1. Articles from A. A. Moiseev

    1-10 of 10

    1. Calibration of Lateral Scanning in Optical Coherence Tomography Devices

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      Calibration of Lateral Scanning in Optical Coherence Tomography Devices

      Methods for determining the dependence of the lateral-scan coordinate on the A-scan number from tomographic images of test samples are investigated and techniques for compensating for horizontal distortions of tomographic images caused by uneven speed of the probing-beam displacement are proposed. An opal-glass Ronchi ruling and an inclined flat surface of the volume-scattering plate were used as test samples .

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      Mentions: Institute of Applied Physics Grigory V. Gelikonov Valentin M. Gelikonov

    2. Optical coherence angiography for pre-treatment assessment and treatment monitoring following photodynamic therapy: a basal cell carcinoma patient study

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      Optical coherence angiography for pre-treatment assessment and treatment monitoring following photodynamic therapy: a basal cell carcinoma patient study

      Microvascular networks of human basal cell carcinomas (BCC) and surrounding skin were assessed with optical coherence angiography (OCA) in conjunction with photodynamic therapy (PDT). OCA images were collected and analyzed in 31 lesions pre-treatment, and immediately/24 hours/3–12 months post-treatment. Pre-treatment OCA enabled differentiation between prevalent subtypes of BCC (nodular and superficial) and nodular-with-necrotic-core BCC subtypes with a diagnostic accuracy of 78%; this can facilitate more accurate biopsy reducing sampling error and better therapy regimen selection. Post-treatment OCA images at 24 hours were 98% predictive of eventual outcome. Additional findings highlight the importance of pre-treatment necrotic core, vascular ...

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      Mentions: University of Toronto Felix I. Feldchtein I. Alex Vitkin

    3. Semi-analytical full-wave model for simulations of scans in optical coherence tomography with accounting for beam focusing and the motion of scatterers

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      Semi-analytical full-wave model for simulations of scans in optical coherence tomography with accounting for beam focusing and the motion of scatterers

      A full-wave model for simulating images in spectral-domain optical coherence tomography (OCT) with rigorous accounting for the beam-focusing effects is developed. Due to the analytical description of beam focusing, the model is computationally rather efficient. It also uses a rigorous numerical summation of the contributions of the localized sub-resolution scatterers, accounting for variations in the phase-amplitude parameters of the incident and backscattered optical waves, with a subsequent integration of the latter over the objective aperture. In the limit of a weakly focused beam, the developed model has allowed for the validatation of the earlier proposed simplified model with a constant-radius ...

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      Mentions: Institute of Applied Physics Grigory V. Gelikonov

    4. Equidistant Recording of the Spectral Components in Ultra-Wideband Spectral-Domain Optical Coherence Tomography

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      Equidistant Recording of the Spectral Components in Ultra-Wideband Spectral-Domain Optical Coherence Tomography

      We develop an effective method for reducing nonequidistance when recording the spectral components of an interference signal in ultra-wideband spectral-domain optical coherence tomography. For this purpose, a corrector consisting of two identical prisms is used in a diffraction-grating spectrometer. The corrector rotation with respect to the diffraction-grating plane and a variation in the angle between the corrector elements allow one to adjust the equidistant spatial distribution of the spectral components in the photoreceiver array. It is shown experimentally that the developed method substitutes digital correction and leads to a significant reduction of the computational load in the optical coherence tomography ...

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      Mentions: Institute of Applied Physics Grigory V. Gelikonov Valentin M. Gelikonov

    5. Quantitative Cross-Polarization Optical Coherence Tomography Detection of Infiltrative Tumor Margin in a Rat Glioma Model: a Pilot Study

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      Quantitative Cross-Polarization Optical Coherence Tomography Detection of Infiltrative Tumor Margin in a Rat Glioma Model: a Pilot Study

      Determining boundaries of infiltrative glial tumors remains a challenging problem in neurooncology. Optical coherence tomography (OCT) with cross-polarization (CP) visualization is a promising technique as a surgical guidance tool. However, the outcome of the procedures performed under OCT guidance strongly depends on the surgeon’s qualification. Thus, a quantitative method for assessing resection margins with OCT is required. The aim of this study was to develop a robust quantitative approach for CP OCT data to differentiate tumorous from non-tumorous tissues in a rat glioma model. Materials and Methods. The study was carried out on the rats’ brains (n=6) with ...

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      Mentions: University of Toronto I. Alex Vitkin Institute of Applied Physics

    6. Cross-Polarization Optical Coherence Tomography in Comparative in vivo and ex vivo Studies of the Optical Properties of Normal and Tumorous Brain Tissues

      Explore Журнал СТМ Neurology
      Cross-Polarization Optical Coherence Tomography in Comparative in vivo and ex vivo Studies of the Optical Properties of Normal and Tumorous Brain Tissues

      The aim of the study was to provide visual and quantitative evaluation of tumorous and normal brain tissue images obtained by cross-polarization optical coherence tomography (CP OCT) in a comparative in vivo and ex vivo study. Materials and Methods. The CP OCT as a non-damaging noninvasive optical method for tissue structure imaging was used in the study. It enables obtaining volumetric images of 2.4×2.4×1.25 mm 3 in size in real time within a short time of 26 s. The objects were tumorous and normal brain tissues of 12 experimental animals (Wistar rats): 4 — intact, 4 ...

