1. Articles from george dobre

    1-19 of 19
    1. Photothermal optical coherence tomography for investigation and imaging photothermal trapping of gold nano-rods in clear media and biological tissue

      Photothermal optical coherence tomography for investigation and imaging photothermal trapping of gold nano-rods in clear media and biological tissue

      A quantitative spectrometer-based photothermal optical coherence tomography (PT-OCT) system is employed to investigate and image the photothermal trapping of gold nano-rods (GNRs) in clear and biological media. The PT-OCT system is calibrated through dynamic phase measurements of piezo motion with known driving parameters. We measure and compare the displacement sensitivities of the PT-OCT system at different camera exposure time settings in two configurations: with a distinct reference path; and with a common path. The displacement sensitivity of the system in the common path configuration is improved from 1.5 nm to 0.17 nm by performing Fourier analysis on the ...

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    2. Geometric & radiometric vignetting associated with a 72-facet, off-axis, polygon mirror for swept source optical coherence tomography (SS-OCT)

      Geometric & radiometric vignetting associated with a 72-facet, off-axis, polygon mirror for swept source optical coherence tomography (SS-OCT)

      Optical Coherence Tomography (OCT) has a broad range of applications in 2D and volumetric imaging of micron scale structures typically used on inaccessible objects such as the retina of the eye. This report focuses on Swept Source OCT (SS-OCT), favoured for its faster scanning speeds and therefore faster data acquisition (highly favourable when imaging live patients). SS-OCT relies on the scanning of a narrow laser line at speeds typically in excess of 100 kHz. We have employed Zemax TM ray tracing software to simulate one method of splitting the spectrum of a broadband, near-infrared source, into its component wavelengths by ...

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    3. Maximum permissible exposure of the retina in the human eye in optical coherence tomography systems using a confocal scanning laser ophthalmoscopy platform

      Maximum permissible exposure of the retina in the human eye in optical coherence tomography systems using a confocal scanning laser ophthalmoscopy platform

      When using scanning laser ophthalmoscopy to produce images of the eye fundus, maximum permissible exposure (MPE) limits must be considered. These limits are set out in international standards such as the National Standards Institute ANSI Z136.1 Safe Use of Lasers (USA) and BS EN 60825-1: 1994 (UK) and corresponding Euro norms but these documents do not explicitly consider the case of scanned beams. Our study aims to show how MPE values can be calculated for the specific case of retinal scanning by taking into account an array of parameters, such as wavelength, exposure duration, type of scanning, line rate ...

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    4. Dual instrument for in vivo and ex vivo OCT imaging in an ENT department

      Dual instrument for in vivo and ex vivo OCT imaging in an ENT department

      A dual instrument is assembled to investigate the usefulness of optical coherence tomography (OCT) imaging in an ear, nose and throat (ENT) department. Instrument 1 is dedicated to in vivo laryngeal investigation, based on an endoscope probe head assembled by compounding a miniature transversal flying spot scanning probe with a commercial fiber bundle endoscope. This dual probe head is used to implement a dual channel nasolaryngeal endoscopy-OCT system. The two probe heads are used to provide simultaneously OCT cross section images and en face fiber bundle endoscopic images. Instrument 2 is dedicated to either in vivo imaging of accessible surface ...

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    5. Ceramic and polymeric dental onlays evaluated by photo-elasticity, optical coherence tomography, and micro-computed tomography

      Ceramic and polymeric dental onlays evaluated by photo-elasticity, optical coherence tomography, and micro-computed tomography
      Dental onlays are restorations used to repair rear teeth that have a mild to moderate amount of decay. They can also be used to restore teeth that are cracked or fractured if the damage is not severe enough to require a dental crown. The use of onlays requires less tooth reduction than does the use of metal fillings. This allows dentists to conserve more of a patient's natural tooth structure in the treatment process. The aims of this study are to evaluate the biomechanical comportment of the dental onlays, by using the 3D photo elasticity method and to investigate ...
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    6. OCT and RX validation of metal-ceramic crowns repaired with ceramic materials

      OCT and RX validation of metal-ceramic crowns repaired with ceramic materials

      Emanuela Petrescu, Cosmin Sinescu, and Meda Lavinia Negrutiu et al. Objective: Study's objectives are focused on non-invasive OCT and RX investigations, of interfaces obtained after repairing a metal-ceramic crown with ceramic materials. Material and method: In this study 40 metal-ceramic crowns were involved. Each crown is restoring the first central incisor 1.1. M ... [Proc. SPIE 8172, 817213 (2011)] published Thu Sep 22, 2011.

