1. Articles from Adrian G. Podoleanu

    1-24 of 58 1 2 3 »
    1. Mitigation of Speckle Noise in Optical Coherence Tomograms

      Mitigation of Speckle Noise in Optical Coherence Tomograms

      Optical Coherence Tomography (OCT) is a promising high-resolution imaging technique that works based on low coherent interferometry. However, like other low coherent imaging modalities, OCT suffers from an artifact called, speckle. Speckle reduces the detectability of diagnostically relevant features in the tissue. Retinal optical coherence tomograms are of a great importance in detecting and diagnosing eye diseases. Different hardware or software based techniques are devised in literatures to mitigate speckle noise. The ultimate aim of any software-based despeckling technique is to suppress the noise part of speckle while preserves the information carrying portion of that. In this chapter, we reviewed ...

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    2. MicroCT and optical coherence tomography imagistic assessment of the dental roots adhesive

      MicroCT and optical coherence tomography imagistic assessment of the dental roots adhesive

      Several obturation methods are available today to study the 3D filling of the root canal. There are also several methods capable to evaluate the ability to seal apically the root canals. However, the common methods of investigation are invasive; they also lead to the destruction of the samples. If the sectioning differs slightly from the desired area, the investigation is non-conclusive regarding the micro-leakages. Also, although the use of Cone-Beam Micro Computer Tomography (CBCT) appears to be most promising for endodontic purposes, its effective radiation doses are higher than with conventional intra-oral and panoramic imaging. In contrast, enface (ef) Optical ...

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    3. Material Defects in Ceramic Crowns Identification by Optical Coherence Tomography and MicroCT

      Material Defects in Ceramic Crowns Identification by Optical Coherence Tomography and MicroCT

      Full ceramic crowns are considered revolutionary in developing the concept of aesthetic dentistry. Appreciate their aesthetic appearance particularly raise the cost prices, they do not ensure the risk of fractures and cracks which sometimes face the clinician after their insertion directly into the mouth. As a result of the fracture may occur between disputes team dentist-dental technician. The purpose of this study was to identify flaws of material included in the pottery table analyzing the full ceramic crowns using non-invasive technologies. As materials we use 25 full ceramic crowns (e. max, IVOCLAR) obtained through the technology of pressing were used ...

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    4. Integral ceramic superstructure evaluation using time domain optical coherence tomography

      Integral ceramic superstructure evaluation using time domain optical coherence tomography

      Optical Coherence Tomography (OCT) is a non-invasive low coherence interferometry technique that includes several technologies (and the corresponding devices and components), such as illumination and detection, interferometry, scanning, adaptive optics, microscopy and endoscopy. From its large area of applications, we consider in this paper a critical aspect in dentistry - to be investigated with a Time Domain (TD) OCT system. The clinical situation of an edentulous mandible is considered; it can be solved by inserting 2 to 6 implants. On these implants a mesostructure will be manufactured and on it a superstructure is needed. This superstructure can be integral ceramic; in ...

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    5. Temperature variation in metal ceramic technology analyzed using time domain optical coherence tomography

      Temperature variation in metal ceramic technology analyzed using time domain optical coherence tomography

      The quality of dental prostheses is essential in providing good quality medical services. The metal ceramic technology applied in dentistry implies ceramic sintering inside the dental oven. Every ceramic material requires a special sintering chart which is recommended by the producer. For a regular dental technician it is very difficult to evaluate if the temperature inside the oven remains the same as it is programmed on the sintering chart. Also, maintaining the calibration in time is an issue for the practitioners. Metal ceramic crowns develop a very accurate pattern for the ceramic layers depending on the temperature variation inside the ...

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    6. Imaging of oral pathological tissue using optical coherence tomography

      Imaging of oral pathological tissue using optical coherence tomography

      Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cancer. Early detection is a cornerstone to improve survival. Interaction of light with tissues may highlight changes in tissue structure and metabolism. We propose optical coherence tomography (OCT), as a non-invasive diagnosis method, being a new high-resolution optical technique that permits tri-dimensional (3-D), real-time imaging of near surface abnormalities in complex tissues. In this study half of the excisional biopsy was directed to the pathologist and the other half was assigned for OCT investigation. Histopathology validated the results. Areas of OSCC of the buccal mucosa were identified in the OCT images ...

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    7. Different matrix evaluation for the bone regeneration of rats' femours using time domain optical coherence tomography

      Different matrix evaluation for the bone regeneration of rats' femours using time domain optical coherence tomography

      The osteoconductive materials are important in bone regeneration procedures. Three dimensional (3D) reconstructions were obtained from the analysis. The aim of this study is to investigate the interface between the femur rat bone and the new bone that is obtained using a method of tissue engineering that is based on two artificial matrixes inserted in previously artificially induced defects. For this study, under strict supervision 20 rats were used in conformity with ethical procedures. In all the femurs a round defect was induced by drilling with a 1 mm spherical Co-Cr surgical drill. The matrixes used were IngeniOss (for ten ...

