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http://hdl.handle.net/2440/37962
Pulsed terahertz (THz) systems are an emergent technology, finding diverse applications as they approach maturity. From their birth in the late 1980's to the wealth of alternate sources and imaging modalities now available, the rise has been fuelled by the expectation that this will prove a world changing technology. This Thesis takes an application focused approach and seeks to provide enabling systems and algorithms for the development of functional imaging systems with broad potential application in security inspection, non-destructive testing and biomedical imaging. Three dimensional pulsed THz imaging systems were first introduced in 1996 using a reflection-mode ultrasound-like configuration. This Thesis builds upon this former work by focusing on transmission mode tomography systems using pulsed THz radiation. Several novel 3D imaging modalities are introduced. The hardware architectures, based on optoelectronic generation and detection of THz radiation are described. Approximations to the wave equation are derived, allowing linear reconstruction algorithms to recover 3D structural information fromthe transmitted THz field. Finally the systems are demonstrated and the achievable resolution and image quality are investigated. Three imaging architectures are developed herein: 1. T-ray holography allows the 3D distribution of point scatters to be resolved based on a single projection image utilising a novel reconstruction algorithm based on the windowed Fourier transform and back-propagation of the Fresnel-Kirchhoff diffraction equation. 2. T-ray diffraction tomography utilises the diffracted THz field to allow a Helmholtz equation based, frequency-dependent reconstruction to be performed and the THz spectrum at each pixel to be calculated. 3. T-ray Computed Tomography (CT) uses analogous techniques to X-ray CT, based on the Radon transform, to provide 3D T-ray reconstructions of unprecedented fidelity. These techniques have important applications in material identification, which is investigated in the second part of this Thesis. Pulsed THz spectroscopy has been widely acclaimed for its potential to identify different materials based on their spectral properties. The second part of this Thesis presents algorithms towards this goal. Three case studies are performed focusing on biomaterial classification, anthrax detection and in vitro osteosarcoma cell differentiation. A classification framework is developed to process the THz spectral data and identify specific materials. A linear filter model is introduced to describe the system response of different materials, and the filter taps are utilised for feature extraction. This technique is demonstrated for biomaterial and anthrax classification. For cell differentiation a genetic algorithm is used to select deconvolved frequency components to train a classifier. In each case a high classification accuracy is demonstrated, highlighting the promise and potential of three dimensional T-ray inspection systems.Thesis (Ph.D.)--School of Electrical and Electronic Engineering, 2004. Language: en_US
Ultrasonic Communication Project, Phase 1, FY1999
2000-06-01
This Phase 1 project has been successful in identifying, exploring, and demonstrating methods for ultrasonic-based communication with an emphasis on the application of digital signal processing techniques. During the project, at the direction of the agency project monitor, particular attention was directed at sending and receiving ultrasonic data through air and through pipes that would be commonly found in buildings. Efforts were also focused on development of a method for transmitting computer files ultrasonically. New methods were identified and evaluated for ultrasonic communication. These methods are based on a technique called DFS. With DFS, individual alphanumeric characters are broken down into a sequence of bits, and each bit is used to generate a discrete ultrasonic frequency. Characters are then transmitted one-bit-at-a-time, and reconstructed by the receiver. This technique was put into practice through the development of LabVIEW{trademark}VIs. These VIs were integrated with specially developed electronic circuits to provide a system for demonstrating the transmission and reception/reconstruction of typed messages and computer files. Tests were performed to determine the envelope for ultrasound transmission through pipes (with and without water) versus through air. The practical aspects of connections, efficient electronics, impedance matching, and the effect of damping mechanisms were all investigated. These tests resulted in a considerable number of reference charts that illustrate the absorption of ultrasound through different pipe materials, both with and without water, as a function of distance. Ultrasound was found to be least attenuated by copper pipe and most attenuated by PVC pipe. Water in the pipe provides additional damping and attenuation of ultrasonic signals. Dramatic improvements are observed, however, in ultrasound signal strength if the transducers are directly coupled to the water, rather than simply attaching them to the outside of the pipe. A major accomplishment of this project was the development and integration of hardware and software into a fully functional ultrasonic communication system for demonstration purposes. The development of this system was a major deliverable of this project and has been successfully demonstrated to the program monitor. Major system considerations are discussed in this report, including signal conditioning electronics, speed and distance of transmission, triggering and noise filtering, and error checking. The methods employed by this system are believed to be capable of transmitting information over long distances (greater than 200 ft) under ideal conditions, and under extreme conditions if several improvements are made. Several improvements are suggested as follow-on work. Brief descriptions of these activities are given.
