Abstract
In this paper, it is demonstrated that the effects of acoustic attenuation may play a significant role in establishing the quality of tomographic optoacoustic reconstructions. Accordingly, spatially dependent reduction of signal amplitude leads to quantification errors in the reconstructed distribution of the optical absorption coefficient while signal broadening causes loss of image resolution. Here we propose a correction algorithm for accounting for attenuation effects, which is applicable in both the time and frequency domains. It is further investigated which part of the optoacoustic signal spectrum is practically affected by those effects in realistic imaging scenarios. The validity and benefits of the suggested modelling and correction approaches are experimentally validated in phantom measurements.
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General scientific summary. Acoustic attenuation affects the propagation of ultrasonic waves in such a way that it causes the reduction of amplitude and the broadening of optoacoustic signals, which in turn cause quantification inaccuracies and loss of resolution in optoacoustic images. However, these effects in the images can also be due to other factors such as optical attenuation, the response of the acoustic transducer or speed of sound variations. In this work, we used a model of acoustic attenuation consistent with experimental measurements to determine in which cases it is the dominant cause of distortion. We also used a procedure based on this model to correct for the effects of acoustic attenuation in optoacoustic signals. The benefits of the correction were shown in optoacoustic signals and in a tomographic optoacoustic reconstruction.