Real-Time FPGA-based Digital Signal Processing and Correction for a Small Animal PET

TL;DR

This paper presents a FPGA-based digital signal processing system for small animal PET imaging that achieves high-speed, real-time data processing, correction, and flexible modes, suitable for precise and efficient small animal brain imaging.

Contribution

The design of a multi-mode FPGA logic for 32-channel PET signal processing with integrated online corrections and high data throughput is novel.

Findings

Supports four online modes including raw data and spectrum construction

Achieves processing beyond 1,000,000 events per second per channel

Meets application requirements in initial tests

Abstract

Small animal Positron Emission Tomography (PET) is dedicated to small animal imaging, which requires high position and energy precision, as well as good flexibility and efficiency of the electronics. This paper presents the design of a digital signal processing logic for a marmoset brain PET system based on LYSO crystal arrays, SiPMs, and the resistive network readout method. We implement 32-channel signal processing in a single Xilinx Artix-7 Field-Programmable Gate Array (FPGA). The logic is designed to support four online modes which are regular data processing mode, flood map construction mode, energy spectrum construction mode, and raw data mode. Several functions are integrated, including two-dimensional (2D) raw position calculation, crystal locating, events filtering, and synchronization detection. Furthermore, a series of online corrections is also integrated, such as photon peak correction to 511 keV and time measurement result correction with crystal granularity. A Gigabit Ethernet interface is utilized for data transfer, Look-Up Tables (LUTs) configuration, and command issuing. The pipeline logic works at 125 MHz with a signal processing capability beyond the required data rate of 1,000,000 events/s/channel. A series of initial tests are conducted. The results indicate that the logic design meets the application requirement.