Download or read book Real time Adaptive optics Optical Coherence Tomography AOOCT Image Reconstruction on a GPU written by Brandon Andrew Shafer and published by . This book was released on 2014 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive-optics optical coherence tomography (AOOCT) is a technology that has been rapidly advancing in recent years and offers amazing capabilities in scanning the human eye in vivo. In order to bring the ultra-high resolution capabilities to clinical use, however, newer technology needs to be used in the image reconstruction process. General purpose computation on graphics processing units is one such way that this computationally intensive reconstruction can be performed in a desktop computer in real-time. This work shows the process of AOOCT image reconstruction, the basics of how to use NVIDIA's CUDA to write parallel code, and a new AOOCT image reconstruction technology implemented using NVIDIA's CUDA. The results of this work demonstrate that image reconstruction can be done in real-time with high accuracy using a GPU.
Download or read book Adaptive Optics Optical Coherence Tomography for in Vivo Retinal Imaging written by Yifan Jian and published by . This book was released on 2014 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is a non-invasive micrometer-resolution volumetric imaging modality that has been employed in diverse applications. In this thesis, we first describe a GPU accelerated program to perform FDOCT data processing and real time 3D volumetric rendering. The real time visualization of volumetric images provided by the GPU acceleration was essential to the rest of the work described in this thesis. Small animal models of retinal diseases serve as a vital component in vision research, and non-invasive in vivo imaging is becoming an increasingly important tool in the field. We describe the first adaptive optics optical coherence tomography (AOOCT) imaging system for high resolution mouse retinal imaging. Images of mouse retina acquired with AOOCT showed significant improvement in the brightness and contrast of capillaries and nerve fiber bundles. However, the accuracy of wavefront sensing limited the performance of AOOCT. A novel wavefront sensorless adaptive optics (WSAO) OCT system was developed to overcome the issues associated with conventional wavefront sensing. Combination of WSAO with OCT allows coherence gated, depth resolved aberration correction. Images of both pigmented and albino mouse retinas acquired using WSAO OCT system demonstrated superior image quality. The real time high resolution WSAO OCT was leveraged for a time course study of laser exposure in the retina.
Download or read book Ophthalmic Imaging Applications with Optical Coherence Tomography and Graphics Processing Units written by Kevin Siu Kwun Wong and published by . This book was released on 2014 with total page 81 pages. Available in PDF, EPUB and Kindle. Book excerpt: In ophthalmology, Optical Coherence Tomography (OCT) is becoming one of the dominant imaging technologies for both clinical diagnostics and vision research. In a previous bachelor's thesis prior to this project, we described a highly optimized Graphics Processing Unit (GPU) implementation of the Fourier Domain (FD)OCT processing and visualization pipeline that was capable of real-time volume rendering at video rate.In this thesis, we describe three applications that build upon the GPU-based processing software: Speckle Variance (sv)OCT, Compressive Sample (CS)OCT, and Wavefront Sensorless Adaptive Optics (WSAO)OCT. We first demonstrate that svOCT can be a powerful fundus imaging technique for visualizing the retinal vasculature network, which may be comparable to the gold-standard technique called Fluorescein Angiography (FA). The strongest attribute of svOCT is that it bypasses the use of intravenous fluorescein for vascular contrast enhancement, and can be highly suitable for longitudinal monitoring of patients with vasculature-related pathologies in the retina. In our second application, we present a GPU-accelerated CS-OCT processing pipeline. The principle behind CS-OCT is to take advantage of the redundancy in biological structures, such as the retina, for reconstructing volumes acquired at a sampling density below the Nyquist criterion; the purpose is to justify decreasing volume acquisition time by significantly subsampling the datasets. In our final application, we present a WSAO-OCT system as a novel technique for cellular resolution imaging of the human photoreceptor layer. This technique leverages on the ultrahigh speed processing rates in our GPU-based processing software in order to produce a real-time intensity-based merit function for en face image quality optimization.
Download or read book Optical Coherence Tomography written by Wolfgang Drexler and published by Springer Science & Business Media. This book was released on 2008-12-10 with total page 1346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is the optical analog of ultrasound imaging and is emerging as a powerful imaging technique that enables non-invasive, in vivo, high resolution, cross-sectional imaging in biological tissue. This book introduces OCT technology and applications not only from an optical and technological viewpoint, but also from biomedical and clinical perspectives. The chapters are written by leading research groups, in a style comprehensible to a broad audience.