Through-Wall Communicatin of Low-Rate Digital Data Using Ultrasound
2006-09-27
Wireless communication is ineffective for communicating through a solid steel wall due to the shielding effect of the metal. In some cases, holes can be made in the wall to allow wires to pass through, enabling the transport of electronic data. However, holes are often undesirable because they can reduce the integrity of the wall. This paper describes several approaches for using ultrasound to communicate low-rate digital data through a steel wall. The techniques minimize the complexity and power consumption of the communications hardware on the side of the wall from which the data is being sent, supporting applications in which a sensor may be either permanently embedded in a structure or is difficult to reach for servicing. Both pulsed and continuous-wave ultrasound techniques are described. Experimental data is presented showing the performance of the techniques when implemented using 1 MHz transducers mounted on a 15.24 cm (6 inch) thick steel wall. The results show that data rates on the order of 500 bits per second are readily available using simple communications techniques. Higher rates are possible if equalization is used to mitigate the effects of the multipath propagation within the steel block.
The design, fabrication, and testing of beryllium capsules for resonant ultrasound experiments
1999-01-01
Inertial Confinement Fusion (ICF) ignition targets require smooth and well-characterized deuterium/tritium (DT) ice layers. Los Alamos is developing Resonant Ultrasound Spectroscopy (RUS) to measure the internal pressure in the targets at room temperature after filling with DT. RUS techniques also can detect and measure the amplitudes of low modal surface roughness perturbations of the target shell interior. The experiments required beryllium capsules with a nominal inside radius of 1 mm and a spherical outside radius of 3 mm. The capsules have various spherical harmonic contours up to mode 12 machined into their interior surfaces. The capsules are constructed from hemispheres using an epoxy adhesive and then filled to approx270 atm with helium or deuterium gas. This paper describes the adhesive joint design, machining techniques, and interior geometry ... >>
Studies on failure kind analysis of the radiologic medical equipment in general hospital
1999-01-01
This paper included a data analysis of the unit of medical devices using maintenance recording card that had medical devices of unit failure mode, hospital of failure mode and MTBF. The results of the analysis were as follows : 1. Medical devices of unit failure mode was the highest in QC/PM such A hospital as 33.9%, B hospital 30.9%, C hospital 30.3%, second degree was the Electrical and Electronic failure such A hospital as 23.5%, B hospital 25.3%, C hospital 28%, third degree was mechanical failure such A hospital as 19.6%, B hospital 22.5%, C hospital 25.4%. 2. Hospital of failure mode was the highest in Mobile X-ray device(A hospital 62.5%, B hospital 69.5%, C hospital 37.4%), and was the lowest in Sono devices(A hospital 16.76%, B hospital 8.4%, C hospital 7%). 3. Mean time between failures(MTBT) was the highest in SONO devices and was the lowest in Mobile X-ray devices which have 200 ... >>
Studies of superfluid 3H using ultrasound and heater induced flow
1987-01-01
An investigation of the attenuation and velocity of ultrasound in superfluid helium-3 was made with several unusual results. This work was done on an adiabatic nuclear demagnetization cryostat using a radio-frequency spectrometer to process the ultrasound signal. A key part of this system is the sound cell which uses quartz crystals for the transmitter and receiver. This sound cell was carefully designed and tested to achieve high gain, thus enabling operation at high frequencies. A melting-curve thermometer was used to provide temperature readings. Mass flow in the sound cell was provide dby a heater. Data runs in the superfluid A1 and A2 phases were made at 15 and 45 megahertz, and in fields of up to 3 Tesla. Several isolated regions of fluctuating attenuation and velocity were observed in the A1 phase. These results are unusual since they have not been seen before and do not have a ... >>
Sonoluminescence from aqueous solutions containing surface active solutes
1996-12-31
