IJS KOLOKVIJ, 18. junij 2008, prof. dr. Martin Frenz

[Andreja Berglez]

Vabim vas na 22. predavanje iz sklopa "Kolokviji na IJS" v letu 2007/08, ki
bo v sredo, 18. junija 2008, ob 13:00 uri v Veliki predavalnici Instituta
»Jožef Stefan« na Jamovi cesti 39 v Ljubljani. Napovednik predavanja najdete
tudi na naslovu http://www.ijs.si/ijsw/Koledar_prireditev, posnetke
preteklih predavanj pa na http://videolectures.net/kolokviji_ijs. 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~



prof. dr. Martin Frenz 

Institute of Applied Physics, University of Bern, Switzerland

Optoakustična tomografija, obetavna tehnika za neinvazivno diagnosticiranje
raka

Z združitvijo kvalitet optičnih in ultrazvočnih metod omogoča opto¬akustika
velik optični kontrast brez upada prostorske ločljivosti v optično sipajočih
bioloških tkivih. V biomedicinski optoakustiki obsevamo tkivo s kratkimi
sunki laserske svetlobe. Kljub sipanju vpadle svetlobe se selektivno
segrejejo le absorbirajoče strukture v notranjosti organa (npr. krvne žile).
Kontrast v sliki tako zagotavljajo velike razlike v absorpcijskih lastnostih
tkivnih kromoforov, bodisi endogenih (npr. oksi- in deoksihemoglobin) ali
vnešenih od zunaj (barvila, nanodelci ali kvantne pike). Hitro nehomogeno
gretje snovi povzroči nastanek tlačnih valov (termo-elastični pojav), ki jih
zaznamo s primernim ultrazvočnim detektorjem na površini vzorca. Pri
enodimenzionalnih optoakustičnih meritvah so amplituda in oblika vala ter
časovni zamik med laserskim obsevanjem in njegovo zaznavo povezani z močjo,
dimenzijo ter globino akustičnega izvora. S sistematičnim premikanjem
detektorja (skeniranjem) lahko iz meritev rekonstruiramo tri-dimenzionalno
sliko podpovršinskih struktur. V predavanju bo podan pregled zmožnosti in
omejitev optoakustičnega slikanja v bioloških tkivih, predvsem z vidika
kontrasta in prostorske ločljivosti. 

Predavanje bo v angleščini.

Lepo vabljeni!

***

 

We would like to invite you to 22nd lecture of the "Kolokvij na IJS" in the
school year 2007/08. The lecture will be held on Wednesday, June 18, 2008,
at 1 pm at JSI main lecture hall, Jamova 39, Ljubljana. The abstract of the
lecture can be found on website:
<http://www.ijs.si/ijsw/Koledar_prireditev>
http://www.ijs.si/ijsw/Koledar_prireditev, the previous recorded lectures
can be found on website:  <http://videolectures.net/kolokviji_ijs>
http://videolectures.net/kolokviji_ijs. 

********************************************



prof. dr. Martin Frenz 

Institute of Applied Physics, University of Bern, Switzerland

Optoacoustic imaging, a promising technique for non-invasive diagnosis of
cancer

Optoacoustics provides high optical contrast without the handicap of poor
resolution in imaging of optically turbid tissues. In biomedical
optoacoustics, tissue is illuminated with short laser pulses. The light is
scattered inside the tissue and heats absorbing structures, such as blood
vessels, hidden deeply inside the tissue. Image contrast is therefore
provided by light absorbing chromophores, either endogenous (such as oxy- or
deoxyhemoglobin) or exogenous (e.g. dyes, nanoparticles or quantum dots). By
means of the thermoelastic effect, the inhomogeneous heating generates
pressure transients exactly representing the absorbing structures. These
acoustic transients propagate to the tissue surface and can be detected with
an appropriate ultrasound transducer. In one-dimensional optoacoustic
measurements, time delay between the laser pulse and detected pressure
transient, its amplitude and temporal profile provide information about the
location, strength and spatial dimension of the acoustic source.
Three-dimensional images can be reconstructed by scanning the transducer.
The image quality depends on a number of factors, including the irradiation
geometry and image reconstruction algorithm. The talk will give an overview
of the possibilities and limitations of optoacoustic imaging in turbid
tissues, especially in terms of image contrast and depth resolution. The
lecture will be given in English.

 

We look forward to meeting you at the “Kolokvij na IJS”!

 

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