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    8. Artifacts cancellation in Fourier domain optical coherence tomography using balance detection

      Artifacts cancellation in Fourier domain optical coherence tomography using balance detection

      A Fourier domain optical coherence tomography system equipped with two spectrometers in balance detection is presented. The set-up was successfully used in reducing two artifacts present in Fourier domain optical coherence tomography images: autocorrelation terms and fixed pattern noise. Conditions and adjustments of spectrometer parameters are presented to ensure an anti-phase channelled spectrum modulation along the length of the two cameras for a majority of wavelengths within the optical source spectrum. By stopping the optical signal to reach one of the spectrometers, the set-up was used to compare the conditions of operation of a single camera with that of a ...

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    9. Time domain optical coherence tomography investigation of bone matrix interface in rat femurs

      Time domain optical coherence tomography investigation of bone matrix interface in rat femurs

      The materials used to fabricate scaffolds for tissue engineering are derived from synthetic polymers, mainly from the polyester family, or from natural materials (e.g., collagen and chitosan). The mechanical properties and the structural properties of these materials can be tailored by adjusting the molecular weight, the crystalline state, and the ratio of monomers in the copolymers. Quality control and adjustment of the scaffold manufacturing process are essential to achieve high standard scaffolds. Most scaffolds are made from highly crystalline polymers, which inevitably result in their opaque appearance. Their 3-D opaque structure prevents the observation of internal uneven surface structures ...

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    10. A versatile frequency domain multiplexer for optical coherence tomography

      A versatile frequency domain multiplexer for optical coherence tomography

      In this paper we present a frequency multiplexed optical coherence tomography imaging method in which simultaneous data acquisition is enabled by a multiplexer. The multiplexer is based on a pair of Bragg cells, simultaneously driven at several frequencies that enable multiple paths in the reference arm. Multiple beams are created in the multiplexer and then recombined again so that the resulting beam multiplex can be inserted into a single mode fiber. In this paper we discuss the design principles for a multiplexer that supports the reflectivity measurements as well as polarization sensitive imaging at several different depths. We show how ...

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    11. Speckle reduction using an artificial neural network algorithm

      Speckle reduction using an artificial neural network algorithm

      This paper presents an algorithm for reducing speckle noise from optical coherence tomography (OCT) images using an artificial neural network (ANN) algorithm. The noise is modeled using Rayleigh distribution with a noise parameter, sigma, estimated by the ANN. The input to the ANN is a set of intensity and wavelet features computed from the image to be processed, and the output is an estimated sigma value. This is then used along with a numerical method to solve the inverse Rayleigh function to reduce the noise in the image. The algorithm is tested successfully on OCT images of Drosophila larvae. It ...

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    12. Bone regeneration assessment by optical coherence tomography and MicroCT synchrotron radiation

      Bone regeneration assessment by optical coherence tomography and MicroCT synchrotron radiation

      Bone grafting is a commonly performed surgical procedure to augment bone regeneration in a variety of orthopaedic and maxillofacial procedures, with autologous bone being considered as the "gold standard" bone-grafting material, as it combines all properties required in a bone-graft material: osteoinduction (bone morphogenetic proteins – BMPs - and other growth factors), osteogenesis (osteoprogenitor cells) and osteoconduction (scaffold). The problematic elements of bone regenerative materials are represented by their quality control methods, the adjustment of the initial bone regenerative material, the monitoring (noninvasive, if possible) during their osteoconduction and osteointegration period and biomedical evaluation of the new regenerated bone. One of the ...

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    13. Polygon mirror scanners in biomedical imaging: a review

      Polygon mirror scanners in biomedical imaging: a review

      We review briefly the different applications of polygonal mirror (PM) scanning heads in biomedical imaging, with a focus on Optical Coherence Tomography (OCT). This overview of biomedical optical systems that employ PMs include: (i) TD (Time Domain) OCT setups, where PM may be utilized for generating the modulation function of the system without separate translation stages; (ii) FD (Fourier Domain) OCT delay line systems, with PM arrays; (iii) broadband laser sources scanned in frequency, for SS (Swept Source) OCT, with the PM placed in various optical configurations; (iv) OCM (Optical Coherence Microscopy) system with double PMs; (v) 2D PM plus ...

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    14. Research Associate in Photonics/Optical coherence tomography/Nonlinear microscopy/Wavefront sensing at University of Kent -School of Physical Sciences

      Research Associate in Photonics/Optical coherence tomography/Nonlinear microscopy/Wavefront sensing at University of Kent -School of Physical Sciences

      Ref STM0331 Location Canterbury Job Type Research Contract Type Fixed Term Salary Type Pro Rata Salary (£) 31,020 - 31,020 We are seeking to appoint a Research Associate which is supported by the grant: "Combined time domain and spectral domain coherence gating for imaging and biosensing", funded by the European Research Council (ERC), "Ideas" Specific programme, Advanced, the 7th framework, for 25 months. http://www.kent.ac.uk/physical-sciences/research/aog/European_Research_Council_Grant.html The research activity of the RA as part of the ERC grant will tackle extensions and applications of multiple path optical configurations for optical coherence tomography (OCT ...

