Bioacoustics Research Lab
University of Illinois at Urbana-Champaign | Department of Electrical and Computer Engineering | Department of Bioengineering
Department of Statistics | Coordinated Science Laboratory | Beckman Institute | Food Science and Human Nutrition | Division of Nutritional Sciences | College of Engineering
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Title Measurement of mechanical properties of bone material in vitro by ultrasound reflection: Methodology and comparison with ultrasound transmission.
Author Antich PP, Anderson JA, Ashman RB, Dowdey JE, Gonzales J, Murry RC, Zerwekh JE, Pak CY.
Journal J Bone Miner Res
Volume
Year 1991
Abstract An ultrasound reflection technique was designed and implemented to study the mechanical properties of bone material. The technique uses the fact that an ultrasound beam produced in water undergoes total internal reflection off a bone sample at a critical angle formally related to the velocity of a pressure wave in bone. When the plane of scattering is rotated around the normal to the sample surface, the critical angle varies with a periodic dependence dictated by the intrinsic symmetry of the bone structure at the point being examined. Most current measurements of sound velocity are made using transmission techniques. A double-blind intercomparison between this technique and a transmission technique, which was previously validated against tensile mechanical testing, was performed for samples of isotropic materials and of human cortical bone. Strong correlations were found for both sets of samples. For the isotropic materials the velocities were approximately equal, but for bone they were on average 11% higher in reflection than in transmission. This was the result both of the higher frequency employed in reflection (3.5 rather than 2.25 MHz) and of the different effects of sample imperfections on the two measurements. In particular, the reflection technique used in this work studied the surface of the sample, but the ultrasound beam in the transmission method propagated through its interior. In assessing the mechanical properties of bone specimens by ultrasound, the reflection technique samples a discrete bone surface element and the transmission method analyzes the entire volume of the specimen. Thus the reflection technique may yield a measure of the mechanical property of bone trabeculae that is largely unaffected by the mass of the entire specimen, but mass and structural density of the specimen affect the transmission method.


Title Measurement of shockwave properties after the passage through a tissue mimicking material.
Author Granz B.
Journal Proc Ultrason Symp IEEE
Volume
Year 1994
Abstract Extracorporeally generated ultrasonic shock waves are successfully used in lithotripsy to disintegrate kidney stones. Their physical parameters in the focus and their disintegration efficiency characterized by water tank measurements exhibit remarkable discrepancies to clinical experiences..To stimulate and understand this clinical data we chose a liquid material (1,3 butanediol) in a polymer housing as a tissue phantom. This material coincides well with tissue for high amplitude applications in ultrasound speed, impedance , absorption, non-linearity parameter, and reaction to acoustic cavitation. Inserting this tissue mimicking material in the pulse passage we measured the pressure parameters near the focus and their disintegration efficiency..The impact of the thickness of a 80 mm and a 50 mm material is negligible. More important is the distance between the absorbers exit window and the stone to be disintegrated. Close to the window the effect of this absorbing material is largest, but it decreases the more the distance behind the absorber is traveled by the again steepening shock wave.


Title Measurement of spatial distribution of refractive index in tissues by ultrasonic computer assisted tomography.
Author Greenleaf JF, Johnson SA, Lent AH.
Journal Ultrasound Med Biol
Volume
Year 1978
Abstract No Abstract Available.


Title Measurement of the acoustic properties of a nerve-muscle preparation.as a function of physiologic state.
Author Bhagat P, Hajjar W, Kadaba M.
Journal Ultrasonics
Volume
Year 1976
Abstract Nerve-muscle preparations of Sprague Dawley rats were exposed to low dosage ultrasound. The objectives were to measure the velocity of propagation and attenuation of ultrasonic energy in both the relaxed and contracted states. A tension-measuring system and associated ultrasonic instrumentation were designed to measure the tension developed in stimulated muscle and its.corresponding acoustic parameters, ie the attenuation coefficient, alpha (db cm-1) and the velocity of propagation, c (ms-1). Each test was performed at ultrasonic frequencies 3.1, 5.35, and 7.68 MHz and with the preparation maintained at 23 +/- 0.5 degrees C. Attenuation of ultrasonic energy was observed to increase by 10 +/- 0.5% in the active state from its value in the relaxed state. The relation between the attenuation and the acoustic frequency was found to be approximately linear over the frequency range tested. The velocity of propagation in the active state did not change appreciably from its value in the relaxed state and was observed to be independent of the acoustic frequency in the range used.


