1. Articles from Risto Myllylä

    1-15 of 15
    1. Glucose sensing in flowing blood and Intralipid by laser pulse time-of-flight and optical coherence tomography techniques

      Glucose sensing in flowing blood and Intralipid by laser pulse time-of-flight and optical coherence tomography techniques
      In this paper, we compare the sensitivities of the two optical modalities, laser pulse time-of-flight (TOF) and optical coherence tomography (OCT), in regard to glucose sensing within the range of 0-1000 mg/dl in flowing blood and tissue-mimicking liquid (Intralipid). We show that TOF technique is about twice more sensitive than OCT, as well for blood as for Intralipid measurements. In case of TOF technique, glucose sensitivity in Intralipid is higher than in blood. We speculate that all this is associated with longer pathlengths of detected photons in TOF than in OCT, which is confirmed by comparison with Monte Carlo ...
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    2. Multilayer tissue phantoms with embedded capillary system for OCT and DOCT imaging

      Multilayer tissue phantoms with embedded capillary system for OCT and DOCT imaging
      We report about manufacturing of fully functional capillary network embedded into the multilayer tissue phantom. Polyvinyl chloride-plastisol was used as a host transparent medium. Scattering was introduced by adding the TiO2submicron particles. OCT technique was used to characterize the manufactured phantoms and to monitor the vessels filling with different liquids.
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    3. Simulation of optical coherence tomography images by Monte Carlo modeling based on polarization vector approach

      Simulation of optical coherence tomography images by Monte Carlo modeling based on polarization vector approach
      Monte Carlo method is applied for simulation of 2D optical coherence tomography (OCT) images of skin-like model. Layer boundaries in skin model feature curved shape which agrees with physiological structure of human skin. The effect of coherence properties of probing radiation on OCT image formation and speckles in the detected OCT signal is considered. The developed model is employed for image simulation both for conventional and polarization dependent time-domain OCT modalities. Simulation of polarized OCT signal is performed using vector approach developed previously for modeling of electromagnetic field transfer in turbid media.
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    4. Optical coherence tomography as an accurate inspection and quality evaluation technique in paper industry

      Optical coherence tomography as an accurate inspection and quality evaluation technique in paper industry
      Optical coherence tomography (OCT), a technique for the noninvasive imaging of turbid media, based on low-coherence interferometry, was originally developed for the imaging of biological tissues. Since the development of the technique, most of its applications have been related to the area of biomedicine. However, from early stages, the vertical resolution of the technique has already been improved to a submicron scale. This enables new possibilities and applications. This article presents the possible applications of OCT in paper industry, where submicron or at least a resolution close to one micron is required. This requirement comes from the layered structure of ...
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    5. Optical coherence tomography as a method of quality inspection for printed electronics products

      Optical coherence tomography as a method of quality inspection for printed electronics products
      Application of time domain, ultra high resolution optical coherence tomography (UHR-OCT) in printed electronics products’ quality inspection is demonstrated. Presented study was done using experimental UHR-OCT device based on a Kerr-lens mode locked Ti:sapphire femtosecond laser, photonic crystal fibre and modified, free-space Michelson interferometer. Possibilities of the technique are demonstrated by analysis of an RF antenna—example of printed electronics products. Measurements were done with submicron axial resolution, offered by UHR-OCT system developed in our laboratory. Such high resolution is necessary due to the thickness of material layers used in printed electronics. In addition to tomography imaging, numerical results ...
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    6. Doppler OCT imaging of cytoplasm shuttle flow in Physarum polycephalum

      The Doppler optical coherence tomography technique was applied to image the oscillatory dynamics of protoplasm in the strands of the plasmodium of slime mould Physarum polycephalum. Radial contractions of the gel-like walls of the strands and the velocity distributions in the sol-like endoplasm streaming along the plasmodial strands are imaged. The motility inhibitor effect of carbon dioxide on the cytoplasm shuttle flow and strand-wall contraction is shown. The optical attenuation coefficient of cytoplasm is estimated.
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    7. Automated segmentation of the macula by optical coherence tomography

      Automated segmentation of the macula by optical coherence tomography
      This paper presents optical coherence tomography (OCT) signal intensity variation based segmentation algorithms for retinal layer identification. Its main ambition is to reduce the calculation time required by layer identification algorithms. Two algorithms, one for the identification of the internal limiting membrane (ILM) and the other for retinal pigment epithelium (RPE) identification are implemented to evaluate structural features of the retina. Using a 830 nm spectral domain OCT device, this paper demonstrates a segmentation method for the study of healthy and diseased eyes.
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    8. Automated retinal pigment epithelium identification from optical coherence tomography images

      Simple and robust method for identifying the retinal pigment epithelium (RPE) from optical coherence tomography images is demonstrated. At first, the maximum intensity value of each A-scans were determined and the depth position of those pixels are identified. The obtained 2D matrix is used as first ... [Proc. SPIE 7168, 716827 (2009)] published Fri Feb 20, 2009.
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    9. Automated retinal shadow compensation of optical coherence tomography images

      We present an automated numerical method of compensating for retinal shadows in the choroid. In this method, signal extinction caused by retinal vessels is estimated by subtracting median A-scans obtained from beneath the retinal vessels and A-scans from the surrounding area. Adding the obtained offset vector to A-scans from beneath the retinal vessels allows compensating for shadows in the choroid. In vivo imaging of the human eye was performed by 840-nm-band standard resolution spectral domain optical coherence tomography (SD-OCT), and choroidal vasculature projection images were calculated. Removal of retinal shadows distinctly improved the readability of choroidal images
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    10. Simulation of polarization-sensitive optical coherence tomography images by a Monte Carlo method