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      Mentions: Nizhny Novgorod State Medical Academy Institute of Applied Physics Natalia D. Gladkova

    7. In-vivo longitudinal imaging of microvascular changes in irradiated oral mucosa of radiotherapy cancer patients using optical coherence tomography

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      In-vivo longitudinal imaging of microvascular changes in irradiated oral mucosa of radiotherapy cancer patients using optical coherence tomography

      Mucositis is the limiting toxicity of radio(chemo)therapy of head and neck cancer. Diagnostics, prophylaxis and correction of this condition demand new accurate and objective approaches. Here we report on an in vivo longitudinal monitoring of the oral mucosa dynamics in 25 patients during the course of radiotherapy of oropharyngeal and nasopharyngeal cancer using multifunctional optical coherence tomography (OCT). A spectral domain OCT system with a specially-designed oral imaging probe was used. Microvasculature visualization was based on temporal speckle variations of the full complex signal evaluated by high-pass filtering of 3D data along the slow scan axis. Angiographic image ...

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      Mentions: University of Toronto Felix I. Feldchtein I. Alex Vitkin

    8. Improvement of lateral resolution of spectral domain optical coherence tomography images inout-of-focus regions with holographic data processing techniques

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      Improvement of lateral resolution of spectral domain optical coherence tomography images inout-of-focus regions with holographic data processing techniques

      An analogy between spectral-domain optical coherence tomography (SD OCT) data and broadband digital holography data is considered. Based on this analogy, a method for processing SD OCT data, which makes it possible to construct images with a lateral resolution in the whole investigated volume equal to the resolution in the in-focus region, is developed. Several issues concerning practical application of the proposed method are discussed.

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      Mentions: Institute of Applied Physics Grigory V. Gelikonov Valentin M. Gelikonov

    9. Achromatic registration of quadrature components of the optical spectrum in spectral domain opticalcoherence tomography

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      Achromatic registration of quadrature components of the optical spectrum in spectral domain opticalcoherence tomography

      We have thoroughly investigated the method of simultaneous reception of spectral components with the achromatised quadrature phase shift between two portions of a reference wave, designed for the effective suppression of the 'mirror' artefact in the resulting image obtained by means of spectral domain optical coherence tomography (SD OCT). We have developed and experimentally tested a phase-shifting element consisting of a beam divider, which splits the reference optical beam into the two beams, and of delay lines being individual for each beam, which create a mutual phase difference of π/2 in the double pass of the reference beam. The phase ...

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      Mentions: Institute of Applied Physics Grigory V. Gelikonov Valentin M. Gelikonov

    10. Digital refocusing for transverse resolution improvement in optical coherence tomography

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      Digital refocusing for transverse resolution improvement in optical coherence tomography

      Based on the fact that spectral domain (SD) optical coherence tomography (OCT) data can be treated as digital holography (DH) data acquired pointwise, we develop a spectral refocusing algorithm and show its ability to shift the focal region of OCT images obtained from SD OCT data acquired with a tightly focused scanning beam. Although refocusing itself depends on the refractive index of the studied media, we propose a procedure capable of restoring images with resolution equal to the resolution in the focal plane in the whole volume even in case of unknown refractive index of the media. As the proposed ...

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      Mentions: Institute of Applied Physics Grigory V. Gelikonov Valentin M. Gelikonov
    1-10 of 10
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    1. (9 articles) Institute of Applied Physics
    2. (9 articles) Grigory V. Gelikonov
    3. (6 articles) Valentin M. Gelikonov
    4. (5 articles) Pavel A. Shilyagin
    5. (4 articles) Dmitry A. Terpelov
    6. (4 articles) Natalia D. Gladkova
    7. (3 articles) Nizhny Novgorod State Medical Academy
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    10. (3 articles) I. Alex Vitkin

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    Digital refocusing for transverse resolution improvement in optical coherence tomography Achromatic registration of quadrature components of the optical spectrum in spectral domain opticalcoherence tomography Improvement of lateral resolution of spectral domain optical coherence tomography images inout-of-focus regions with holographic data processing techniques In-vivo longitudinal imaging of microvascular changes in irradiated oral mucosa of radiotherapy cancer patients using optical coherence tomography Cross-Polarization Optical Coherence Tomography in Comparative in vivo and ex vivo Studies of the Optical Properties of Normal and Tumorous Brain Tissues Quantitative Cross-Polarization Optical Coherence Tomography Detection of Infiltrative Tumor Margin in a Rat Glioma Model: a Pilot Study Equidistant Recording of the Spectral Components in Ultra-Wideband Spectral-Domain Optical Coherence Tomography Semi-analytical full-wave model for simulations of scans in optical coherence tomography with accounting for beam focusing and the motion of scatterers Optical coherence angiography for pre-treatment assessment and treatment monitoring following photodynamic therapy: a basal cell carcinoma patient study Calibration of Lateral Scanning in Optical Coherence Tomography Devices In vivo dynamic characterization of the human tympanic membrane using pneumatic optical coherence tomography Negative Vessel Remodeling in Stargardt Disease Quantified with Volume-Rendered Optical Coherence Tomography Angiography