The sonoluminescence generated in water with pulsed 500 kHz ultrasound has been studied in the presence of different chain length aliphatic alcohols and the surfactant sodium dodecylsulfate(SDS). The ultrasound pulse widths used ranged from 1 ms to 10 ms, with duty cycles (on/off ratios) of 1:3 to 1:9. In the presence of alcohol the maximum signal decreased with increasing alcohol concentration, and the signal decline was more pronounced with increasing chain length of the alcohol. In the presence of SDS the opposite trend was observed; the maximum signal was significantly enhanced over that obtained in pure water. However, on the addition of 0.1 M NaCI to the SDS solution the emission signal decreased markedly. This result is significant since the addition of 0.1 M salt to pure water gave the same intensity as that of pure water. These results have been interpreted in terms of the ability of the alcohols to enhance bubble coalescence during pulsing. The higher the alcohol concentration in solution, the greater the amount that will be adsorbed at the bubble/water interface. The role of surface active solute molecules, in general, on the sonoluminescence yield from a pulsed ultrasound signal will be presented.
Report on Security 82. Bericht ueber die Security 82
1982-01-01
The 1982 trade fair Security 82 presented a variety of equipment and systems for protection and security in general. Apart from physical protection devices to prevent theft, a great number of fire protection devices, transmitting apparatus, locator systems, metal detectors, protective devices against signal interception, and complete alarm systems were exhibited and explained. By means of specifications and brief descriptions, sometimes with figures, predominantly passive and active infrared sensors, light and microwave sensors, ultrasound and microwave Doppler effect devices for indoor and outdoor physical protection, as well as other alarm systems and fire alarm systems or entry control systems are presented in this report. Design and functioning mode of the equipment presented are illustrated by explaining the fields of employment. (orig.)
Real-Time Ellipsometry-Based Transmission Ultrasound Imaging
2007-02-14
Ultrasonic imaging is a valuable tool for non-destructive evaluation and medical diagnosis. Reflection mode is exclusively used for medical imaging, and is most frequently used for nondestructive evaluation (NDE) because of the relative speed of acquisition. Reflection mode imaging is qualitative, yielding little information about material properties, and usually only about material interfaces. Transmission imaging can be used in 3D reconstructions to yield quantitative information: sound speed and attenuation. Unfortunately, traditional scanning methods of acquiring transmission data are very slow, requiring on the order of 20 minutes per image. The sensing of acoustic pressure fields as optical images can significantly speed data acquisition. An entire 2D acoustic pressure field can be acquired in under a second. The speed of data acquisition for a 2D view makes it feasible to obtain multiple views of an object. With multiple views, 3D reconstruction becomes possible. A fast, compact (no big magnets or accelerators), inexpensive, 3D imaging technology that uses no ionizing radiation could be a boon to the NDE and medical communities. 2D transmission images could be examined in real time to give the ultrasonic equivalent of a fluoroscope, or accumulated in such a way as to acquire phase and amplitude data over multiple views for 3D reconstruction (for breast cancer imaging, for example). Composite panels produced for the aircraft and automobile industries could be inspected in near real time, and inspection of attenuating materials such as ceramics and high explosives would be possible. There are currently three optical-readout imaging transmission ultrasound technologies available. One is based on frustrated total internal reflection (FTIR) [1,2], one on Fabry-Perot interferometry [3], and another on critical angle modulation [4]. Each of these techniques has its problems. The FTIR based system cannot currently be scaled to large aperture sizes, the Fabry-Perot system has never been fully implemented for area imaging, and the critical angle modulation system is not sensitive enough for medical imaging. We proposed an entirely new way of using acoustic pressure to modulate a light beam. This new technology should be sensitive enough to be useful for medical imaging and have a large enough aperture to speed acquisition by orders of magnitude over point sampling. Unfortunately, we were unable to bring this technology to fruition.
