Download Book of Abstracts - Center for Biomedical Optics

Program
Book of Abstracts
Organized by
Lund University, Sweden
Technical University of Denmark, Denmark
In collaboration with
SPIE
Preface
Lasers, optical methods and instruments based on light interaction with tissues have
emerged as powerful techniques for medical diagnostics, monitoring wide spectra of
tissue pathology and function, and therapy. In biophysics and biology, optical sensing
and manipulation of cells have furthered understanding of basic cell function.
Ten years ago, in the beginning of 2002 we decided to organize a graduate school in
the field of biophotonics. Our motivation then was to strengthen education and
scientific exchange of results and ideas. The five schools were held on the Island of
Ven in June 2003, June 2005, June 2007, June 2009, and May 2011, respectively.
Since 2007, we collaborate with the Journal of Biomedical Optics on publishing a
special section (Selected Topics in Biophotonics) containing invited review papers
from lecturers at the school and contributed papers from students at the school,
respectively. In time, these special sections, especially the invited review papers, will
serve as valuable educational material for students in our field.
Since the first school, we have been overwhelmed with the positive feedback from
students and lecturers and, therefore, we decided to make the school a bi-annual
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event. In June 2013, we open the 6 International Graduate Summer School
Biophotonics ‘13.
The format of the school is a combination of lectures, student poster presentations –
and leisure time. However, the leisure time is also spent studying, discussing, learning
and exchanging new scientific ideas. Following the first school held at the Island of
Ven, the small island situated between Sweden and Denmark, it became clear to us
that this is a perfect setting for our school. By making this choice, we follow in the
footpath of the renowned Danish scientist Tycho Brahe (1546-1601) who inhabited the
Island of Ven some centuries ago and had his laboratory there. Hence, we decided
that this place was perfectly suited for a graduate school combining science and the
history of our two countries.
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Our purpose with the 6 International Graduate Summer School Biophotonics ‘13 is to
provide education for students and young scientists at the highest international level
within biophotonics. Moreover, by inviting renowned lecturers from all over the world,
the educational program is held in an international atmosphere enhancing exchange
of scientific ideas and technological advances within the field of biomedical optics and
closely related areas. Biophotonics ‘13 covers the following main areas:
•
Tissue optics
•
Optical trapping and their applications in biophotonics
•
Nanoscopy With Focused Light
•
Fluorescence life-time imaging
•
Green Fluorescent Protein and their applications in biophotonics
•
Biomolecular Imaging With Coherent Raman Scattering Microscopy
•
Diffusion tomography for biomedical imaging
•
Optical coherence tomography
•
Photo-acoustic imaging
•
Photodynamic therapy
•
Lasers and their application in medicine
We have invited experts, who will give extended presentations reviewing these areas.
Moreover, in order to promote scientific exchange of ideas and results, the attendees
at the summer school will present their current research projects, results or ideas at
three poster sessions.
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Special issue in Journal of Biomedical Optics
Related to Biophotonics ‘13, we are pleased to announce that a special section will
appear in Journal of Biomedical Optics (JBO) entitled “Selected Topics in
Biophotonics” comprising review papers and contributed papers from the school.
Participants at Biophotonics ‘13 are encouraged to submit their manuscript for this
special section in JBO, which is scheduled to be published in August 2014 (online
following acceptance).
We would like to express our gratitude to the lecturers for taking time to teach at the
school and spending time with the students, and to the scientific advisory board for
their helpful suggestions. We also greatly appreciate the financial support and
donations we received from various sponsors making this event possible.
We hope that attending the school will be a fruitful and educational experience for all
participants.
Peter E. Andersen
Technical University of Denmark
Roskilde, Denmark
Stefan Andersson-Engels
Lund University
Lund, Sweden
June 2013
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Organizers
Peter E. Andersen
Department of Photonics Engineering, Technical University of Denmark,
DK-4000 Roskilde, Denmark
[email protected]
Stefan Andersson-Engels
Department of Physics, Lund University, S-221 00 Lund, Sweden
[email protected]
Organizing committee
Peter E. Andersen (DTU), Maria Welling (DTU), Stefan Andersson-Engels (LU), and
Camilla Nilsson (LU)
Scientific Advisory Committee
Darryl J. Bornhop, Chemistry Department, Vanderbilt University, USA
Cornelia Denz, Institute of Applied Optics, University of Münster, Germany
Kishan Dholakia, School of Physics and Astronomy, University of St. Andrews,
Scotland
James Fujimoto, Department of Electrical Engineering and Computer Science,
Massachusetts Institute of Technology (MIT), USA
Stefan W. Hell, Dept. of NanoBiophotonics, Max-Planck-Institute for Biophysical
Chemistry, Germany
Joseph Izatt, Department of Biomedical Engineering, Duke University, USA
Steven Jacques, Oregon Health & Science University, USA
Paul Michael Petersen, Technical University of Denmark, Denmark
Brian W. Pogue, Dartmouth College, USA
Jürgen Popp, Institute of Photonic Technology, Jena, Germany
Eric O. Potma, University of California Irvine, USA
Eva Sevick-Muraca, University of Texas, USA
Katarina Svanberg, Lund University, Sweden
Sune Svanberg, Lund University, Sweden
Roy Taylor, Imperial College London, United Kingdom
Bruce J. Tromberg, Beckman Laser Institute, University of California, Irvine, USA
Hubert van den Bergh, Ecole Polytechnique Fédérale de Lausanne, Institut de
l'environnement, Switzerland
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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List of Lecturers
Professor Kishan Dholakia, University of St. Andrews, Scotland
Professor Wolfgang Drexler, Medical University of Vienna, Austria
Professor Paul French, Imperial College London, United Kingdom
Professor Stefan W. Hell, Max-Planck-Institute for Biophysical Chemistry, Germany
Professor Steven Jacques, Oregon Health & Science University, USA
Professor Konstantin Lukyanov, Russian Academy of Sciences, Moscow, Russia
Dr. Eric O. Potma, University of California, Irvine, USA
Professor, MD Katarina Svanberg, Lund University Hospital, Sweden
Professor Roy Taylor, Imperial College London, United Kingdom
Professor Bruce Tromberg, University of California, Beckman Laser Institute, USA
Professor Lihong Wang, Washington University in St. Louis, USA
School Location
The school is held at the conference center Backafallsbyn on the Island of Ven,
Sweden (www.backafallsbyn.se).
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Sponsors of Biophotonics ‘13
The following institutions and organizations support the graduate summer school:
•
Lund Laser Centre and Lund Medical Laser Centre, Sweden
•
Technical University of Denmark, DTU Fotonik, Denmark
•
Danish Optical Society (DOPS), Denmark
•
NKT Photonics A/S, Denmark
•
Royal Swedish Academy of Sciences (through its Nobel Institute for Physics),
Sweden
•
SPIE, United States
•
Thorlabs Sweden AB, Sweden
Sponsor of Best Poster Presentation
At Biophotonics ‘13 all students present their research or planned research project
(depending on the level of the student) during three poster sessions. During these
presentations, the lecturers will evaluate the posters and presenters and the best
poster is awarded a prize:
• SPIE Poster Award 2013
The prize consists of a diploma and a cash award of 400 Euro sponsored by SPIE.
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Biophotonics ‘13 – Programme
Saturday 8 June 2013
9.00−12.00 ...................... Arrival at Biophotonics ‘13
Registration in Lund (meeting point address):
Department of Physics, Lund University
Sölvegatan 14, Lund, Sweden
12.00 ............................... Light refreshments (sandwiches, fruit, and beverages)
12.45 ............................... Opening: Welcome to Biophotonics ‘13
Peter E. Andersen, Technical University of Denmark,
Denmark, and
Stefan Andersson-Engels, Lund University, Sweden
13.30−14.00 .................... Royal Swedish Academy of Sciences And Its Activities
Professor Anne L'Huillier, Lund University, Sweden
14.30 ............................... Departure for Ven (ferry)
The bus ride from Lund University to the ferry is arranged by
the summer school.
The ferry departs from Landskrona at 16.00.
17.00 ............................... Arrival and check-in at Backafallsbyn on the Island of Ven
19.00 ............................... Dinner
20.30 ............................... Saturday Night Hot Topics
Speakers and organizers present themselves and their topic.
Sunday 9 June 2013
7.00 ................................. Breakfast
8.20−8.30 ........................ Practical notes and announcements
8.30−12.00 ...................... Session 1 – Nanoscopy With Focused Light
Professor Stefan Hell, Max-Planck-Institute for Biophysical
Chemistry, Germany
8.30−9.10:
9.25−10.05:
10.25−11.05:
11.20−12.00:
Lecture I
Lecture II
Lecture III
Lecture IV
12.15 ............................... Lunch
13.30−17.00 .................... Session 2 – Tissue Optics
Professor Steven Jacques, Oregon Health & Science
University, USA
13.30−14.10:
14.25−15.05:
15.25−16.05:
16.20−17.00:
Tissue optics I
Tissue optics II
Tissue optics III
Tissue optics IV
18.00 ............................... Dinner
19.30−22.30 .................... Poster Session I
Presentations by students of their research (posters).
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Monday 10 June 2013
7.00 ................................. Breakfast
8.20−8.30 ........................ Practical notes and announcements
8.30−11.30 ...................... Poster Session II
Presentations by students of their research (posters).
12.00 ............................... Lunch
13.15−16.15 .................... Poster Session III
Presentations by students of their research (posters).
17.15 ............................... Dinner
18.30−22.00 .................... Session 3 – Strategies For Cancer Treatment Using
Lasers And Photodynamic Therapy
Professor, MD Katarina Svanberg, Lund University Hospital,
Dept. Of Oncology, Lund, Sweden
18.30−19.10:
19.25−20.05:
20.25−21.05:
21.20−22.00:
Strategies for cancer treatment using lasers and
photodynamic therapy I
Strategies for cancer treatment using lasers and
photodynamic therapy II
Strategies for cancer treatment using lasers and
photodynamic therapy III
Strategies for cancer treatment using lasers and
photodynamic therapy IV
Tuesday 11 June 2013
7.00 ................................. Breakfast
8.20−8.30 ........................ Practical notes and announcements
8.30−12.00 ...................... Session 4 – Medical Imaging In Thick Tissues Using
Diffuse Optics
Professor Bruce J. Tromberg, Beckman Laser Institute and
Medical Clinic, University of California, Irvine, USA
8.30−9.10:
9.25−10.05:
10.25−11.05:
11.20−12.00:
Medical imaging in thick tissues
using diffuse optics I
Medical imaging in thick tissues
using diffuse optics II
Medical imaging in thick tissues
using diffuse optics III
Medical imaging in thick tissues
using diffuse optics IV
12.15 ............................... Lunch
Afternoon free for discussions and recreation.
17.15 ............................... Dinner
18.30−22.00 .................... Session 5 – Optical Micromanipulation For Biophotonics
Professor Kishan Dholakia, University of St. Andrews, UK
18.30−19.10:
19.25−20.05:
20.25−21.05:
21.20−22:00:
Optical micromanipulation for biophotonics I
Optical micromanipulation for biophotonics II
Optical micromanipulation for biophotonics III
Optical micromanipulation for biophotonics IV
6th International Graduate Summer School Biophotonics ‘13
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Wednesday 12 June 2013
7.00 ................................. Breakfast
8.20−8.30 ........................ Practical notes and announcements
8.30−12.00 ...................... Session 6 – Supercontinuum Light Sources And Lasers
Professor J. Roy Taylor, Physics Department, Imperial
College, United Kingdom
8.30−9.10:
9.25−10.05:
10.25−11.05:
11.20−12.00:
Supercontinuum light sources and lasers I
Supercontinuum light sources and lasers II
Supercontinuum light sources and lasers III
Supercontinuum light sources and lasers IV
12.15 ............................... Lunch
Afternoon free for discussions and recreation.
17.15 ............................... Dinner
18.30−22.00 .................... Session 7 – Genetically Encoded Tools For Optical
Imaging And Control of Cells And Organisms
Professor Konstantin Lukyanov, Laboratory of Molecular
Technologies, Russian Academy of Sciences, Moscow,
Russia
18.30−19.10:
19.25−20.05:
20.25−21.05:
21.20−22.00:
Genetically encoded tools I
Genetically encoded tools II
Genetically encoded tools III
Genetically encoded tools IV
Thursday 13 June 2013
7.00 ................................. Breakfast
8.20−8.30 ........................ Practical notes and announcements
8.30−12.00 ...................... Session 8 – Multidimensional Fluorescence Imaging
And Metrology
Professor Paul French, Imperial College London, United
Kingdom
8.30−9.10:
9.25−10.05:
10.25−11.05:
11.20−12.00:
Multidimensional fluorescence imaging I
Multidimensional fluorescence imaging II
Multidimensional fluorescence imaging III
Multidimensional fluorescence imaging IV
12.15 ............................... Lunch
Afternoon free for discussions and recreation.
