1,409 research outputs found

    Low dose and fast grating-based x-ray phase-contrast imaging using the integrating-bucket phase modulation technique

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    X-ray phase-contrast imaging has experienced rapid development over the last few decades, and in this technology, the phase modulation strategy of phase-stepping is used most widely to measure the sample's phase signal. However, because of its discontinuous nature, phase-stepping has the defects of worse mechanical stability and high exposure dose, which greatly hinder its wide application in dynamic phase measurement and potential clinical applications. In this manuscript, we demonstrate preliminary research on the use of integrating-bucket phase modulation method to retrieve the phase information in grating-based X-ray phase-contrast imaging. Experimental results showed that our proposed method can be well employed to extract the differential phase-contrast image, compared with the current mostly used phase-stepping strategy, advantage of integrating-bucket phase modulation technique is that fast measurement and low dose are promising.Comment: 14 pages, 6 figure

    Potential of X-ray computed tomography for 3D anatomical analysis and microdensitometrical assessment in wood research with focus on wood modification

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    Studying structure and chemistry of wood and wood-based materials is the backbone of all wood research and many techniques are at hand to do so. A very valuable modality is X-ray computed tomography (CT), able to non-destructively probe the three-dimensional (3D) structure and composition. In this paper, we elaborate on the use of Nanowood, a flexible multi-resolution X-ray CT set-up developed at UGCT, the Ghent University Centre for X-ray Tomography. The technique has been used successfully in many different fields of wood science. It is illustrated how 3D structural and microdensitometrical data can be obtained using different scan set-ups and protocols. Its potential for the analysis of modified wood is exemplified, e.g. for the assessment of wood treated with hydrophobing agents, localisation of modification agents, pathway analysis related to functional tissues, dimensional changes due to thermal treatment, etc. Furthermore, monitoring of transient processes is a promising field of activity too

    NDE Software Developed at NASA Glenn Research Center

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    NASA Glenn Research Center has developed several important Nondestructive Evaluation (NDE) related software packages for different projects in the last 10 years. Three of the software packages have been created with commercial-grade user interfaces and are available to United States entities for download on the NASA Technology Transfer and Partnership Office server (https://sr.grc.nasa.gov/). This article provides brief overviews of the software packages

    Chip Based Optical Nanoscopy: System Integration and Automation

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    An integrated photonic chip based nanoscopy system has previously been developed at UiT, which allows for several advantages over conventional total internal reflection fluorescence microscopy and nanoscopy (i.e. super-resolutionnanoscopy). While the proof-of-concept has been demonstrated, there were several important system optimization tasks that were needed for making the system practical and more usable. This thesis tackles three major system optimization tasks, namely efficient and automatic coupling of light into waveguide in the photonic chip, precise control and stablization of feed point into the waveguide, and synchronization of illumination and collection arms of the photonic chip based microscope. For a novel and more flexible light feed setup designed at the department, a new mechanism for measuring the coupling efficiency was designed, an initial coupling and parasitic interaxis cross-talk compensation mechanism was designed, and two optimiztion algorithms were explored for the final fine coupling. Testing of the implementation showed promising results with close to optimal coupling efficiency achieved in a reasonable amount of time. A piezoelectric stage with large travel range was tuned to provide the best possible performance for controlling illumination. This was used to adapt a nanoscopy algorithm named multiple signal classification algorithm (MUSICAL) for exploiting the variable illumination property of multimode waveguides on the photonic chip. Lastly, imaging and illumination control was inplemented in software allowing the capture of datasets suitable for use with MUSICAL. Thus, the goals of this thesis were achieved successfully and the practical use ofthe photonic-chip for microscopy and nanoscopy was greatly enhanced