Radiation damage of polymers in ultrasonic fields
2008-07-01
Radiation damage has always been a topic of great interest in various fields of sciences. In this work, an attempt is made to probe into the effect of subthreshold ultrasonic waves on the radiation damage created by irradiation of deuterons in polymer samples wherein the polymer samples act as model systems. Two equal volumes of radiation damage were produced in a single polymer sample wherein a standing wave of ultrasound was introduced into one. Three polymers namely, Polycarbonate, Polymethylmethacrylate and Polyvinyl chloride were used in this work. Four independent techniques were used to analyze the irradiated samples and visualize the radiation damage. Interferometric measurements give a measure of the refractive index modulation in the irradiated sample. Polymers, being transparent, do not absorb in the visible region of the electromagnetic spectrum. UV-Vis absorption spectroscopy shows absorption peaks in the visible region in irradiated polymer samples. Ion irradiation causes coloration of polymers. The light microscope is used to measure the absorption of white light by the irradiated polymers. Positron annihilation spectroscopy is used to obtain a measure of the open volume created by irradiation in polymers. A comparison between the irradiated region and the region exposed to ultrasonic waves simultaneously with irradiation in a polymer sample shows the polymer specific influence of the ultrasonic standing wave. (orig.)
Program for fundamental and applied research of fuel cells in VNIIEF
1996-04-01
According to VNIIEF the integral part of development of fuel cell power plants is fundamental and applied research. This paper describes areas of research on molten carbonate fuel cells. Topics include the development of mathematical models for porous electrodes, thin film electrolytes, the possibility of solid nickel anodes, model of activation polarization of anode, electrolyte with high solubility of oxygen. Other areas include research on a stationary mode of stack operation, anticorrosion coatings, impedance diagnostic methods, ultrasound diagnostics, radiation treatments, an air aluminium cell, and alternative catalysts for low temperature fuel cells.
Predictive maintenance and inspection through airborne ultrasound technology
1997-12-31
Airborne ultrasound can be considered an ideal integrating technology in that these instruments can stand alone to detect a variety of potential problems or they can be used to support vibration and infrared inspection programs. Usually portable, these instruments detect leaks in both pressurized gas systems or vacuum systems and related equipment such as tanks, pipes, heat exchangers, valves and steam traps. Additional applications include inspection of high voltage apparatus for corona, arcing and tracking. They are used to trend bearing failure as well as to detect conditions such as lack of lubrication and rubbing. A brief overview of the technology, its applications and suggested inspection techniques are explained. (orig.) 2 refs.
Power ultrasound effects for in situ compatibilization of polymer-clay nanocomposites
2004-01-01
Polymer-clay nanocomposites of various concentrations were prepared by ultrasonically assisted polymerization and melt mixing processes. The sonication process using power ultrasonic wave was employed to enhance nano-scale dispersion during melt mixing of monomer, polymer and organically modified clay. According to the unique mode of power ultrasound wave, we expected enhanced breakup of layered silicate bundle and further reduction in the size of dispersed phase with better homogeneity compared to the in situ polymerization. The optimum conditions to perform stable exfoliated nanocomposites were studied by various compositions and conditions. Dispersion characteristics and morphology of the nanocomposites were verified by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Rheological behaviors were measured under dynamic frequency ... >>
On-machine sensors to measure paper mechanical properties. Final report
1993-10-01
The measurement of the velocity of ultrasound provides a nondestructive means to characterize the elastic stiffness properties of paper. The objective of this project is to develop sensors capable of measuring the velocity of ultrasound in the thickness and in-plane directions of moving paper webs. On-machine measurements would allow continuous monitoring of product quality as well as provide data for controlling the papermaking process. This final report first reviews the background and various technical approaches explored. Then the preferred configurations and examples of measurements on moving paper webs in the laboratory are presented and discussed. The report concludes with a summary of project results and recommendations for further developments. Transducers mounted in fluid-filled wheels are used to make thickness direction, ZD, ultrasound velocity measurements on paper webs moving in the nip between two such wheels. Comparisons of the arrival times of echo and transmitted pulses with and without the paper web in the nip provide a measure of the transit time and caliper. Bimorph transducers mounted in an aluminum cylinder are used for machine direction (MD) and cross direction (CD) in-plane measurements. These ZD and in-plane sensors are mounted on a web handler in the IPST laboratory.
