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Lecture

Application of Scattering in OCT

In course

CH-448: Photomedicine

The most important clinical diagnostic and therapeutic applications of light will be described. In addition, this course will address the principles governing the interactions between light and biological tissues, their optical properties and basic concept ...

Description

This lecture by the instructor covers the application of light scattering in Optical Coherence Tomography (OCT) for tissue imaging. It explains the principles of OCT, including interferometry and coherence gating, to achieve high-resolution 3D imaging in highly scattering media. Various technologies used in OCT, such as time of flight and photon migration, are discussed. The lecture also delves into the concepts of coherence and interferometry, emphasizing their importance in OCT imaging. Different light sources for OCT, including continuous sources and pulsed lasers, are explored. The lecture concludes with a detailed overview of the medical applications of OCT in ophthalmology, dermatology, cardiology, and endoscopy.

Instructor

Georges Wagnières

Georges Wagnières received his diploma degree (MSc) in physics from the University of Lausanne, Switzerland, in 1986. He obtained his doctorate in science (PhD) in physics (Biomedical optics) from the Swiss Federal Institute of Technology at Lausanne (EPFL) in 1992 and did a postdoctoral work in the Wellman Laboratories of Photomedicine (Harvard Medical School), Boston, USA, from 1993 to 1994. He also obtained a Master degree in Management of Technology delivered by the Ecole des Hautes Etudes Commerciales (HEC) of Lausanne University and the EPFL in 2001. Georges Wagnières manages a research group active in the fields of: - Detection of early superficial cancers by fluorescence imaging. - Characterization of early superficial cancers by high magnification narrow band imaging. - In vivo and in vitro measurement of the vascular and tissular oxygen concentration by time-resolved luminescence spectroscopy and imaging. - Preclinical and clinical study of new photosensitizers for photodynamic therapy (PDT). - Treatment of neurodegenerative conditions (Alzheimer, Parkinson's diseases) by photobiomodulation. - Preclinical and clinical photodynamic therapy of inflammatory bowel diseases and atheroscerotic plaque. - Improvement of the selective vascular extravasation of chemotherapeutic agents by PDT. - Monitoring the light dosimetry during PDT by fluorescence spectroscopy and imaging. - Monitoring laser treatments of the retina by reflectance imaging. - Light dosimetry and tissue optical spectroscopy. - Radiometry. - Development of light delivery systems for biomedical applications. Georges Wagnières is also co-founder and was chairman of one spin-off companies: - Medlight SA, founded in July 1997, which develops, produces and commercializes light distributors for photodynamic therapy. Georges Wagnières has currently authored more than 235 papers (more than 150 in international journals with review board) and is inventor of 18 patents. He supervised 12 PhD students up to now, and currently teaches biomedical optics and photomedicine in master programs and doctoral schools. In addition, he gives the course entitled "Physique Générale I" to biology first year students registered to the Biology School of the Lausanne's University. MAIN PUBLICATIONS Please visit: https://www.epfl.ch/labs/lifmet/wagnieres/publications/

Official source

Related concepts (32)

Optical coherence tomography

Optical coherence tomography (OCT) is an imaging technique that uses low-coherence light to capture micrometer-resolution, two- and three-dimensional images from within optical scattering media (e.g., biological tissue). It is used for medical imaging and industrial nondestructive testing (NDT). Optical coherence tomography is based on low-coherence interferometry, typically employing near-infrared light. The use of relatively long wavelength light allows it to penetrate into the scattering medium.

Scattering

Scattering is a term used in physics to describe a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiation) in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection.

Raman scattering

Raman scattering or the Raman effect (ˈrɑːmən) is the inelastic scattering of photons by matter, meaning that there is both an exchange of energy and a change in the light's direction. Typically this effect involves vibrational energy being gained by a molecule as incident photons from a visible laser are shifted to lower energy. This is called normal Stokes Raman scattering. The effect is exploited by chemists and physicists to gain information about materials for a variety of purposes by performing various forms of Raman spectroscopy.

Brillouin scattering

Brillouin scattering (also known as Brillouin light scattering or BLS), named after Léon Brillouin, refers to the interaction of light with the material waves in a medium (e.g. electrostriction and magnetostriction). It is mediated by the refractive index dependence on the material properties of the medium; as described in optics, the index of refraction of a transparent material changes under deformation (compression-distension or shear-skewing).

Coherence (physics)

In physics, coherence expresses the potential for two waves to interfere. Two monochromatic beams from a single source always interfere. Physical sources are not strictly monochromatic: they may be partly coherent. Beams from different sources are mutually incoherent. When interfering, two waves add together to create a wave of greater amplitude than either one (constructive interference) or subtract from each other to create a wave of minima which may be zero (destructive interference), depending on their relative phase.

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Radiative Properties of Particulate Media: Mie Theory and Applications

Discusses the radiative properties of particulate media, focusing on Mie theory and its practical applications in analyzing light interactions with particles.

Stimulated Scatterings: Nonlinear Fibre Optics

Explores stimulated scatterings in nonlinear fibre optics, covering Brillouin and Raman scattering, spectral characteristics, and power limitations.

Diffraction and Interference: Waves Phenomena

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