    Smart Surgical Microscope based on Optical Coherence Domain Reflectometry

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    Department of Biomedical EngineeringOver the several decades, there have been clinical needs that requires advanced technologies in medicine. Optical coherence tomography (OCT), one of the newly emerged medical imaging devices, provides non-invasive cross-sectional images in high resolution which is mainly used in ophthalmology. However, due to the limited penetration depth of 1-2 mm in bio-samples, there is a limit to be widely used. In order to easily integrate with existing medical tools and be convenient to users, it is necessary that the sample unit of OCT should be compact and simple. In this study, we developed high-speed swept-source OCT (SS-OCT) for advanced screening of otolaryngology. Synchronized signal sampling with a high-speed digitizer using a clock signal from a swept laser source, its trigger signal is also used to synchronize with the movement of the scanning mirror. The SS-OCT system can reliably provide high-throughput images, and two-axis scanning of galvano mirrors enables real-time acquisition of 3D data. Graphic processing unit (GPU) can performs high-speed data processing through parallel programming, and can also implement perspective projection 3D OCT visualization with optimal ray casting techniques. In the Clinical Study of Otolaryngology, OCT was applied to identify the microscopic extrathyroidal extension (mETE) of papillary thyroid cancer (PTC). As a result to detect the mETE of around 60% in conventional ultrasonography, it could be improved to 84.1% accuracy in our study. The detection ratio of the mETE was calculated by the pathologist analyzing the histologic image. In chapter 3, we present a novel study using combined OCT system integrated with a conventional surgical microscope. In the current set-up of surgical microscope, only two-dimensional microscopic images through the eyepiece view are provided to the surgeon. Thus, image-guided surgery, which provides real-time image information of the tissues or the organs, has been developed as an advanced surgical technique. This study illustrate newly designed optical set-up of smart surgical microscope that combined sample arm of the OCT with an existing microscope. Specifically, we used a beam projector to overlay OCT images on existing eyepiece views, and demonstrated augmented reality images. In chapter 4, in order to develop novel microsurgical instruments, optical coherence domain reflectometry (OCDR) was applied. Introduces smart surgical forceps using OCDR as a sensor that provides high-speed, high-resolution distance information in the tissue. To attach the sensor to the forceps, the lensed fiber which is a small and high sensitivity sensor was fabricated and the results are shown to be less affected by the tilt angle. In addition, the piezo actuator compensates the hand tremor, resulting in a reduction in the human hand tremor of 5 to 15 Hz. Finally, M-mode OCT needle is proposed for microsurgery guidance in ophthalmic surgery. Stepwise transitional core (STC) fiber was applied as a sensor to measure information within the tissue and attached to a 26 gauge needle. It shows the modified OCT system and the position-guided needle design of the sample stage and shows the algorithm flowchart of M-mode OCT imaging software. The developed M-mode OCT needle has been applied to animal studies using rabbit eyes and demonstrates the big-bubble deep anterior lamellar keratoplasty (DALK) surgery for corneal transplantation. Through this study, we propose a novel microsurgical instrument for lamellar keratoplasty and evaluate its feasibility with conventional regular OCT system images. In conclusion, for fundamental study required new augmented reality guided surgery with smart surgical microscope, it is expected that OCT combined with surgical microscope can be widely used. We demonstrated a novel microsurgical instrument to share with light source and the various optical components. Acquired information throughout our integrated system would be a key method to meet a wide range of different clinical needs in the real world.ope

    Development of the acquisition software for a cone beam in-vitro micro-CT

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    During the 70’s Computed Tomography (CT) opened the door to the possibility of obtaining anatomical information from living subjects non-invasively. Since then, this technology has become indispensable for clinical diagnostic in medicine as well as for sanitary research. Consequently, micro-CTs rose from the necessity in the preclinical environment of the advantages that CT offers to the clinicians, providing high-resolution images of small samples. The Universidad Carlos III de Madrid has designed a new high-resolution in-vitro x-ray micro-CT that will serve as a test bench for wide number of applications in research and teaching. The goal of this project is to implement a control and data acquisition software for this device. LabVIEW has been used as the development environment due to the advantages that offers in the creation of graphical user interfaces, its commodious configuration to communicate with many types of hardware elements and its flexibility to expand the software in future works with few modifications. This project comprises the development of a set of libraries to control the hardware elements: x-ray source, flat-panel detector and mechanical system of the UC3M test bench. In addition, the implementation of a “step and shoot” acquisition protocol is needed, which combines control libraries previously developed. The architecture of the implemented software leads to the possibility of expanding its functionalities into more advanced features such as advanced acquisition protocols or imaging techniques. The work included in this project is framed in one of the lines of research carried out at the Biomedical Imaging and Instrumentation Group at the Departamento de Bioingeniería e Ingenería Aereospacial of the University Carlos III de Madrid.Ingeniería Biomédic
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