Laser-ultrasound characterization of spherical objects. G.L. report No. 5097
1993-06-01
Ceramic bearing balls are desired for high-temperature, nonlubricated use, but because of brittleness, it is important to inspect them for small (1--10 {mu}m) surface defects. Resonance spectrum of a sphere can provide information about its material properties (shear, longitudinal wave velocities); surface wave resonant modes at high frequencies provide information about surface crack density. As surface waves encounter a defect, the resonant energy will be attenuated. By comparing the surface wave mode Quality factors (Q) between a perfect and an imperfect sphere, one can quickly detect the existence of surface imperfection; a single defect will reduce the surface wave resonant Q by about 30%. A non-contacting detection method is presented for measuring resonances of a sphere. A computer controlled system was constructed to excite resonances on a sphere with a transducer by a single Hertzian contact, and an optical heterodyne interferometer is used to detect both amplitude and phase of surface variations on the opposite pole of the sphere. This system can inspect bearing balls with diameters 12 to 1 mm.
High definition ultrasound imaging for battlefield medical applications
1996-06-23
A team has developed an improved resolution ultrasound system for low cost diagnostics. This paper describes the development of an ultrasound based imaging system capable of generating 3D images showing surface and subsurface tissue and bone structures. We include results of a comparative study between images obtained from X-Ray Computed Tomography (CT) and ultrasound. We found that the quality of ultrasound images compares favorably with those from CT. Volumetric and surface data extracted from these images were within 7% of the range between ultrasound and CT scans. We also include images of porcine abdominal scans from two different sets of animal trials.
Fuels Preparation Department monthly report, November 1962
1962-12-07
This document details activities of the Fuels Preparation Department during the month of November 1962.
Enhanced zero-valent metal permeable wall treatment of contaminated groundwater
1997-12-31
On-going research at the University of Central Florida, supported by NASA, is investigating the use of sonicated zero-valent metal permeable treatment walls to remediate chlorinated solvent contaminated groundwater. Use of ultrasound within the treatment wall is proposed to enhance and/or restore the activity of the zero-valent metal. Batch studies designed to evaluate the destruction of chlorinated hydrocarbons using enhanced zero-valent metal reduction found a nearly three-fold increase in reaction rates after ultrasound treatment. Column studies substantiated these results. It is hypothesized that ultrasound serves to remove corrosion products from the iron surface and will prolong the reactive life and efficiency of the permeable treatment wall, thus decreasing long-term costs of wall construction and maintenance.
