Reconstruction of the Optical Acoustic Signal for Visualization of Biological Tissues

Abstract

One of the most important applications of optoacoustics is the visualization of oxygenation, hemoglobin concentration, and monitoring. The paper presents the results of processing an acoustic signal obtained as a result of thermoelastic expansion under the influence of an ND: YAG laser with a duration of 84 ns on an aqueous solution using a modified back projection algorithm based on a combined wavelet for high-frequency optoacoustic tomography. The results show that the above wavelet-based back projection algorithm effectively improves the resolution and contrast of reconstruction images under conditions of strong background noise. It is shown that the method can be used in optoacoustic signal reconstruction to obtain images of biological tissues. The paper presents a modified reverse projection algorithm based on a combined wavelet for high-frequency optoacoustic tomography. The given wavelet-based back projection algorithm will improve the resolution and contrast images during reconstruction under strong background noise. The aqueous solution was irradiated with nanosecond laser pulses, and acoustic waves were formed in the result of thermoelastic expansion of the irradiated volume. The model liquid was exposed to a laser with a constant intensity. The results of the experimentally obtained and restored acoustic signals formed as a result of ND: YAG laser exposure were presented with an optoacoustic effect in an aqueous solution. Signal processing was performed using the reverse projection algorithm. A method for processing the acoustic signal based on the reverse filtering method is proposed, which showed that the modified algorithm can significantly improve the quality of the reconstructed image.