1. Articles from Virgil-Florin Duma

    1-24 of 24
    1. Dental Diagnosis and Treatment Assessments: Between X-rays Radiography and Optical Coherence Tomography

      Dental Diagnosis and Treatment Assessments: Between X-rays Radiography and Optical Coherence Tomography

      A correct diagnosis in dental medicine is typically provided only after clinical and radiological evaluations. They are also required for treatment assessments. The aim of this study is to establish the boundaries from which a modern, although established, imaging technique, Optical Coherence Tomography (OCT), is more suitable than the common X-ray radiography to assess dental issues and treatments. The most common methods for daily-basis clinical imaging are utilized in this study for extracted teeth (but also for other dental samples and materials), i.e., panoramic, intraoral radiography, and three-dimensional (3D) cone beam computed tomography (CBCT). The advantages of using OCT ...

      Read Full Article
    2. Quantitative assessment of rat bone regeneration using complex master-slave optical coherence tomography

      Quantitative assessment of rat bone regeneration using complex master-slave optical coherence tomography

      ackground: The need for hard and soft tissues in oral implantology determined the development of methods and techniques to increase bone volume and their quality with different alternative materials used as substituents of patient’s natural bone. In addition, laser radiation can be used to accelerate the repair of fractures and to produce an increased volume of formed callus, as well as an increased bone mineral density. Methods: The aim of this work is to evaluate the capability of an in-house developed multimodal complex master slave (CMS) enhanced swept source (SS) optical coherence tomography (OCT) imaging instrument to analyze the ...

      Read Full Article
    3. Optical Coherence Tomography Investigations and Modeling of the Sintering of Ceramic Crowns

      Optical Coherence Tomography Investigations and Modeling of the Sintering of Ceramic Crowns

      Dental prostheses are sintered in ovens that sometimes suffer from a loss of calibration. This can lead to variations of the sintering temperature outside the range recommended by the manufacturer. Stress and even fractures in dental ceramics may occur, and this leads to the necessity to rebuild the dental construct. The aim of this work is to monitor the quality of sintering processes using an established biomedical imaging technique—optical coherence tomography (OCT). Conventional current procedures imply the fabrication of supplemental samples that add to the expenses and are only evaluated visually. To our knowledge, we were the first to ...

      Read Full Article
    4. Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

      Assessment of Ductile, Brittle, and Fatigue Fractures of Metals Using Optical Coherence Tomography

      ome forensic in situ investigations, such as those needed in transportation (for aviation, maritime, road, or rail accidents) or for parts working under harsh conditions (e.g., pipes or turbines) would benefit from a method/technique that distinguishes ductile from brittle fractures of metals—as material defects are one of the potential causes of incidents. Nowadays, the gold standard in material studies is represented by scanning electron microscopy (SEM). However, SEM instruments are large, expensive, time-consuming, and lab-based; hence, in situ measurements are impossible. To tackle these issues, we propose as an alternative, lower-cost, sufficiently high-resolution technique, Optical Coherence Tomography ...

      Read Full Article
    5. Effects of Temperature Variations during Sintering of Metal Ceramic Tooth Prostheses Investigated Non-Destructively with Optical Coherence Tomography

      Effects of Temperature Variations during Sintering of Metal Ceramic Tooth Prostheses Investigated Non-Destructively with Optical Coherence Tomography

      Calibration loss of ovens used in sintering metal ceramic prostheses leads to stress and cracks in the material of the prostheses fabricated, and ultimately to failure of the dental treatment. Periodic calibration may not be sufficient to prevent such consequences. Evaluation methods based on firing supplemental control samples are subjective, time-consuming, and rely entirely on the technician’s skills. The aim of this study was to propose an alternative procedure for such evaluations. Fifty prostheses were sintered in a ceramic oven at a temperature lower, equal to or larger than the temperature prescribed by the manufacturer. A non-destructive imaging method ...

      Read Full Article
    6. Analysis of polygonal scanning heads: from industrial to high-end applications in swept sources for OCT

      Analysis of polygonal scanning heads: from industrial to high-end applications in swept sources for OCT

      An analysis of polygonal mirror (PM) scanning heads has been performed, in order to provide a tool for their optimal design. The theory developed brings under the same umbrella applications that range from industrial dimensional measurements to high-end biomedical imaging, for example for broadband laser sources swept in frequency for Swept Source Optical Coherence Tomography (SS-OCT). The different characteristic parameters of the PM scanning heads were considered in order to achieve a rigorous analysis: number of PM facets, inner radius of the PM, eccentricity of the PM pivot with regard to the incident fixed laser beam, distance from this beam ...