1999-01-01
It has been shown that special mode of ultrasound treatment may be used for the improving the quality of initial and radiation degraded red GaP light diodes.The mechanism of investigated phenomena is discussed
2002-01-01
The pulser/receiver constitutes the most vital part of an ultrasonic flaw detector or an ultrasonic imaging system used for inspection of materials. The ultrasonic properties of the material and resolution requirements govern the choice of the frequency of ultrasound that can be optimally used. The pulser/receiver in turn decides the efficiency of excitation of the transducer and the overall signal to noise ratio of the system for best sensitivity and resolution. A variety of pulsers are used in the ultrasonic instruments employed for materials inspection. This report describes a square wave type of an ultrasonic pulser-receiver unit developed at Ultrasonic Instrumentation Section, Electronics Division, BARC. It has been primarily designed for excitation of the transducer that is used with a multi-channel ultrasonic imaging system ULTIMA 100M targeted for inspection ... >>
Defect engineering by ultrasound treatment in polycrystalline silicon
1995-08-01
By applying ultrasound treatment (UST) to bulk and thin film polycrystalline Si (poly-Si) we have found a dramatic improvement of recombination and transport properties. The increasing of minority carrier lifetime by as much as one order of magnitude was found in short diffusion length regions, while exhibiting a strong dispersion for entire solar-grade poly-Si wafer. Relevant mechanisms are attributed to ultrasound processing on crystallographic defects, as well as UST stimulated dissociation of Fe-B pairs followed by Fe{sub i} gettering. A spectacular improvement of hydrogenation efficiency in poly-Si thin-films on glass substrate is demonstrated by resistivity study and confirmed using spatially resolved photoluminescence and nanoscale contact potential difference mapping. By applying UST to commercial solar cells we found the increasing of cell efficiency at low light excitation.
Application of Ultrasonic Techniques for Brain Injury Diagnosis
1999-09-19
In this work, we evaluate methods for detecting brain injury using ultrasound. We have used simulations of ultrasonic fields in the head to model the phase distortion of the skull. In addition we present experimental data from the crania of large animals. The experimental data help us understand and evaluate the performance of different transducers in acquiring the backscatter data from the brain through the skull. Both the simulations and acquired data illustrate the superiority of lower-frequency (<= 1 MHz) ultrasonic fields for transcranial acquisition of signals from inside the brain. Additionally, the experimental work shows that the higher-frequency (5 MHz) ultrasound can also be useful in acquiring clean nearfield data to help detect the position of the inner boundary of the skull.
Advanced Imaging Catheter: Final Project Report
2001-07-20
Minimally invasive surgery (MIS) is an approach whereby procedures conventionally performed with large and potentially traumatic incisions are replaced by several tiny incisions through which specialized instruments are inserted. Early MIS, often called laparoscopic surgery, used video cameras and laparoscopes to visualize and control the medical devices, which were typically cutting or stapling tools. More recently, catheter-based procedures have become a fast growing sector of all surgeries. In these procedures, small incisions are made into one of the main arteries (e.g. femoral artery in the thigh), and a long thin hollow tube is inserted and positioned near the target area. The key advantage of this technique is that recovery time can be reduced from months to a matter of days. In the United States, over 700,000 catheter procedures are performed annually representing a market of over $350 million. Further growth in this area will require significant improvements in the current catheter technology. In order to effectively navigate a catheter through the tortuous vessels of the body, two capabilities must exist: imaging and positioning. In most cases, catheter procedures rely on radiography for visualization and manual manipulation for positioning of the device. Radiography provides two-dimensional, global images of the vasculature and cannot be used continuously due to radiation exposure to both the patient and physician. Intravascular ultrasound devices are available for continuous local imaging at the catheter tip, but these devices cannot be used simultaneously with therapeutic devices. Catheters are highly compliant devices, and manipulating the catheter is similar to pushing on a string. Often, a guide wire is used to help position the catheter, but this procedure has its own set of problems. Three characteristics are used to describe catheter maneuverability: (1) pushability -- the amount of linear displacement of the distal end (inside body) relative to an applied displacement of the proximal end (outside body); (2) torquability -- the amount of rotation of the distal end relative to an applied rotation of the proximal end; and (3) trackability -- the extent to which the catheter tracks along the guide wire without displacing it.
A- and B-mode ultrasound biometry in the proton beam irradiation of uveal melanomas
1984-01-01
Ultrasound biometry data were used for a treatment planning computer program that allows three-dimensional viewing of the eye containing a uveal melanoma. This program enables one to select an orientation of the eye relative to the path of the proton beam which best covers the tumor while avoiding important ocular structures. (Auth.)
