. Spatial resolution
II.B.4. Imaging capability
III.A. Energy and timing resolutions
III.C. Spatial resolution
III.D. Phantom image
- Positron emission tomography
- Image reconstruction
- Image sensors
- Spatial resolution
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