Download or read book Light Scattering and Imaging Techniques Applied to Sonoluminescence and Ultrasound Contrast Bubbles written by Jingfeng Guan and published by . This book was released on 2004 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Sonoluminescence written by F. Ronald Young and published by CRC Press. This book was released on 2004-08-30 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: While it is still a mystery of how a low-energy-density sound wave can concentrate enough energy in a small enough volume to cause the emission of light, research in acoustic cavitation and sonoluminescence has lead to plausible theories in which the source of light can be experimentally sustained. It has also lead to promising applications, such a

Download or read book Acoustic Characterization of Contrast Agents for Medical Ultrasound Imaging written by L. Hoff and published by Springer Science & Business Media. This book was released on 2001-12-31 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The book consists of nine chapters. The first 3 chapters give a broad overview of the acoustic theory for bubble-sound interaction, both linear and nonlinear. Most contrast agents are stabilized in a shell, and this shell can have a strong influence on the interaction between the bubbles and the ultrasound. The effect of the shell is given special attention, as this is not easily found in other bubble literature. Chapters 4, 5, 6 and 7 describe experimental and theoretical methods used to characterize the acoustic properties of the agents, and results of studies on some agents. Chapter 8 shows how the theory and the experimental results can be combined and used to model various phenomena by means of computer simulations. The main purpose of the simulations is to get insight into the mechanisms behind the described phenomena, not to get accurate predictions and values.

Download or read book Sonochemistry and Sonoluminescence written by L.A. Crum and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt: Sonochemistry is studied primarily by chemists and sonoluminescence mainly by physicists, but a single physical phenomenon - acoustic cavitation - unites the two areas. The physics of cavitation bubble collapse, is relatively well understood by acoustical physicists but remains practically unknown to the chemists. By contrast, the chemistry that gives rise to electromagnetic emissions and the acceleration of chemical reactions is familiar to chemists, but practically unknown to acoustical physicists. It is just this knowledge gap that the present volume addresses. The first section of the book addresses the fundamentals of cavitation, leading to a more extensive discussion of the fundamentals of cavitation bubble dynamics in section two. A section on single bubble sonoluminescence follows. The two following sections address the new scientific discipline of sonochemistry, and the volume concludes with a section giving detailed descriptions of the applications of sonochemistry. The mixture of tutorial lectures and detailed research articles means that the book can serve as an introduction as well as a comprehensive and detailed review of these two interesting and topical subjects.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2004 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Ultrasonic Scattering in Biological Tissues written by K. Kirk Shung and published by CRC Press. This book was released on 2022-09-16 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrasonic Scattering in Biological Tissues contains 14 chapters written by world-renowned authorities who describe current work related to theoretical and experimental aspects of ultrasonic scattering phenomenon in biological tissues. Introductory material regarding ultrasonic scattering in biological tissues is presented, followed by discussions on theoretical treatments, experimental approaches, in vitro results on selective tissues, in vivo results on various tissues, and the current status of quantitative backscatter imaging. Ultrasonic Scattering in Biological Tissues will be an excellent reference for biomedical engineers, ultrasound specialists, biophysicists, and radiology researchers.

Download or read book Acoustic Characterization of Ultrasound Contrast Agents with Lipid coated Monodisperse Microbubbles written by Yanjun Gong and published by . This book was released on 2013 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Lipid-coated microbubbles, which have been widely used in diagnostic ultrasound as contrast agents, also show promising applications in medical therapy. The knowledge of acoustic behaviors and shell properties with respect to Ultrasound Contrast Agents (UCA) microbubbles can greatly enhance and extend their clinical applications. A polydimethylsiloxane (PDMS-based microfluidic flow-focusing device was fabricated to produce lipid-coated microbubbles with narrow size distribution and controllable mean diameters (3-12um). These monodisperse microbubbles show unique acoustic properties compared with commercial UCA microbubbles with wide size distribution, which makes it possible to investigate the relationship between microbubble size and attenuation coefficient, resonance frequency, or backscattering experimentally. Our studies show that monodisperse microbubbles can be tailored for optimal contrast enhancement in ultrasound imaging. By using an ultrasound spectroscopy method, the frequency-dependent attenuation coefficient for monodisperse microbubbles and polydisperse microbubbles were measured and compared. The results showed that decreasing the width of the microbubble size distribution would lead to a reduction in the bandwidth, and an increase in the magnitude of the attenuation spectrum. The resonance frequency determined by the attenuation coefficient peak was inversely proportional to the mean diameter of the monodisperse microbubble suspension. These conclusions corroborated the theoretical predications. The dependence of resonance frequency on acoustic pressure and lipid composition have also been examined and compared with theoretical calculations. The results demonstrated that the lipid shell of microbubbles behaviors nonlinearly, even at low pressure, which results in a decrease of resonance frequency as incident pressure was increased, approaching the resonance frequency of uncoated bubbles. Moreover, the length of the lipid hydrocarbon chain impacts the dependences of shell stiffness, attenuation coefficient, and resonance frequency on the excitation pressure. The frequency-dependent backscattering coefficients for monodisperse microbubbles have been investigated using a broadband pulses technique over different sizes, concentrations and pressures. The experimental results showed the same size-dependent resonance peaks as attenuation coefficient. It demonstrated that increasing the acoustic pressure caused a frequency shift of resonance peak, but no significant changes on magnitude. A linear dependence on microbubble concentration for backscatter coefficient was confirmed. In addition, the pressure-dependent backscattering coefficients at 2.25 MHz were studied. It is interesting to note that with the increase of incident pressure, the change of backscattering coefficients values, increase or decrease, were strongly dependent on the mean size of microbubbles.