1989-04-01
The first project deals with examining ceramics when they are in the green state, and evaluating the effect of density and mechanical property variations on the final hot-pressed parts. The second aspect of the project deals with the direct characterization of surface and near-surface defects that are induced by machining operations. For the ultrasonic inspection of green ceramics, it is necessary to introduce ultrasound in the sample without immersing it in water. The author`s approach is to develop air transducers based on using new types of matching layers. The paper describes the development of these air transducers. The work on the characterization of machining damage in ceramics considered the special problem of ball bearings. Ball bearings may be the first wide-range industrial application for hot-pressed ceramic materials. The major problem with the ball bearings is their sensitivity to small surface and near-surface defects. Presently, inspection is performed by optical microscopy. The author developed an amplitude and phase acoustic microscopy method and constructed a special fixture to rotate the ball bearings under a focused transducer.
A Comparison of Ultrasound Tomography Methods in Circular Geometry
2002-01-24
Extremely high quality data was acquired using an experimental ultrasound scanner developed at Lawrence Livermore National Laboratory using a 2D ring geometry with up to 720 transmitter/receiver transducer positions. This unique geometry allows reflection and transmission modes and transmission imaging and quantification of a 3D volume using 2D slice data. Standard image reconstruction methods were applied to the data including straight-ray filtered back projection, reflection tomography, and diffraction tomography. Newer approaches were also tested such as full wave, full wave adjoint method, bent-ray filtered back projection, and full-aperture tomography. A variety of data sets were collected including a formalin-fixed human breast tissue sample, a commercial ultrasound complex breast phantom, and cylindrical objects with and without inclusions. The resulting reconstruction quality of the images ranges from poor to excellent. The method and results of this study are described including like-data reconstructions produced by different algorithms with side-by-side image comparisons. Comparisons to medical B-scan and x-ray CT scan images are also shown. Reconstruction methods with respect to image quality using resolution, noise, and quantitative accuracy, and computational efficiency metrics will also be discussed.
3D ultrasound imaging for prosthesis fabrication and diagnostic imaging
1995-06-01
The fabrication of a prosthetic socket for a below-the-knee amputee requires knowledge of the underlying bone structure in order to provide pressure relief for sensitive areas and support for load bearing areas. The goal is to enable the residual limb to bear pressure with greater ease and utility. Conventional methods of prosthesis fabrication are based on limited knowledge about the patient`s underlying bone structure. A 3D ultrasound imaging system was developed at Sandia National Laboratories. The imaging system provides information about the location of the bones in the residual limb along with the shape of the skin surface. Computer assisted design (CAD) software can use this data to design prosthetic sockets for amputees. Ultrasound was selected as the imaging modality. A computer model was developed to analyze the effect of the various scanning parameters and to assist in the design of the overall system. The 3D ultrasound imaging system combines off-the-shelf technology for image capturing, custom hardware, and control and image processing software to generate two types of image data -- volumetric and planar. Both volumetric and planar images reveal definition of skin and bone geometry with planar images providing details on muscle fascial planes, muscle/fat interfaces, and blood vessel definition. The 3D ultrasound imaging system was tested on 9 unilateral below-the- knee amputees. Image data was acquired from both the sound limb and the residual limb. The imaging system was operated in both volumetric and planar formats. An x-ray CT (Computed Tomography) scan was performed on each amputee for comparison. Results of the test indicate beneficial use of ultrasound to generate databases for fabrication of prostheses at a lower cost and with better initial fit as compared to manually fabricated prostheses.
