Noise Reduction in Inherently low-SNR PLD-based PAT images

Abstract

High energy solid state lasers such as Nd:YAG are most commonly used as source of illumination in Photoacoustic (PA) imaging. However, recently, pulsed laser diodes (PLD)are being increasingly explored as a potential alternative to solid state sources due to its advantages such as portability, high pulse repetition rate and affordability. However, PLD has low energy per pulse which results in weaker signal, especially, from deep-seated photoacoustic targets. Hence, additional noise from external sources, such as, electronic noise, jitter, etc. have more pronounced detrimental effect on the quality of the reconstructed PA images resulting in low Signal-to-Ratio (SNR) values. Recently, several works have been reported to reduce the effect of noise by taking advantage of the high pulse-repetition rate offered by PLD and performing averaging. In this work we demonstrate that by strategically employing noise-reduction filter on the raw data prior to reconstruction stage yields significant improvement in SNR compared to mere averaging (∼61%) in PLD-based PAT systems.