Microwavephysics and Atmospheric Physics
Biomedizinische Photonik
HS 2018  ·  FS 2018
HS 2017  ·  FS 2017
HS 2016  ·  FS 2016
HS 2015  ·  FS 2015
HS 2014  ·  FS 2014
HS 2013  ·  FS 2013
HS 2012  ·  FS 2012
Ultrafast Science and Technology
Last update: 19.07.2018
HS 2017: Seminare über Biomedizinische Photonik
Wednesday 10-12
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Dienstag, 25.07.2017

PhD Defense: Exploration of the phase diagram of liquid water in the metastable region using synthetic fluid inclusions

Zeit: 10:00 Uhr
Hörsaal: B007
 
Chen Qiu
Institute of Applied Physics
University of Bern

 
Mittwoch, 27.09.2017

Understanding the essence of an optical extinction measurement

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

Notwithstanding the everyday use of photospectrometers to optically characterize absorbing materials such as dyes, the applicability of optical extinction measurements on strongly scattering media remains strenuous. Arguably, the reason thereof is the lack of an accepted definition of a "true extinction measurement". In this seminar, we shall revisit the essence of such measurements and provide a general definition based on mode coupling.

 
Mittwoch, 11.10.2017

Bachelor Thesis presentation: Experimental investigation of the applicability of the diffusion model on the boundary of a semi-infinite medium

Zeit: 10:15 Uhr
Hörsaal: A97
 
Cyril Kobel
Institute of Applied Physics
University of Bern

The goal of this bachelor thesis was to investigate the influence of a boundary on the measurement of the light propagation in scattering phantoms. In this presentation, I will describe the experimental setup and protocol, as well as the different light propagation models used to describe the measurements.

 
Mittwoch, 18.10.2017

Fourier-Based Image Reconstruction: a viable Alternative to Time-Domain Algorithms in Optoacoustic Microscopy

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

Image Reconstruction is important in optoacoustic microscopy as it allows the region of acceptable resolution around the plane of focus to be increased dramatically, which in turn greatly improves the usability of the technique. In recent times however, there have been few improvements to the widely used delay-and-sum algorithm. In this seminar, a fourier-based approach to the problem is presented and an in-depth comparison with the established method is made.

 
Mittwoch, 25.10.2017

Clutter reduction methods in epi-optoacoustic imaging: a review

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 ultrasound probe, providing hand-held scanning for flexible imaging of the human body. Such an epi-style system, however, generates clutter, which strongly reduces contrast and imaging depth. In this seminar, a review of various clutter reduction methods will be presented and compared.

 
Mittwoch, 01.11.2017

Er-YAG laser fiber transmission and bone ablation

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

Er-YAG (2.94µm wavelength) laser is a promising tool for cutting or drilling in tissues. While various applications require the use of robotic articulated arms, a compact and flexible system can only be achieved via incorporating optical fibers. Fiber used for the experiments is germanium dioxide fiber. The transmission measured at the output end of the fiber is approximately 60-70% of the input power. The study was to use a minimal optics after the fiber to perform bone ablation. We will discuss the influence various parameters on ablation using fiber optics.

 
Mittwoch, 08.11.2017

From bench to bedside: challenges of quantitative hypoxia imaging

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

Spectral optoacoustic (OA) imaging allows a spatially resolved estimation of oxygen saturation levels in tissue. However, wavelength-dependent light attenuation in the bulk tissue causes a distortion of the spectral OA signal and therefore makes quantitative imaging challenging. In a feasibility study, we combined OA imaging with near infrared optical tomography to perform a spectral correction of the OA signals. The use of a simplified tissue phantom allowed us to identify the challenges of the combined technique and to develop a more general methodology for the quantitative analysis of OA signals originating from vessels. This is a prerequisite for a future clinical application of the combined system.

 
Mittwoch, 15.11.2017

Common mid-angle method applied to CUTE

Zeit: 10:15 Uhr
Hörsaal: A97
 
Patrick Stähli
Institute of Applied Physics
University of Bern

Computed ultrasound tomography in echo-mode (CUTE) aims at complementing handheld diagnostic pulse-echo ultrasound by reconstructing the spatial distribution of speed of sound (SoS), based on measuring the changing local phase of beamformed echoes when changing the transmit beam steering angle.

In this seminar, I will give a short recap of the RF-data processing steps that are required for determining the echo phase shift. Further, I will introduce a novel RF-data processing technique, the common mid-angle approach applied to sliced samples, which links conceptually CUTE to conventional CT and potentially allows tomographic reconstructions. In addition, first simulation results using this approach will be shown.

