Download or read book Model of image formation and 2D velocity estimation with a high frequency swept scan ultrasound imaging system anglais written by Yang Liu Li and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Imaging and Velocity Analysis by Target oriented Wavefield Inversion written by Yaxun Tang and published by Stanford University. This book was released on 2011 with total page 239 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis develops a novel target-oriented inversion framework that uses wavefields as carriers of information to image both low-wavenumber component (a.k.a. background velocity) and high-wavenumber component (a.k.a. reflectivity) of the earth model in complex geological settings, such as subsalt regions. I address the problem of reflectivity imaging with target-oriented wavefield least-squares migration, and the problem of velocity estimation with target-oriented wavefield tomography. Reflectivity images of the subsurface are commonly produced by prestack depth migration. When the overburden is complex and the reflectors are unevenly or insufficiently illuminated, the migration operator alone is inadequate to provide an optimal image. I tackle the problem of distorted illumination in reflectivity imaging by wavefield least-squares migration. I formulate least-squares migration in the image domain and solve it in a target-oriented fashion. In the image-domain formulation, explicit computation of the Hessian operator (the resolution function that measures the illumination deficiency of the imaging system) is the most important and challenging step. I develop a novel method based on phase encoding to efficiently and accurately compute the target-oriented Hessian operator. The Hessian operator is then used to recover the reflectivity by iterative inverse filtering. I regularize the inversion with dip constraints, which naturally incorporate interpreted geological information into the inversion. Accurate imaging of the reflectivity also requires an accurate background velocity model. High-quality velocity model-building in complex geology requires wavefield-based velocity analysis to properly model band-limited wave phenomena. However, the high cost and lack of flexibility of target-oriented model-building prevent this method from being widely used in practice. I overcome the cost and flexibility issues of wavefield-based migration velocity analysis by developing target-oriented wavefield tomography. Target-oriented wavefield tomography is achieved by synthesizing a new data set specifically for velocity analysis. The new data set is generated based on an initial unfocused target image and by a novel application of generalized Born wavefield modeling, which correctly preserves velocity kinematics by modeling both zero and non-zero subsurface-offset-domain images. The new data set can be synthesized for a chosen target region with velocity inaccuracies. The reduced data size and computation domain, therefore, greatly improve the efficiency and flexibility of wavefield tomography, allowing fast and interpretation-driven interactive wavefield-based velocity analysis, where different geological scenarios or hypotheses can be tested in quasi-real time. The proposed target-oriented inversion framework successfully estimates subsalt velocities and recovers subsalt reflectivities from distorted illumination from 2-D synthetic and 3-D field data.
Download or read book Basic Physics of Ultrasonographic Imaging written by N. M. Tole and published by World Health Organization. This book was released on 2005 with total page 106 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present volume on basic physics of ultrasonographic imaging procedures provides clear and concise information on the physics behind ultrasound examinations in diagnostic imaging. It attempts to present the subject from a simple approach that should make it possible for the target groups to comprehend the important concepts which form the physical basis of ultrasonic imaging. The main target group of this manual is radiological technologists and radiographers working with diagnostic ultrasound in developing countries. Clinicians and nurse practitioners may also find the simple presentation appealing. A conscious effort has been made to avoid detailed mathematical treatment of the subject. The emphasis is on simplicity.
Download or read book Generating Pictures from Waves written by Anthony Joseph Accardi and published by . This book was released on 2010 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research communities, technologies, and tools for image formation are diverse. On the one hand, computer vision and graphics researchers analyze incoherent light using coarse geometric approximations from optics. On the other hand, array signal processing and acoustics researchers analyze coherent sound waves using stochastic estimation theory and diffraction formulas from physics. The ability to inexpensively fabricate analog circuitry and digital logic for millimeter-wave radar and ultrasound creates opportunities in comparing diverse perspectives on image formation, and presents challenges in implementing imaging systems that scale in size. We present algorithms, architectures, and abstractions for image formation that relate the different communities, technologies, and tools. We address practical technical challenges in operating millimeter-wave radar and ultrasound systems in the presence of phase noise and scattering. We model a broad class of physical phenomena with isotropic point sources. We show that the optimal source location estimator for coherent waves reduces to processing an image produced by a conventional camera, provided the sources are well separated relative to the system resolution, and in the limit of small wavelength and globally incoherent light. We introduce quasi light fields to generalize the incoherent image formation process to coherent waves, offering resolution tradeoffs that surpass the traditional Fourier uncertainty principle by leveraging time-frequency distributions. We show that the number of sensors in a coherent imaging array defines a stable operating point relative to the phase noise. We introduce a digital phase tightening algorithm to reduce phase noise. We present a system identification framework for multiple-input multiple-output (MIMO) ultrasound imaging that generalizes existing approaches with time-varying filters. Our theoretical results enable the application of traditional techniques in incoherent imaging to coherent imaging, and vice versa. Our practical results suggest a methodology for designing millimeter-wave imaging systems. Our conclusions reinforce architectural principles governing transmitter and receiver design, the role of analog and digital circuity, and the tradeoff between data rate and data precision.