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    15. Optical coherence tomography

      Optical coherence tomography

      The review provides a concise explanation of principles of operation of different optical coherence tomography methods. A comparative analysis of their advantages and disadvantages is presented in relation to specific applications. The review will assist the reader in making an educated choice on the most suitable optical coherence tomography method to be used in a particular application.

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    16. The assessment of orthodontic bonding defects: optical coherence tomography followed by three-dimensional reconstruction

      The assessment of orthodontic bonding defects: optical coherence tomography followed by three-dimensional reconstruction
      Orthodontic bonding is a simple yet important procedure that can influence the outcome of treatment in case it is performed incorrectly. An orthodontic treatment shadowed by repeated bonding failures can become unduly long and will decrease patient trust and compliance. Optical coherence tomography has been widely used in ophtalmology but is relatively new to dentistry. Using OCT one can detect aerial inclusions within the orthodontic adhesive or even identify incongruence between the bracket base and the tooth surface. The aim of our study was to identify bonding defects and reconstruct them three-dimensionally in order to be able to characterize them ...
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    17. Time-domain coherence-gated Shack-Hartmann wavefront sensor

      Time-domain coherence-gated Shack-Hartmann wavefront sensor
      In the present paper we investigate the possibility of narrowing the depth range of a physical Shack - Hartmann wavefront sensor (SH-WFS) by using coherence gating. We have already demonstrated a low coherence interferometry (LCI) set-up, capable of generating similar spots patterns as a conventional SH-WFS and also capable of eliminating stray reflections. Here, we evaluate the accuracy of wavefront measurements using a coherence-gated (CG)/SH-WFS. This is based on a Mach-Zehnder interferometer combined with a SH-WFS, that implements time-domain (TD)-LCI acquisition. The wavefront measurement errors introduced by the non-uniform distribution of the reference power over the photo-detector array were ...
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    18. 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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    19. Imagistic evaluation of direct dental restoration: en face OCT versus SEM and microCT

      Imagistic evaluation of direct dental restoration: en face OCT versus SEM and microCT
      There are several methods known which are used to assess the quality of direct dental restorations, but most of them are invasive. These lead to the destruction of the probes and often no conclusion could be drawn in respect to the existence of any microleakage in the investigated areas of interest. Optical tomographic techniques are of particular importance in the medical imaging field, because these techniques can provide non-invasive diagnostic images. Using an en-face version of OCT, we have recently demonstrated real time thorough evaluation of quality of dental fillings. The purpose of this in vitro study was to validate ...
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    20. Morphological characterization of dental prostheses interfaces using optical coherence tomography

      Morphological characterization of dental prostheses interfaces using optical coherence tomography
      Fixed partial prostheses as integral ceramic, polymers, metal-ceramic or metal-polymers bridges are mainly used in the frontal part of the dental arch (especially the integral bridges). They have to satisfy high stress as well as esthetic requirements. The masticatory stress may induce fractures of the bridges. These may be triggered by initial materials defects or by alterations of the technological process. The fractures of these bridges lead to functional, esthetic and phonetic disturbances which finally render the prosthetic treatment inefficient. Dental interfaces represent one of the most significant aspects in the strength of the dental prostheses under the masticatory load ...
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    21. 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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    22. Variable lateral size imaging of the human retina in vivo by combined confocal/ en face optical coherence tomography with closed loop OPDlocked low coherence interferometry based active axial eye motion tracking

      Variable lateral size imaging of the human retina in vivo by combined confocal/ en face optical coherence tomography with closed loop OPDlocked low coherence interferometry based active axial eye motion tracking
      We reported recently an active tracking device based on white light coherence ranging using a spectrally interrogated Michelson interferometer, which was used to monitor and correct for the axial displacement of the eye and head of the imaged subject in a confocal scanning ophthalmoscope/ en face OCT system (SLO/OCT) by tracking the axial position of the eye fundus. Both the tracking and imaging interferometers share the eye interface optics and the patient eye and also an optical path difference (OPD) changing device in the reference (fast voice coil mounted retroreflector), that keeps them locked at constant OPD values. As ...
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    23. Perspectives of optical scanning in OCT

      Perspectives of optical scanning in OCT

      We present an overview of our contributions and directions of research in the domain of optical scanners, with regard to their perspectives of use in optical coherence tomography (OCT). The performances, advantages and drawbacks of the different types of scanning systems are summarized. Both 1-D and 2-D scanners for various applications in OCT, from swept source filters to flying the beam over the target are considered. We briefly present our developments of polygon mirror (PM) scanners. We study galvoscanners (GS) in order to increase their duty cycle in general and for high speed scanners in particular. The limitations in reaching ...

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    24. 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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    1-24 of 58 1 2 3 »
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    1. (56 articles) Adrian G. Podoleanu
    2. (55 articles) University of Kent
    3. (22 articles) Cosmin Sinescu
    4. (20 articles) Victor Babes University of Medicine and Pharmacy
    5. (19 articles) Adrian Bradu
    6. (14 articles) George M. Dobre
    7. (9 articles) Virgil-Florin Duma
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