17.15 ............................... Dinner
18.30−22.00 .................... Session 9 – Optical Coherence Tomography
Professor Wolfgang Drexler, Medical University of Vienna,
Austria
18.30−19.10:
19.25−20.05:
20.25−21.05:
21.20−22:00:
Optical coherence tomography I
Optical coherence tomography II
Optical coherence tomography III
Optical coherence tomography IV
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Friday 14 June 2013
7.00 ................................. Breakfast
8.20−8.30 ........................ Practical notes and announcements
8.30−12.00 ...................... Session 10 – Photoacoustic Tomography: Ultrasonically
Breaking through the Optical Diffusion Limit
Professor Lihong Wang, Washington University in St. Louis,
Department of Biomedical Engineering, USA
8.30−9.10:
9.25−10.05:
10.25−11.05:
11.20−12.00:
Photoacoustic Tomography I
Photoacoustic Tomography II
Photoacoustic Tomography III
Photoacoustic Tomography IV
12.15 ............................... Lunch
13.30−17.00 .................... Session 11 – Biomolecular Imaging With Coherent
Raman Scattering Microscopy
Dr. Eric O. Potma, University of California, Irvine, USA
13.30−13.10:
14.25−15.05:
15.25−16.05:
16.20−17.00:
Lecture I
Lecture II
Lecture III
Lecture IV
18.30 ............................... Gala dinner
Best Poster Presentation Award sponsored by SPIE
Saturday 15 June 2013
Before 9.00 ..................... Check-out
7.30−10.00 ...................... Breakfast
10.15 ............................... Departure for ferry
On the mainland, there will be shuttle buses for Lund Train
Station and Kastrup Airport, Copenhagen, Denmark
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Poster presentations
Poster session I: Sunday 9 June 2013
Tatiana Alexandru, University of Bucharest (Romania)
Poster title: Laser Induced Cleavage of Molecules For Application On Biological
Targets
Simona Bartkova, Technical University of Denmark (Denmark)
Poster title: Colonization and Dissemination of luxCDABE-Marked Aeromonas
salmonicida In Rainbow Trout
Shadi Chreiteh, Technical University of Denmark (Denmark)
Poster title: Reflective Pulse Oximetry on Sternum
Frédéric Fantoni, CEA-LETI-MINATEC (France)
Poster title: Laser Line Scanning Illumination Scheme For The Enhancement of
Contrast and Resolution For Fluorescence Reflectance Imaging
Gesa Franke, University of Lübeck (Germany)
Poster title: High Resolution Holoscopy
Richelle Hoveling, University of Amsterdam, Academic Medical Center (The
Netherlands)
Poster title: Hyperspectral Imaging of The Spatiotemporal Behavior of Chromophores
In Aging Bruises
Tschackad Kamali, Medical University of Vienna (Austria)
Poster title: Multimodal Fourier transform CARS and Spectral Domain OCT using a
single ultrafast Ti:Sapphire laser
Joao Lagarto, Imperial College London (United Kingdom)
Poster title: Development And Application of Compact, Low-Cost Multispectral TimeResolved Fluorometric Fibre-Optic Probes For In Vivo Diagnosis And Study of
Disease
Jonathan Nylk, University of St Andrews (United Kingdom)
Poster title: Wavefront Shaping in Light Sheet Microscopy
Uros Orthaber, Optotek d.o.o. (Slovenia)
Poster title: Observation of Laser-Induced Cavitation Bubble Dynamics Near A Thin
Elastic Membrane With A High Speed Camera
Tatiana Pryanikova, Institute of Applied Physics RAS (Russia)
Poster title: Influence of Different Kinds of Therapy On The Oxygenation of
Experimental Tumor Estimated by Diffuse Optical Spectroscopy
Peter Rejmstad, Linköping University (Sweden)
Poster title: Optical Monitoring in Neurointensive Care Using Laser Doppler and
Reflectance Spectroscopy
Emanuel Saerchen, Rowiak GmbH (Germany)
Poster title: Physical Investigation of Self-Induced Laser Focus Displacement during
Photodisruption with Ultrashort Pulses
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Paulien Stegehuis, Leiden University Medical Center (The Netherlands)
Poster title: Discrimination of Benign And Malignant Human Breast Tissue Using Full
Field Optical Coherence Tomography
Fatma Tümer, Max Planck Institute for the Science of Light (Germany)
Poster title: Long-Distance laser Propulsion And Deformation Monitoring of Cells In
Hollow-Core Photonic Crystal Fiber
Naja Villadsen, Aarhus University (Denmark)
Poster title: Laser Manipulation of Optically Trapped Objects
Daniel Wangpraseurt, University of Technology, Sydney (Australia)
Poster title: Coral Tissue Optics
Muhammad Nur Salihin Yusoff, Universiti Sains Malaysia (USM) (Malaysia)
Poster title: Optical Reflectance And Morphology of Poly(Vinyl Alcohol) Cryogel
Tailored By Rock Salt
Behrooz Zabihian, Medical University of Vienna (Austria)
Poster title: Towards Multimodal all Optical Detection Photoacoustic Tomography and
Swept Source OCT
6th International Graduate Summer School Biophotonics ‘13
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Poster session II: Monday 10 June 2013
Maria Carmela Cardilli, Università degli studi di Bari (Italy)
Poster title: Self-Mixing Effect In A Multi-Transverse-Mode VCSEL And Polarization
Dynamics of The First Order Transverse Modes
Jeffrey Cassidy, University of Toronto (Canada)
Poster title: FullMonte: Fast 3D Monte Carlo Simulation For Turbid Media
Chieh-Li Chen, University of Pittsburgh (United States)
Poster title: Signal Normalization Reduced Systematic Differences in Retinal Nerve
Fiber Layer Thickness Measurements Between Spectral Domain Optical Coherence
Tomography Devices
Elizabeth Huynh, University of Toronto (Canada)
Poster title: Optically Controlled Pore Formation in Cell-Size Porphyrin Vesicles
Wiebke Knoll, Universität zu Lübeck (Germany)
Poster title: In vivo Two-Photon Microscopy and UV Laser Nanosurgery of Murine
Small Intestine
Philipp Krauter, Institut für Lasertechnologien in der Medizin und Meßtechnik
(Germany)
Poster title: NIR Remission Spectroscopy of Turbid Media
Riya Menezes, Institute of Photonic Technology Jena (Germany)
Poster title: Raman Spectroscopy - A Fast And Reliable Tool To Detect Secondary
Fungal Metabolites
Paul O'Mahoney, University of Dundee (Scotland)
Poster title: Optical Red Blood Cell Sorting
Dino Ott, University of Copenhagen (Denmark)
Poster title: Biophotonic Interactions of Individual Nanoparticles
Lukasz Paluchowski, NTNU (Norway)
Poster title: Dual-Mode Imaging System For Characterization of Wound Surface
Sidsel Petersen, Technical University of Denmark (Denmark)
Poster title: Ytterbium Doped Fiber Amplifiers Above 1100 nm For Generation of
Yellow Laser Light
Radoslaw Sadowski, McMaster University (Canada)
Poster title: Quantitative Optical Molecular Imaging
Eric Seifert, Medical Lasercenter Lübeck (Germany)
Poster title: Automatic Irradiation Control By An Optical Feedback Technique For
Selective Retina Treatment (SRT) In A Rabbit Model
Kristian Sexton, Dartmouth College (United States)
Poster title: Pulsed Light Excitation And Image Gating For Fluorescence Guided
Surgery In Normal Lighting Conditions
Jacob Staley, University of Twente (The Netherlands)
Poster title: Photoacoustic Contrast Agents as Acoustic Time-Reversal Sources For
Targeted Acousto-Optics
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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Idan Steinberg, Tel Aviv University (Israel)
Poster title: Frequency Domain Photoacoustic Phase Measurements of the Acoustic
Modes in Bone for the Early Detection and Diagnosis of Osteoporosis
Peter Van Es, University of Twente (The Netherlands)
Poster title: Photoacoustic Imaging of Human and Murine Joints: Towards
Assessment of Rheumatoid Arthritis
Luka Vidovic, Jozef Stefan Institute (Slovenia)
Poster title: Prediction of the Maximal Safe Laser Radiant Exposure on an Individual
Patient Basis Based on Photothermal Temperature Profiling
Kari Vienola, Rotterdam Eye Hospital (The Netherlands)
Poster title: Imaging of Optic Nerve Head With Motion Corrected OCT Using Tracking
SLO
6th International Graduate Summer School Biophotonics ‘13
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Poster session III: Monday 10 June 2013
Mitra Almasian, University of Amsterdam, Academic Medical Center (The
Netherlands)
Poster title: i-OCT: Integrated Smart Optics For Low Super Resolution OCT
Nico Bodenschatz, Institut für Lasertechnologien in der Medizin und Meßtechnik
(Germany)
Poster title: Optical Reconstruction in Modulated Spatial Imaging: Frequent
Assumptions And Their Validity
Lisa Bürgermeister, Fraunhofer Institute for Laser Technology (Germany)
Poster title: Physical and Mathematical Modeling of Photodynamic Therapy
Andrea Curatolo, The University of Western Australia (Australia)
Poster title: Speckle In Optical Coherence Tomography: Simulation And Experiment
With A Structured Phantom
Ahmed Elmaklizi, Institute for Laser Technology in Medicine and Metrology
(Germany)
Poster title: Analytical and Numerical Analysis of Electromagnetic Scattering using
Gaussian and Focused Beams
Adam Glaser, Dartmouth College (United States)
Poster title: Optical Imaging And Tomographic Dosimetry of Radiation Beams By The
Cerenkov Effect
Altaf Hussain, University of Twente (The Netherlands)
Poster title: Fluence Mapping Inside The Highly Scattering Medium Using Reflection
Mode Acousto-Optics
Deepa Kasaragod, University of Tsukuba (Japan)
Poster title: Polypyrrole Nanopartcles: A New Contrast Agent At 1300nm And Its
Optical Detection Using Photothermal Optical Coherence Tomography
Kelsey Kennedy, The University of Western Australia (Australia)
Poster title: Probing Elastic Contrast In Human Tissues Using Needle Optical
Coherence Elastography
Elena Kiseleva, Nizhny Novgorod State Medical Academy (Russia)
Poster title: In Vivo Evaluation of The Depolarizing Properties of Collagen By CrossPolarization OCT
Kelly Michaelsen, Dartmouth College (United States)
Poster title: Effects of Breast Compression on Digital Breast Tomosynthesis Guided
Diffuse Optical Spectroscopy
Christian Myrtus, University of Lübeck (Germany)
Poster title: Analyse And Visualize Ciliary Beat Frequency Ex Vivo Using Spectral
Domain Optical Coherence Microscopy
Kamilla Nørregaard, University of Copenhagen (Denmark)
Poster title: Nanoparticle Mediated Photothermal Therapy and Integrated miRNA
Delivery
6th International Graduate Summer School Biophotonics ‘13
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Stéphane Perrin, FEMTO-ST (France)
Poster title: Optical Coherence Tomography Microsystem For Early Diagnosis of Skin
Pathologies
Frederico Pimenta, Aarhus University (Denmark)
Poster title: Towards the Control and Quantification of Singlet Oxygen Influence in
Cellular Mechanisms
Ana Rita Ribeiro, University of Porto (Portugal)
Poster title: Towards Optofluidic Systems For Single Cell Manipulation And Analysis
Hendrik Spahr, University of LÜbeck (Germany)
Poster title: Imaging Temperature Distributions of Laser Irradiated Tissue via Phase
Sensitive Optical Coherence Tomography
Yolanda Villanueva, University of Twente (The Netherlands)
Poster title: Determination of The Grüneisen Parameter of Absorbing Liquids Using
Photoacoustic Measurements In An Integrating Sphere
Chiara Vitelli, Istituto Italiano di Tecnologia (Italy)
Poster title: Realization of A Micro-Optical Coherence Tomography (mOCT) Setup For
Cell Imaging With Micron Resolution In Tissues
6th International Graduate Summer School Biophotonics ‘13
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Abstracts
The book of abstracts contains name of the presenting author, title and abstract for the
th
participants’ poster presentations for the 6 International Graduate Summer School
Biophotonics ‘13.
Tatiana Alexandru
Faculty of Physics, University of Bucharest, Romania
[email protected]
Laser Induced Cleavage of Molecules For Application On Biological Targets
Recent reports show that in the case of multiple drug resistance (MDR) acquired by bacteria
and/or malignant tumors, the method which is based on medicine molecules modifications
and/or generation of new and stable photoreaction products originating from them by exposure
to laser radiation is promising for enhancing the efficiency of the treatments. At the same time
the procedure constitutes a new prospective domain in the synthetic chemistry. Possible
alternatives to synthesize new drugs, which may optimize the medication and reduce side
effects, include the development of photoactivated drug carriers, light activated drugs and their
delivery by controlled release of the active form of the drug. The current report presents recent
results obtained by the authors in the application of lasers on photosensitive medicines in view
of biomedical applications.
Mitra Almasian
Biomedical Engineering and Physics, University of Amsterdam, Academic Medical Center, The
Netherlands
[email protected]
i-OCT: Integrated Smart Optics For Low Super Resolution OCT
Optical coherence tomography (OCT) is a standard used tool in ophthalmology. Although it
provides nice cross-sectional images of the retina there is a need from the clinic to improve the
resolution to enable better and more direct diagnosis of retinal diseases e.g. Glaucoma (2nd
cause of blindness). A convenient benefit of OCT is that the axial resolution depends only on
the coherence length of the light source, allowing a depth resolution up to 2 µm. The lateral
resolution on the other hand is determined by the optics in the sample arm. For ophthalmologic
use the lateral resolution of the OCT signal is hampered by the aberrations introduced by the
optics of the eye, which results in a spot size around 20 µm on the retina. The much lower
lateral resolution hinders the visualisation of the photoreceptor cells responsible for colour
vision, the cones. A high resolution OCT system can improve diagnosis through better
visualisation of the structure and physiological function (e.g. blood perfusion and oxygenation)
of the retina. The use of adaptive optics (AO) has proven to successfully correct for such
aberrations resulting in high resolution images. However a standard AO-OCT system entails
practical and economical problems for the use in a clinical setting. In this project we aim to
develop a low cost-super resolution OCT system to overcome the practical and economic
disadvantages of a conventional AO-OCT set-up . This system will be extended with a tracking
mechanism for the temporal motion of the aberrations, resulting in an AO-OCT super resolution
at reduced cost and size by to meet the needs of the clinic.
Simona Bartkova
DTU Veterinary Institute, Technical University of Denmark, Denmark
[email protected]
Colonization and Dissemination of luxCDABE-Marked Aeromonas salmonicida
In Rainbow Trout
Aeromonas salmonicida, the causative agent of the disease furunculosis, is one of the major
bacterial pathogens in aquaculture throughout the world, affecting many fish species. In
Denmark furunculosis causes the greatest problems in sea reared rainbow trout (Oncorhynchus
mykiss) production, where outbreaks occur repeatedly, even with A. salmonicida antigen
included in the applied commercial vaccines, and thereby cause economically devastating
losses in aquaculture. Fish harboring A. salmonicida can moreover be covertly infected and
thus not show any symptoms nor can the bacterium be isolated from them, while still being able
to shed bacteria into the surrounding environment. One of the most crucial factors for trying to
prevent spread of the disease is therefore gaining a deeper understanding on the covert stage
of infection, for which early detection of the pathogen and its route of entry and subsequent
dissemination in the fish is crucial. One way to of being able to track the bacterial infection
progression in the fish is to use in vivo imaging for visualization of the bacterium. For this both
the green fluorescence protein (GFP) and bioluminescence i.e. luciferase has been used
6th International Graduate Summer School Biophotonics ‘13
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extensively. Nevertheless, luciferase is known to be more sensitive, less toxic and respond
faster to changing environments (such as a progression of an infection) than GFP. Using
luciferase is thus the most sensible choice for tracking A. salmonicida in trout.
The objective of my project is to determine the route of entry and subsequent tissue
dissemination of the disease-causing A. salmonicida in Denmark, through in vivo imaging
studies. Currently the project is still in its initial stages and certain factors thus remain to be
determined. Nevertheless, the general plan is to follow a modified procedure from previous
research by Dr Attila Karsi and Dr Mark L. Lawrence, University of Mississippi, where the fish
bacterium Edwardsiella ictaluri was tagged with bioluminescence. In short, the plan will be to
tag A. salmonicida with a broad host range plasmid vector pAKlux1 that has an inserted
luciferase from Photorhabdus luminescens. Through an immersion and cohabitation challenge
respectively, rainbow trout will be infected with the bioluminescence tagged A. salmonicida,
whereby colonization and subsequent dissemination of A. salmonicida in the trout could be
monitored via an IVIS imaging system at several time points. Due to use of bioluminescence
tagging, the same rainbow trout could be used for visualization at each time point, although this
is one of the factors that remain to be decided. Moreover, the plasmid vector pAKlux1 can be
obtained from the laboratory of Dr Attila Karsi through Addgene as agreed upon via
communication with Dr Karsi. Transfer of the plasmid into a strain of A. salmonicida will be done
via Escherichia coli by conjugation as described by previous research of Dr Karsi. This should
result in a constitutive expression of the bacterial luciferase operon in the A. salmonicida and
thus a constitutive luminescence allowing detection and quantification of bacteria using the IVIS
Imaging System.