      Read Full Article
    7. 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 ...

      Read Full Article
    8. Galvanometer Laser Scanning: Custom-Made Input Signals for Maximum Duty Cycles in High-End Imaging Applications

      Galvanometer Laser Scanning: Custom-Made Input Signals for Maximum Duty Cycles in High-End Imaging Applications

      The paper presents some of the contributions achieved in the study of galvanometer-based scanners (GSs) utilized for high-end applications. The optomechatronic aspects of this most used type of laser scanners are presented, in relationship with the high requirements of biomedical imaging, for example. The use of GSs with common input signals, such as triangular, sawtooth, and sinusoidal for domains like Optical Coherence Tomography (OCT) for example are discussed—as studied in several researches. Custom-made input signals for GSs are considered in this presentation, and the analysis made on their effect on the of GS duty cycle (i.e., on the ...

      Read Full Article
    9. MEMS-based handheld scanning probe with pre-shaped input signals for distortion-free images in Gabor-domain optical coherence microscopy

      MEMS-based handheld scanning probe with pre-shaped input signals for distortion-free images in Gabor-domain optical coherence microscopy

      High-speed scanning in optical coherence tomography (OCT) often comes with either compromises in image quality, the requirement for post-processing of the acquired images, or both. We report on distortion-free OCT volumetric imaging with a dual-axis micro-electro-mechanical system (MEMS)-based handheld imaging probe. In the context of an imaging probe with optics located between the 2D MEMS and the sample, we report in this paper on how pre-shaped open-loop input signals with tailored non-linear parts were implemented in a custom control board and, unlike the sinusoidal signals typically used for MEMS, achieved real-time distortion-free imaging without post-processing. The MEMS mirror was ...

      Read Full Article
    10. Optimization of galvanometer scanning for optical coherence tomography

      Optimization of galvanometer scanning for optical coherence tomography

      We study experimentally the effective duty cycle of galvanometer-based scanners (GSs) with regard to three main parameters of the scanning process: theoretical/imposed duty cycle (of the input signal), scan frequency, and scan amplitude. Sawtooth and triangular input signals for the device are considered. The effects of the mechanical inertia of the oscillatory element of the GS are analyzed and their consequences are discussed in the context of optical coherence tomography (OCT) imaging. When the theoretical duty cycle and the scan amplitude are increased to the limit, the saturation of the device is demonstrated for a useful range of scan ...

      Read Full Article
    11. Noninvasive Quantitative Evaluation of the Dentin Layer during Dental Procedures Using Optical Coherence Tomography

      Noninvasive Quantitative Evaluation of the Dentin Layer during Dental Procedures Using Optical Coherence Tomography

      A routine cavity preparation of a tooth may lead to opening the pulp chamber. The present study evaluates quantitatively, in real time, for the first time to the best of our knowledge, the drilled cavities during dental procedures. An established noninvasive imaging technique, Optical Coherence Tomography (OCT), is used. The main scope is to prevent accidental openings of the dental pulp chamber. Six teeth with dental cavities have been used in this ex vivo study. The real time assessment of the distances between the bottom of the drilled cavities and the top of the pulp chamber was performed using an ...

      Read Full Article
    12. Optical Coherence Tomography for Non-Invasive ex vivo Investigations in Dental Medicine — a Joint Group Experience (Review)

      Optical Coherence Tomography for Non-Invasive ex vivo Investigations in Dental Medicine — a Joint Group Experience (Review)

      This review emphasizes the current knowledge related to optical coherence tomography (OCT) as a non-invasive diagnostic tool to perform ex vivo and showing great potential for in vivo structural imaging of features in the oral cavity. OCT technology can generate high-resolution cross-sectional and en-face images of the internal architecture of the investigated sample (2–3 mm in depth). To this goal, en-face time domain OCT (TD-OCT) and spectral domain OCT (SD-OCT) were employed. Topics included in this review refer to OCT non-destructive evaluations of: dental abfraction and attrition, material defects and micro-leakages at the tooth-filling interface, temporal-mandibular joint disc, quality ...

      Read Full Article
    13. 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 ...

