Systematic analysis of frequency dependent differential photoacoustic cross-section data for source size estimation

Abstract

A frequency dependent differential photoacoustic cross-section (DPACS) over a large frequency band (100–1000 MHz) was computed, and subsequently, morphological parameters of a photoacoustic (PA) source were quantified. The Green’s function approach was utilized for calculating the DPACS for spheroidal droplets with varying aspect ratios, Chebyshev particles with different waviness and deformation parameters, and normal red blood cells and cells affected by hereditary disorders (e.g., spherocytosis, elliptocytosis, and stomatocytosis). The theoretical framework considers that PA waves propagate through an acoustically dispersive and absorbing medium and are detected by a planar detector of finite size. The frequency dependent DPACS profile was fitted with tri-axial ellipsoid, finite cylinder, and toroid form factor models to obtain size and shape information of the PA source. The tri-axial ellipsoid form factor model was found to provide better estimates of the shape parameters compared to other models for a variety of sources. The inverse problem framework may motivate developing PA-based technology to assess single-cell morphology.

Estimation of photoacoustic spectra for normal and pathological red blood cells using a modified Green’s function approach

“…The standard approach is to iteratively expand Eq. ( 5) to obtain a faithful solution [4,5]. It has been recently shown that an approximate solution can also be obtained by consiedering only the first term of Eq.…”

“…Efforts have been made to measure optoacoustic (OA) signals from individual cells in vitro [3]. Several theoretical studies have also been conducted to examine OA emission from normal and pathological cells both in the time and frequency domains [4]. It has been concluded that the OA spectral features depend upon the size and shape of the source and also on the direction of the measurement.…”