Nico Bodenschatz
Material Optics, Institut für Lasertechnologien in der Medizin und Meßtechnik, Germany
[email protected]
Optical Reconstruction in Modulated Spatial Imaging: Frequent Assumptions
And Their Validity
Evaluation of experimental data in spatially modulated imaging aims at spatially resolved
reconstruction of optical diffusion and absorption coefficients. This reconstruction is often based
on various simplifying assumptions. Among these are the diffusion approximation and
assumptions for scattering phase function and anisotropy. Furthermore, surface roughness also
influences the captured light intensity and thus alters the experimentally derived optical
properties. Analysis of the validity of these frequent simplifying assumptions in spatially
modulated imaging is the aim of this study. Thereby, the possible error in the derived optical
properties is assessed for various parameter combinations.
Lisa Bürgermeister
Modelling and Simulation, Fraunhofer Institute for Laser Technology, Germany
[email protected]
Physical and Mathematical Modeling of Photodynamic Therapy
Laser-induced antimicrobial photodynamic therapy (aPDT) is already being used today on a
large scale to treat infectious diseases, e.g. periodontitis. How aPDT functions basically in
clinical practice is well-known: A photoactive chemical compound, the so-called photosensitizer,
is introduced into the infected area where it adheres to the disease-causing bacteria. When a
laser with minimal power – in the range of mW – irradiates the photosensitizer, the
photosensitizer is excited to higher electronic states by the absorption of laser light, which
enables the generation of highly reactive singlet oxygen. The targeted bacteria are oxidized,
thus destroyed. Unfortunately physicians cannot tap the potentials of this treatment, as its
underlying physical and biochemical processes are not clearly understood. To enable this
understanding, mathematical-physical modelling is necessary. In particular, this includes
physical and mathematical modelling of how laser radiation propagates in strongly scattering
biological tissues and what the kinetics of the photochemical reactions occurring there are. In a
case with fixed parameters, the concentrations of the substances involved in the aPDT can be
described by a system of ordinary differential equations (ODE). The solution is a time-series
depending on treatment parameters and initial concentrations. The treatment success can be
calculated and predicted with this ODE system. Using methods of model reduction, we simplify
the complexity of the existing aPDT models. This leads to the quantification of the initial
concentrations, which lead to good treatment results. We aim at developing an aPDT strategy
which guides the treating physician and increases the prediction of the therapy outcome. Our
research hypothesis is that spatially distributed intensity and photosensitizer concentration
determine each other and thereby influence the extend of the successfully treated area. This
area increases in time and its increasing speed determines the irradiation time which is
necessary for good aPDT outcomes.
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Maria Carmela Cardilli
Dipartimento Interateneo di Fisica, Università degli studi di Bari, Italy
[email protected]
Self-Mixing Effect In A Multi-Transverse-Mode VCSEL And Polarization
Dynamics of The First Order Transverse Modes
We present an experimental study of a sensor that can be used to simultaneously measure
target translations along the optical axis and target rotations in the orthogonal plane. We used a
multi-transverse mode Vertical- Cavity surface-emitting laser subject to optical feedback. When
the operating conditions preserved the moderate feedback regime, the power along the two
polarization modes was modulated according to both target linear displacement and rotation.
The simultaneous measurement of both polarization intensity modulations allowed for the
independent estimation of the two degrees of freedom of motion.
Jeffrey C. Cassidy
Electrical & Computer Engineering, University of Toronto, Canada
[email protected]
FullMonte: Fast 3D Monte Carlo Simulation For Turbid Media
Emerging clinical applications including bioluminescence imaging require fast and accurate
modelling of light propagation through turbid media with complex geometries. Monte Carlo
simulations are widely recognized as the standard for high-quality modelling of light propagation
in turbid media, albeit with high computational requirements. We present FullMonte: a flexible,
extensible software framework for Monte Carlo modelling of light transport from extended
sources through general 3D turbid media including anisotropic scattering and refractive index
changes. The problem geometry is expressed using a tetrahedral mesh, giving accurate surface
normals and avoiding artifacts introduced by voxel approaches. Input formats from two other
popular simulators, TIM-OS (Monte Carlo) and NIRFAST (Finite- Element Method), are
accepted to help users integrate the software into their application.
We present a discussion of current state-of-the-art algorithms and accel- erated
implementations of the modelling problem. Results and performance are compared against
existing implementations, showing that FullMonte achieves best-in-class performance for
general geometries and material prop- erties using entirely free and open-source libraries.
The software uses multithreading, Intel SSE vector instructions, and optimized data structures
to achieve high performance. Thorough software design permits a great deal of compile-time
flexibility in what information is gathered and how it is stored, with no performance overhead at
run time. It also incorporates novel hardware-friendly performance optimizations in the
scattering calculation that should be useful for GPU and custom hardware implementations.
In addition, control is provided of a new parameter permitting accuracy- performance tradeoffs.
Significant performance gains of over 25% can be realized for bioluminescence imaging
problems with no measurable result- quality difference. For applications requiring quick rough
estimates, even faster run times can be achieved.
Since run time is an important limiting factor in the utility of turbid- media Monte Carlo
simulation, we also discuss the advantages and limita- tions of both CPU and GPU
implementations, with observations important to future advances. Our current work is on
creating a custom hardware implementation of the FullMonte algorithm to achieve large-integerfactor speedup and power efficiency gains of an order of magnitude or better.
Chieh-Li Chen
Department of Bioengineering, University of Pittsburgh, United States
[email protected]
Signal Normalization Reduced Systematic Differences in Retinal Nerve Fiber
Layer Thickness Measurements Between Spectral Domain Optical Coherence
Tomography Devices
Purpose: Differences in retinal nerve fiber layer (RNFL) thickness measurements between
spectral-domain optical coherence tomography (SD-OCT) devices pose significant difficulty in
both clinical and research settings where multiple devices are in use. The purpose of this study
was to develop and test a novel signal normalization method that reduced systematic
differences.
Methods: One hundred and nine eyes (36 glaucomatous, 40 glaucoma suspect, and 33 healthy
eyes) from 59 subjects were scanned with two SD-OCT devices on the same day (Cirrus HDOCT; Carl Zeiss Meditec, Inc., Dublin, CA; Optic Disc Cube 200x200 scan pattern, and RTVue;
Optovue, Fremont, CA; RNFL 3.45 Circle scan pattern). RTVue data had 768 pixels for 2.3 mm
scan length on each A-scan, which was oversampled to match with the Cirrus specification
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(1024 pixels for 2.0 mm). Then both the original Cirrus signal and RTVue derived Cirrus signal
were normalized in amplitude so that the meaningful signal range was stretched to the full gray
scale range of 0 to 255. To compensate signal strength differences, custom high dynamic range
(HDR) processing was also applied to images showing significantly poorer image quality than its
Cirrus/RTVue counterparts (difference of quality index percentile below 5 percentile or above 95
percentile of the entire set of images.) Conventional global mean circumpapillary RNFL
thicknesses were measured automatically using software of our own design and then compared
to the original device outputs. Structural equation models were used to analyze the absolute
RNFL thickness difference between original device outputs and our software outputs after signal
normalization. P<0.05 was considered as statistically significant.
Results: The mean absolute difference in RNFL thicknesses between Cirrus and RTVue were
significantly different before normalization (10.39 ± 3.98 µm), but not after normalization (5.81 ±
4.06 µm). The absolute difference of RNFL thickness between Cirrus and RTVue was
statistically significantly reduced by signal normalization. The median of the absolute difference
of the RNFL thickness after normalization was 4.7 µm, which is within the inherent device
measurement variability.
Conclusion: The reported novel signal normalization method successfully reduced the
systematic difference in RNFL thickness measurements between Cirrus and RTVue to the level
of the inherent device measurement variability. Enabling direct comparison of RNFL thickness
obtained from multiple devices would broaden the use of OCT technology in both clinical and
research applications.
Shadi S. Chreiteh
DTU Nanotech, Technical University of Denmark, Denmark
[email protected]
Reflective Pulse Oximetry on Sternum
This project is about development of a new wearable reflectance mode pulse oximetry sensor
for integration in an electronic patch (ePatch), manufactured by DELTA, that can be placed on
the chest bone (sternum) of humans. Pulse oximetry is a non-invasive photo-metric technique
that provides information about the heart rate and the arterial blood oxygen saturation (SpO2). It
has become a standard of care in many areas of clinical medicine. The arterial blood oxygen
saturation is determined by measuring the light absorbance of tissue at two different
wavelength, usually red (660 nm) and infrared (940 nm), through vascular tissue. The chosen
wavelengths are based on the characteristics of the absorption spectra of deoxygenated
haemoglobin (Hb) and oxygenated haemoglobin (HbO2). The oxygen saturation is the ratio
between HbO2 and Hb and can be calculated from the ratios between the systole and diastole
scattered signals at both 660 nm and 940 nm. The ePatch is capable of measuring
(electrocardiogram) ECG and saving or sending the measured data. Since the sensor is located
on the sternum, it is also possible to measure the respiratory rate with almost the same optical
method. Thus by combining pulse oximetry, respiratory rate and ECG a unique product that
monitors three important vital signs can be achieved. A device that is able to monitor the
mentioned three vital signs wirelessly is needed in Tele-monitoring, at the emergency
departments or other hospital wards.
Andrea Curatolo
Optical + Biomedical Engineering Laboratory, The University of Western Australia, Australia
[email protected]
Speckle In Optical Coherence Tomography: Simulation And Experiment With A
Structured Phantom
Speckle, an intrinsic feature of coherent imaging modalities such as optical coherence
tomography (OCT), manifests itself as rapid fluctuations of the detected intensity over the
spatial extent of the image, conveying a granular texture. The ability to verify theoretical
predictions about speckle statistical properties, whether to extract useful information from a
speckle pattern or to select the most appropriate speckle reduction techniques, depends on
correctly modelling the phenomenon. It also lies in the development of powerful computer
simulations on one hand, and contrived tissue targets, where the geometry of scattering is
known, on the other. In this work we present a model of OCT image formation under several
assumptions: single scattering and negligible attenuation and beam divergence. Under these
assumptions the OCT signal can be analysed in terms of linear systems theory with the sample
susceptibility as input and a spatially invariant point spread function (PSF) as convolution
kernel. The results of this speckle simulation code are corroborated by representing the sample
susceptibility of a contrived experimental target, a tissue-mimicking 3D silicone structured
phantom produced by replica-molding soft lithography. The combined use of the OCT speckle
simulation code and a 3D structured phantom with controlled optical and structural properties
shows promising results in terms of verification of statistical properties (first and second order)
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of OCT speckle and proves very useful in the quantification of the speckle contrast/resolution
degradation trade-off to evaluate appropriate speckle reduction techniques.
Ahmed A. Elmaklizi
Material- und Gewebeoptik, Institute for Laser Technology in Medicine and Metrology, Germany
[email protected]
Analytical and Numerical Analysis of Electromagnetic Scattering using
Gaussian and Focused Beams
Many modern optical instruments for optical particle characterization and biomedical diagnostics
use laser as light sources. Modeling these laser beams as simple plane waves is not valid once
the beam waist becomes equal or smaller than the particle under test. In this work, the
propagation of light having focused and Gaussian beam profile is investigated both analytically
and numerically in the scheme of finite difference time domain. The different phenomena that
appear due to the interaction between the incident beam and the scattering media is studied in
order to enhance the efficiency of microscopy systems.
Frédéric Fantoni
DTBAS-STD-LISA, CEA-LETI-MINATEC, France
[email protected]
Laser Line Scanning Illumination Scheme For The Enhancement of Contrast
and resolution for fluorescence reflectance imaging
Intraoperative fluorescence imaging in reflectance geometry is an attractive imaging modality as
it allows to noninvasively monitor fluorescence targeted tumors located below the tissue
surface. The drawbacks of this technique are the poor resolution in the axial and lateral
directions due to multiple light scattering and background fluorescence decreasing the contrast.
The aim of this PhD is to develop new illumination and detection methods to overcome these
drawbacks. We propose a novel fluorescence imaging method based on laser line illumination
in reflectance geometry. We scan the medium with the laser line and acquire images at each
position of the line. We then have access to a large amount of information that we can use in
different ways. The first and simplest thing to do is to sum the stack of images to obtain the
equivalent of a classical wide-field fluorescence reflectance image. This then serves as the
basis we want to enhance in terms of contrast and resolution. Another possible processing is to
detect only single stripes of each image located on the excitation line or farther from it. We can
also subtract the surrounding signal to the detected stripe, the optimal detection scheme
depending on the depth of the object of interest. This allows us to be less sensitive to photons
that are scattered multiple times and lead to a blurred image. We have also studied the results
obtained with a post-processed structured illumination. To do this, we modulate the sum of the
stack of images with a sine wave and then apply the classical processing used in structured
illumination to obtain the AC contribution. Finally, we have used the excitation line profile to get
an insight on the level of background fluorescence that we want to subtract to the final images
to improve the contrast. This technique has been validated with tissue-like liquid phantoms with
different levels of background fluorescence. Fluorescent inclusions were observed in several
configurations at depths ranging from 1 mm to 1 cm. Our results are compared to those
obtained with a more classical wide-field detection scheme. The most recent work done has
been the design of a setup which would allow to optically implement the masking detection that
will fasten the detection scheme and lead to a real-time enhanced detection of the fluorescence.