 
Mittwoch, 22.11.2017

Towards an accurate physical model for imaging speed-of-sound in pulse-echo sonography

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

Computed ultrasound tomography in echo mode (CUTE) generates an image of the spatial distribution of speed-of-sound (SoS) inside the human body using handheld echo-ultrasound, based on analysing the phase shift of echoes when insonifying the tissue under various different angles. This talk focuses on our new physical model of how the phase shift relates to SoS (remember ‘the mysterious factor 2 uncovered’). In phantoms with mixed cylindrical and layered structure, more accurate quantitative SoS imaging is achieved than using the initial model. At the same time, the greater accuracy made it obvious that the current model is still incomplete, which may explain some of the past in vivo results. A possible extension to the model is discussed that hopefully will solve these problems.

 
Mittwoch, 29.11.2017

Receive Beam Steering for Speed of Sound Reconstruction: Application to Carotid Plaque Imaging

Zeit: 10:15 Uhr
Hörsaal: A97
 
Dr. Maju Kuriakose
Institute of Applied Physics
University of Bern

Recently, we have demonstrated that the Speed of Sound reconstruction from the classical ultrasound data is possible with the Computed Ultrasound Tomography in Echo mode (CUTE) technique. Until now, the technique is limited to the imaging of time in varying Speed of Sound imaging due to the time consuming Transmit beam steering. So our goal is to get use of the directional information in the receive signal and to invert the situation from transmit beam steering to Receive beam steering.

 
Mittwoch, 06.12.2017

Speed of Sound reconstruction combining transmission and echo mode

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

Conventional through-transmission tomography reconstructs the spatial distribution of speed of sound (SoS) based on the arrival time of ultrasound outside the tissue after having propagated through the tissue from various different angles. This technique suffers from artefacts associated with refraction and total internal reflection of ultrasound that propagates parallel to the skin surface. Computed Ultrasound Tomography in Echo mode (CUTE), on the other hand, is based on the phase shift of internal echoes measured under reflection mode perpendicular to the skin surface. My research is focused on investigating whether a combination of these two complementing techniques results in an over-all improved SoS image. In my seminar I will explain the experimental setup, show some preliminary results, and elaborate on how a SoS reconstruction combining the two data types can be implemented.

 
Donnerstag, 14.12.2017

Photoacoustic imaging in breast, and moving towards minimally invasive imaging

Zeit: 09:15 Uhr
Hörsaal: B116
 
Prof. Dr. Srirang Manohar, Adjunct Hoogleraar Biomedical Photonic Imaging
Mira Institute of Biomedical Technology and Technical Medicine
University of Twente

I will give an update of the latest work performed in photoacoustic breast imaging. Clinical results from 2014-2015 with a planar geometry system (PAM 1) will be shown. The developments leading to a computed tomography (CT) photoacoustic imager (PAM 2), and results on healthy volunteers will be presented. This will be followed by a short overview of a running project to develop a definitive version of a CT photoacoustic imager. Finally some first results in performing minimally-invasive imaging will be discussed.

 
Donnerstag, 14.12.2017

PhD Defense: Towards deep quantitative clinical optoacoustic imaging: System optimization and accurate fluence correction

Zeit: 13:00 Uhr
Hörsaal: B5
 
Kai Gerrit Held
Institute of Applied Physics
University of Bern

 
Mittwoch, 20.12.2017

Subdermal Solar Energy Harvesting

Zeit: 10:15 Uhr
Hörsaal: A97
 
Maximilien Tholl
PhD Student at ARTORG Center for Biomedical Engineering Research
University of Bern

Intracorporeal energy harvesting aims at generating energy within the body to drive various electronic implants such as cardiac event recorders or pacemakers. Cardiac pacemakers (PMs) are the most common electronic implant and currently last 5-15 years before battery replacement is due. We hypothesize that the lifetime of PMs can be improved by introducing an energy harvesting mechanism in form of a subdermal solar cell. First prototypes were successfully tested in animal trials. A study with 32 volunteers in Switzerland showed that subdermal solar cell implants would generate sufficient power to drive a PM in everyday life. A current study aims to estimate a subdermal solar cell’s power output in different locations worldwide based on solar irradiation data from weather stations. The light transport within through epidermis and dermis shall be modelled with Monte-Carlo methods. The results of this study shall reveal refined requirements for the solar PM development, e.g. the necessary intermediate power storage, solar cell area and possibly regional restrictions.