Spatial resolution and reconstructed size accuracy using advanced beamformers in linear array-based PAT systems

Irene Pi-Martín; Alejandro Cebrecos; Juan J García-Garrigós; Noé Jiménez; Francisco Camarena

doi:10.1016/j.pacs.2023.100576

Spatial resolution and reconstructed size accuracy using advanced beamformers in linear array-based PAT systems

Photoacoustics. 2023 Nov 29:34:100576. doi: 10.1016/j.pacs.2023.100576. eCollection 2023 Dec.

Authors

Irene Pi-Martín¹, Alejandro Cebrecos¹, Juan J García-Garrigós¹, Noé Jiménez¹, Francisco Camarena¹

Affiliation

¹ Instituto de Instrumentación para Imagen Molecular (i3M), CSIC - Universitat Politècnica de València, Camino de Vera S/N, 46022, Valencia, Spain.

Abstract

Limitations associated with linear-array probes in photoacoustic tomography are partially compensated by using advanced beamformers that exploit the temporal and spatial coherence of the recorded signals, such as Delay Multiply and Sum (DMAS), Minimum Variance (MV) or coherence factor (CF), among others. However, their associated signal processing leads to an overestimation of the spatial resolution, as well as alterations in the reconstructed object size. Numerical and experimental results reported here support this hypothesis. First, we show that the Rayleigh criterion (RC) is the most suitable choice to characterize the spatial resolution instead of the Point Spread Function (PSF) when considering advanced beamformers. Then, we observe that several advanced beamformers fail to properly reconstruct target sizes slightly above the spatial resolution, underestimating their size. This work sheds light on the suitability of this type of beamformers combined with linear probes for determining sizes and morphology in photoacoustic images.

Keywords: Advanced beamformers; Coherent radiation; Full-Width-at-Half-Maximum (FWHM); Photoacoustic imaging; Point Spread Function (PSF); Rayleigh criterion.