Showing papers by "Osama M. Mukdadi published in 2007"

P5A-10 Assessment of Human Jawbone Using Ultrasonic Guided Wave: In Vitro Study

Abstract: This work is motivated by the lack of current imaging modalities to accurately predict the mechanical properties and defects in jawbone. Ultrasonic guided waves are sensitive to changes in microstructural properties and thus have been widely used for non-invasive material characterization. Guided waves propagating along the mandibles may exhibit dispersion behavior which depends on material properties, geometry and embedded cavities. In this work, we present the first theoretical and experimental study for the analysis of guided wave propagation in jawbone. Semi-analytical finite-element (SAFE) method is employed to analyze dispersion behavior of guided waves propagating in human mandibles. The cross section of the mandible is divided in two regions representing the cortical and trabecular bones. The experimental set-up for the guided waves experiment is described. Gabor Wavelet is used to calculate the experimental dispersion behavior from the ultrasound radio frequency (RF) signals. Results from both numerical analysis and guided waves experiment exhibit variations in the group velocity of the first arrival signal and also in the dispersion behavior of healthy and defected mandibles. These results shall provide a means to non-invasively characterize the jawbone and assess the bone mechanical properties.

Entropy Based Phase Aberration Correction Technique in Ultrasound Imaging

Abstract: Ultrasound technology has been widely used in medical imaging. Techniques using phased array transducers use an array of transducer elements to transmit a focused beam into the body, and each element then becomes a receiver to collect the echoes. The received echoes from each element are dynamically focused to form an image. These systems assume a constant acoustic velocity in the tissue of 1540 m/s while steering and focusing the beam. However, soft tissues have a range of acoustic velocities that vary from 1470 m/s for fat to 1665 m/s for collagen [1]. The acoustic wavefront propagation through a region with locally different acoustic velocities will be phase shifted relative to the rest of the wavefront. This effect is known as phase aberration. The effects of phase aberration include broadening of the system point spread function that deteriorate the image resolution, and increasing the off-axis response leading to multiple images for the target [2].© 2007 ASME