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    7. Early characterization of occlusal overloaded cervical dental hard tissues by en face optical coherence tomography

      Early characterization of occlusal overloaded cervical dental hard tissues by en face optical coherence tomography
      Early diagnosis of occlusal overload is an important issue in dental medicine. The high occlusal forces can cause irreversible damage to the dental hard tissues. Our study proposes the early microstructural characterization of occlusal overloaded bicuspids, with abnormal crown morphology, by en face optical coherence tomography (eFOCT). The dental samples were investigated using an eFOCT system operating at 1300 nm in B-scan and C-scan mode. The eFOCT images obtained from these teeth visualized cracks, which didn't reach the tooth surface. The μCT and histological images confirmed the microstructural defects identified on eFOCT images. In conclusion, eFOCT is a promising ...
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    8. Adhesive improvement in optical coherence tomography combined with confocal microscopy for class V cavities investigations

      Adhesive improvement in optical coherence tomography combined with confocal microscopy for class V cavities investigations
      The purpose of this study is to present a non invasive method for the marginal adaptation evaluation in class V composite restorations. Standardized class V cavities prepared in human extracted teeth were filled with composite resin (Premise, Kerr). The specimens were thermocycled. The interfaces were examined by Optical Coherence Tomography (OCT) combined with confocal microscopy and fluorescence. The optical configuration uses two single mode directional couplers with a superluminiscent diode as the source at 1300 nm. The scanning procedure is similar to that used in any confocal microscope, where the fast scanning is en-face (line rate) and the depth scanning ...
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    9. Analysis of dental abfractions by optical coherence tomography

      Analysis of dental abfractions by optical coherence tomography
      im and objectives. Abfraction is the pathological loss of cervical hard tooth substance caused by biomechanical overload. High horizontal occlusal forces result in large stress concentrations in the cervical region of the teeth. These stresses may be high enough to cause microfractures in the dental hard tissues, eventually resulting in the loss of cervical enamel and dentin. The present study proposes the microstructural characterization of these cervical lesions by en face optical coherence tomography (eFOCT). Material and methods: 31 extracted bicuspids were investigated using eFOCT. 24 teeth derived from patients with active bruxism and occlusal interferences; they presented deep buccal ...
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    10. Preliminary optical coherence tomography investigation of the temporo-mandibular joint disc

      Preliminary optical coherence tomography investigation of the temporo-mandibular joint disc
      Aim and objectives. The morphology and position of the temporo-mandibular disc are key issues in the diagnosis and treatment of arthrogenous temporo-mandibular disorders. Magnetic resonance imaging and arthroscopy are used today to identify: flattening of the pars posterior of the disc, perforation and/or adhesions in the pars intermedia of the disc and disc displacements. The present study proposes the investigation of the temporo-mandibular joint disc by optical coherence tomography (OCT). Material and methods. 8 human temporo-mandibular joint discs were harvested from dead subjects, under 40 year of age, and conserved in formalin. They had a normal morphology, with a ...
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    11. Marginal adaptation of ceramic veneers investigated with en face optical coherence tomography

      The aim of this study was to analyze the quality of marginal adaptation and gap width of Empress veneers using en-face optical coherence tomography. The results prove the necessity of investigating the marginal adaptation after each veneer bonding process
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    12. Optical coherence tomography combined with confocal microscopy for investigation of interfaces in class V cavities

      Standardized class V cavities, prepared in human extracted teeth, were filled with Premise (Kerr) composite. The specimens were thermo cycled. The interfaces were examined using a system employing two simultaneous imaging channels, an en-face Optical Coherence Tomography channel and a confocal microscopy channel.
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    13. Occlusal overload investigations by noninvasive technology: fluorescence microscopy and en-face optical coherence tomography

      The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-Face Optical coherence tomography (eF-OCT) and fluorescence microscopy (FM) were used for the imaging of several anterior teeth extracted from patients with light active bruxism. We found a characteristic pattern of enamel cracks, that reached the tooth surface. We concluded that the combination of the en-Face OCT and FM is a promising non-invasive alternative technique for reliable monitoring of occlusal overload.
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    14. Optical coherence tomography and confocal microscopy investigations of dental structures and restoration materials