Download or read book The Scattering of Light and Other Electromagnetic Radiation written by Milton Kerker and published by Elsevier. This book was released on 2016-06-03 with total page 685 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Scattering of Light and other Electromagnetic Radiation covers the theory of electromagnetic scattering and its practical applications to light scattering. This book is divided into 10 chapters that particularly present examples of practical applications to light scattering from colloidal and macromolecular systems. The opening chapters survey the physical concept of electromagnetic waves and optics. The subsequent chapters deal with the theory of scattering by spheres and infinitely long cylinders. These topics are followed by discussions on the application of light scattering to the determination of the size distribution of colloidal particles. The last chapters are devoted to the Rayleigh-Debye scattering and the scattering by liquids, as well as the concept of anisotropy. These chapters also describe the effect upon light scattering of partial orientation of anisotropic particles in electrical and magnetic fields and in viscous flow. This book is of value to physical chemists and physical chemistry researchers, teachers, and students.

Download or read book Acoustic Bubble Detection written by Donald C. Winter and published by . This book was released on 1972 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The acoustic-optical imaging process utilizes Bragg diffraction of light by a beam of sound to produce an optical image of an acoustically irradiated object. Inasmuch as many materials which are quite opaque to light are, to varying degrees, transparent to certain acoustic frequencies, the technique offers the possibility of visually examining the internal structure of optically opaque bodies. The imaging of internal features is made possible by the fact that different materials and structures often have different acoustic characteristics, thus causing the sound to be reflected, scattered, absorbed and diffracted. These factors cause perturbations in the acoustic wavefronts which are transformed in the light-sound interaction into a visual image, in real time, which may be observed by eye, photographed by a camera, or processed by other conventional optical methods. In addition to bubble detection, acoustic-optical imaging techniques appear to be applicable to a wide range of diagnostic procedures and methods of medical instrumentation where the ability to observe internal structures is of significance. (Author).

Download or read book Applied Optics written by and published by . This book was released on 1999 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Manipulating Microbubbles written by Alicia Clark and published by . This book was released on 2018 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultrasound contrast agents are micron-sized bubbles that are used for ultrasound imaging enhancement and that can potentially be used for targeted drug delivery applications. One strategy to manipulate them inside the cardiovascular system is to use the Bjerknes force, caused by the phase difference between a transmitted ultrasound pressure wave and the microbubble volume oscillations induced by the pressure wave. Although the mechanism causing this force is well established, the balance between ultrasound-induced forces and hydrodynamic forces is poorly understood when the microbubbles are immersed in physiologically-realistic Reynolds and Womersley number flows. In this thesis, experiments were conducted in a cylindrical tube under steady and pulsatile flows over a range of Reynolds and Womersley numbers relevant to drug delivery in the systemic circulation. Two experimental setups were developed: one in which the microbubbles were imaged using a clinical ultrasound imaging system, and a second in which they were imaged by high-speed video using a long distance microscope. In the ultrasound experimental setup, a commercial L15-7io transducer was used to image microbubbles in quiescent, steady, and pulsatile flows. These experiments were extended in the optical experimental setup to explore higher Reynolds numbers. In the optical experiments, individual microbubble trajectories were captured at high magnification and high temporal resolution to determine the relationship between acoustic and hydrodynamic forces. The relative scaling of these forces was computed for different acoustic pressure amplitudes and pulse repetition frequencies. The Bjerknes force scaled linearly with pulse repetition frequency and quadratically with acoustic amplitude. The displacement of the microbubbles due to the ultrasound decreased with increasing Reynolds number suggesting a threshold for clinical applications due to the residence time of microbubbles in the ultrasound beam.