Gesa Franke
Institute of Biomedical Optics, University of Lübeck, Germany
[email protected]
High Resolution Holoscopy
In Fourier-domain optical coherence tomography (FD-OCT) the axial and lateral resolutions are
decoupled. The axial resolution is constant over the whole imaging depth and is defined by the
center wavelength and the spectral width of the light source. The lateral resolution and depth of
focus are given by imaging optics and both are defined by the numerical aperture (NA). While
the lateral resolution in the focal plane increases with NA, the focal depth (twice the Rayleigh
length) decreases quadratically. In scanning OCT systems out-of-focus photons are rejected by
confocal detection. In full-field FD-OCT photons from all depths are detected, but outside the
focal depth a degraded lateral resolution causes blurred images. Holoscopy is a new imaging
approach combining digital holography and full-field FD-OCT. As in digital holography the
interference pattern between light scattered by a sample and a defined reference wave is
recorded. The amplitude and phase of the light field backscattered by the sample are encoded
in the interference pattern. During reconstruction numerical refocusing is applied, overcoming
the limitation of the focal depth. In holoscopy multiple holograms are recorded at different
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wavelengths during the sweep of a tunable light source. The reconstruction process is applied
to each hologram with the respective wavelength. As in FD-OCT a one-dimensional Fourier
transform with suitable re-sampling is applied along the wave number axis and gives the
specific depth information for each scatterer within the sample. Thus a uniform, diffraction
limited lateral resolution over the whole measurement depth can be obtained. This advantage of
holoscopy has been demonstrated at quite low NA but becomes more significant at high lateral
resolutions. In most other optical imaging techniques z-scanning is inevitable for measuring a
high-resolution tomographic volume of a sample. In high-resolution holoscopy imaging of deep
volumes is possible without z-scanning. The setup is based on a Mach-Zehnder interferometer
with a high-resolution microscope objective (NA = 0.75) in the sample arm. The fringe patterns
of the interference signal between sample and reference light are recorded with an area
detector. With this setup measurements of reflecting and scattering samples with no axial
dimension have been demonstrated. For recording volumes of scattering samples the lateral
and axial resolution of the setup need to be similar. Thus, for a 0.75 NA objective a tunable light
source with a sweeping range of approximately 300nm is required. To provide this, a modified
tunable Ti:sapphire laser with sufficient tuning range was implemented into the setup. The Lyot
filter in the resonator is rotated by a galvanometric scanner to provide fast automated tuning. So
far the feasibility of this light source for high-resolution holoscopy has been demonstrated only
with a smaller tuning range.
Adam K. Glaser
Thayer School of Engineering, Dartmouth College, United States
[email protected]
Optical Imaging And Tomographic Dosimetry of Radiation Beams By The
Cerenkov Effect
Since its discovery during the 1930s the Cerenkov effect (light emission from charged particles
traveling faster than the local speed of light in a dielectric medium) has been paramount in the
development of high-energy physics research. The ability of the emitted light to describe a
charged particle’s trajectory, energy, velocity, and mass has allowed scientists to study
subatomic particles, detect neutrinos, and explore the properties of interstellar matter. More
recently, the phenomenon has found applications in the context of biomedical research through
Cerenkov luminescence imaging (CLI), a novel method for tracking β-emitting radionuclides in
vivo, as well as fluorescence and absorption spectroscopy of linear accelerator induced light
emission for treatment monitoring during radiation therapy. Herein we explore optical imaging of
the Cerenkov effect during radiation therapy for dosimetry and quality assurance (QA) of
megavoltage x-ray photon beams and present a novel Monte Carlo package capable of
simulating the complex radiation induced light transport dynamics for investigatory purposes.
The proposed QA technique has several advantages over alternative methods (e.g., ionization
chambers, scintillation, and gel dosimetry) including speed and flexibility, and necessitates only
water, which serves as a cheap, abundant, and easily standardized tissue equivalent medium.
Upon future refinement and improved accuracy the proposed modality may prove to be an
important dosimetric tool with both clinical and research applications.
Richelle Hoveling
Biomedical Engineering and Physics, University of Amsterdam, Academic Medical Center, The
Netherlands
[email protected]
Hyperspectral Imaging of The Spatiotemporal Behavior of Chromophores In
Aging Bruises
One of the diagnostic factors of child abuse is the determination of the age of inflicted bruises,
which is based on the judgment of the physician who compares the color of the bruise to a color
chart. This is a subjective method that lacks sufficient accuracy. Research in the department of
Biomedical Engineering and Physics proved that the age of bruises is contained in the timevarying areas and concentration distributions of hemoglobin and bilirubin. The combination of
this information with a finite element model that includes skin thickness and chromophore
diffusivities allowed age determination of specific bruises. Before this technique can be applied
in clinical practice, the current finite element bruise model needs further development to
improve the accuracy of the method. For practical application of the current finite element
model, the model will be expanded by refining the finite element geometry of the skin and
chromophore behavior. Hereto, we will include gravity for the better assessment of
chromophore diffusivities and implement light propagation physics to determine the influence of
the skin’s optical properties on the measured spectra and predict the color appearance of
bruises. For the spectroscopic assessment, two measurement systems are used. Localized
measurements are performed using a fiber based system and a hyperspectral camera is used
for spectral imaging of a larger area. This latter setup enables us to obtain spectral information
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of every pixel in the image and determine the chromophore concentration in different areas in
the bruise in one measurement. We will image and determine the potential (an)isotropic
diffusion on fresh tissue specimen by injecting hemoglobin and different forms of bilirubin. Noninvasive in vivo measurements will be performed on bruise baring volunteers. To give us better
insight in the morphology of the skin and the thickness of the different layers at different
locations on the body non-invasive in vivo measurements of the skin at different locations on the
body will be performed using Optical Coherence Tomography (OCT) (HSL-2000, Santec,
Japan). For the development of tissue equivalent phantoms a mixture of scattering and
absorbing media will be used to create phantoms that represent the optical properties of (skin)
tissue and the chromophores that are present in the bruise (hemoglobin, bilirubin). The first
measurements on volunteers and the development of tissue equivalent phantoms have recently
started. Findings will be integrated in the finite element model after which validation studies will
be performed. Preliminary results show a difference in the distribution of bilirubin and
hemoglobin in a 147 hour old bruise at the volar forearm of a 28 year old female volunteer.
Previous exploratory research indicates that the change in bilirubin and hemoglobin areas
measured over a certain period of time can serve as an input for the finite element model to
determine the age of the bruise. The evaluation of this method will be continued and improved if
necessary. Phantom preparations and measurements of bruises on volunteers will be continued
together with the refinement of the finite element model.
Altaf Hussain
MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, The
Netherlands
[email protected]
Fluence Mapping Inside The Highly Scattering Medium Using Reflection Mode
Acousto-Optics
Optical excitation based imaging modalities, with aim to image structures deep inside the
scattering medium, suffer from quantification problem. We propose a methodology to solve the
problem of non-invasively mapping the fluence in optically heterogeneous medium without the
need of prior knowledge of its optical properties. We present a theoretical model of our concept
and provide proof of principle with Monte Carlo simulations. Simulation results show that it is
possible to measure the local light fluence in highly scattering medium in absolute terms.
Furthermore, we performed an experiment to validate the concept as a strategy to measure
local fluence in relative manners. We used reflection mode acousto optics (AO) in our
experiment, and showed that with this method we can measure local light fluence (in relative
term) in highly scattering medium.
Elizabeth Huynh
Medical Biophysics, University of Toronto, Canada
[email protected]
Optically Controlled Pore Formation in Cell-Size Porphyrin Vesicles
Efforts to develop self-contained microreactors and artificial cells have been limited by difficulty
in generating membranes that can be robustly and repeatedly manipulated to load and release
cargo from phospholipid compartments. Here we describe a purely optical method to form pores
in a membrane generated from porphyrin-phospholipid conjugates electro-assembled into
microscale giant porphyrin vesicles and manipulated using confocal microscopy. The pores in
the membrane resealed within a minute allowing for repeated pore formation with precise
spatial and temporal control and optical gating to allow selective diffusion of biomolecules
across the membrane. Temporal control of pore formation was illustrated by performing
sequential DNA hybridization reactions. A biotin-avidin based strategy was developed to
selectively attach enzymes to the interior of the vesicle, demonstrating spatial control and the
potential of giant porphyrin vesicles as versatile microreactors.
Tschackad Kamali
Center for medical physics and biomedical engineering, Medical University of Vienna, Austria
[email protected]
Multimodal Fourier transform CARS and Spectral Domain OCT using a single
ultrafast Ti:Sapphire laser
Abstract: A FTCARS-OCT system based on a homemade Ti:sapphire laser has been set-up. In
a first step interferometric FTCARS has been realized. Based on an ultrashort-pulse Ti:sapphire
laser this method provides a simple scheme for obtaining high resolution CARS spectra with a
single femtosecond light source. CARS developments with spectral shaping and phase control
of ultrashort pulses are replaced by this straightforward and cost-effective method. An
approximately 2 mm wide excitation beam is focused with a high NA objective onto a sample
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(acetone, isopropanol, polysterol, oil) to enable the collection of the F-CARS signal with a
photomultiplier after re-collimation with a second objective. This geometry only allows the
investigation of very thin (300µm) or transparent samples. A spectral OCT is integrated in the
setup using the same ultrafast laser. FTCARS and OCT imaging was performed with Polybeads
of various diameters.
Deepa K. Kasaragod
Computational Optics group, University of Tsukuba, Japan
[email protected]
Polypyrrole Nanopartcles: A New Contrast Agent At 1300nm And Its Optical
Detection Using Photothermal Optical Coherence Tomography
This paper details a new absorptive type contrast agent, polypyrrole nanoparticles (PPy), for
optical coherence tomography (OCT)imaging with good absorption spectra at wavelengths from
700-1300nm and the photothermal based optical detection of its contrast properties using swept
source based OCT system at 1300nm and a pump laser source at 975nm.
Kelsey M. Kennedy
Optical + Biomedical Engineering Laboratory, The University of Western Australia, Australia
[email protected]
Probing Elastic Contrast In Human Tissues Using Needle Optical Coherence
Elastography
Optical coherence elastography (OCE) provides images of tissue elasticity on the micro-scale
and has potential for several clinical applications, including guidance of tumor resection.
However, advancement toward clinical implementation of OCE is currently limited by the
technique’s small imaging depth in tissue (1-2 mm), as well as a lack of validation of the elastic
contrast generated in OCE. We have overcome the depth limitation of current OCE techniques
by developing a method for performing OCE via a needle probe. Our technique, needle OCE,
uses an OCT needle probe to perform axial measurements of tissue deformation during needle
insertion, and has demonstrated potential for subsurface detection of the boundaries of
diseased tissue. In this paper, we present initial needle OCE results in a fresh human
mastectomy sample, demonstrating elastic contrast between adipose and tumor tissue. In
addition, we have developed a finite element model of tissue deformation in compression OCE
as a first step toward better understanding of the generation and interpretation of contrast in
OCE images. We show initial results demonstrating excellent agreement between measured
and simulated deformation in a tissue phantom. Development of this model provides a
foundation for extension to more complex models of tissue deformation, such as that due to
needle insertion, which will be essential for characterizing the contrast generated by needle
OCE.
Elena B. Kiseleva
Research Institute of Applied and Fundamental Medicine, Nizhny Novgorod State Medical
Academy, Russia
[email protected]
In Vivo Evaluation of The Depolarizing Properties of Collagen By CrossPolarization OCT
Collagen has optical anisotropy at all levels of its hierarchical organization and, consequently, is
able to depolarize the polarized light wave. This property is used for high-resolution imaging of
collagen by noninvasive optical method - cross-polarization optical coherence tomography (CP
OCT), which is widely applicable in clinical diagnostics. The purpose of this study was to
develop and test the method of quantitative assessment of the useful signal in the orthogonal
CP OCT image reflecting the depolarizing properties of collagen fibers in clinical examples. As a
numerical criterion we offered the dimensionless parameter - the integral factor of depolarization
(IFD), which represents the ratio of the received power of OCT signal in the original and
orthogonal channels, averaged over the area of an image. This factor eliminates the effect of
speckle noise, as well as the instrumental noise, that create specific background signal.
Quantitative analysis of 162 CP OCT images of the bladder mucosa, obtained with the "OCT
1300-U" device (IAP RAS, Nizhny Novgorod), had been done with a semi-automatic method in
the ImageJ program (version 1.43u). Of these, 94 images: healthy volunteers and patients with
primary disorders of the bladder mucosa, as an example of an inflammatory or neoplastic
process of collagen fibers damage; 68 images of patients with radiation cystitis as an example
of radiation induced damage of the collagen fibers. It was shown that IFD offered to quantify the
relative useful signal in the CP OCT image objectifies visual characteristics of the image and
estimates the depolarizing properties of collagen fibers with different nature of pathology with
statistically significant difference (p<0,005).
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Wiebke Knoll
Institute for Biomedical Optics, Universität zu Lübeck, Germany
[email protected]
In vivo Two-Photon Microscopy and UV Laser Nanosurgery of Murine Small
Intestine
The intestinal epithelium is only protected by a thin layer of mucus that is produced by goblet
cells, small lesions occur daily in the human body due to ingestion. These lesions can cause
pathogen penetration into the lamina propria, which provokes an immune response. Repeated
damage of the mucosal surface barrier often causes diverse intestinal disorders leading to
inflammation, uncontrolled immune response and disequilibrium of the homeostasis. Up to now,
inflammatory bowel diseases, which cause severe tissue impairments, are not yet understood.
In order to gain insight into the dynamics of the highly complex intestinal system, processes in
the small intestinal mucosa of mice were studied in vivo over several hours using spectrally
resolved two-photon excited autofluorescence microscopy (2PAM). This technique provides a
threedimensional imaging with subcellular resolution and allowed a non-damaging
discrimination of various cell types and cell organelles that exhibit characteristic autofluorescent
spectra. Moreover, to better understand intestinal immune response and healing processes,
murine small intestinal epithelium was exposed to laser-induced micro-lesions and investigated
in vivo. Another aim in this project is the direct imaging of interactions between bacteria and the
intestinal epithelium, using fluorescence-labeled bacteria strains and strains that were
expressed in green fluorescent proteins (GFPs). Therefore, the study of local laser-induced
lesions is of great interest, in order to understand the significance of accidental leaks for the
invasion of bacteria.
Philipp Krauter
Material Optics, Institut für Lasertechnologien in der Medizin und Meßtechnik, Germany
[email protected]
NIR Remission Spectroscopy of Turbid Media
In process control the knowledge of the quantitative concentration of the ingredients is
important. This can be achieved by measuring the remission spectrum and by comparison with
calibration spectra. However, this method cannot separate the reduced scattering coefficient
from the absorption coefficient, e.g. an unnoticed change of reduced scattering is interpreted as
a change in absorption. In contrast, a combination of the spatially resolved reflectance and the
total reflectance enables the determination of absorption undisturbed by scattering. At the same
time, it delivers a high wavelength resolution. In the following, reduced scattering was
determined using the spatially resolved reflectance in the VIS. An empirical description of the
wavelength dependence of reduced scattering is given by a power law. In the NIR the reduced
scattering is obtained by extrapolating this law. Compared to our recent work the focus of this
work is the enhancement of the spectral range of the total reflectance to 450 nm-1700 nm. An
optimized data analysis allows fast interpretation of the measured remission spectrum by use of
a lookup table. The distribution of light is calculated numerically with the radiative transfer
equation. For these calculations, the detection geometry is taken into account. Verification of
the method is done by determination of the absorption coefficient of an optical phantom,
consisting of a known concentration of polystyrene spheres in water. Finally, the absorption
spectrum of butter is shown, representing a possible application of the method. Even though
only the total reflectance is regarded here, it is important to remember, that the knowledge of
reduced scattering is needed for proper evaluation of absorption.