Title Measurement of the intensity of ultrasound using the dilatometric method.
Author Szorek R, Zapior B.
Journal Acustica
Volume
Year 1978
Abstract No abstract available.


Title Measurement of the nonlinearity parameter B/A in biological materials using the finite amplitude and thermodynamic method.
Author Law WK.
Journal Thesis(PhD): Univ of Illinois
Volume
Year 1984
Abstract It is well-known that materials exhibit a decrease in compressibility when subjected to high compression. This decrease in compressibility may be described by the nonlinearity parameter B/A. Organic liquids have been shown to possess a wide variation of the parameter, ranging from 5 to 12. This thesis reports on the measurement of the parameter in biological materials, including tissue models and soft tissues. An acoustic method with the potential for in vivo measurements is developed for this purpose. The result of measurements is confirmed by a second method which determines the change of the sound of speed and hence the compressibility, which changes in hydrostatic pressure and temperature. The measurements indicate that: (1) B/A increases approximately linearly with solute concentration for protein solutions; (2) B/A is relatively insensitive to the molecular weight of the solute for a fixed concentration; (3) B/A ranges from 6.5 to 11 for various soft tissues is destroyed. It is felt that details of nonlinear ultrasonic propagation in living systems should contribute to the development of clinical diagnostic and therapeutic applications of ultrasound.


Title Measurement of the stiffness coefficients of a viscoelastic composite material with laser-generated and detected ultrasound.
Author Guilbaud S, Audoin B.
Journal J Acoust Soc Am
Volume
Year 1999
Abstract A point source-point receiver technique, based on laser generation and laser detection of acoustic waves, is used to measure the stiffness tensor of a composite material. Because of the dispersive nature of these materials, the acoustic signature provided in polymer matrix composites is difficult to interpret. A model for acoustic propagation in composites is developed to analyze the accuracy of the stiffness coefficients determined from the measured acoustic signals. The frequency dependence associated with viscoelastic rheology leads to the numerical implementation of a double inverse transform to calculate the surface displacement generated by a line impact. The model accurately predicts the focusing effects caused by anisotropy and the spreading of the signals caused by dispersion and attenuation. The predicted displacements are in good agreement with the result of experiments performed with a composite plate. The model is used to test a signal processing method based on wavelet transform to measure the group velocities of bulk waves propagating through the plate. Despite dispersion and echoes overlapping, the stiffness coefficients are identified from group velocities with good reliability. The process is then successfully applied to an actual viscoelastic composite material.


Title Measurement of the temperature increases generated in soft tissue by ultrasonic diagnostic Doppler equipment.
Author Filipczynski L.
Journal Ultrasound Med Biol
Volume
Year 1978
Abstract Temperature increases on the body surface from the use of two different ultrasonic Doppler blood flow meters were determined experimentally. Using a thermographic method it was shown that the temperature increase can be significant. Two continuous wave ultrasonic Doppler blood flow meters induced temperature increases on the body surface of 12.5 degrees C and 2.3 degrees C, respectively, after an insonation time of 100 sec. Theoretical estimates and experimental results have shown an approximate agreement in the values of the temperature increase.


Title Measurement of the total ultrasound energy absorbed by biological specimens in a reverberant field.
Author Christman CL.
Journal Thesis(MS): Catholic Univ of America
Volume
Year 1980
Abstract No abstract available.


Title Measurement of the ultrasonic energy radiated by transducers used in echography.
Author Baboux JC, Lakestani F, Perdrix M.
Journal Ultrasound Med Biol
Volume
Year 1979
Abstract No abstract available


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