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Journal of Biomedical Optics

Image reconstruction in photoacoustic tomography with variable speed of sound using a higher-order geometrical acoustics approximation
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Paper Abstract

Previous research correcting for variable speed of sound in photoacoustic tomography (PAT) based on a generalized radon transform (GRT) model assumes first-order geometrical acoustics (GA) approximation. In the GRT model, the pressure is related to the optical absorption, in an acoustically inhomogeneous medium, through integration over nonspherical isochronous surfaces. Previous research based on the GRT model assumes that the path taken by acoustic rays is linear and neglects amplitude perturbations to the measured pressure. We have derived a higher-order GA expression that takes into account the first-order effect in the amplitude of the measured signal and higher-order perturbation to the travel times. The higher-order perturbation to travel time incorporates the effect of ray bending. Incorrect travel times can lead to image distortion and blurring. These corrections are expected to impact image quality and quantitative PAT. We have previously shown that travel-time corrections in 2-D suggest that perceivable differences in the isochronous surfaces can be seen when the second-order travel-time perturbations are taken into account with a 10% speed-of-sound variation. In this work, we develop iterative image reconstruction algorithms that incorporate this higher-order GA approximation assuming that the speed of sound map is known. We evaluate the effect of higher-order GA approximation on image quality and accuracy.

Paper Details

Date Published: 1 March 2010
PDF: 9 pages
J. Biomed. Opt. 15(2) 021308 doi: 10.1117/1.3333550
Published in: Journal of Biomedical Optics Volume 15, Issue 2
Show Author Affiliations
Dimple Modgil, The Univ. of Chicago Medical Ctr. (United States)
Mark A. Anastasio, Illinois Institute of Technology (United States)
Patrick J. La Rivière, The Univ. of Chicago Medical Ctr. (United States)

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