Joao Lagarto
Physics, Imperial College London, United Kingdom
[email protected]
Development And Application of Compact, Low-Cost Multispectral TimeResolved Fluorometric Fibre-Optic Probes For In Vivo Diagnosis And Study of
Disease
Autofluorescence lifetime (AFL) measurements are used to characterize tissue components and
provide label-free contrast and information about structural and metabolic state of tissue without
the need for the application of exogenous fluorescent labels and the associated concerns of
toxicity and pharmacokinetics. Measurement of AFL has been shown to detect qualitative
chemical changes of tissue. This project aims to translate the fluorescence lifetime imaging and
measurement technology developed at the Photonics Group to the clinical study and prognosis
of cancer, heart disease and osteoarthritis. We present a compact fibre-optic time-resolved
spectrofluorometer to be deployed in animal laboratories and clinical settings for extended labelfree studies disease by exploiting tissue AFL to make a systematic study of structural and
biochemical changes in tissues and to correlate these with changes in metabolic signals at
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different stages of disease progression. Preliminary results for AFL measurements of cartilage
tissue suggest that AFL of cartilage tissue is a potential non-invasive readout to monitor
cartilage matrix integrity that may contribute to future diagnosis of cartilage defects as well as
monitoring the efficacy of anti-joint therapeutic agents. An ultimate goal of this research is to
develop a low-cost, compact and portable fibre-optic fluorometer probe that could be easily
replicated and applied in a range of investigations. If clinical efficiency and practicality is
demonstrated throughout these studies, such an instrument could have significant potential for
commercial development and clinical deployment.
Riya C. Menezes
Spectroscopy and Imaging, Institute of Photonic Technology Jena, Germany
[email protected]
Raman Spectroscopy - A Fast And Reliable Tool To Detect Secondary Fungal
Metabolites
Fungal competition for territory and resources is inevitable in habitats with overlap between the
niches of different species or strains. Interactions between wood-decaying basidiomycetes are
excellent examples of such competition and the outcome determines the size of territory held by
one mycelium, and hence access to nutrients. It is a major impetus of community change, and
affects decay rates in woodland ecosystems. Competition is brought about by antagonistic
mycelial interactions which elicit mycelial morphology, metabolic, secondary metabolite release
and extracellular enzyme pattern changes. The basidiomycete studied, Schizophyllum
commune, is a white-rot fungus which is most widely distributed world-wide. The abundance of
S. commune can not only be attributed to its incredible mating ability (more than 23,000
different sexes), but also to its superior competition ability. It has been noted that S. commune
produces secondary metabolites, especially in the interaction zone or zone of contact with
competitor species. The nature of these compounds is unknown and may be the result of the
action of the fungal oxidative enzymes in response to stress caused in the face of a stimulans
excreted from the competitor. We attempted to elucidate the composition of the compounds
produced during these interactions using Raman micro-spectroscopy. The principle is that
Raman spectra contain information on molecular vibrations providing a highly specific fingerprint
of the molecular structure and biochemical composition of cells and tissues. Spectra are
obtained non-invasively without interference from water. The employment of external labels is
not necessary and the sample requires little or no preparation. Moreover, the coupling of
Raman spectroscopy with microscopy (Raman Micro-spectroscopy) enables high spatial
resolution (below ~ 1 µm) and sensitivity. Using particularly resonance Raman spectroscopy, we
show the presence of Indigo in the zones of interaction of the fungi.
Kelly E. Michaelsen
Thayer School of Engineering, Dartmouth College, United States
[email protected]
Effects of Breast Compression on Digital Breast Tomosynthesis Guided Diffuse
Optical Spectroscopy
Diffuse optical spectroscopy of the breast has been successfully used to obtain functional
information about tissue including hemoglobin, deoxygenated hemoglobin, water, lipid and
scattering properties. These metabolic indicators can be altered by disease, leading to
detectable changes in near infrared light signals, when measured at multiple wavelengths.
However, due to the high propensity of light scattering, the resolution of these techniques is
quite low in stand-alone systems. An integrated digital breast tomosynthesis (DBT) and near
infrared (NIR) system combines high spatial resolution for identification of anatomic structures
with information on the metabolic status of tissue, completely co-registered. NIR is non-ionizing,
non-invasive and inexpensive modality that can be easily integrated into existing DBT systems.
DBT provides excellent 3D spatial resolution with less superposition artifacts than traditional
mammography while maintaining similar clinical workflow procedures. DBT/NIR is a synergistic
combination with the potential to decrease the recall rate for breast cancer screening. A first
generation prototype DBT/NIR system has been developed at Dartmouth. The system uses
eight wavelengths of light from 660-940 nm and is not fiber based, keeping the system cost and
complexity to a minimum while taking 46,000 measurements at different sources, detectors and
wavelengths in under a minute. However, this time under full mammographic compression is
quite long, given that the DBT exam takes under ten seconds. Here we compare the results of
optical scans taken at full compression to those at slightly less compression to determine the
effects of lower compression on functional tissue markers. Eleven normal subjects have been
imaged to date on the DBT/NIR system, at both mild and full compression levels and for both
cranio-caudal and medio-lateral oblique views. This study characterizes hemoglobin, oxygen
saturation, water and lipid fractions in two segmented tissue types (adipose, and fibroglandular)
as determined by full three-dimensional tomographic reconstructions. Comparisons between
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mild and full compression levels effect contrast between the regions for the different
chromophores. Changes in contrast between these two normal tissue types may provide insight
into the likely effects of compression on contrast between malignant and fibroglandular tissues
although addition studies on patients with known malignancy are needed. This analysis
assesses the feasibility of decreasing the compression level during the NIR portion of the
DBT/NIR exam for future patients.
Christian Myrtus
Institut of biomedical optics, University of Lübeck, Germany
[email protected]
Analyse And Visualize Ciliary Beat Frequency Ex Vivo Using Spectral Domain
Optical Coherence Microscopy
An important topic in lung research is the understanding of mechanisms that continuously clean
the airways from inhaled particles by transport of mucus. This transport is maintained by the
continuous beating of cilia that are present on airway epithelial cells. To date, the beat
frequency of individual ciliated cells is measured as an indicator of mechanical clearance
activity. The current frequency analysis is usually performed using Wide Field Microscopy
(WFM). The main disadvantages of this technique are the low contrast of the ciliated cells in
resulting images and the inability to be adapted to in-vivo diagnosis. One example is the
problem, how to adapt the transmission illumination that it can be built in a probe (for example a
bronchoscope). This work focuses on the verification of the spectral domain optical coherence
microscopy (SDOCM) to be used for ciliary beat frequency analysis. The advantages of
SDOCM compared to WFM are the improved contrast and higher resolution. Additionally, there
are possibilities to integrate this technology e.g. in an endoscop to bring it into probes. For this
purpose a microscope was developed, that is a combination of a SDOCM and a WFM. The
integrated WFM acts as a reference system. The results show that the determination of ciliary
beat frequency with the SDOCM is possible.
Jonathan Nylk
Department of Physics and Astronomy, University of St Andrews, United Kingdom
[email protected]
Wavefront Shaping in Light Sheet Microscopy
Light sheet microscopy is a powerful, bio-compatible imaging technique. Although a fast and
high contrast method, traditional light sheet microscopes cannot yield high resolution images
over a large field of view due to the increasing beam divergence associated with narrowing of
the beam waist. Illumination with propagation-invariant Bessel light modes has shown promising
results to circumvent this issue, however, the extended transverse structure associated with
propagation-invariant beam types causes contrast reduction and additional photo-damage. The
use of beam shaping techniques, such as Bessel beam generation and more general wavefront
shaping methods, can be advantageous to light sheet microscopy. Light sheet microscopy with
any type of illumination beam suffers from sample based aberrations and scattering. The light
sheet thickness and uniformity, which ultimately limit the image quality, are degraded in the
presence of such aberrations. To extend the imaging capabilities of light sheet microscopy at
depth in turbid specimens, in situ wavefront correction may be used to correct for aberrations in
the illumination light sheet at a point of interest. In trials with scattering tissue phantoms the
correction method gave intensity enhancements of ~2 times and reductions in sheet thickness
by ~3 times, in all cases yielding a light sheet of diffraction-limited thickness. The use of novel
beam types for light sheet microscopy has been demonstrated primarily with Bessel beam
illumination but there has been little investigation into the how the properties of these beams
impact on the image quality. By analysing the modular transfer function for different beam types,
a detailed study of the beam properties and their impact on image quality is accomplished.
From this analysis it is seen that Bessel beam illumination in light sheet microscopy can yield
uniform resolution over a larger field of view due to the propagation-invariance of the Bessel
beam, although a greater extent of propagation-invariance of the Bessel beam reduces the
attainable resolution.
Kamilla Nørregaard
Niels Bohr Institute, University of Copenhagen, Denmark
[email protected]
Nanoparticle Mediated Photothermal Therapy and Integrated miRNA Delivery
Conventional cancer therapies are highly invasive, limited by tumor accessibility, and patients
typically suffer from severe side effects. Here we will investigate a novel strategy that combines
thermal cancer therapy with microRNA (miRNA) silencing of cancer specific genes. By
irradiating intracellular gold nanoparticles (AuNPs) with near-infrared light (NIR) we wish to
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accomplish remote thermally assisted release of AuNPs from cellular endosomes, as well as
systematic release of miRNA from AuNPs. This dual strategy is particularly promising since
AuNPs are easily taken up by living cells and are promising as biomedical drug carriers or as
local heat inducers. Plasmonic nanoparticles are strong photoabsorbers, and when irradiated at
their resonance frequency the absorbed energy is converted into heat leading to elevated
temperatures in the surrounding medium. AuNPs can be tailored to absorb and scatter light in
the NIR region by modifying their size, shape and surface properties. NIR is preferable for
cancer therapies since it has the lowest absorption and highest penetration depth in biological
material. In addition, because of their surface properties AuNPs can easily be decorated with
anticancer targeting agents, such as miRNA, and used for delivery. Functional miRNA can be
released from the AuNPs by controlled heating, and silence or destructing specific pathogenic
genes and consequently down regulating their encoded proteins. However, to obtain specific
delivery of the miRNA the AuNPs must be taken up by the cancer cells, and escape the
endosomes to prevent enzymatic degradation of the miRNA. Hence, we are tracking the AuNPs
when taken up by MCF-7 cancer cells via the endosomal pathway and aiming to find a method
to trigger externally controlled endosomal escape and miRNA release from the AuNPs. More
precisely, we will use a Leica SP5 confocal microscope with an optical trap based on a 1064 nm
laser beam to monitor the time-dependent transport of AuNPs encapsulated in fluorescently
tagged endosomes by subcellular colocalization experiments. Subsequently, we will trigger
release from a single endosome by laser induced membrane rupture. For the purpose of
elucidating delivery of miRNA, we will use AuNPs coated with ~20 nm “carrier” miRNA and
loaded with a complementary miRNA tagged with a dye. Hence, upon laser induced endosomal
membrane rupture we expect to be able to reach temperatures that will also be sufficient to
release the dye tagged miRNA from the “carrier” miRNA. This release can be monitored by a
decrease of the fluorescent signal from the dye tagged miRNA. Provided with information on
both the kinetics of the transport of encapsulated AuNPs and the release characteristic, i.e. how
release depends on laser power and exposure time, we can control and systematically release
the miRNA into the cytosol. When the miRNA are released into the cytosol they can mediate
their therapeutic effect before fusion and degradation in the lysosomes. Due to their
extraordinary physical, chemical, and optical properties and biocompatibility, we expect
plasmonic nanoparticles to have great potential as delivery agents, and in therapeutic and
diagnostic applications.
Paul O'Mahoney
Institute of Medical Science and Technology, University of Dundee, Scotland
[email protected]
Optical Red Blood Cell Sorting
Cell based therapies are becoming a reality and hold great promise in applications as wide
ranging as eye surgery and blood transfusion. In the latter, large numbers of industrially
generated red blood cells need to be monitored and/or sorted to remove the risk of the
teratomas which are associated with non-fully differentiated stem cells. Because of the volumes
of cells involved, and their subsequent in vivo use, a passive monitoring/sorting approach is
needed which does not rely on cell labelling. We have previously shown that optical techniques
have the ability to sort according to size-dependant polarisability: i.e. between different particles
depending on their intrinsic properties, i.e. size, shape, and refractive index. We exploit this
passive sorting ability to sort stem cell derived RBC models made of both inert and biological
content: i) using polymer spheres and ii) using an HL60 cell line. The latter is a cell model being
used to develop the scaling up RBC production. Hence, the results of the HL60 experiments
can be used as a good indicator of how red blood cells will perform under similar conditions. In
initial experiments, an optical line trap was used to sort different sizes of polymer particles with
reasonable success. A more sophisticated optical landscape has now been constructed and will
be the basis for future experiments.
Uros Orthaber
Research and development, Optotek d.o.o., Slovenia
[email protected]
Observation of Laser-Induced Cavitation Bubble Dynamics Near A Thin Elastic
Membrane With A High Speed Camera
The presented research focuses on ophthalmic application of laser, more precisely on wellestablished surgical procedure known as posterior capsulotomy. This is a procedure where
opacification occuring on the posterior capsule of the intraocular lens in the eye is removed by
laser. A highly focused laser beam triggers rapid ionization in the intraocular environment which
leads to plasma formation. Its subsequent expansion produces a shock wave that propagates
spherically from the point of optical breakdown. Vaporization of the liquid in the focal volume
leads to the formation of a cavitation bubble. The bubble contains significant amount of the laser
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pulse energy, which is released during the bubble collapse. Combination of all the mentioned
effects following the optical breakdown is called photodisruption. Mechanisms of
photodisruption are responsible for the rupture of posterior capsule in the surgical procedure.
Behavior of the cavitation bubble near a thin elastic membrane has been studied by recording
the bubble-membrane interaction with a high speed camera. Cavitation bubble was generated
as a result of a laser produced optical breakdown. Laser pulse energy and the distance
between the bubble and the membrane was varied, leading to the observation of different
regimes of bubble-membrane interaction. It has been discovered that at fixed energy the time of
the membrane rupture is roughly independent of the distance between bubble and the
membrane. It has been demonstrated that in the case of laser focus coinciding with the
membrane surface, the bubble has little damaging effects. By increasing the distance between
the bubble and membrane the rupturing becomes more pronounced, while at larger distances
interaction becomes weaker. In order to produce maximum damage on the membrane, the laser
focus should be shifted away from it. The whole picture of the interaction was obtained by
recording events on both sides of the membrane. Membrane bending is followed by the jet
intrusion, whereby the remainings of the bubble penetrate to the other side forming a conical
shape which is eventually reduced. Results of presented work are of great importance for
further improvements of the posterior capsulotomy surgery. Strong indications exist that by
shortening the pulse duration it is possible to obtain same disruptive effects at lower energy,
which can reduce unwanted damage to surrounding intraocular structares and thus improve
safety, while also making the operation more efficient.
