Improvement of LED-based photoacoustic imaging using sign coherence factor based on lag-delay-multiply-and-sum beamformer

Delay-and-sum (DAS) is a widely utilized beamforming algorithm in PAI because of its simplicity and real-time capabilities. However, it leads to strong sidelobes and low resolution. A beamformer called delay-multiply-and-sum (DMAS) was proposed, which improved the image quality compared to DAS in PAI. We introduce a weighting factor for DMAS called LAG-DMAS-SCF based on the phase correlation of signals in photoacoustic imaging (PAI). In LAG-DMAS-SCF, the pair-wised signals from DMAS are reorganized in terms of lag and the sign coherence factor (SCF) is applied based on the new signal to the output of DMAS. We have tested the performance of this technique using simulated and experimental data. We have used an LED-based PAI system for the experimental setup. Results show that the proposed algorithm improves the image quality compared to DAS and DMAS by suppressing sidelobes and reducing noise. In phantom imaging, the proposed algorithm showed improvement of around 45dB and 30dB in Signal-to-noise ratio (SNR), and improvement of around 30% and 20% in full-width-half-maxima (FWHM) compared to DAS and DMAS, respectively. Hence, this algorithm can be an appropriate choice for improving image quality in the LED-based PAI system.