Prof. Andreas Fichtner Profile

Prof. Andreas Fichtner

Professor at ETH Zurich

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Publications (14)

Proceedings Article | 1 April 2024 Presentation + Paper

Towards elastic bone characterization in transcranial ultrasound

Patrick Marty, Trevor Mitcham, Rehman Ali, Christian Boehm, Neb Duric, Andreas Fichtner

Proceedings Volume 12932, 129320K (2024) https://doi.org/10.1117/12.3006769

KEYWORDS: Skull, Acoustic waves, Wave equations, Ultrasound tomography, Inverse imaging problems

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Proceedings Article | 1 April 2024 Presentation + Paper

Waveform inversion with calibrated source-time functions for improving in-vivo ultrasound computed tomography

Ines Ulrich, Christian Boehm, Patrick Marty, Naiara Korta Martiartu, Berkan Lafci, Xose Luis Dean-Ben, Daniel Razansky, Andreas Fichtner

Proceedings Volume 12932, 129320H (2024) https://doi.org/10.1117/12.3006768

KEYWORDS: Wavelets, Data modeling, Calibration, Transducers, Ultrasonography, Tunable filters, Receivers, In vivo imaging, Tissues, Deconvolution

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Proceedings Article | 10 April 2023 Presentation + Paper

Shape optimization for transcranial ultrasound computed tomography

Patrick Marty, Christian Boehm, Andreas Fichtner

Proceedings Volume 12470, 124700I (2023) https://doi.org/10.1117/12.2654328

KEYWORDS: Skull, Ultrasonography, Mathematical optimization, Wave equations, Data modeling

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Proceedings Article | 4 April 2022 Poster + Presentation + Paper

Full-waveform ultrasound modeling of soft tissue-bone interactions using conforming hexahedral meshes

Patrick Marty, Christian Boehm, Catherine Paverd, Marga Rominger, Andreas Fichtner

Proceedings Volume 12031, 120313H (2022) https://doi.org/10.1117/12.2611548

KEYWORDS: Tissues, Interfaces, Ultrasonography, Bone, Skull, Wave propagation, Computer simulations

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Proceedings Article | 4 April 2022 Presentation + Paper

Using optimal transport to mitigate cycle-skipping in ultrasound computed tomography

Christian Boehm, Lion Krischer, Ines Ulrich, Patrick Marty, Michael Afanasiev, Andreas Fichtner

Proceedings Volume 12038, 1203809 (2022) https://doi.org/10.1117/12.2605894

KEYWORDS: Data modeling, Ultrasonography, Computed tomography, Clouds, Transducers, Wavelets, Tissues, Smoothing, Computer simulations, Breast

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Proceedings Article | 4 April 2022 Presentation + Paper

Analyzing resolution and model uncertainties for ultrasound computed tomography using Hessian information

Ines E. Ulrich, Christian Boehm, Andrea Zunino, Andreas Fichtner

Proceedings Volume 12038, 120380A (2022) https://doi.org/10.1117/12.2608546

KEYWORDS: Data modeling, Tomography, Ultrasonography, Computed tomography, Fluctuations and noise, Inverse problems, Receivers, Image resolution, Tissues, Spatial resolution

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Proceedings Article | 15 February 2021 Presentation + Paper

Sparsifying regularizations for stochastic sample average minimization in ultrasound computed tomography

Ines E. Ulrich, Andrea Zunino, Christian Boehm, Andreas Fichtner

Proceedings Volume 11602, 116020Y (2021) https://doi.org/10.1117/12.2580926

KEYWORDS: Ultrasonography, Stochastic processes, Computed tomography, Data modeling, Tissues, Mammography, Machine learning, Inverse problems, Computational imaging, Breast cancer

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Proceedings Article | 15 February 2021 Presentation + Paper

Acoustoelastic full-waveform inversion for transcranial ultrasound computed tomography

Patrick Marty, Christian Boehm, Andreas Fichtner

Proceedings Volume 11602, 1160211 (2021) https://doi.org/10.1117/12.2581029

KEYWORDS: Ultrasonography, Computed tomography, Skull, Interfaces, Data modeling, Acoustics, Tissues, Solids, Physics, Computing systems

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Proceedings Article | 15 February 2021 Presentation