Download or read book Despeckle Filtering Algorithms and Software for Ultrasound Imaging written by Christos Loizou and published by Springer Nature. This book was released on 2008-06-27 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is well-known that speckle is a multiplicative noise that degrades image quality and the visual evaluation in ultrasound imaging. This necessitates the need for robust despeckling techniques for both routine clinical practice and teleconsultation. The goal for this book is to introduce the theoretical background (equations), the algorithmic steps, and the MATLABTM code for the following group of despeckle filters: linear filtering, nonlinear filtering, anisotropic diffusion filtering and wavelet filtering. The book proposes a comparative evaluation framework of these despeckle filters based on texture analysis, image quality evaluation metrics, and visual evaluation by medical experts, in the assessment of cardiovascular ultrasound images recorded from the carotid artery. The results of our work presented in this book, suggest that the linear local statistics filter DsFlsmv, gave the best performance, followed by the nonlinear geometric filter DsFgf4d, and the linear homogeneous mask area filter DsFlsminsc. These filters improved the class separation between the asymptomatic and the symptomatic classes (of ultrasound images recorded from the carotid artery for the assessment of stroke) based on the statistics of the extracted texture features, gave only a marginal improvement in the classification success rate, and improved the visual assessment carried out by two medical experts. A despeckle filtering analysis and evaluation framework is proposed for selecting the most appropriate filter or filters for the images under investigation. These filters can be further developed and evaluated at a larger scale and in clinical practice in the automated image and video segmentation, texture analysis, and classification not only for medical ultrasound but for other modalities as well, such as synthetic aperture radar (SAR) images. Table of Contents: Introduction to Ultrasound Imaging / Despeckle Filtering Algorithms / Evaluation Methodology / Applications of Despeckle Filtering in Ultrasound Imaging / Comparison and Discussion of Despeckle Filtering Algorithms / Summary and Future Directions
Download or read book High Resolution Imaging in Microscopy and Ophthalmology written by Josef F. Bille and published by Springer. This book was released on 2019-08-13 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book provides a comprehensive overview of the application of the newest laser and microscope/ophthalmoscope technology in the field of high resolution imaging in microscopy and ophthalmology. Starting by describing High-Resolution 3D Light Microscopy with STED and RESOLFT, the book goes on to cover retinal and anterior segment imaging and image-guided treatment and also discusses the development of adaptive optics in vision science and ophthalmology. Using an interdisciplinary approach, the reader will learn about the latest developments and most up to date technology in the field and how these translate to a medical setting. High Resolution Imaging in Microscopy and Ophthalmology – New Frontiers in Biomedical Optics has been written by leading experts in the field and offers insights on engineering, biology, and medicine, thus being a valuable addition for scientists, engineers, and clinicians with technical and medical interest who would like to understand the equipment, the applications and the medical/biological background. Lastly, this book is dedicated to the memory of Dr. Gerhard Zinser, co-founder of Heidelberg Engineering GmbH, a scientist, a husband, a brother, a colleague, and a friend.
Download or read book Estimation of Blood Velocities Using Ultrasound written by Jørgen Arendt Jensen and published by . This book was released on 2013 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Study of the High Frame Rate Imaging Method and Its Application to the Strain and Strain Rate Imaging written by Hong Chen and published by . This book was released on 2012 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: The high frame rate imaging method is expected to be a leading technology of ultrasound imaging in the future. In this dissertation, the high frame rate imaging method is further studied, and the applications of the high frame rate imaging method are explored. To achieve the real-time 3D ultrasound imaging with a full 2D ultrasound transducer in a high frame rate imaging system, a new model of an ultrasound probe is proposed using the data compression technique. Raw echo data is first compressed by the JPEG algorithm, and then transferred to the image processing system with a reasonable number of wires in the cable connecting an ultrasound probe and the image processing system. The results show that the quality of the image after the JPEG data compression technique is still close to the image before the data compression. In addition, the effects of phase aberration and noise on the high frame rate imaging method is quantitatively studied. The parameters of energy ratio and sidelobe ratio are proposed and combined with the traditional -6-dB lateral resolution to analyze the image quality over the entire imaging area. The results show that the high frame rate imaging method has higher lateral resolution than the D & S imaging method, and the high frame imaging method is influenced less by the phase aberration and noise than the D & S imaging method. The results also indicate that the proposed parameters of energy ratio and sidelobe ratio could potentially be used for the correction of phase aberration. Finally, the high frame rate imaging method is applied to the strain and strain rate imaging of soft tissues. The two dimensional speckle tracking technique is used to measure the values of strain and strain rate. In the speckle tracking technique, the algorithm of the summation of absolute difference is used to search matched blocks between two consecutive images. Both simulation and experimentation studies were conducted to verify the method of applying the high frame rate imaging method to estimate the strain and strain rate. It is found that the high frame rate imaging method can be used to accurately measure the strain and strain rate. Considering the long computation time of speckle tracking, a new kernel using two crossing diagonal lines is proposed. The results of the preliminary study show that it is possible for the new kernel to reduce the computation time while retaining the accuracy of the estimation of strain and strain rate various imaging methods.
Download or read book Ultrasound Elastography written by Monica Lupsor-Platon and published by BoD – Books on Demand. This book was released on 2020-03-04 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: Elastography, the science of creating noninvasive images of mechanical characteristics of tissues, has been rapidly evolving in recent years. The advantage of this technique resides in the ability to rapidly detect and quantify the changes in the stiffness of soft tissues resulting from specific pathological or physiological processes. Ultrasound elastography is nowadays applied especially on the liver and breast, but the technique has been increasingly used for other tissues including the thyroid, lymph nodes, spleen, pancreas, gastrointestinal tract, kidney, prostate, and the musculoskeletal and vascular systems. This book presents some of the applications of strain and shear-wave ultrasound elastography in hepatic, pancreatic, breast, and musculoskeletal conditions.
Download or read book Design and Analysis of a High frequency Needle based Ultrasound Imaging System written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Impulse Response Synthesis in Ultrasound Imaging for Vectorial Displacement Estimation written by Hervé Liebgott (Auteur d'une thèse en acoustique (2005))) and published by . This book was released on 2005 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work of this thesis deals with tissue elasticity imaging with ultrasound, also called elastography. The principle of the method is to estimate, by signal and image processing, the displacement or strain that appears in a tissue when it is mechanically compressed. This work proposes a displacement vector estimation method between two ultrasound images based on the search of the zero crossing of the complex correlation between signals taken in the ultrasound image. The image formation is adapted to the requirements of the estimator and an impulse response showing oscillations in both directions of the image is synthesized. The quality of the estimated displacement maps is highly increased thanks to the use of this impulse response. Simulation and experimental results acquired with a Danish research ultrasound scanner illustrate the work.
Download or read book Software Design of a High Frequency Ultrasound Imaging System written by Horst Eyermann and published by . This book was released on 1996 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diagnostic Ultrasound written by Peter R. Hoskins and published by Cambridge University Press. This book was released on 2010-06-17 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: All healthcare professionals practising ultrasound in a clinical setting should receive accredited training in the principles and practice of ultrasound scanning. This second edition of Diagnostic Ultrasound: Physics and Equipment provides a comprehensive introduction to the physics, technology and safety of ultrasound equipment, with high quality ultrasound images and diagrams throughout. It covers all aspects of the field at a level intended to meet the requirements of UK sonography courses. New to this edition: • Updated descriptions of ultrasound technology, quality assurance and safety. • Additional chapters dedicated to 3D ultrasound, contrast agents and elastography. • New glossary containing definitions of over 500 terms. The editors and contributing authors are all authorities in their areas, with contributions to the scientific and professional development of ultrasound at national and international level.
Download or read book Electromagnetic Models for Ultrasound Image Processing written by Hugo Ariel Navarrete Hurtado and published by . This book was released on 2016 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt: Speckle noise appears when coherent illumination is employed, as for example Laser, Synthetic Aperture Radar (SAR), Sonar, Magnetic Resonance, X-ray and Ultrasound imagery. Backscattered echoes from the randomly distributed scatterers in the microscopic structure of the medium are the origin of speckle phenomenon, which characterizes coherent imaging with a granular appearance. It can be shown that speckle noise is of multiplicative nature, strongly correlated and more importantly, with non-Gaussian statistics. These characteristics differ greatly from the traditional assumption of white additive Gaussian noise, often taken in image segmentation, filtering, and in general, image processing; which leads to reduction of the methods effectiveness for final image information extraction; therefore, this kind of noise severely impairs human and machine ability to image interpretation. Statistical modeling is of particular relevance when dealing with speckled data in order to obtain efficient image processing algorithms; but, additionally, clinical ultrasound imaging systems employ nonlinear signal processing to reduce the dynamic range of the input echo signal to match the smaller dynamic range of the display device and to emphasize objects with weak backscatter. This reduction in dynamic range is normally achieved through a logarithmic amplifier i.e. logarithmic compression, which selectively compresses large input signals. This kind of nonlinear compression totally changes the statistics of the input envelope signal; and, a closed form expression for the density function of the logarithmic transformed data is usually hard to derive. This thesis is concerned with the statistical distributions of the Log-compressed amplitude signal in coherent imagery, and its main objective is to develop a general statistical model for log-compressed ultrasound B-scan images. The developed model is adapted, making the pertinent physical analogies, from the multiplicative model in Synthetic Aperture Radar (SAR) context. It is shown that the proposed model can successfully describe log-compressed data generated from different models proposed in the specialized ultrasound image processing literature. Also, the model is successfully applied to model in-vivo echo-cardiographic (ultrasound) B-scan images. Necessary theorems are established to account for a rigorous mathematical proof of the validity and generality of the model. Additionally, a physical interpretation of the parameters is given, and the connections between the generalized central limit theorems, the multiplicative model and the compound representations approaches for the different models proposed up-to-date, are established. It is shown that the log-amplifier parameters are included as model parameters and all the model parameters are estimated using moments and maximum likelihood methods. Finally, three applications are developed: speckle noise identification and filtering; segmentation of in vivo echo-cardiographic (ultrasound) B-scan images and a novel approach for heart ejection fraction evaluation.
Download or read book Standard Methods for Calibration of Two Dimensional and Three Dimensional Spatial Measurement Capabilities of Pulse Echo Ultrasound Imaging Systems written by American Institute of Ultrasound in Medicine and published by . This book was released on 2004-01-01 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt: This document describes techniques for the calibration of measurement systems as found in pulse echo ultrasonic imaging systems. The calibration techniques described are designed to be used with any type of pulse-echo imaging system and the measurement tools on the imaging system. The calibration techniques are designed to be carried out with test objects that are stable and reproducible. The measurement techniques for 3D imaging are described under the assumption that image volumes are formed from series of image planes. However, the techniques could be adapted to image volume formation in other formats.
Download or read book Digital Image Enhancement Algorithms for 2D Ultrasound Imaging Systems written by Fan Zhang and published by . This book was released on 2007 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Medical Imaging Systems written by Andreas Maier and published by Springer. This book was released on 2018-08-02 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book gives a complete and comprehensive introduction to the fields of medical imaging systems, as designed for a broad range of applications. The authors of the book first explain the foundations of system theory and image processing, before highlighting several modalities in a dedicated chapter. The initial focus is on modalities that are closely related to traditional camera systems such as endoscopy and microscopy. This is followed by more complex image formation processes: magnetic resonance imaging, X-ray projection imaging, computed tomography, X-ray phase-contrast imaging, nuclear imaging, ultrasound, and optical coherence tomography.
