B-Mode Photoacoustic Imaging Using Linear Array: Numerical Study for Forward-Backward Minimum Variance Beamformer Combined with Delay-Multiply-and-Sum

Photoacoustic imaging (pai) is a promising medical imaging modality which provides the resolution of ultrasound (us) and the contrast of optical imaging modalities. one of the most important challenges in pai is image formation, especially in the case that a linear-array us transducer is used for data acquisition. this is due to the fact that in the linear-array scenario, there is only 60 degrees view-angle available to detect the photoacoustic waves. because of the nature of photoacoustic waves, the image formation procedure is inherently a limited angle-view problem. delay-and-sum (das) is the most prevalent beamforming algorithm in pai due to its simple implementation, but it provides lowquality images. one of the alternatives is minimum variance (mv) and its derivatives. in this paper, we introduce a novel beamforming algorithm based on the combination of forward-backward mv (fbmv) and delay-multiply-and-sum (dmas) beamforming algorithms, called dmas_fbmv. it is shown that the fbmv can be integrated into the expansion of the dmas algorithm. the proposed method is evaluated numerically. the results demonstrate that the dmas_fbmv significantly outperforms the fbmv in terms of sidelobes (12 db improvement at 45 mm). quantitative metrics such as signal-to- noise and full-width-half-maximum are calculated for a better evaluation.