Download or read book Multi GPU Accelerated Real time Retinal Image Segmentation written by Maxwell Miao and published by . This book was released on 2016 with total page 79 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, Optical Coherence Tomography (OCT) has become one of the dominant imaging technologies for ophthalmic diagnostics and vision research. The fast and high-resolution cross-sectional data that OCT provides has brought a new possibility in the role of intra-operative imaging. However, existing commercial OCT systems lack the automated real-time functionality for providing immediate feedback of changes in anatomical configuration as the result of surgical actions. The predominant reason for lacking such functionality is because high complexity algorithms are hard to implement in real-time imaging due to their computationally expensive nature. In this thesis, we will present a Graphics Processing Unit (GPU) accelerated retinal layer segmentation for real-time intra-operative imaging applications. Modern GPUs has emerged as a strong tool for mass computation in scientific researches. The computational power of the GPU outpaces Central Processing Unit (CPU) significantly when the processing task is parallelizable. Image segmentation is a computationally expensive algorithm and traditionally implemented in sequential instructions. An example of a parallelizable segmentation algorithm is Push-Relabel (PR) Graph-Cut(GC), which can be implemented using GPU. The GPU Retinal Segmentation (GRS) presented in this thesis is built upon such an algorithm. To ensure the run time of the GRS meets the real-time requirement for its application, multiple GPUs are used to accelerate the segmentation processing further in parallel. As a result of using GRS, we were able to achieve the visualization of the retinal thickness measurement and the enhancement of retinal vasculature networks in real-time.
Download or read book Wavefront Sensorless Adaptive Optics Swept Source Optical Coherence Tomography at 1060nm written by Sujin Tom Lee and published by . This book was released on 2015 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography (OCT) has revolutionized modern ophthalmology, providing depth resolved images of the retinal layers in a system that is suited to a clinical environment. A limitation on the performance and utilization of the OCT systems has been the lateral resolution; whereas the axial resolution is a function of the light source, the lateral resolution is dependent on the delivery optics. In this thesis, a compact lens based OCT system is presented that is capable of imaging the different retinal layers at a cellular lateral resolution with the combination of wavefront sensorless adaptive optics with dual variable optical elements. The central operating imaging wavelength of the wavelength swept OCT engine was 1060nm, close to the dispersion minimum of water (and the vitreous humor in the eye). A commercially available variable focal length lens is utilized to correct for a wide range of defocus commonly found in patient's eyes, and a multi-actuator deformable lens for aberration correction to obtain near diffraction limited imaging at the retina. A parallel processing computational platform permitted real-time image acquisition and display. Cross-sectional images of the retinal layers and en face images of the cone photoreceptor mosaic acquired in vivo from research subjects are presented.
Download or read book Retinal Optical Coherence Tomography Image Analysis written by Xinjian Chen and published by Springer. This book was released on 2019-07-05 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the latest optical coherence tomography (OCT) imaging and computerized automatic image analysis techniques, and their applications in the diagnosis and treatment of retinal diseases. Discussing the basic principles and the clinical applications of OCT imaging, OCT image preprocessing, as well as the automatic detection and quantitative analysis of retinal anatomy and pathology, it includes a wealth of clinical OCT images, and state-of-the-art research that applies novel image processing, pattern recognition and machine learning methods to real clinical data. It is a valuable resource for researchers in both medical image processing and ophthalmic imaging.
Download or read book Optical Coherence Tomography written by Rui Bernardes and published by Springer Science & Business Media. This book was released on 2012-05-08 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography represents the ultimate noninvasive ocular imaging technique although being in the field for over two-decades. This book encompasses both medical and technical developments and recent achievements. Here, the authors cover the field of application from the anterior to the posterior ocular segments (Part I) and present a comprehensive review on the development of OCT. Important developments towards clinical applications are covered in Part II, ranging from the adaptive optics to the integration on a slit-lamp, and passing through new structural and functional information extraction from OCT data. The book is intended to be informative, coherent and comprehensive for both the medical and technical communities and aims at easing the communication between the two fields and bridging the gap between the two scientific communities.
