Low-Cost Photoacoustic Tomography System Based on Multi-Channel Delay-Line Module

Photoacoustic tomography (PAT) combining both optical absorption and ultrasound detection, is a unique and emerging technology in the field of medical imaging developed in recent years. PAT is based on the generation and detection of high-frequency pulsed PA signals. Therefore, a multi-channel data acquisition (DAQ) system with high sampling rate is crucial to simultaneously receive the multiway PA signals for real-time imaging. However, the cost of a high-speed multi-channel DAQ is quite high. In this brief, a multiway PA signal delay-line module for PAT was proposed, which merges four channels of PA signals in one channel that significantly reduces DAQ's channel number needed for PAT system. Specifically, an analog circuit design is proposed to accurately delay four-channel PA signals and sum them into one channel before digitization, which records both timing and amplitude of the raw PA signals. Additionally, we reconstruct the four PA waveforms from the recorded signal for image reconstruction by delay-and-sum (DAS) algorithm. To verify the feasibility of the delay-line module in the PAT system, we conducted both simulations and experiments with promising results.