Dino Ott
Niels Bohr Institute, University of Copenhagen, Denmark
[email protected]
Biophotonic Interactions of Individual Nanoparticles
In recent studies, it has been shown that optically trapped nanoparticles can serve as ultrasensitive probes for acoustic signals [Ohlinger et al., “Optically trapped gold nanoparticle
enables listening at the microscale”, PRL (2012)]. Notably, Fourier spectral analysis of the
dynamics of an optically trapped particle even allows to sense periodic processes that would
normally be hidden behind Brownian motion. This capability allows for unique biophysical
insights into the interplay between cell biology and cell mechanics. We present a dual-beam
optical tweezers setup which is capable of both exerting a well-defined force via optically
generated pressure waves and simultaneous detection of low amplitude pressure waves with
high temporal resolution. Cross-talk, i.e. the incomplete separation of the detectable position
signals of the individual particles, would typically limit the precision of this optical system. To
circumvent this problem, a novel cross-talk eliminating detection method based on spatial
filtering was established. Biophotonic applications of the presented setup include the
investigation of the periodic beating of bacterial flagella and the response of mechanosensitive
cells, e.g. auditory cells, to a mechanical stimulus of well-defined magnitude.
Lukasz A. Paluchowski
Dept. of Electronics and Telecommunications, NTNU, Norway
[email protected]
Dual-Mode Imaging System For Characterization of Wound Surface
Evaluation of wound bioburden and wound severity is an important prognostic factor in optimal
wound care. However, complete wound assessment should also include information about the
depth, volume, length, width and surface area of a wound as well as its extent in time. While
vascular and molecular aspect of wound assessment by using spectroscopic methods has been
already investigated by our group, the main goal of this work is to study possible improvement
of wound diagnosis by analyzing additional parameters like wound surface and wound
geometry. In this project a dual-mode vision system to collect optical properties, shape and
volume of chronic skin ulcers is under development. This system combines the functionality of
3D stereo-photogrammetry and 2D imaging spectroscopy. A high resolution pushbroom
hyperspectral camera and monochromatic video frame camera are mounted on the same
scanning system. Stereo images can be acquired with different baselines by controlling the
position of the camera on the translation stage only in the scanning direction. Image processing
algorithms have been implemented to combine the functionality of imaging spectroscopy and
stereo-photogrammetry. In the first stage a Digital Surface Model (DSM) of the wound surface is
computed after the rectification. The resulting DSM of normal skin surrounding the wound is
then used to reconstruct the top surface above the wound and thus estimate the wound volume.
Additionally, the hyperspectral image is co-registered to the monochromatic frame image. This
allows for metric measurements of parameters delivered from spectroscopic and statistical
analysis (e.g. tissue oxygenation, pigmentation, classification). Simultaneous analysis of the
hyperspectral data and the surface model give a promising, new, non-invasive tool for
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characterization of chronic wounds. Changes of the wound surface can indicate the rate of
wound healing. Furthermore, the spectroscopic analyses can, if desired, be limited to a certain
depth of interest, like the wound bed or wound border. Further work will concentrate on
automated image acquisition and implementation of real time analysis.
Stéphane Perrin
Micro Nano Sciences & Systems, FEMTO-ST, France
[email protected]
Optical Coherence Tomography Microsystem For Early Diagnosis of Skin
Pathologies
Cutaneous cancer is nowadays the most commonly diagnosed type of cancer. Its early
diagnosis increases the chances of successful treatment. Existing OCT systems can perform
non-invasive 3D optical biopsies of skin, improving patient’s quality of life. Nevertheless these
bulk systems are expensive, only affordable for Hospital and hence not sufficiently employed by
physicians and dermatologists as an early diagnosis tool. VIAMOS project aims to improve this
situation developing a handheld, low-cost and multifunctional Optical Coherence Tomography
microsystem. It will enable doctors to perform a painless and earlier detection of skin
pathologies such as melanoma and non-melanoma cancers. The goal of this project is to
benefit from advanced MOEMS technologies proper to FEMTO-ST Institute (French National
Centre for Scientific Research), enabling a new generation of miniature OCT instruments. This
OCT system will allow getting an axial resolution and a lateral resolution equal to 5μm with a
total penetration of 600μm. Thanks to array interferometer, filed of view of the system reaches
to 8 x 8 mm². The main objective of my thesis work is to create the Optical Coherence
Tomography microsystem, including the optical setup, software development (motion control,
data acquisitions, processing, graphical user interface…), and validation (clinical trials on
patient and volunteers) in collaboration with hospital.
Sidsel R. Petersen
DTU Fotonik, Technical University of Denmark, Denmark
[email protected]
Ytterbium Doped Fiber Amplifiers Above 1100 nm For Generation of Yellow
Laser Light
Ytterbium-doped photonic crystal fiber amplifiers are investigated as amplifiers for wavelengths
above 1100 nm. The Ytterbium gain spectrum reaches from approximately 900 nm to 1200 nm
and to realize an amplifier above 1100 nm the light generated below 1100 nm by spontaneous
emission must be filtered out of the core, to avoid amplified spontaneous emission and parasitic
lasing. In the fibers considered in this work a distributed spectral filter is incorporated in the fiber
cladding, allowing for filtering of spontaneous emission, while the light propagates in the fiber
core. Thereby the maximum gain is achieved at wavelengths above 1100 nm. The yellow light
regime can be reached by frequency doubling of the amplified light, a regime which is of high
interest for the medical industry, since it can be utilized for removal of birthmarks and treatment
of blood vessel disorders.
Frederico M. Pimenta
Department of Chemistry, Aarhus University, Denmark
[email protected]
Towards the Control and Quantification of Singlet Oxygen Influence in Cellular
Mechanisms
Singlet oxygen, O2(a ∆g), the first electronic excited state of molecular oxygen, has been known
in the community for over 80 years. Even though singlet oxygen can be produced in a variety of
ways, the most used is by electronic energy transfer from an organic molecule (commonly
referred to as photosensitizer) to ground state oxygen. Despite this method of generating singlet
oxygen being widely used in photoinitiated cell death (e.g. photodynamic therapy) the ability to
quantify the amount of singlet oxygen necessary to trigger any cell response is still limited by
several things: (1) photobleaching and sensitizer re-localization (2) knowing the sensitizer
concentration in the irradiation domain and (3) control over the local environment immediately
surrounding the sensitizer. In short, a better mechanistic understanding of the roles played by
singlet oxygen in cell death is limited to a dosimetry problem: controlling and quantifying the
amount of singlet oxygen that perturbs a cell. To provide solutions to this rather complicated
issue, two approaches have been examined. First, capitalizing on the fact that singlet oxygen
produced outside a cell is also cytotoxic, a hydrophilic dendrimer-encased membraneimpermeable sensitizer was used to generate an extracellular population of singlet oxygen upon
spatially localized two-photon irradiation. Through the use of this sensitizer and this approach, it
is now possible to better control the singlet oxygen dose in selected microscope-based time1
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and space-resolved single cell experiments. Afterwards, taking the knowledge obtained from
this first study, specifically the control over the immediate environment surrounding the
sensitizer, a protein designated “miniSOG” (for mini Singlet Oxygen Generator), was tested to
ascertain if it could in fact be used as an intracellular sensitizer. MiniSOG is an FMN-containing
flavoprotein engineered from Arabidopsis thaliana phototropin 2 genetically engineered by
Roger Tsien. In contrast to claims made by those who developed miniSOG, we show that this
protein-encased FMN is actually a very poor singlet oxygen photosensitizer; enclosing FMN in
this protein facilitates the photosensitized production of oxygen-dependent radicals (Type I
chemistry) at the expense of singlet oxygen production (Type II chemistry). Nonetheless, efforts
are being made to further improve MiniSOG by specific mutations that will increase singlet
oxygen formation, effectively decreasing radical chemistry. The results presented here not only
show the much-needed development of standards for the intracellular production of singlet
oxygen, but also provide the important tools for the development of well-controlled sensitizers
suitable for use in heterogeneous environment such as a mammalian cell.
Tatiana Pryanikova
Department for Radiophysical Methods in Medicine, Institute of Applied Physics RAS, Russia
[email protected]
Influence of Different Kinds of Therapy On The Oxygenation of Experimental
Tumor Estimated by Diffuse Optical Spectroscopy
Tumor oxygen state is considered to be one of the key factors influencing the disease prognosis
and treatment effectiveness. Studying of the dynamics of oxygenation of tumor and normal
tissues influenced by the different kinds of therapy (radiotherapy, radiomodifying agents) are
necessary for optimization of dose and time parameters of the treatment. Diffuse Optical
Spectroscopy (DOS) makes it possible the noninvasive determination of the tissue oxygen
status based on information on the local changes in the optical parameters, and visualization of
metabolic processes in the region of interest. DOS allows reconstruction of two-dimensional
distribution of main tissue chromophores, that characterize the processes of oxygen supply
(oxygenated hemoglobin) and oxygen consumption (deoxygenated hemoglobin), as well as the
blood oxygen saturation level (StO2) that indirectly reflects the tissue oxygenation.
The aim of the study was to investigate the experimental tumor oxygen status using DOS in vivo
during tumor growth and under different types of treatment. Experiments were performed using
white outbreed male rats on DOS setup (Institute of Applied Physics RAS, Russia). Plyss
lymphosarcoma (PLS) was transplanted subcutaneously into the right lower third of the
abdominal wall. Prior to investigation the animals were anaesthetized and placed in a cuvette
filled with an immersion liquid of known optical parameters.
PLS tumors were irradiated with
single dose of 10 Gy using Co60 unit and studied by DOS before (7th day of tumor growth) and
repeated every 24 hours after irradiation for 96 hours. A direct measurement of pO2 of tumor
tissue was used as a method of verification of DOS results in three irradiated animals. For
modification of tissue oxygenation hemorheologic agent pentoxifylline (Ptx) was used.
Pentoxifylline was administered intraperitoneally at a dose of 10 mg/kg. The first DOS study
was performed before drug administration on the 5-7th day of tumor growth. Further
observations were conducted randomly with the interval of 15, 30 or 60 min for 4 hours.
Radiation-induced changes of LSP oxygenation demonstrated a biphase character. 24 hours
after irradiation the level of StO2 was decreased comparing to the initial level, and comparing to
non-irradiated tumor. 48 hours after irradiation there was a statistically significant increase
oxygen saturation comparing to non-irradiated tumor, comparing to non-irradiated tumor, which
persisted during the next 24 hours; in later terms saturation had been gradually reduced and
reached a control level in 96 hours after irradiation. Comparison between the tumor tissue
oxygenation data obtained by the DOS and direct pO2 measurements demonstrated high
correlation coefficient between two methods. Ptx caused increase of StO2 level in the tumor
zone in 15 min after injection due to increase of oxyhemoglobin concentration. The increase of
saturation was maintained up to 100 minutes after administration. In normal tissue Ptx did not
effect the level of the oxygenation. DOS allows providing information on tumor oxygen state and
its dynamics in the course of of therapy. The differences in the nature of changes of tumor’s
oxygenation under influence of different types of treatment have been demonstrated.
Peter Rejmstad
Department of Biomedical Engineering, Linköping University, Sweden
[email protected]
Optical Monitoring in Neurointensive Care Using Laser Doppler and Reflectance
Spectroscopy
The high mortality rates of patients that experience secondary bleeding linked to traumatic brain
injury (TBI) and the risk of delayed ischemia in patients with subarachnoid hemorrhage (SAH)
motivate the development of new monitoring methods in neurointensive care. To gain more
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information about the continuous cerebral events that occurs following brain damage an optical
monitoring system using combined laser Doppler perfusion monitoring (LDPM) and diffuse
reflectance spectroscopy (DRS) is implemented. LDPM gives information about the
microcirculatory blood flow (perfusion) and level of reflected light in the sample volume. The
DRS technique makes use of a spectrometer that collects the reflected light that has been
affected by scattering or absorption. The collected spectra can be used to extract the
chromophore content in the sample through multi-linear regression analysis and known
absorption spectra of relevant chromophores. The optical monitoring system including software
was first tested on skin and later evaluated during brain tumor resection operations. The
gathered data was analyzed in order to distinguish the differences in blood flow and optical
properties among the tissue types; white matter, gray matter and tumor tissue. Results were
collected using a fiber optic probe containing four adjacent optical fibers, placed in cerebral
tissue. Gathered data included microcirculatory perfusion with reflected light alongside diffuse
reflectance spectroscopy data from which chromophore content could be extracted resulting in
tissue oxygenation values. The laser Doppler measurement could discriminate between
cerebral gray and white matter by looking at the reflected light intensity. The perfusion was
found to be higher in gray tissue compared to white, in agreement with literature. However the
relative perfusion values between gray and tumor tissue needs further investigation to elucidate
their relation. The DRS results from the evaluation during tumor operations imply that tumorous
and gray brain tissues have similar levels of oxygen saturation. Lower oxygen saturation values
were recorded in the tumor border while the lowest values were found in white brain tissue. The
work includes evaluation of an optical monitoring system, intended for use in neurointensive
care, that records online perfusion data and can be used to collect spectroscopic information to
assess chromophore information in a post analyzing step. Data collected during the evaluation
phase of the optical monitoring system points out similarities and differences in perfusion and
oxygenation values between various cerebral tissue types. The optical system has a promising
ability to monitor patient status and help to gain more understanding about the cerebral
circulation following brain damage.
Ana Rita S. R. Ribeiro
Physics and Astronomy, University of Porto, Portugal
[email protected]
Towards Optofluidic Systems For Single Cell Manipulation And Analysis
Laser manipulation or optical trapping, as it is also known, refers to techniques for mechanical
control of small objects, with sizes ranging from nanometers to micrometers, using the radiation
force. This phenomenon was discovered by Arthur Ashkin in 1970. Optical Tweezers
technology has been used in numerous directions, namely in the manipulation and sorting of
small particles, or as a force sensor. In addition, Optical Tweezers are usually useful in the
fields of biology, biochemistry and biophysics, where they are used to manipulate and
interrogate individual cells or even molecules. The use of Optical Tweezers typically depends of
bulk optical system, including conventional light microscopes combined with objectives with high
numerical apertures. However, these types of setups are frequently expensive and also take up
a lot of space. Nevertheless, Optical Tweezers systems can also be realized using optical fibers
or other guided wave platforms, which reveal relevant advantages as low cost, miniaturized
setups and flexibility. Optofluidics is a multidisciplinary area, which integrates both optics and
fluids in the same platform, and which has been developed in order to provide techniques for
sensing and analysis of biological samples. Additionally, these setups are designed to work in
the micro scale, what makes them very useful to study and characterize single cells. However,
optofluidic setups lack ability in the manipulation of particles/cells. Therefore, they become a
much powerful tool when combined with fiber optical tweezers systems, allowing accurate
sensing, and characterization of micron sized bodies. My PhD research aims to develop low
cost optoelectronic systems for manipulation and monitoring of single cells. Therefore, this work
addresses the problem of manipulating and sensing of small particles using both optical
tweezers and optofluidic devices. Concerning to optical tweezers, a simulation program of the
optical trapping forces will be presented, and also some results will be discussed. In addition, an
implementation of fiber optical tweezers will be briefly presented. Furthermore, an optofluidic
chip for red blood cell study (refractometric and spectroscopic measurements) will be
presented. Further improvements of the setup will allow both manipulation and characterization
of cells in the same platform.
