Wiener filtering for deblurring of reconstructed images in photoacoustic tomography with finite size apodized transducers

Abstract

The combined effect of the transducer size and the width of the incident exciting light pulse in photoacoustic tomography (PAT) imaging has been studied. The transducers have been apodized with the Gaussian function and its full width at half-maximum (FWHM) has been varied to see its effect on blurring in PAT imaging. The Wiener filter has been used to deconvolve the PA signal with the input light pulse in order to reduce the blurring effect caused by the broad light pulse. Finally, the PA image was reconstructed using the time reversal interpolation algorithm. The two dimensional simulations were conducted for disc and vasculature phantoms using k-Wave toolbox. The results generated using finite transducers were compared with that of point detectors. The Pearson correlation coefficient value, for a Gaussian excitation pulse of width $1.0 \mu \mathbf{s}$ and for a vasculature phantom, increased from 0.17 to 0.82 when FWHM of a 6 mm transducer was 1.2 mm whereas it increased from 0.30 to 0.69 for the same transducer with 12.9 mm as FWHM. In general, it has been found that the larger diameter transducers have more blurring effect. Moreover, the images produced for small FWHM values are having less blur than those formed for larger FWHM values.