Evaluation of lateral and axial resolution of pixel-based beamformers in photoacoustic tomography using a linear US probe

Abstract

Many photoacoustic tomography (PAT) systems have been developed using conventional linear ultrasound probes with reduced angular spectra, which limits the resolution of tomographic reconstructions. These limitations are partially compensated by employing advanced reconstruction algorithms that take advantage of the intrinsic characteristics of the photoacoustic signals. The aim of this work is to theoretically, numerically and empirically characterise the lateral and axial resolution using two nearby point objects that are separated until they can be distinguished as two independent sources in the reconstructed image. It is also intended to study the effect of the main limitations of linear probes (geometry, frequency response and angular spectrum) on the spatial resolution. The results of this study shed light on the suitability of using each type of algorithm depending on the limiting conditions of the probe used and the imaging objective.