Photoacoustic and Thermoacoustic Tomography: Image Formation Principles

Purpose: Optoacoustic tomography (OAT) is inherently a three-dimensional (3D) inverse problem. However, most studies of OAT image reconstruction still employ two-dimensional imaging models. One important reason is because 3D image reconstruction is computationally burdensome. The aim of this work is to accelerate existing image reconstruction algorithms for 3D OAT by use of parallel programming techniques. Methods: Parallelization strategies are proposed to accelerate a filtered backprojection (FBP) algorithm and two different pairs of projection/backprojection operations that correspond to two different numerical imaging models. The algorithms are designed to fully exploit the parallel computing power of graphics processing units (GPUs). In order to evaluate the parallelization strategies for the projection/backprojection pairs, an iterative image reconstruction algorithm is implemented. Computer simulation and experimental studies are conducted to investigate the computational efficiency and numerical accuracy of the developed algorithms. Results: The GPU implementations improve the computational efficiency by factors of 1000, 125, and 250 for the FBP algorithm and the two pairs of projection/backprojection operators, respectively. Accurate images are reconstructed by use of the FBP and iterative image reconstruction algorithms from both computer-simulated and experimental data. Conclusions: Parallelization strategies for 3D OAT image reconstruction are proposed for the first time. These GPU-based implementations significantly reduce the computational time for 3D image reconstruction, complementing our earlier work on 3D OAT iterative image reconstruction.

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“…When sampling effects are considered, an OAT system is properly described as a continuous-to-discrete (C-D) imaging model 14,22,35,38,39 […”

Section: Iib Discrete-to-discrete Imaging Models and Iterative Imagmentioning

confidence: 99%

Accelerating image reconstruction in three-dimensional optoacoustic tomography on graphics processing units

et al. 2013

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“…Photoacoustic computed tomography (PACT), also known as thermoacoustic or optoacoustic tomography, is an emerging imaging modality that holds great promise for biomedical imaging [1]–[5]. It is a hybrid modality that exploits the high optical contrast of soft tissue and the high spatial resolution of ultrasonic methods.…”

Section: Introductionmentioning

confidence: 99%

“…Equation (1), which neglects the response of the imaging system as well as other physical factors [5], represents an idealized imaging model for PACT in its continuous form. The associated image reconstruction problem is to determine an estimate of A ( r ) from knowledge of p ( r 0 , t ).…”

Section: Introductionmentioning

confidence: 99%

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A Constrained Variable Projection Reconstruction Method for Photoacoustic Computed Tomography Without Accurate Knowledge of Transducer Responses

Sheng

Wang

Matthews

et al. 2015

IEEE Trans. Med. Imaging

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Photoacoustic computed tomography (PACT) is an emerging computed imaging modality that exploits optical contrast and ultrasonic detection principles to form images of the absorbed optical energy density within tissue. When the imaging system employs conventional piezoelectric ultrasonic transducers, the ideal photoacoustic (PA) signals are degraded by the transducers’ acousto-electric impulse responses (EIRs) during the measurement process. If unaccounted for, this can degrade the accuracy of the reconstructed image. In principle, the effect of the EIRs on the measured PA signals can be ameliorated via deconvolution; images can be reconstructed subsequently by application of a reconstruction method that assumes an idealized EIR. Alternatively, the effect of the EIR can be incorporated into an imaging model and implicitly compensated for during reconstruction. In either case, the efficacy of the correction can be limited by errors in the assumed EIRs. In this work, a joint optimization approach to PACT image reconstruction is proposed for mitigating errors in reconstructed images that are caused by use of an inaccurate EIR. The method exploits the bi-linear nature of the imaging model and seeks to refine the measured EIR during the process of reconstructing the sought-after absorbed optical energy density. Computer-simulation and experimental studies are conducted to investigate the numerical properties of the method and demonstrate its value for mitigating image distortions and enhancing the visibility of fine structures.

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“…In PACT, [1][2][3][4][5] tissues are illuminated by short laser pulses to generate internal broadband photoacoustic wavefields via the photoacoustic effect.…”

Section: Introductionmentioning

confidence: 99%

Photoacoustic computed tomography without accurate ultrasonic transducer responses

et al. 2015

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Photoacoustic computed tomography (PACT) holds great promise for biomedical imaging. When the imaging system employs conventional piezoelectric ultrasonic transducers, the ideal photoacoustic (PA) signals are degraded by the transducers' acousto-electric impulse responses (EIRs) during the measurement process. If unaccounted for, this can degrade the accuracy of the reconstructed image. In principle, the effect of the EIRs on the measured PA signals can be ameliorated via deconvolution; images can be reconstructed subsequently by application of a reconstruction method that assumes an idealized EIR. Alternatively, the effect of the EIR can be incorporated into an imaging model and implicitly compensated for during reconstruction. In either case, the efficacy of the correction can be limited by errors in the assumed EIRs. In this work, a joint optimization approach to PACT image reconstruction is proposed for mitigating errors in reconstructed images that are caused by use of an inaccurate EIR. A variable projection method is employed to refine the measured EIR during the process of reconstructing the sought-after absorbed optical energy density. Computer-simulation and experimental studies are conducted to investigate the numerical properties of the method and demonstrate its value for mitigating image distortions and enhancing the visibility of fine structures.

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Photoacoustic and Thermoacoustic Tomography: Image Formation Principles

Cited by 44 publications

References 61 publications

Accelerating image reconstruction in three-dimensional optoacoustic tomography on graphics processing units

Accelerating image reconstruction in three-dimensional optoacoustic tomography on graphics processing units

A Constrained Variable Projection Reconstruction Method for Photoacoustic Computed Tomography Without Accurate Knowledge of Transducer Responses

Photoacoustic computed tomography without accurate ultrasonic transducer responses

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