Speed-of-sound anisotropy estimation using reflector-based pulse-echo ultrasound

Naiara Korta Martiartu, Saule Simute, Christian Boehm, Lisa Ruby, Thomas Frauenfelder, Andreas Fichtner, Marga Rominger, Sergio Sanabria

Proceedings Volume 11602, 116020W (2021) https://doi.org/10.1117/12.2580952

KEYWORDS: Anisotropy, Ultrasonography, Tissues, Wave propagation, Ultrasonics, Reflectors, Modeling, Magnetism, Magnetic resonance imaging, In vivo imaging

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Proceedings Article | 16 March 2020 Paper

Random field interferometry for medical ultrasound

Ines Elisa Ulrich, Christian Boehm, Andreas Fichtner

Proceedings Volume 11319, 1131912 (2020) https://doi.org/10.1117/12.2559852

KEYWORDS: Receivers, Signal attenuation, Interferometry, Transducers, Tomography, Breast, Ultrasonography, Tissues, Data modeling, Medical imaging

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Proceedings Article | 16 August 2019 Open Access

Seismo-medical tomography (Conference Presentation)

Andreas Fichtner

Proceedings Volume 10955, 109550Z (2019) https://doi.org/10.1117/12.2517080

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Proceedings Article | 6 March 2018 Paper

Optimized transducer configuration for ultrasound waveform tomography in breast cancer detection

Nicolas Vinard, Naiara Korta Martiartu, Christian Boehm, Ivana Jovanović Balic, Andreas Fichtner

Proceedings Volume 10580, 105800I (2018) https://doi.org/10.1117/12.2293600

KEYWORDS: Transducers, Data modeling, Breast, Tomography, Inverse problems, Ultrasonography, Quality measurement, Tissues, Computer simulations, Breast cancer

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Waveform inversion is a promising method for ultrasound computed tomography able to produce high-resolution images of human breast tissue. However, the computational complexity of waveform inversion remains a considerable challenge, and the costs per iteration are proportional to the number of emitting transducers. We propose a twofold strategy to accelerate the time-to-solution by identifying the optimal number and location of emitters using sequential optimal experimental design (SOED). SOED is a powerful tool to iteratively add the most informative transducer or remove redundant measurements, respectively. This approach simultaneously provides optimized transducer configurations and a cost-benefit curve that quantifies the information gain versus the computational cost.

First, we propose a method to identify the emitters that provide reconstructions with minimal expected uncertainties. Using a Bayesian approach, model uncertainties and resolution can be quantified with the trace of the posterior covariance. By linearizing the wave equation, we can compute the posterior covariance using the inverse of the Gauss-Newton approximation of the Hessian. Furthermore, this posterior is independent of the breast model and the experimental data, thus enabling pre-acquisition experimental optimization. Then, for the post-acquisition inversion, we present an approach to select a subsample of sources that accurately approximates the full gradient direction in each iteration. We control the convergence of the angular differences between consecutive gradient directions by randomly adding new emitters into the subsample.

We present synthetic studies in 2D and 3D that consider a ring-shaped and a semi-ellipsoidal scanning device, respectively. Numerical results suggest that the provided methods have the potential to identify redundancies from the corresponding cost-benefit curves. Furthermore, the gradient direction rapidly converges to the direction of the full gradient, which appears to be independent of the model and the emitter locations.

Proceedings Article | 6 March 2018 Paper

Time-domain spectral-element ultrasound waveform tomography using a stochastic quasi-Newton method

Christian Boehm, Naiara Korta Martiartu, Nicolas Vinard, Ivana Jovanović Balic, Andreas Fichtner

Proceedings Volume 10580, 105800H (2018) https://doi.org/10.1117/12.2293299

KEYWORDS: Transducers, 3D modeling, Data modeling, Ultrasonography, Stochastic processes, Acoustics, Computer simulations, Breast, Wave propagation, Instrument modeling

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Proceedings Article | 13 March 2017 Paper

Optimal experimental design to position transducers in ultrasound breast imaging

Naiara Korta Martiartu, Christian Boehm, Nicolas Vinard, Ivana Jovanović Balic, Andreas Fichtner

Proceedings Volume 10139, 101390M (2017) https://doi.org/10.1117/12.2252514

KEYWORDS: Ultrasound tomography, Transducers, Breast imaging, Image resolution, Breast cancer, Acoustics, Inverse problems, Quality measurement, Breast, Tomography, Tissues, 3D modeling, Data modeling

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Showing 5 of 14 publications

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