Download or read book A Theoretical Evaluation of Ultrasonic Detection of Small Gas Bubbles written by William M. Carey and published by . This book was released on 1972 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The scattering of ultrasound (such as is commonly used in medical diagnosis) by small bubbles was analyzed. A bubble larger than the acoustic wavelength casts an acoustic shadow as predicted by geometric acoustics; a bubble the same size as the acoustic wavelength imparts strong directionality to the scattered wave. A bubble smaller than the acoustic wavelength radiates a scattered spherical wave of less than 0.1% of the incident energy because of dissipative losses. For a random distribution of these bubbles (of sub-wavelength size) the intensity of the scattered wave is directly proportional to the bubble density. A direct acoustic-optical imaging system (ultrasonic Bragg imaging) is insufficiently sensitive to detect bubbles smaller than an acoustic wavelength. The image detail in acoustic-optical imaging systems is limited by the acoustic wavelength, the numerical aperture of the optics, and spatially abrupt near-field acoustic intensity variations. (Modified author abstract).

Download or read book Ultrasound contrast agents written by Gaio Paradossi and published by Springer Science & Business Media. This book was released on 2010-07-16 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent advancements in nano/micro materials and related characterization approaches allow the design of a new type of ultrasound contrast agents (UCAs) with enhanced multifunctional behaviour. This is chance is also supported by the recent achievements in modelling and signal processing. This book provides the state of art of the research activity of two successful European projects, TAMIRUT and SIGHT, addressing an integrated system, encompassing the contrast agent, the hardware equipment and the processing strategies, as a key tool for a combined diagnostic and therapeutic approaches (theranostics) in medical ultrasound. The work provides a highlight of the state of art in the research of novel ultrasound contrast agents (UCAs). Main progresses on the multifunctional aspects of next-generation UCAs concern targeting and drug release properties, perfusion and biointerface behaviour, ultrasound scattering performance, signal processing, electronic equipment.

Download or read book Proceedings of Optical Tomography and Spectroscopy of Tissue written by and published by . This book was released on 1999 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Light and Ultrasound written by Ali Vakili and published by . This book was released on 2018 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In optical imaging, the depth and resolution are limited due to scattering. Unlike light, scattering of an ultrasound waves in tissue is negligible. Hybrid imaging methods such as ultrasound modulated optical tomography (UOT) use the advantages of both modalities. UOT tags light by inducing phase change caused by modulating the local index of refraction of the medium. The challenge in UOT is detecting the weak signal. The displacement induced by the acoustic radiation force (ARF) is another ultrasound effect that can be utilized to tag the light. It induces greater phase change, resulting in a stronger signal. Moreover, the absorbed acoustic energy generates heat, resulting in a change in the index of refraction and a strong phase change. Since the speckle pattern is governed by the phase of the interfering scattered waves speckle pattern analysis can obtain information about local displacement and temperature changes in the tissue. We have presented a model to simulate the insonation processes. Simulation results based on fixed-particle Monte Carlo and experimental results show that the signal acquired by utilizing ARF is stronger compared to UOT. The introduced mean irradiance change (MIC) signal reveals both thermal and mechanical effects of the focused ultrasound wave in different timescales. Simulation results suggest that variation in the MIC signal can be used to generate a displacement image of the medium. In addition to the displacement correlated image, the MIC signal can provide images based on the morphology of the tissue. The MIC signal can provide for tumor detection in a healthy tissue"--Author's abstract.