Download or read book Progress Towards Detecting Neural Activity in Optical Coherence Tomography Using Phase written by Jasmine Kavan Shah and published by . This book was released on 2017 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography (OCT) is non-invasive, real time optical imaging method based on low coherence interferometry with high resolution. It is capable of imaging microstructure by measuring the light backscattered from the sample. Under the AGI grant, I have built a Swept Source OCT (SS-OCT) / phase resolved OCT to detect the nanometer(nm) scale changes in the cell membrane that occur during membrane depolarization and Ion influx. This type of small changes can be seen using phase. Intensity is robust but is less sensitive to the small-scale changes whereas phase is highly sensitive. The noise level for phase difference quantification depends on the lateral motion, triggering of the wavelength mismatch and signal to noise ratio (SNR). To detect the nm scale changes phase noise should be minimum. The phase noise is inversely proportional to SNR. The SNR of the system should be maximum. The SS-OCT has swept source with sweep rate 100 kHz and it is not phase stable. It needs post processing algorithm to match the triggering wavelength to stabilize the phase. I wrote the code in GPU to reduce the computation time for post processing algorithm. Due to a few setbacks related to moving the system to a collaborating lab, the biological portion of my thesis work, trying to find the neural activity in the walking leg nerve of the Lobster using phase, was done with a spectral domain OCT (SD-OCT). To see any action potential change in the nerve I realigned the SD-OCT system with center wavelength to increase the SNR of the system and the sample arm with the nerve chamber (3D printed) to stimulate the nerve at one end and take the OCT image at the other end to see the action potential.
Download or read book Optical Coherence Tomography and Its Non medical Applications written by Michael Wang and published by BoD – Books on Demand. This book was released on 2020-05-27 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical coherence tomography (OCT) is a promising non-invasive non-contact 3D imaging technique that can be used to evaluate and inspect material surfaces, multilayer polymer films, fiber coils, and coatings. OCT can be used for the examination of cultural heritage objects and 3D imaging of microstructures. With subsurface 3D fingerprint imaging capability, OCT could be a valuable tool for enhancing security in biometric applications. OCT can also be used for the evaluation of fastener flushness for improving aerodynamic performance of high-speed aircraft. More and more OCT non-medical applications are emerging. In this book, we present some recent advancements in OCT technology and non-medical applications.
Download or read book Pseudo real time Retinal Layer Segmentation for OCT written by Worawee Janpongsri and published by . This book was released on 2019 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we present a pseudo-real-time retinal layer segmentation for high-resolution Sensorless Adaptive Optics-Optical Coherence Tomography (SAO-OCT). Our pseudo-real-time segmentation method is based on Dijkstra's algorithm that uses the intensity of pixels and the vertical gradient of the image to find the minimum cost in a geometric graph formulation in a limited search region. It segments six retinal layer boundaries in an iterative process according to their order of prominence. The segmentation time is strongly related to the number of retinal layers to be segmented. Our program permits en face images to be extracted during data acquisition to guide the depth specific focus control and depth dependent aberration correction for high-resolution SAO-OCT systems. The average processing times for our entire pipeline for segmenting six layers in a retinal B-scan of 992x400 pixels, 496x400 pixels and 240x400 pixels are around 23 ms, 26 ms and 14 ms, respectively.
Download or read book Development and Application of Optical Coherence Tomography OCT written by Michael Pircher and published by MDPI. This book was released on 2018-03-23 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Development and Application of Optical Coherence Tomography (OCT)" that was published in Applied Sciences
Download or read book Multi scale Optical Coherence Tomography Imaging written by Michael Christopher Oliveira and published by . This book was released on 2014 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: An optical modality capable of quantitative, label-free, high-speed and high-resolution imaging across spatiotemporal scales coupled with sophisticated software for image reconstruction and quantitative analyses would be of great utility to scientists and engineers in the medical and life sciences fields. Currently, a combination of optical imaging techniques and software packages are needed to address the list of capabilities described previously. Optical coherence tomography is an optical imaging technique based on low coherence interferometry capable of measuring light backscattered from the sample at micrometer-level resolutions over millimeter-level penetration depths in biological tissue. Phase-sensitive extensions of OCT enable the functional assessment of biological tissue samples as well as the structural examination of samples down to the single-cell level. This dissertation describes the development and application of high-speed real-time multi-functional spectral-domain OCT (MF-SD-OCT) for structural and functional examination of biological samples across spatiotemporal scales. A discussion of the development of a GPU-accelerated high-speed MF-SD-OCT imaging system accompanied by demonstrations of the performance enhancements due to the GPU are presented initially. Next, the development of MF-SD-OCT-based quantitative methods for the structural and functional assessment and characterization and classification of biological tissue samples is discussed. The utility of these methods is demonstrated through structural, functional and optical characterization and classification of peripheral nerve and muscle tissue. The dissertation concludes with a discussion of the improvements made to spectral-domain optical coherence phase microscopy (SD-OCPM) to enable dynamic live cell imaging and the application of dynamic live cell SD-OCPM for morphological visualization of cheek epithelial cells and examination of functionally stimulated morphological changes in neurons. The work described in this dissertation demonstrates the versatility of OCT imaging technology to perform quantitative, label-free, high-speed and high-resolution imaging across spatiotemporal scales, enabling the examination of native dynamic tissue and cellular physiology.
