Ton van Leeuwen graduated in physics at the University of Amsterdam in 1989. After his PhD and post doc at the Lab. for Exp. Cardiology at the UMC Utrecht and an ICIN fellowship at CWRU (Cleveland), he became staff member of the Laser Center at the AMC. In 2001, Ton was appointed as professor in Clinical Application of Biomedical Optics at the University of Twente, at which he headed the Biomedical Optics group from 2003 - 2008. In 2008 he was appointed as professor in Biomedical Photonics and head of the new BME & Physics department at the Academic Medical Center of the University of Amsterdam. In 2009, he was appointed as full professor in Biomedical Physics.
Current research focuses on the physics of the interaction of light with tissue, and to use that knowledge for the development, introduction and clinical evaluation of (newly developed) optical imaging techniques for gathering quantitative functional and molecular information of tissue.
The research is structured along the following research lines:
The use of the intrinsic contrast of OCT is explored for the in vivo staging and grading of tumors;
Novel OCT signal analysis to determine blood velocity profiles, perfusion and diffusion and relate this information to pathology;
The integration and combination of different imaging technologies (e.g. OCT and CT, (Raman) spectroscopy and OCT);
Hyper-spectral monitoring and imaging to assess the concentration of blood and blood derivatives as bilirubin, met-, deoxy- and oxyhemoglobin in the skin (for age determination of bruises) and hemichrome (for ex-vivo blood-stain analysis);
New optical techniques for the detection of microvesicles in blood plasm as a "liquid biopsy";
Novel photonic devices, based on minimally invasive designs and integrated optics, which are suitable for small and dedicated monitoring and imaging devices in the clinic ("cleanroom to clinic")
Current research focuses on the physics of the interaction of light with tissue, and to use that knowledge for the development, introduction and clinical evaluation of (newly developed) optical imaging techniques for gathering quantitative functional and molecular information of tissue.
The research is structured along the following research lines:
The use of the intrinsic contrast of OCT is explored for the in vivo staging and grading of tumors;
Novel OCT signal analysis to determine blood velocity profiles, perfusion and diffusion and relate this information to pathology;
The integration and combination of different imaging technologies (e.g. OCT and CT, (Raman) spectroscopy and OCT);
Hyper-spectral monitoring and imaging to assess the concentration of blood and blood derivatives as bilirubin, met-, deoxy- and oxyhemoglobin in the skin (for age determination of bruises) and hemichrome (for ex-vivo blood-stain analysis);
New optical techniques for the detection of microvesicles in blood plasm as a "liquid biopsy";
Novel photonic devices, based on minimally invasive designs and integrated optics, which are suitable for small and dedicated monitoring and imaging devices in the clinic ("cleanroom to clinic")
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To detect small-scale changes in tissue with optical techniques, small sampling volumes are required. Single fiber reflectance (SFR) spectroscopy has a sampling depth of a few hundred micrometers. SFR spectroscopy uses a single fiber to emit and collect light. The only available model to determine optical properties with SFR spectroscopy was derived for tissues with modified Henyey–Greenstein phase functions. Previously, we demonstrated that this model is inadequate for other tissue phase functions. We develop a model to relate SFR measurements to scattering properties for a range of phase functions, in the absence of absorption. Since the source and detector overlap, the reflectance cannot be accurately described by diffusion theory alone: SFR measurements are subdiffuse. Therefore, we describe the reflectance as a combination of a diffuse and a semiballistic component. We use the model of Farrell et al. for the diffuse component, solved for an overlapping source and detector fiber. For the semiballistic component, we derive a new parameter,
When analyzing multidiameter single-fiber reflectance (MDSFR) spectra, the inhomogeneous distribution of melanin pigments in skin tissue is usually not accounted for. Especially in heavily pigmented skins, this can result in bad fits and biased estimation of tissue optical properties. A model is introduced to account for the inhomogeneous distribution of melanin pigments in skin tissue.
We demonstrated the feasibility of hyperspectral imaging of the crime scene to detect and identify blood stains remotely. Blood stains outside the human body comprise the main chromophores oxy-hemoglobin, methemoglobin and hemichrome. Consequently, the reflectance spectra of blood stains are influenced by the composite of the optical properties of the individual chromophores and the substrate. Using the coefficient of determination between a non-linear least squares multi-component fit and the measured spectra blood stains were successfully distinguished from other substances visually resembling blood (e.g. ketchup, red wine and lip stick) with a sensitivity of 100 % and a specificity of 85 %. The practical applicability of this technique was demonstrated at a mock crime scene, where blood stains were successfully identified automatically.
Photoacoustic imaging of blood vessels with a double-ring sensor featuring a narrow angular aperture
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You will have access to both the presentation and article (if available).
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