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Radoslaw Sadowski
Medical Physics and Applied Radiation Sciences, McMaster University, Canada
[email protected]
Quantitative Optical Molecular Imaging
Bioluminescence and fluorescence tomography are used in optical molecular imaging to
visualize tumours in small animals. Cone-Beam Computed Tomography (CBCT) integrated with
an optical imaging system is described to perform 3D optical molecular imaging on optical
phantoms. The work attempts to co-register CBCT images with optical images using a
projective transformation to perform 3D optical tomography.
Emanuel Saerchen
Ophthalmic Laser Surgery, Rowiak GmbH, Germany
[email protected]
Physical Investigation of Self-Induced Laser Focus Displacement during
Photodisruption with Ultrashort Pulses
The usage of lasers in medicine gains more and more popularity in public. For instance, the
huge advantage of femtosecond-laser-surgery is dominated by the precise cutting technique at
the focal position with limited thermal influence of surrounding tissue. The cutting process is
achieved by laser-induced photodisruption to create micro-cavities. This principle was already
extensively investigated for single pulses. However, several phenomena of fs-laser processing
are still not entirely understood, when using multiple pulses with variable parameters. Focusing
the laser inside the material and scanning the laser spot for planar dissection results in a
periodic, step-like structure oriented in the axial direction of the laser beam with variable step
height up to 100 µm. The influence of laser parameters as pulse energy, pulse-to-pulse
distance, numerical aperture and repetition rate was investigated for single pulses, applied lines
and planes. Therefore, the laser was focused inside the copolymer Hydroxy-Ethyl-Methacrylat
(HEMA). The resulted height of the step-like structures was measured for evaluation.
Apparently, the parameter pulse-to-pulse distance has the major effect on self-induced focus
displacement. A decrease of the pulse-to-pulse distance below 50 nanometers (nm) resulted in
an exponential increase of step height on pulse distance up to 40 µm. Furthermore, increasing
pulse energy enhances the effect. For constant pulse distance of 0.13 nm the step height and
width increases from ca. 7 to 16 µm with increasing laser pulse energy from 80 to 240 nJ. The
size of step height and width increases consistently. Those periodic structures are unwanted for
any application in the field of precise laser cutting. Since the focus displacement occurs for two
neighbored laser lines too, the effect is no pulse-to-pulse interaction. A local refractive index
change around the laser focal spot is assumed as micro-scale reason for the focal displacement
of those macroscopic unwanted structures. Digital-holographic microscopy was used for relative
refractive index measurement of single pulse fs-laser application. A single applied femtosecond
laser pulse with 210 nJ pulse energy revealed a central relative refractive index change of 0.005
in HEMA. The measured refractive index change per pulses was also used for numerical ray
tracing simulation with Zemax. A microscopic focus displacement caused by a single local
refractive index profile was shown. First clues for microscopic investigation of macroscopic
unintended structures were revealed. The experiments indicate the importance to gather the
triggering parameters to suppress this phenomenon. Since, fs-laser treatment should remain a
fast and precise treatment.
Eric Seifert
Medical Lasercenter Lübeck, Medical Lasercenter Lübeck, Germany
[email protected]
Automatic Irradiation Control By An Optical Feedback Technique For Selective
Retina Treatment (SRT) In A Rabbit Model
Purpose: Selective retina therapy (SRT) is a laser method which targets the retinal pigment
epithelium (RPE) with repetitive microsecond laser pulses, while causing no thermal damage to
the neural retina, the photoreceptors as well as the chorioidea. Microbubbles arising at the
melanosomes inside the RPE cells are the origin of selective RPE cell death. This makes SRT
to a potential treatment for several retinal diseases. Beneficial effects on Central Serous
Retinopathy (CSR) and diabetic macula edema (DME) have already been shown. The
pigmentation variation of the RPE makes the treatment procedure impossible without additional
feedback techniques, because the required laser pulse energy to achieve selective lesions
varies with it. Furthermore, there is just a low therapeutic window of two times the laser pulse
energy of angiographic visibility until the SRT loses its selectivity. This is why dosimetrycomponents designed to detect signals correlated with RPE-cell damage are a mandatory
element in SRT devices. Optical techniques to detect micro bubble formation based on the
evaluation off the backscattered light (“reflectometry”) just need to analyze one single pulse to
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accomplish this. This makes it possible to build an SRT system able to increase the pulse
energy with every pulse and to turn off the laser irradiation automatically (“automatic
dosimetry”). Our purpose was to evaluate the safety, selectivity and healing of the retinal lesions
by using an automatic dosimetry technique for SRT based on the evaluation of reflected light
during irradiation.
Methods: Ten eyes of Chinchilla Bastard rabbits were treated with SRT using a Q-switched NdYLF laser (wavelength: 527 nm, pulse duration: 1.7 µs, repetition rate: 100Hz, max. number of
pulses in a burst: 30, retinal spot diameter: 120µm, typical maximum energy: 85µJ to 100µJ).
The pulse energy has been increased with every pulse within a burst by 3% of the maximum
energy. The signals are extracted from the backscattered light and analyzed by an algorithm
which calculates a final value for each pulse within 2ms. In the experimental treatments of the
rabbit eyes the laser irradiation has been ceased as soon as the reflectometry value was larger
than the chosen threshold value.
Results: Typical fundus photographs obtained 1 hour after irradiation showed that all lesions
produced by SRT with automatic turnoffs were not visible ophthalmoscopically at all energy
levels used. The lesions could be detected only by angiography. Fundus examination showed
focal pigmented areas due to healing status and no fluorescein leakage after 7 days. OCT
images revealed an inner retina continuity. By 3 weeks, histology showed selective RPE
damage sparing photoreceptor continuity without inner retinal effects and focally proliferated.
Conclusions: SRT controlled by an automatic dosimetry system based on analyzing reflected
light to detect micro bubble formation achieves selective targeting of the RPE. Reflectometry is
a reliable noncontact technique to monitor RPE disintegration and can serve as real-time
dosimetry control during SRT.
Kristian J. Sexton
Thayer School of Engineering, Dartmouth College, United States
[email protected]
Pulsed Light Excitation And Image Gating For Fluorescence Guided Surgery In
Normal Lighting Conditions
Optical imaging may prove to have its greatest clinical impact in the area of fluorescence guided
surgery. In order for this impact to be realized fluorescence guided surgical systems must both
prove efficacy and be integrated into the operating room. Outlined is a surgical imaging system
that utilizes the gating capabilities of an intensified CCD as well as high powered pulsed lights
to allow for imaging in normal room light. This system also has the potential to allow real time
spectral imaging due to the fast rate of acquisition. Together these two features may provide a
superior technology moving forward in this field.
Hendrik Spahr
Institute of Biomedical Optics, University of LÜbeck, Germany
[email protected]
Imaging Temperature Distributions of Laser Irradiated Tissue via Phase
Sensitive Optical Coherence Tomography
The thermal processes taking place during retinal photocoagulation treatment can be visualized
via phase sensitive OCT with high lateral as well as temporal resolution. We demonstrate that
the observed effects are caused by thermal expansions and that the underlying temperature
distribution can be estimated from the recorded OCT data. Therefore the reversible thermal
expansion of laser irradiated multilayered silicone phantoms is investigated. The silicone
samples are irradiated by a photocoagulation laser (ZEISS Visulas 532s) and the thermal
expansion is measured by a commercially available high speed Fourier domain OCT system
(Hyperion Spectral Radar, Thorlabs GmbH, Munich, Germany). A comparison between the
measured temperature distribution (and its temporal evolution) to Monte Carlo simulations of the
photon propagation inside the sample and analytical solutions of the heat equation show good
accordance. Also in measurements of retinal photocoagulation in ex vivo porcine eyes and in
vivo rabbit eyes, that are done using the above mentioned OCT system and photocoagulation
laser as well as a setup for optoacoustical temperature measurements attached to a laser
slitlamp, the temperature distribution can be visualized by measuring the thermal expansion. As
one would expect, the highest temperature increase is observed in the retinal pigment
epithelium (RPE), that absorbs the biggest part of the incoming laser power. The temporal
evolution of this expansion is strongly correlated to the optoacoustically measured temperature
increase. For a quantitative comparison, first of all the thermal expansion coefficients and the
temperature dependence of the refractive index for retinal tissue have to be determined. This
can also be done very accurately via phase sensitive OCT by imaging the optical and
geometrical thickness of a tissue sample in the temperature range of interest. Between 30°C
and 40°C the thermal expansion of retinal tissue is reversible and about three times larger than
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the one of water. At higher temperatures irreversible and highly anisotropic tissue alterations
occur, that cause a strong increase of the thermal expansion. These effects can possibly be
used for an OCT based real time dosimetry system for retinal photocoagulation treatment. For
in vivo measurements a robust motion correction is necessary. It is based on a separation of
physiological global movement of the retina due to breathing and heartbeat from the differential
movement inside the retina due to thermal expansion. In in vivo studies on rabbit eyes,
physiological reactions to the laser irradiation are observed, that did not occur in ex vivo porcine
eyes. Therefore, the investigations will soon be continued in a clinical study on
photocoagulation in human eyes.
Jacob Staley
MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, The
Netherlands
[email protected]
Photoacoustic Contrast Agents as Acoustic Time-Reversal Sources For
Targeted Acousto-Optics
To overcome speed of sound aberrations of the acoustic focus in acousto-optic imaging we
utilize the time-reversal invariance characteristics of the lossless wave equation, extending
time-reversal acoustics (TRA) to time-reversal photoacoustics (TRPA) for targeted
measurements.
Paulien L. Stegehuis
Surgery and Radiology, Leiden University Medical Center, The Netherlands
[email protected]
Discrimination of Benign And Malignant Human Breast Tissue Using Full Field
Optical Coherence Tomography
Introduction: Despite many technological developments, accurate detection and imaging of
human tumors intraoperative remains difficult and time consuming. During surgery it is
extremely important that borders of the excised specimen do not contain tumor cells, since
these positive margins are associated with an increased risk of local recurrence of the primary
tumor. To remove the whole tumor and achieve clear margins, surgeons still rely mainly on
visual assessment and palpation. In breast conserving surgery (BCS), this results in positive
margins found in 20-40% of patients.
Full field OCT: We propose an optical coherence tomography (OCT) principle which is able to
image with microscopic resolution tissue specimens intraoperative: full field OCT (FF-OCT).
OCT detects back-reflected light in a tissue sample; an interference pattern arises when light
returning from the sample and an oscillating reference mirror have traveled the same distance.
This allows determination of the depth from which the light is reflected in the tissue sample.
Areas in the sample exhibiting great reflectivity will consequently generate higher interference,
creating a larger signal than areas with lower reflectivity. The combined signal is collected by
the detector, and an OCT image, typically cross-sectional, can be created. FF-OCT is different
from conventional OCT in several aspects. First, en face images are made instead of crosssectional images. Moreover, a field of view of 0.8 x 0.8 mm is illuminated and reconstructed
without need for scanning, and larger fields are obtained by stitching the images automatically.
Second, with FF-OCT images with a high resolution of ~ 1 µm in 3D, an isotropic resolution is
achieved.
Margin assessment and future applications: With its high resolution and non-invasive, nondestructive nature and because tissue preparation, coloring and staining is not needed, we think
FF-OCT will be a good technique to examine tissue specimens. Currently, the FF-OCT device
used (light-CTTM device, LLTech, Paris, France) is not yet fast enough for intraoperative
purposes, and also the measurements of the scanned tissue are limited. However, when these
issues are resolved, this technique has the potential to become a powerful tool to substantially
improve the surgical treatment of cancer patients, enabling direct feedback to surgeons on the
excised tissue. Because of the great clinical relevance of resection margins in BCS, in the first
clinical study, we will focus on breast margin assessment. If successful, this technique can
easily be used for the complete resection of other tumor types.
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Idan Steinberg
Faculty of Engineering; Department of Biomedical Engineering, Tel Aviv University, Israel
[email protected]
Frequency Domain Photoacoustic Phase Measurements of the Acoustic Modes
in Bone for the Early Detection and Diagnosis of Osteoporosis
Osteoporosis is a major public health problem worldwide. It is extremely widespread, has a
catastrophic impact on patients life expectancy and quality and has an overwhelming related
healthcare costs. Early diagnosis of patients at risk of fracture, but who have not yet sustained a
fracture, can substantially reduce the healthcare costs and improve patient's lives. The risk of
osteoporotic fracture depends not only on the bone mineral density, measured in clinical
practice using the Dual-energy X-ray Absorptiometry (DXA) method, but also on the bone
microstructure and functional status. In addition DXA is costly and involves ionizing radiation.
Attempts to develop alternatives to DXA using quantitative ultrasound technology achieved
limited success due to their insensitivity to bone functionality. Pure optical method, fail as well
due to tissue scattering. Thus, there is an unmet need for a non-invasive, non-ionizing and costeffective method to detect the disease based on its pathological expressions. We propose a
hybrid multispectral photoacoustic measurement that has great advantages over pure ultrasonic
or optical methods as it allows deducing: a) bone functionality from the bone absorption
spectrum and b) bone resistance to fracture from the characteristics of the ultrasound
propagation. Here we describe a single experiment to demonstrate the feasibly of such
photoacoustic method to differentiate between naïve and demineralized bone. To this end, a
single wavelength, phase measurements were performed on fowl bone sample. We used
amplitude modulated, fiber coupled laser diode at 830 nm to excite acoustic signals in a distal
location along the bone. The excitation position is scanned along the bone while the acoustic
response is measured proximally. As phase accumulation is highly non-linear with the changes
in distance, a multimodal phasor based model is presented to account for such behavior. We
demonstrate that frequency domain, multimodal phase analysis can yield the phase velocities
and relative amplitude of two significant acoustic modes. This process was repeated for multiple
acoustic frequencies. Theoretical results are shown to predict experimental results very well.
However, there is great variability in the esimated speed from freqncy to frequncy. This can be
explained by both numerical inaccuracies due to the fitting of a complicated model as well as
the extreme dispersion as predicted by theoretical models. The bone is then soaked in mild
acetic acid to simulate the effect of osteoporosis and all measurements were performed again
for comparison. It is shown that bone demineralization is accompanied by significant changes in
the speeds of the acoustic mode and in their relative amplitude. To conclude, Frequency
domain photoacoustic measurements of bone parameters were demonstrated over multiple
acoustic frequencies. We have shown that the measurements of phase of the photoacoustic
signal in the modulation frequency revels the existence of fast and slow modes which propagate
in the bone. The speed of each mode and their relative amplitude convey biomechanical
information regarding the bone strength. It was shown that such method has a potential to
provide important information regarding the bone status.
Fatma Tümer
Russell Division, Max Planck Institute for the Science of Light, Germany
[email protected]
Long-Distance laser Propulsion And Deformation Monitoring of Cells In HollowCore Photonic Crystal Fiber
In optical tweezers, radiation forces near the focus of a laser beam allow trapping and
micromanipulation of particles and cells. In hollow-core photonic crystal fibre (HC-PCF), light
propagates in a single, non-diffracting optical mode, allowing particles to be trapped laterally at
the center of the core. The radiation forces are highly uniform along the fibre, enabling guidance
and propulsion of particles over long distances. In the past years, our group has shown that µmsized particles can be controllably launched into and propelled by the fundamental mode in both
fluid-and air-filled HC-PCF. This system may have important applications in biomedicine, as it
makes possible the laser propulsion of cells over distances of 10s of cm through a liquid-filled
HC-PCF. In these recent experiments, individual red blood cells were optically trapped at the
center of the core, several microns away from the glass interface, thus eliminating adherence
effects and external perturbations. The velocity of the cells was monitored by Doppler
velocimetry, and dynamic changes in velocity at constant optical powers up to 350 mW
indicated strong stress-induced changes in the cell morphology. In future work we plan to
integrate HC-PCFs into microfluidic circuits, allowing high-throughput biomechanics
experiments. This will allow us to develop biomechanical assays capable of measuring the
mechanical properties at the single-cell level. Such assays would allow detailed measurements
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of the changes in physical properties during cellular processes such as differentiation,
progression of disease and oncogenics.
Peter Van Es
BioMedical Photonic Imaging, University of Twente, The Netherlands
[email protected]
Photoacoustic Imaging of Human and Murine Joints: Towards Assessment of
Rheumatoid Arthritis
Rheumatoid arthritis is a chronic and progressive disease that affects about 1% of the
population. Inflammation and proliferation of synovial tissue leads to degradation of the cartilage
and subchondral bone. Hypoxia is suggested to contribute significantly to the disease
progression and maintenance by promoting angiogenesis. Angiogenesis results in a significant
increase in the blood vessels density in and around the synovial membrane. This makes
Photoacoustic imaging is a good candidate for the assessment of rheumatoid arthritis because
the hemoglobin, which is abundantly present in the inflamed synovial membrane, is an intrinsic
chromophore that highly absorbs the visible and near-infrared light that is typically used for
photoacoustic imaging. Currently two projects have started. The first is on photoacoustic joint
imaging on healthy finger joints with a reflection-mode geometry with the goal to assess
inflammatory arthritis. The second project focusses on ex-vivo imaging of mouse knees in a CTmode geometry with top illumination. Imaging in human subjects still proves difficult without
more sophisticated reconstruction algorithms because acoustic reflections from tendons and
bone obscure the signals of the synovial membrane. Imaging mouse knees seems to be
promising in detecting blood vessels around the knee joint but the imaging device and
reconstruction algorithms should be improved first.
Luka Vidovic
Complex Matter, Jozef Stefan Institute, Slovenia
[email protected]
Prediction of the Maximal Safe Laser Radiant Exposure on an Individual Patient
Basis Based on Photothermal Temperature Profiling
Efficancy of several laser procedures in dermatology and aesthetic surgery is compromised by
the risk of permanent side effects, such as dyspigmentation or scarring. Strong absorption in
epidermal melanin can cause overheating of superficial layer of skin and hence limits applied
radiant exposure in the treatment. Although the concentration and distribution of melanin in skin
exhibit large inter- and intra-patient variation, the applied laser radiant exposure is currently
selected based on subjective visual impression and expert opinion of the treating physician. Our
motivation is to predict the maximal safe radiant exposure on an individual patient basis based
on photothermal temperature profiling. Pulsed photothermal radiometry (PPTR) allows
noninvasive determination of laser-induced temperature profiles in strongly scattering layered
samples (e.g. skin). PPTR measures transient change of IR emission from tissue following the
short laser pulse. The temperature depth profiles can then be reconstructed by solving the
inverse problem of heat diffusion and blackbody emission using a custom iterative algorithm.
We show that such information can be used to derive rather accurate predictions of the maximal
safe radiant exposure (Hmax) on an individual patient basis. We use a dedicated numerical
model of heat transfer and protein denaturation dynamics to compute the predicted level of
epidermal thermal damage (Ω) at the applied radiant exposure. Finally, we establish a
quantitative relationship between the predicted thermal damage (Ω) and clinically observed
severity of injury in a former clinical study of Verkruysse et al. of laser injuries induced by 3 ms
laser pulses at 755 nm. The quality of correlation enables us to define the thermal damage
threshold value and thus objective determination of the maximal safe radiant exposure (Hmax)
on individual patient basis. This approach may increase safety and efficiency of dermatologic
laser treatments in the near future.
Kari V. Vienola
Rotterdam Ophthalmic Institute, Rotterdam Eye Hospital, The Netherlands
[email protected]
Imaging of Optic Nerve Head With Motion Corrected OCT Using Tracking SLO
Fixational eye movements remain a major cause of artifacts in optical coherence tomography
(OCT) images despite the increases in acquisition speeds. One approach to eliminate the eye
motion is to stabilize the ophthalmic imaging system in real-time. In our research project, an
experimental OCT instrument was combined with an active image-based eye tracking system to
compensate for eye motion in OCT imaging. The OCT instrument was a phase-stabilized optical
frequency domain imaging (OFDI) system operating at a center wavelength of 1040 nm and the
eye tracker was an 840 nm scanning laser ophthalmoscope (SLO). Retinal tracking was
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performed using real-time analysis of the distortions within SLO frames. OFDI had axial
resolution of 4.8 µm (6.5 µm in air) and the theoretical spot-size on the retina was calculated to
be 13.7 µm. Eye motion was reported at a rate of 960 Hz and motion signals were inverted to
correction signals and used to keep the OCT scanning grid locked on the same retinal target
throughout the measurement. In the case of a tracking lock failure (e.g. blink or large saccade),
the tracker signaled the OFDI system to rescan corrupted B-scans immediately stepping back
10 B-scans and holding the position until signal was valid again. The achieved tracking
bandwidth was 32 Hz due to an internal time lag of the hardware. The combined system
allowed visualization of the optic nerve head (ONH) and the lamina cribrosa with negligible
artifacts from eye motion. The measured residual motion in the OCT B-scans was 0.32 minutes
of arc (~1.6 µm) in a human eye, which is in a good agreement with the residual motion
measured from the model eye. Four volumes from the same location were registered together
to visualize the different depths of the retina with a high signal-to-noise ratio. The pore structure
was clearly visible up to 430 µm from the bottom of the ONH cup. Tracking OCT can be
advantageous for routine clinical use, but also for patients who have weakened fixation
capabilities due to a disease, age or recent trauma in the eye.
Naja Villadsen
Department of Chemistry, Aarhus University, Denmark
[email protected]
Laser Manipulation of Optically Trapped Objects
We present two specific examples where optically trapped particles are manipulated with a
femtosecond (fs) and a nanosecond (ns) laser, respectively. The ns laser has a low repetition
rate and will result in a kicking movement away from the centre of the trap, as opposed to the fs
laser which has a high repetition rate and will result in a pushing movement. In both applications
the dislocation is observed along the direction of pushing while a synchronised observation of
the intensity is made. The results reveal viscoelastic characteristics of the media. The
experiments are made with a unique counter propagating optical trap [1]. Central for the setup
are two objectives of relatively low NA, giving a large working distance. The large working
distance enables manipulation and detection orthogonal to the trapping beams. High speed
three dimensional detection occurs through two CMOS cameras and a newly installed position
sensitive detector (PSD), which increases the time resolution from 1 kHz to 250 kHz. For the fs
pushing - because of viscoelastic effects of the fluid surrounding the particle, a time delay will
appear between the pushing force and the resulting position of the particle. The intensity of the
pushing laser is manipulated to get a sinusoidal force, for which the time delay can be analysed
either through Fourier analysis or through cross correlation. In both cases the time delay fits the
theoretical prediction for a sinusoidal force, confirming that the pushing force of a fs laser with
high repetition rate resembles a CW-laser source. Furthermore, knowing the time delay, one
can post-eliminate the Brownian motion, thus enabling a more precise determination of the
relationship between the power of the pushing laser and the resulting displacement of the
trapped particle. Now for the ns kicking. By synchronizing the kick to the detection system and
by repetition of the kick, the Brownian nature of the particle can once again be post-eliminated
to reveal the underlying deterministic dynamic [2]. For the ns laser with low repletion rate it is
the relaxation after a kick that appears. With the new PSD the time resolution can be improved we hope to get a time resolution below the impulse relaxation time for our system to get an even
closer look at the relaxation. A high power trap mode and the possibility of side-view
observations of trapped objects with cameras, enables viscoelastic observation of these trapped
objects. Among these, observations of cell stretching reveal cellular characteristics, with the
application of detecting deceased cells. As the setup is best suited for objects larger than three
microns it is ideal for handling cell size objects. All of our current experiments have application
within microrheology with the focus on either the trapping media or the trapped objects.
[1] T. B. Lindballe, M. V. Kristensen, et al. , Journal of the European Optical Society-Rapid
Publications 6 (2011).
[2] T. B. Lindballe, et al. , Opt. Express 21, 1986 (2013).
Yolanda Villanueva
MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, The
Netherlands
[email protected]
Determination of The Grüneisen Parameter of Absorbing Liquids Using
Photoacoustic Measurements In An Integrating Sphere
A method for determining the Grüneisen parameter of absorbing liquids is presented. An
integrating sphere is used as a platform for accurate and simultaneous detection of optical and
photoacoustic signals. Calibration of the setup is done using aqueous ink solutions. The method
is validated using human blood sample.
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Chiara Vitelli
Center of Life Nanoscience at La Sapienza, Istituto Italiano di Tecnologia, Italy
[email protected]
Realization of A Micro-Optical Coherence Tomography (mOCT) Setup For Cell
Imaging With Micron Resolution In Tissues
Our project is devoted to the realization of a micro-OCT (ƒÝOCT) setup for the study of cellular
and subcellular tissues structures, achieved by the use of a supercontinuum laser source, able
to provide bandwidth of 250nm at 800nm and 1300nm wavelength, corresponding to an axial
resolution equal to 1.2ƒÝm and 3ƒÝm in air, respectively. A first application will be related to
cardiovascular research, in particular we will address the identification of endothelial cells lining
coronary arteries, whose discrimination is important on the one hand for the identification of
artheriosclerotic plaques, on the other hand is crucial for the analysis of stent implantation.
Daniel Wangpraseurt
Department of Environmental Sciences, University of Technology, Sydney, Australia
[email protected]
Coral Tissue Optics
Light quantity and quality are among the most important factors determining the physiology and
stress response of symbiotic corals. Yet, almost nothing is known about the light field that coral
photosymbionts experience within their coral host, and the basic optical properties of coral
tissue are unknown. We used fibre optic microsensor for scalar irradiance and field radiance to
directly measure vertical and lateral light gradients within coral tissues. Our results revealed the
presence of steep light gradients with PAR (photosynthetically available radiation) decreasing
by about one order of magnitude from the tissue surface to the coral skeleton. Upper coral
tissue layers are characterised by scalar irradiance maxima of ~200% of the incident irradiance,
whilst deeper tissue layers, e.g. ~1000 µm into aboral polyp tissues, harbor optical microniches,
where only ~10% of the incident irradiance remains. When corals were illuminated with a laser
beam (636 nm) intense scattering of both tissue and skeleton was observed. Scalar irradiance
measurements within the coral tissue showed that light was laterally transported up to 15–20
mm away from the beam. We conclude that the optical microenvironment of corals exhibits
strong lateral and vertical gradients of scalar irradiance, which are affected by both tissue and
skeleton optical properties. Our results imply that populations of photosymbionts inhabit a
strongly heterogeneous light environment and highlight the presence of different optical
microniches in corals; an important finding for understanding the photobiology and stress
response of coral symbionts.
Muhammad Nur Salihin Yusoff
School of Physics, Universiti Sains Malaysia (USM), Malaysia
[email protected]
Optical Reflectance And Morphology of Poly(Vinyl Alcohol) Cryogel Tailored By
Rock Salt
Poly(vinyl alcohol) (PVA) is widely used as tissue-mimicking phantom in magnetic resonance
imaging (MRI) and ultrasound studies by cross-linking of its monomer. Freeze-thawing is one of
the cross-linking techniques in which the polymer obtained is called PVA cryogel (PVA-C). The
chemical and mechanical properties of PVA-C have been extensively studied. However, in
biomedical optics it is still new and not much explored yet. One of the challenges of using PVAC in optical studies is its apparent whiteness, which gives scattering effect. In this study we
evaluate to what extent a rock salt with 2.5 %, 5 % and 7.5 % concentrations can alter the
optical reflectance and morphology of PVA-C. Besides that, the effect of PVA-water ratios of 11, 1-2 and 1-3 (without rock salt) on PVA-C characteristics was also analysed. The optical
reflectance of PVA-C samples across 380 – 780 nm of wavelengths was measured using Jaz
Spectrometer equipped with HL 2000 Tungsten Halogen light source (Ocean Optics). Our
results show that, adding rock salt to PVA can alter the optical reflectance of PVA-C and gives
an advantage of a smoother structure. However, the amount of rock salt is only limited to
concentration below 7.5 %. At this concentration, immediate coagulation occurred during the
stirring process forming a PVA hydrogel. While different concentrations of rock salt below this
limit did not give much variation on optical reflectance of PVA-C. Besides that, using different
PVA-water ratio during preparation can also alter the optical reflectance of PVA-C but its effect
is not consistent across the wavelengths. The different of PVA-water ratios have no significant
effects on PVA-C structure obtained.
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Behrooz Zabihian
Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Austria
[email protected]
Towards Multimodal all Optical Detection Photoacoustic Tomography and
Swept Source OCT
Optical Coherence tomography (OCT) is a well establish noninvasive biomedical imaging
modality that is based on back scattered laser light incident on a sample. Since the introduction
of the Fourier Domain OCT (FD-OCT), performance of OCT imaging systems is constantly
improving. Newer sources with higher speed and better sensitivity are realized. With OCT one
could obtain depth resolved morphological information of the sample under study with
penetration depth of 1-2 mm. Swept Source OCT (SS-OCT) uses a coherent narrow band light
source that sweeps wavelengths across a certain bandwidth. On the other hand, Photoacoustic
Imaging (PAI) combines optical absorption contrast with ultrasonic spatial resolution. PAI is
based on the detection of ultrasound waves produced by thermoelastic expansion of absorbers.
In this technique, short pulsed laser beam is used to excite the sample so that the endogenous
chromophores selectively absorb the laser energy and therefore cause the thermoelastic
expansion. Photoacoustic Tomography is one approach to PAI in which the sample is
illuminated light in full-field manner.
6th International Graduate Summer School Biophotonics ‘13
8-15 June 2013 • Island of Ven • Sweden
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