This study aimed to develop a multichannel field programmable gate array (FPGA) based data acquisition
(DAQ) system that could process 8 analog signals from a 1 × 8 LYSO array coupled with a Geiger-mode avalanche
photodiode (GAPD) for fan-beam dual-energy X-ray absorptiometry (DEXA) system. Each analog
input signal was digitized using an 8-channel analog-to-digital converter (ADC) with a 125 MHz sampling rate
and an input range of -1.0 to 1.0 V. The 14-bit digital signals were then fed into a Xilinx Virtex-6 FPGA-based
evaluation board that implemented digital signal processing logic. The collected low- and high-energy events of
each pixel for each input channel were stored in an on-chip block ram-based first-in-first-out (FIFO) module,
and then further transmitted to a personal computer (PC) via the USB port. The intrinsic characteristics, spectral
responses, and image acquisition were performed. The estimated coefficient of determination (R2) was
0.999 in voltage linearity and no considerable alterations in voltage resolution were observed. The energy resolutions
of the peak 59.5 keV (Am-241) were ~28.2 %. Dual-energy peaks were isolated in the X-ray energy spectra.
The synchronization between the movement part of the DEXA system and the timing control block inside
the FPGA chip was well controlled in various conditions. The DEXA phantom images for each pixel were
clearly resolved. This study demonstrated that FPGA with only on-chip memory resources can be used to build
a multichannel DAQ system for fan-beam DEXA systems.