Iterative methods for photoacoustic tomography in attenuating acoustic media

Abstract

The development of efficient and accurate reconstruction methods is an important aspect of tomographic imaging. In this article, we address this issue for photoacoustic tomography. To this aim, we use models for acoustic wave propagation accounting for frequency dependent attenuation according to a wide class of attenuation laws that may include memory. We formulate the inverse problem of photoacoustic tomography in attenuating medium as an illposed operator equation in a Hilbert space framework that is tackled by iterative regularization methods. Our approach comes with a clear convergence analysis. For that purpose we derive explicit expressions for the adjoint problem that can efficiently be implemented. In contrast to time reversal, the employed adjoint wave equation is again damping and, thus has a stable solution. This stability property can be clearly seen in our numerical results. Moreover, the presented numerical results clearly demonstrate the efficiency and accuracy of the derived iterative reconstruction algorithms in various situations including the limited view case.

Passive ultrasound aided acoustic resolution photoacoustic microscopy imaging for layered heterogeneous media

“…3(h) are caused by non-uniform light scattering losses and acoustic attenuations in the shell layer which can be compensated. 30,31 In this paper, the SOS distribution is indirectly acquired by combining the calculated layer structure and the catalog of sound speed of materials. For the cases without prior sound speed, it is also possible to use the genetic algorithm to estimate both the material sound speed and media structure.…”

Well-Posedness for Photoacoustic Tomography with Fabry--Perot Sensors

“…6]. In the context of PAT, the Landweber iteration has been employed previously because of its simplicity and compatibility with regularization methods [17,25,35,36,37,52,64]. Other approaches, such as the conjugate gradient method, may also be employed to solve PAT problems [2,3,37,49,52,66,67,68,76].…”

“…For qualitative photoacoustic tomography, the goal is to form an image of the initial state of the pressure field using boundary measurements of the transient pressure waves. Most of the reconstruction methods assume that the actual pressure field (Dirichlet data) can be measured at the boundary [2,3,4,5,11,22,32,35,36,37,38,42,44,51,52,55,59,60,61,63]. In reality, ultrasound sensors are not able to measure the pressure field directly.…”

Optoacoustic imaging of the skin

“…In contradistinction, acoustic resolution methods are based on unfocused illumination and ultrasound beamforming, that is, the images are formed via acoustic inversion methods at diffuse light depths. [23][24][25][26] In this depth range, the achievable resolution progressively decays due to acoustic attenuation and distortion, [27][28][29][30] typically scaling with 1/200 of the imaging depth. 9 Taken together, optical and acoustic resolution OA imaging systems can visualize shallow to deep layers across the entire thickness of the skin and beyond with high-resolution, thus bridging the longstanding gap between microscopic and macroscopic observations.…”