      Read Full Article
    14. Assessment of the sealant/tooth interface using optical coherence tomography

      Assessment of the sealant/tooth interface using optical coherence tomography

      Sealant materials are typically employed in dentistry in order to prevent the development of cavities on the teeth. They prevent bacterial adhesion to enamel, thus arresting the development of demineralization and of caries. In this study, the critical zone of the interface between different sealant materials and the results of the dental work for the teeth processed were investigated ex vivo using swept source (SS) optical coherence tomography (OCT). Optical inspection and X-ray investigation revealed no defects, while SS-OCT proved capable to asses exactly the position, the nature, and the dimensions of each type of these defects. Specifically, different failures ...

      Read Full Article
    15. Surface imaging of metallic material fractures using optical coherence tomography

      Surface imaging of metallic material fractures using optical coherence tomography

      We demonstrate the capability of optical coherence tomography (OCT) to perform topography of metallic surfaces after being subjected to ductile or brittle fracturing. Two steel samples, OL 37 and OL 52, and an antifriction Sn–Sb–Cu alloy were analyzed. Using an in-house-built swept source OCT system, height profiles were generated for the surfaces of the two samples. Based on such profiles, it can be concluded that the first two samples were subjected to ductile fracture, while the third one was subjected to brittle fracture. The OCT potential for assessing the surface state of materials after fracture was evaluated by ...

      Read Full Article
    16. Design and testing of prototype handheld scanning probes for optical coherence tomography

      Design and testing of prototype handheld scanning probes for optical coherence tomography

      Three simple and low-cost configurations of handheld scanning probes for optical coherence tomography have been developed. Their design and testing for dentistry applications are presented. The first two configurations were built exclusively from available off-the-shelf optomechanical components, which, to the best of our knowledge, are the first designs of this type. The third configuration includes these components in an optimized and ergonomic probe. All the designs are presented in detail to allow for their duplication in any laboratory with a minimum effort, for applications that range from educational to high-end clinical investigations. Requirements that have to be fulfilled to achieve ...

      Read Full Article
    17. 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 ...

      Read Full Article
    18. 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 ...

      Read Full Article
    19. 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 ...

      Read Full Article
    20. 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 ...

      Read Full Article
    21. 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 ...

      Read Full Article
    22. 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 ...

      Read Full Article
    23. Experimental investigations of the scanning functions of galvanometer-based scanners with applications in OCT

      Experimental investigations of the scanning functions of galvanometer-based scanners with applications in OCT

      We analyze the three most common profiles of scanning functions for galvanometer-based scanners (GSs): the sawtooth, triangular and sinusoidal functions. They are determined experimentally with regard to the scan parameters of the input signal (i.e., frequency and amplitude). We study the differences of the output function of the GS measured as the positional error of the oscillatory mirror from the ideal function given by the input signal of the device. The limits in achieving the different types of scanning functions in terms of duty cycle and linearity are determined experimentally for the possible range of scan parameters. Of particular ...

      Read Full Article
    24. 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 ...

      Read Full Article
    1-24 of 24
  1. Categories

    1. Applications:

      Art, Cardiology, Dentistry, Dermatology, Developmental Biology, Gastroenterology, Gynecology, Microscopy, NDE/NDT, Neurology, Oncology, Ophthalmology, Other Non-Medical, Otolaryngology, Pulmonology, Urology
    2. Business News:

      Acquisition, Clinical Trials, Funding, Other Business News, Partnership, Patents
    3. Technology:

      Broadband Sources, Probes, Tunable Sources
    4. Miscellaneous:

      Jobs & Studentships, Student Theses, Textbooks
  2. Topics in the News

    1. (24 articles) Virgil-Florin Duma
    2. (19 articles) University of Kent
    3. (18 articles) Adrian G. Podoleanu
    4. (14 articles) Victor Babes University of Medicine and Pharmacy
    5. (13 articles) Cosmin Sinescu
    6. (11 articles) Adrian Bradu
    7. (9 articles) Meda-Lavinia Negrutiu
    8. (4 articles) University of Rochester
    9. (4 articles) Jannick P. Rolland
    10. (3 articles) Dorin Demian
  3. Popular Articles

  4. Picture Gallery

    Perspectives of optical scanning in OCT Experimental investigations of the scanning functions of galvanometer-based scanners with applications in OCT Polygon mirror scanners in biomedical imaging: a review Time domain optical coherence tomography investigation of bone matrix interface in rat femurs Imaging of oral pathological tissue using optical coherence tomography Temperature variation in metal ceramic technology analyzed using time domain optical coherence tomography Integral ceramic superstructure evaluation using time domain optical coherence tomography Design and testing of prototype handheld scanning probes for optical coherence tomography Surface imaging of metallic material fractures using optical coherence tomography Optimization of galvanometer scanning for optical coherence tomography 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