Delay-multiply-and-standard-deviation weighting factor improves image quality in linear-array photoacoustic tomography

One of the most common algorithms used in Photoacoustic and ultrasound image reconstruction, is the nonadaptive Delay-and-Sum (DAS) beamformer. The results show that this algorithm suffers from low resolution and high level of sidelobes. In this paper, it is suggested to weight the DAS beamformed signals to address these limitations and improve the image quality. The new weighting factor, named Delay-Multiply-and-StandardDeviation (DMASD) is designed in the way that the standard deviation of the mutual coupled and multiplied delayed signals is calculated, normalized and multiplied to the DAS formula. Quantitative results obtained from the numerical study show that the proposed DMASD weighting factor improves the Signal-to-Noise-Ratio for about 48.62 dB and 46.53 dB, compared to DAS and the Delay-and-Standard-Deviation (DASD) weighting factor, respectively, at the depth of 35 mm. Also, the Full-Width-Half-Maximum is improved about 0.78 mm and 0.84 mm, compared to DAS and DASD weighting factor, respectively, at the same depth using the proposed DMASD weighting factor, which indicates the improvement of resolution.