      Nowadays, optical tomographic techniques are of particular importance in the medical imaging field, because these techniques can provide non-invasive diagnostic images. The present study evaluates the potential of en-face optical coherence tomography (OCT) as a possible non-invasive high resolution imaging method in supplying the necessary information on the quality of dental hard tissues and defects of dental restorative materials. Teeth after several treatment methods are imaged in order to asses the material defects and micro-leakage of tooth-filling interface as well as to evaluate the quality of dental hard tissue. C-scan and B-scan OCT images as well as confocal images are ...
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    15. Marginal adaptation analysis performed with en-face optical coherence tomography in fixed partial dentures

      Frameworks for fixed partial denture made out of dental alloys thought classic techniques currently involve many errors like marginal and internal gaps. The aim of this study is to present alternative technologies in making frameworks from dental alloys using selective laser sintering/ selective las ... [Proc. SPIE 7258, 72584H (2009)] published Fri Mar 13, 2009.

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    16. Early detection of tooth wear by en-face optical coherence tomography

      Excessive dental wear (pathological attrition and/or abfractions) is a frequent complication in bruxing patients. The parafunction causes heavy occlusal loads. The aim of this study is the early detection and monitoring of occlusal overload in bruxing patients. En-face optical coherence tomography w ... [Proc. SPIE 7162, 716205 (2009)] published Wed Feb 18, 2009.
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    17. Multi-channel time domain spectroscopic optical coherence tomography system

      A detection method based on 7 spectral windows at the photodetection stage in an optical coherence tomography system was tested. We investigated its utility in two directions: spectroscopic optical coherence tomography and signal to noise ratio improvement. A diffraction grating was used in the photodetection unit to diffract light over a 16 photodetector array. Currently, this array has been configured to deliver 7 channels only by binning two adjacent photodetectors. The improvement of the signal to noise ratio has been investigated. Preliminary results of spectroscopy analysis which will be shown are B-scan OCT imaging of paint layers. The ultimate aim ...

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    18. Simultaneous OCT/SLO/ICG Imaging

      Purpose: To evaluate how information from combined coronal Optical Coherence Tomography (OCT) and confocal laser scanning ophthalmoscopy (SLO) with integrated simultaneous Indocyanine Green dye (ICG) angiography can be used in the diagnosis of a variety of macular pathologies. Methods: A compact chin-rest based OCT/confocal imaging system was used to produce the OCT image and excite fluorescence in ICG dye. The same eye fundus area can be visualized with coronal (C-scans, en-face) OCT and ICG angiography simultaneously. Fast T-scanning (transverse scanning, en-face) is used to build B-scan or C-scan OCT images along with confocal SLO views with and without ICG ...
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    19. Optical-coherence tomography, extension to imaging of low coherence interferometry

      Adrian Gh. Podoleanu, Radu G. Cucu, John A. Rogers et al. Results are presented in using low coherence interferometry in quantifying the reflectivity and imaging of different objects, such as tissue, paintings and fruits. All images have been obtained using en-face flying spot technology. This allows simultaneous generation of optical coherence tomography ... [Proc. SPIE Int. Soc. Opt. Eng. 6785, 67851I (2007)] published Wed Aug 1, 2007.
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    1-19 of 19
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    1. (19 articles) University of Kent
    2. (18 articles) George M. Dobre
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    5. (12 articles) Adrian Bradu
    6. (12 articles) Cosmin Sinescu
    7. (2 articles) New York Eye and Ear Infirmary
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    Analysis of dental abfractions by optical coherence tomography Adhesive improvement in optical coherence tomography combined with confocal microscopy for class V cavities investigations Early characterization of occlusal overloaded cervical dental hard tissues by en face optical coherence tomography OCT and RX validation of metal-ceramic crowns repaired with ceramic materials Dual instrument for in vivo and ex vivo OCT imaging in an ENT department Fantom Encore Sirolimus-eluting Bioresorbable Scaffold for Treatment of De-novo CAD: the ENCORE-I Study Assessment of Microcirculatory Dysfunction in Septic Shock Patients by OCTA OCT system used at home demonstrates potential for daily monitoring of AMD Optical Coherence Tomography Biomarkers of the Outer Blood—Retina Barrier in Patients with Diabetic Macular Oedema Retinal Boundary Segmentation in Stargardt Disease Optical Coherence Tomography Images Using Automated Multi-channel swept source optical coherence tomography concept based on photonic integrated circuits Assessment of Retinal Vessel Density in Adult-Onset Foveomacular Vitelliform Dystrophy by Optical Coherence Tomography Angiography