### Location

Johann Radon Institute for Computational and Applied Mathematics (RICAM)

July 10–14, 2017

Summer School: July 10th-July 12th

### Speakers

- P. Beard (UCL, London)
- E. Bonnetier (University Grenoble)
- B. Cox (UCL, London)
- H. Haddar (INRIA, Paris)
- R. Leitgeb
- P. Monk (Delaware, USA)

Workshop: July 13th-14th

This interdisciplinary workshop brings together scientists from Physics, Medical Physics and Mathematics, which are developing models, methods and experiments for Coupled Physics Imaging (CPI). These tomographic techniques use different physical fields for illumination and probing. The prime example in this field is Photoacoustics, which uses (typically) pulsed infrared light for illumination and measures the ultrasonic response of the material. The techniques for modeling the illumination process is typically done with simplified models of Maxwell's equation, the discovery of the possibility of sound waves into electromagnetic waves and vice verse is associated with Alexander Graham Bell. This effect is of inherent use in telecommunication technology. Last but not least, the reconstruction of the imaging parameter of CPI is performed by solving Inverse Problems for the wave equation, which is realized by generalized Radon transform. In this workshop we bring together scientists from these areas to interact on all aspects of CPI.

### Organizers

- M. Bergounioux (Orleans, France)
- U. Langer (RICAM)
- O. Scherzer (RICAM)

### Office

- A. Weihs (RICAM)

### Scientific Committee

- G. Bal (Columbia, USA)
- P. Beard (UCL, UK)
- A. Litman (Fresnel, France)
- L. Mindrinos (Vienna, Austria)

### Confirmed Invited Speakers

- G. Alberti (University of Genoa, Italy)
- S. Arridge (UCL, UK)
- A. Da Silva (Fresnel, France)
- P. Elbau (Vienna, Austria)
- P. Kuchment (Texas A&M, USA)
- P. Monk (Delaware, USA)
- K. Ren (Austin, USA)
- T. Tarvainen (University of Eastern Finland)

### Program

## Program

School

Mon, July 10 | |
---|---|

09:00 | Welcome |

09:30–11:00 | H. HaddarOverview of so-called qualitative methods in inverse scattering theory (1) |

11:00–12:30 | E. BonnetierIntegral equations for the modeling of plasmonic resonance of nanoparticles (1) |

12:30–14:00 | Lunch Break |

14:00–15:30 | H. HaddarOverview of so-called qualitative methods in inverse scattering theory (2) |

15:30–15:45 | Break |

15:45–17:30 | E. BonnetierIntegral equations for the modeling of plasmonic resonance of nanoparticles (2) |

Tue, July 11 | |

09:00–10:30 | B. CoxForward and Inverse Problems in Photoacoustic Tomography (1) |

10:30–10:45 | Break |

10:45–12:15 | R. LeitgebOptical Coherence Tomography: Technology and Applications (1)Ricam-Part_ONE_vRL2.pdf (PDF-File, 48.7MB) |

12:15–13:30 | Lunch Break |

13:30–15:00 | P. BeardPractical aspects of photoacoustic imaging |

15:00–15:15 | Break |

15:15–17:00 | B. CoxForward and Inverse Problems in Photoacoustic Tomography (2) |

Wed, July 12 | |

09:00–10:30 | P. MonkFinite element methods for electromagnetic scattering (1) |

10:30–10:45 | Break |

10:45–12:15 | R. LeitgebOptical Coherence Tomography: Technology and Applications (2) |

12:15–13:30 | Lunch Break |

13:30–15:00 | P. MonkFinite element methods for diffraction gratings (2) |

Workshop

(45 min talk + questions)

Thu, July 13 | |
---|---|

09:00–10:00 | P. MonkStekloff eigenvalues in inverse scatter |

10:00–11:00 | A. Da SilvaQuantitative Photoacoustic imaging "On mice and Men": development of imaging systems, signal information content and processing. |