Download or read book Real time Retinal Blood Flow Imaging with Fourier Domain Optical Coherence Tomography written by Jing Xu and published by . This book was released on 2014 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: Optical Coherence Tomography (OCT) is a non-invasive micrometer-resolution depth resolved medical imaging tool for diagnostic visualization of the retinal structures in vivo. In this thesis, we first describe the capability of OCT for providing structural information by quantitative retinal thickness measurements in animal models of diseases causing vision loss. In the rest of the work described in this thesis, we focus on the development of an extension of OCT called speckle variance (sv) OCT, which provides functional information such as detecting capillaries within in the retina. Retinal capillary networks are critically linked to retinal neuronal health and disease. The ability to perform accurate in vivo examination of human retinal capillary networks is therefore valuable for studying mechanisms that govern retinal homeostasis and retinal vascular diseases. A real-time implementation of the svOCT provided by the GPU acceleration was described to provide visualization of en-face vasculature networks during acquisition. A qualitative comparison study was described in this thesis by comparing the retinal vasculature images acquired from svOCT and Florescence Angiography (FA) for both healthy and diseased patients. The capability of svOCT with respect to quantifying capillary network information has been also validated in this thesis. The results of these studies suggest that this GPU accelerated svOCT has the potential to non-invasively provide useful quantitative information about human retinal capillary networks, and may have clinical and research applications for the management of retinal microvascular diseases, a major cause of vision loss worldwide. To further adapt the svOCT to be more clinical friendly, preliminary work on enhancing the real-time visualization of vascular information from distinct retinal capillary beds during acquisition was proposed and implemented in this thesis.
Download or read book Image Processing in Optical Coherence Tomography Using Matlab written by Robert Koprowski and published by Robert Koprowski. This book was released on 2011 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the results of the creation of methods for ophthalmologists support in OCT images automated analysis. These methods, like the application developed on their basis, are used during routine examinations carried out in hospital. The monograph comprises proposals of new and also of known algorithms, modified by authors, for image analysis and processing, presented on the basis of example of Matlab environment with Image Processing tools. The results are not only obtained fully automatically, but also repeatable, providing doctors with quantitative information on the degree of pathology occurring in the patient. In this case the anterior and posterior eye segment is analysed, e.g. the measurement of the filtration angle or individual layers thickness. To introduce the Readers to subtleties related to the implementation of selected fragments of algorithms, the notation of some of them in the Matlab environment has been given. The presented source code is shown only in the form of example of implementable selected algorithm. In no way we impose here the method of resolution on the Reader and we only provide the confirmation of a possibility of its practical implementation.
Download or read book Real time Photon noise Limited Optical Coherence Tomography Based on Pixel level Analog Signal Processing written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the development of a CMOS smart imager for real-time optical coherency tomography (OCT). OCT, a measuring technique based on low-coherence interferometry, allows the acquisition of three-dimensional pictures of discontinuities in the refractive index of the sample. Due to the achieved depth resolution in the micrometer range, it has gained a lot of impact not only for many biomedical but also for industrial applications over the last few years. OCT allows the determination of surfaces as well as the acquisition of tomographic images of transparent and turbid objects with an outstanding depth resolution in the sub-micrometer scale over a depth range of up to several millimeters. The goal of this thesis was the realization of a very fast, robust 3D OCT system performing at close to the physical limit. A multi-channel approach has been chosen and a CMOS smart imager has been developed as they key component of the total system that includes an appropriate electrical, optical, and mechanical system. This system proves that by the use of parallel optical coherence tomography (pOCT) in combination with custom designed CMOS image sensors, real-time imaging with compact devices is realizable. For time domain (TD- ) OCT, the reference path length of the interferometer is varied and a simultaneous amplitude demodulation of the optical signal generates the depth image. The cross-sectional or volumetric image of a conventional TD-OCT system is generated by combining many laterally shifted one-dimensional depth scans throughout the object. Therefore, very fast reference path scanners and one or two translation stages are required. This results in a non-negligible mechanical system complexity. In pOCT, the translation scanners are replaced by image-forming optics and a two-dimensional image sensor. This step reduces the depth scan speed greatly and renders 3D image acquisition in some tens of milliseconds possible. On the other hand, the image sensor requiremen.