      Igor Meglinski, Mikhail Kirillin, Vladimir Kuzmin, Risto Myllylä We introduce a new Monte Carlo (MC) method for simulating optical coherence tomography (OCT) images of complex multilayered turbid scattering media. We demonstrate, for the first time of our knowledge, the use of a MC technique to imitate two-dimensional polarization-sensitive OCT images with ... [Opt. Lett. 33, 1581-1583 (2008)]
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    11. Effect of paper porosity on OCT images: Monte Carlo study

      Non-invasive measurement of paper porosity is an important problem for papermaking industry. Presently used techniques are invasive and require long time for processing the sample. In recent years optical coherence tomography (OCT) has been proved to be an effective tool for non-invasive study of optically non-uniform scattering media including paper. The aim of present work is to study the potential ability of OCT for sensing the porosity of a paper sample by means of numerical simulations. The paper sample is characterized by variation of porosity along the sample while numerical simulations allow one to consider the samples with constant porosity ...
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    12. Detecting glucose-induced changes in in vitro and in vivo experiments with optical coherence tomography

      Matti Kinnunen, Risto Myllyla, and Seppo Vainio Optical clearing is a well-known phenomenon. It is based on the matching of refractive indices of a bulk material and scattering particles. The same principle is also used in scattering-based optical measurements of different constituents, such as glucose. By registering changes in scattering, it is ... [J. Biomed. Opt. 13, 021111 (2008)] published Mon Apr 14, 2008.
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    13. Application of optical coherence tomography, pulsed photoacoustic technique, and time-of-flight technique to detect changes in the scattering properties of a tissue-simulating phantom

      Matti Kinnunen and Risto Myllyla Intralipid is a well-known emulsion used as a tissue-simulating phantom in developing optical imaging and diagnostic techniques for medical applications. The optical coherence tomography (OCT), pulsed photoacoustic (PA), and time-of-flight (TOF) techniques were used to detect glucose-induced changes ... [J. Biomed. Opt. 13, 024005 (2008)] published Wed Mar 26, 2008.
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    14. Measurement of microfluidic flow velocity profile with two Doppler optical coherence tomography systems

      Janne Lauri, Meng Wang, Matti Kinnunen et al. Doppler Optical Coherence Tomography (DOCT) is a useful technique for flow measurements. Its potential applications include industrial suspension viscosity measurements and blood flow measurements. In this work, a flow velocity profile of 1% Intralipid was measured in a capillary with an inner diame ... [Proc. SPIE Int. Soc. Opt. Eng. 6863, 68630F (2008)] published Wed Feb 20, 2008.
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    15. Contribution of various scattering orders to OCT images of skin

      Simulated OCT images of skin were obtained implementing Monte Carlo simulations. The multilayer skin model used in simulations was based on the experimental OCT images obtained at the wavelength of 910 nm. The following skin layers were considered in the model: stratum corneum, epidermis prickle layer, epidermis basal layer, dermis with upper plexus, dermis, and dermis with lower plexus. The images were obtained both with and without speckle accounting. The latter case is calculated from the envelopes of calculated interference signals while the former accounts for the interference fringe patterns. The contributions of least and multiple scattering, diffusive and non-diffusive ...
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    1-15 of 15
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  2. Topics in the News

    1. (15 articles) University of Oulu
    2. (15 articles) Risto A. Myllylä
    3. (5 articles) Moscow State University
    4. (5 articles) Alexander V. Priezzhev
    5. (4 articles) Mikhail Y. Kirillin
    6. (4 articles) Matti Kinnunen
    7. (3 articles) University of Tsukuba
    8. (3 articles) Shuichi Makita
    9. (3 articles) Yoshiaki Yasuno
    10. (3 articles) Tapio E. J. Fabritius
    11. (2 articles) Topcon Medical Systems
    12. (1 articles) Tohoku University
    13. (1 articles) Duke University
    14. (1 articles) Massachusetts Institute of Technology
    15. (1 articles) Hiroshi Mashimo
    16. (1 articles) James G. Fujimoto
    17. (1 articles) Oscar Carrasco-Zevallos
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    19. (1 articles) Thorlabs
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    Automated segmentation of the macula by optical coherence tomography Optical coherence tomography as an accurate inspection and quality evaluation technique in paper industry Optical coherence tomography as a method of quality inspection for printed electronics products Simulation of optical coherence tomography images by Monte Carlo modeling based on polarization vector approach Multilayer tissue phantoms with embedded capillary system for OCT and DOCT imaging Spectral Domain Optical Coherence Tomography Imaging Performance Improvement Based on Field Curvature Aberration-Corrected Spectrometer Pentosan polysulfate maculopathy versus inherited macular dystrophies: comparative assessment with multimodal imaging Complementary Use of Active Infrared Thermography and Optical Coherent Tomography in Non-destructive Testing Inspection of Ancient Marquetries Spectral domain optical coherence tomography–based prevalence of hydroxychloroquine maculopathy in Indian patients on hydroxychloroquine therapy: A utopia of underdiagnosis Consistency Between Optical Coherence Tomography and Humphrey Visual Field for Evaluating Glaucomatous Defects in High Myopic Eyes Tethered capsule en face optical coherence tomography for imaging Barrett’s esophagus in unsedated patients Radial peripapillary capillary density in superior segmental optic hypoplasia measured with OCT angiography