Abstract
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The purpose of this study was to investigate a compact
readout for silicon photomultiplier (SiPM) array in the development
of high-resolution imaging detector to reduce the readout channels
while maximizing the detectors performance. The detector module
was composed of a LYSO scintillation crystal array and a SensL's
SPMArray4. The crystal array was coupled to the SiPM array with
a 2mm-thick silicone pad to improve the light sharing among the
SiPM array elements. Three LYSO crystal arrays of 4x4, 8x8 and
12x12 crystal elements with pixel sizes of 3.2, 1.6 and 1.0 mm were
investigated in this study. Two compact multiplexed readouts based
on the light sharing principle have been developed to reduce the
detectors readout channels from 16 to 4 outputs while achieving a
maximized performance in its spatial resolution. One is based on a
conventional charge division method which was utilized with a
discretized positioning circuit (DPC). The other is based on a novel
two-stage charge division which was utilized with a symmetric
charge division circuit to divide the charges from 16 SiPM elements
into a 4-row and 4-column resistive network and then used a
subtractive readout circuit to further reduce the readout channels
from 8 to 4 outputs. The performance of the detector module with
two compact multiplexed readouts was evaluated with LYSO arrays
with different crystal sizes using a 137Cs point source. The
preliminary results show that both compact multiplexed readouts
can provide very good spatial resolution with good uniformity and
resolve up to 1mm pixel elements of LYSO arrays. The compact
readout based on the two-stage charge division with subtractive
resistive-readout shows a slightly better improvement in the crystal
identification while reducing the non-linearity of the flood image as
compared to the DPC readout. In conclusion, both compact
multiplexed readouts are effective approaches for the development
of high-resolution detector module for compact micro-PET.