11:00–12:00 | S. ArridgeDynamic PhotoAcoustic Tomography |

12:00–13:30 | Lunch Break |

13:30–14:30 | P. KuchmentMathematical problems of Compton camera imaging |

14:30–15:30 | K. RenRecent Progress on Quantitative Reconstructions in Photoacoustics with Nonlinear Physics |

15:30–16:00 | Break |

16:00–17:00 | G. AlbertiNon-zero constraints in quantitative coupled physics imaging |

17:00–18:00 | Short talks |

Fri, July 14 | |

09:00–10:00 | T. TarvainenQuantitative photoacoustic tomography using transport and diffusion models |

10:00–11:00 | P. Elbau |

### Abstracts

## Abstracts

K. Ren*Recent Progress on Quantitative Reconstructions in Photoacoustics with Nonlinear Physics*

Photoacoustic tomography (PAT) is a non-invasive imaging modality that aims at inferring optical properties of heterogeneous media from photoacoustic measurements. I will review some recent mathematical and computational progresses on quantitative reconstructions in different variants of photoacoustic tomography.

S. Arridge*Dynamic PhotoAcoustic Tomography*

PhotoAcoustic tomography (PAT) has become a powerful new imaging technique combining high-resolution and novel contrast mechanisms as an example of so-called "Coupled Physics Imaging" methods. As in many imaging modalities there is a trade-off between acquisition speed and resolution. This is especially relevent when considering time-varying imaging (4D) and multispectral imaging (5D). In this talk we present recent developments in i) a compressed sensing approach to data acqusition using novel multi-detector/random sampling schemes and ii) the application of novel spatio-temporal regularisation methods.

Joint work with : Paul Beard, Marta Betcke, Ben Cox, Nam Huynh, Felix Lucka, Edward Zhang

H. Haddar*Overview of so-called qualitative methods in inverse scattering theory*

We shall give first a unified presentation of so-called sampling methods to solve the inverse shape problem, where one would like to reconstruct the geometry of an inclusion from multi-static measurements at a fixed frequency. We put a focus on three methods: the Linear Sampling Method, the Factorization Method and the Generalized Linear Sampling Method. Extension of these methods to handle the case of unknown backgrounds will then be discussed. We finally present how these methods can be used to construct various spectral signatures of the material properties. We end up with some applicative perspectives and open questions.

G. Alberti*Non-zero constraints in quantitative coupled physics imaging*

The reconstruction in quantitative coupled physics imaging often requires that the solutions of certain PDEs, e.g. the conductivity equation, the Helmholtz equation or Maxwell's equations, satisfy certain non-zero constraints, such as the absence of critical points. From the mathematical point of view, it is then interesting to see whether one can construct suitable boundary values (the illuminations used to probe the object), possibly independently of the unknown coefficients, in such a way that the corresponding solutions satisfy the required properties. In this talk, I will discuss several techniques used for this aim, as well as some negative results.

### Accommodation

## Accommodation

### Invited Speakers:

Our secretary will reserve a room for you at Sommerhaus Hotel very close to the RICAM.

### Regular participants/visitors:

We made a provisional reservation of 40 single rooms (from 9–14 July 2017) on special terms (€ 48 per night) at Sommerhaus Hotel very close to the RICAM. The hotel grants the special terms for reservations until 12 June 2017 and the reservation has to be done by yourself via e-mail or fax.

Please mention "**Tomographie**" with your reservation to receive the special terms.

### Hotels

- Harry's Home Linz
- Sommerhaus Hotel (As of June, 13th there are only a few rooms available anymore)
- Arcotel Nike
- Hotel Kolping
- Hotel Schillerpark
- Hotel Wolfinger

### Touristic Sites

- Accommodations in Linz
- Tiscover (Touristic information about Linz)
- Tiscover (Touristic information about Austria)

If you need help please contact annette.weihs(at)ricam.oeaw.ac.at

### Contact

## Contact

### Office:

Annette Weihs

Email: annette.weihs(at)ricam.oeaw.ac.at

Tel.: ++43 (0)732 2468 5233

Fax: ++43 (0)732 2468 5212

Address:

Johann Radon Institut (RICAM)

Altenberger Str. 69

4040 Linz

Austria