ultrasound studies of superfluid 3He in high magnetic fields
1986-01-01
Measurements of ultrasound propagation in superfluid helium-three in magnetic fields of up to 94 kG are reported. The experiments were performed on an adiabatic nuclear demagnetization cryostat using a sensitive radio frequency spectrometer. In addition to observing the expected collective mode splittings, an anomaly near the A-two transition was intensively investigated. The effect is interpreted in terms of a first order transformation in the superfluid I-texture driven by the second order bulk phase transition at the point. Numerical computations give fair agreement with the experimental data
Ultrasound-based guidance of intensity-modulated radiation therapy
2006-01-01
In ultrasound-guided intensity-modulated radiation therapy (IMRT) of prostate cancer, ultrasound imaging ascertains the anatomical position of patients during x-ray therapy delivery. The ultrasound transducers are made of piezoelectric ceramics. The same crystal is used for both ultrasound production and reception. Three-dimensional (3D) ultrasound devices capture and correlate series of 2-dimensional (2D) B-mode images. The transducers are often arranged in a convex array for focusing. Lower frequency reaches greater depth, but results in low resolution. For clear image, some gel is usually applied between the probe and the skin contact surface. For prostate positioning, axial and sagittal scans are performed, and the volume contours from computed tomography (CT) planning are superimposed on the ultrasound images obtained before radiation delivery at the ... >>
Ultrasound reflection-mode computerized tomography for in-vivo imaging of small organs
1987-01-01
Based on the theory of ultrasonic reflection-mode computerized tomography an imaging system has been developed which utilizes a conventional B-scanner in as multi-view operation mode. The superposition of several B-scans from different aspect angles of one cross-sectional area and a subsequent 2-dimensional inverse filtering is equivalent to transmission procedures known from X-ray CT-scanning. The system has high isotropic resolution and significant speckle reduction. Limited-angle imaging is possible. The system was applied for in-vivo imaging of small organs. Images of testicles, thyroids, and other objects verify theoretical results with respect to resolution and speckle reduction. Technical details of the imaging system as well as in-vivo imaging results are presented
Ultrasound in environmental protection - Recent developments
2002-07-01
There can be little doubt that there is an increasing interest in the development of new methods for environmental protection and remediation. Driven by the interests of scientists and engineers but increasingly by legislation a very wide range of new technologies is being examined. Amongst these power ultrasound is proving to be a front-runner and offers a wide range of applications. Not all of these are likely to become industrial realities nevertheless there are a few which have a real chance of adoption. Some of the stronger contenders are reviewed below. (orig.)
Ultrasound in environmental engineering. Papers
1999-07-01
This book presents recent research and state-of-the-art information on the scientific basis, modes of use, and engineering developments of ultrasound application in the field of environmental protection. The information is loosely grouped into the following themes: ultrasound and sonochemistry, design of sonoreactors, applications in water, waste water and sludge treatment: aggregation of suspended particles, degradation of hazardous pollutants, disinfection, disintegration of biosolids. Ultrasound is generated and applied at frequencies from 20 kHz to several MHz. Reactor design, applied intensity, duration of sonication, and physico-chemical parameters of the sonicated media influence ultrasound effects. Thus, ultrasound, at a first glance, is a complex and probably confusing matter. This book has been compiled from presentations held at the first workshop 'Ultrasound in Environmental Engineering' on March 22nd and 23rd, 1999, at the Technical University of Hamburg-Harburg in cooperation with the German Association for the Water Environment (ATV) and the DECHEMA e.V. (orig.)
1986-01-01
Diagnostic ultrasound was used as early as 1950 in attempts to detect malignant tumors within the human breast and brain. In the years following, however, little attention was paid to this method of imaging by the radiologic community. Extensive work with this technique was not begun until the 1960s, when bistable ultrasound enabled sonographers to display organ outlines for the first time. Prior to the development of bistable ultrasound, sonographic images were limited to A-mode displays, which were merely a series of amplitude spikes on a graph. Over the past 20 or so years, major advances in ultrasound technology have gradually taken us from the simple graphic A-mode display, through bistable organ outlines, to gray-scale images with excellent parenchymal detail, and finally to real-time ultrasound
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