Download or read book Acoustic Characterization of Ultrasound Contrast Microbubbles and Echogenic Liposomes written by Shirshendu Paul and published by . This book was released on 2014 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micron- to nanometer - sized ultrasound agents, like encapsulated microbubbles and echogenic liposomes, are being actively developed for possible clinical implementations in diagnostic imaging and ultrasound mediated drug/gene delivery. Contrast microbubbles (1-10 micron in diameter) contain a low solubility gaseous core stabilized by an encapsulation made of lipids/proteins/polymers/surfactants. Echogenic liposomes (ELIPs), which combine the advantages of liposomes such as biocompatibility and ability to encapsulate both hydrophobic and hydrophilic drugs with a strong reflection of ultrasound, are also excellent candidates for concurrent ultrasound imaging and drug delivery applications. The primary objective of this thesis is to characterize the acoustic behavior and the ultrasound-mediated content release of these contrast agents for developing multi-functional ultrasound contrast agents. The first part of this thesis reports the investigation of encapsulated microbubbles utilized as ultrasound contrast agents, whereas the second part reports the experimental characterizations of echogenic liposomes (ELIPs) and echogenic polymersomes. Contrast microbubbles are nonlinear systems capable of generating a subharmonic response i.e., response at half the excitation frequency, which can improve image quality by providing a higher signal to noise ratio. However, design and development of contrast microbubbles with favorable subharmonic behavior requires accurate mathematical models capable of predicting their nonlinear dynamics. To this goal, 'strainsoftening' viscoelastic interfacial models of the encapsulation were developed and subsequently utilized to formulate a modified form of the Rayleigh-Plesset equation to model the nonlinear dynamics of these encapsulated microbubbles. A hierarchical twopronged approach of modeling -- a model is applied to one set of experimental data to obtain the model parameters (material characterization), and then the model isvalidated against a second independent experiment -- is demonstrated in this thesis for two lipid coated (Sonazoid"!and Definity®) and a few polymer (polylactide) encapsulated microbubbles. We performed in vitro acoustic characterization with these contrast microbubbles, i.e., determined the material properties of their encapsulations and compared model predictions with experimental observations. The nonlinear elastic models developed were successful in predicting several experimentally observed behaviors e.g., low subharmonic thresholds and "compression-only" radial oscillations. Results indicate that neglecting the polydisperse size distribution of contrast agent suspensions, a common practice in the literature, can lead to inaccurate predictions and unsatisfactory results. Recent numerical investigations of the nonlinear dynamics of encapsulated microbubbles from our group contradicted previously published experimental results on the dependence of subharmonic behaviors on ambient pressure. We wanted to investigate this issue through new in vitro acoustic experiments by designing a modified experimental setup. Preliminary results indicate that the previously published conclusion that subharmonic response from contrast microbubbles linearly decreases with increasing ambient pressure might not be correct under all excitation conditions; it may both increase or decrease under appropriate excitations in conformity with the results of numerical investigations. Experimental characterization of the ELIPs and polymersomes was performed with the goal of demonstrating their potential as ultrasound agents with simultaneous imaging and drug/gene delivery applications -- 'dual-purpose' contrast agents. Carefully performed experiments conclusively demonstrate the ultrasound reflectivity (echogenicity) of the liposomes prepared using an established protocol. Although, no subharmonic response from these ELIPs was observed, altering the constituents of the lipid bilayer and polymerizing it generated a subharmonic response indicating that the echogenic properties of ELIPs can be controlled by altering the preparation protocol. Our results indicate that the freeze-thaw cycle and lyophilization in presence of mannitol followed by reconstitution in a buffer was critical for generating echogenic response from these liposomes. A finite amount of mannitol (above 100 mM) proved critical for echogenicity, but increasing the mannitol concentration above that amount did not change the echogenicity. Lyophilized powders create a polydisperse suspension of liposomes upon reconstitution, which in turn results in a response without a distinct resonance peak. We believe that the echogenicity of the liposomes results from the larger diameter liposomes present in this polydisperse suspension. In spite of the conclusive experimental evidence of echogenicity, the underlying mechanisms are not completely understood primarily due to the uncertainty regarding the exact location of the gas pockets. An accurate knowledge of the locations and dimensions of the gas pockets is critical for developing improved mathematical models of their acoustic behaviors. For the experimental validation of the concept of 'dual-purpose' contrast agents, four novel formulations were investigated--a lipopeptide conjugated ELIP formulation that can be triggered by the extracellular enzyme matrix metalloproteinase-9 (MMP- 9), a polymer coated redox triggered ELIP formulation for cytosolic drug delivery, pH sensitive liposomes with tunable echogenicity capable of drug-release in mildly acidic micro-environment and redox sensitive echogenic polymersomes. Both in vitro acoustic studies and ultrasound imaging (the latter performed in NDSU by our collaborators) demonstrated the echogenicity of each of these formulations. Although, ultrasound excitation (

Download or read book Nonlinear Scattering of Ultrasound by Bubbles written by Brian Clare Eatock and published by . This book was released on 1981 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: