Microwavephysics and Atmospheric Physics
Biomedizinische Photonik
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Ultrafast Science and Technology
Last update: 03.04.2017
FS 2017: Seminare über Biomedizinische Photonik
Wednesday 10-12
Vorträge, die innerhalb der nächsten Tage stattfinden, sind speziell markiert.
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Mittwoch, 01.03.2017

Polarimetric imaging to characterize isotropic,anisotropic/birefringent and optically active matter

Zeit: 10:15 Uhr
Hörsaal: A97
 
Linda Geisser
Institute of Applied Physics
University of Bern

In this talk, I will give a quick overview of the work I have carried out as part of my Bachelor Thesis in the Biomedical Photonics (BP) Group. I have performed a calibration study and preliminary experiments on the polarimetric microscope built in BP-Lab. The aim here was to assess whether different type of biological structures can be differentiated, based on the backscattered intensity patterns recorded with the microscope, as the latter can potentially serve as a valuable diagnostics tool.

 
Mittwoch, 08.03.2017

Image reconstruction of transmission tomography

Zeit: 10:15 Uhr
Hörsaal: A97
 
Louis Wyss
Institute of Applied Physics
University of Bern

In this talk, I will give a quick overview of the work I have carried out as part of my Bachelor Thesis in the Biomedical Photonics (BP) Group. I have changed the actual set-up and programmed an image reconstruction for transmission tomography to reconstruct the spatial distribution of the slowness of ultrasound. The aim was to program an image reconstruction which explicitly takes into account the missing data regions which occur due to the setup. It can be shown that the new image reconstruction needs less data and has also less artefacts than the reconstruction based on the inverse Radon transform.

 
Mittwoch, 15.03.2017

Optoacoustic Imaging with a handheld multi-wavelength probe

Zeit: 10:15 Uhr
Hörsaal: A97
 
Janos Metzger
Institute of Applied Physics
University of Bern

In this seminar I will give an overview of the work I have done in the Biomedical Photonics (BP) Group for my bachelor thesis in optoacoustics. The goal of my thesis was to gather experience with the optoacoustic (OA) probe that was developed within the European project "fullphase". This probe features miniaturized multi-wavelength diode laser sources that are integrated together with the ultrasound detector inside a handpiece. In comparison to conventional OA systems that, this prope features a small laser pulse energy but a higher pulse repetition rate. As a basis for further studies, I investigated the imaging depth of this probe as a function of the number of signal averaging and gathered first experience in spectral OA imaging of blood-vessel mimicking tissue phantoms.

 
Mittwoch, 22.03.2017

Propagation and Detection of Acoustic Waves in Optoacoustic Microscopy Setups

Zeit: 10:15 Uhr
Hörsaal: A97
 
Florentin Spadin
Institute of Applied Physics
University of Bern

We explore how acoustic waves propagate inside the glass prism assembly commonly used in optoacoustic microscopy setups. We also look at how acoustic pressure waves can be detected and how the above two processes influence and change the design of such setups.

 
Mittwoch, 29.03.2017

Clutter reduction for clinical optoacoustic imaging using comb LOVIT with fast scanning field-of-view

Zeit: 10:15 Uhr
Hörsaal: A97
 
Tigran Petrosyan
Institute of Applied Physics
University of Bern

In epi-optoacoustic (OA) imaging, optical components are attached or directly integrated into the acoustic probe providing flexible single-handed clinical diagnosis of human body. Such setup, however, generates strong clutter signals originated from tissue irradiation site, which interfere with signals of interest and substantially reduce OA imaging depth. With the goal to allow efficient clutter reduction, localized vibration tagging (LOVIT) has previously been developed. A long-pulsed (few 100 microseconds) focused ultrasonic beam generates acoustic radiation force (ARF) that induces localized tissue displacement at its focus. In the basic single-focus approach, two OA images are acquired, one without and one with a preceding single-focus ARF push. Subtraction of the two images resulted in a LOVIT image that highlights true OA signal in the focus but strongly reduces the clutter signals that originate from outside the focal regions where the displacement is comparably small or even zero. The performance of single-focus LOVIT was successfully demonstrated in a clinically realistic setup where the same linear array probe was used for both, imaging and ARF generation. In this study, we propose a novel approach of LOVIT where multiple horizontally aligned foci are created simultaneously, forming grid-shaped ARF patterns (comb approach). A substantially faster scanning time within field-of-view by a factor of two times the number of foci created simultaneously with the comb approach makes it more clinically applicable compared to single-focus approach. Additionally, the comb approach demonstrates a further reduction in residual echo clutter down towards the noise level resulting in further increase in signal-to-background ratio compared to single-focus approach.

 
Mittwoch, 12.04.2017

Towards blood oxygenation saturation level measurements using MIS-OA imaging

Zeit: 10:15 Uhr
Hörsaal: A97
 
Kai-Gerrit Held
Institute of Applied Physics
University of Bern

As part of our research on quantitative deep optoacoustic (OA) imaging – of e.g. blood oxygen saturation – we focus on the spectral correction of the measured OA signals. In a proof-of-principle study we demonstrated that the spectral distortion caused by the wavelength-dependent optical attenuation can be corrected on a broad spectral range, based solely on multiple-irradiation sensing OA (MIS-OA) imaging. As a natural continuation of the aforementioned study and as a precursor to in-vivo applications, we investigated the performance of MIS-OA in heterogeneous, solid phantoms, where boundaries are strongly influential. We quantify the influence of geometric irregularities on the accuracy of the achieved spectral correction and provide insight into the limitations of the proposed technique, thereby assessing its practical value for clinical quantitative OA imaging.

 
Mittwoch, 19.04.2017

Dense assemblies of fibroblast cells in suspensions

Zeit: 10:15 Uhr
Hörsaal: A97
 
Arbnor Zenuni
Department of Physics, University of Fribourg

The properties of dense particle suspensions in food, paint and pharmaceuticals has been studied for decades. The physical behavior of living cells in suspensions is, however, a relatively new topic. In this work the structure and the dynamics of suspensions of NIH 3T3 fibroblast cells over time is investigated. With two-photon microscopy we obtain three dimensional (3D) images from which the structural and dynamical data can be extracted in two- and three dimensions. In addition, the global behavior can be analyzed by time-lapse measurements of cell sedimentation. Since cell adhesion is a non-equilibrium living process the interplay can be influenced by addition of chemicals interfering with cell-cell interactions.

 
Mittwoch, 03.05.2017

Er-YAG fiber delivery and applications

Zeit: 10:15 Uhr
Hörsaal: A97
 
Arushi Jain
Institute of Applied Physics
University of Bern

 
Mittwoch, 10.05.2017

Polarimetric patterns a summary

Zeit: 10:15 Uhr
Hörsaal: A97
 
Manes Hornung
Institute of Applied Physics
University of Bern

 
Mittwoch, 17.05.2017

tba

Zeit: 10:15 Uhr
Hörsaal: A97
 
Tobias Schweizer
Institute of Applied Physics
University of Bern

 
Mittwoch, 24.05.2017

tba

Zeit: 10:15 Uhr
Hörsaal: A97
 
Dr. Michael Jäger
Institute of Applied Physics
University of Bern

 
Mittwoch, 31.05.2017

tba

Zeit: 10:15 Uhr
Hörsaal: A97
 

Dr. Robert Nuster

 
Mittwoch, 07.06.2017

tba

Zeit: 10:15 Uhr
Hörsaal: A97
 
Leonie Ulrich
Institute of Applied Physics
University of Bern

 
Mittwoch, 14.06.2017

tba

Zeit: 10:15 Uhr
Hörsaal: A97
 
Dr. Günhan Akarçay Hidayet
Institute of Applied Physics
University of Bern