Research Abstracts Online
January 2010 - March 2011
University of Minnesota Twin Cities
College of Science and Engineering
of Electrical and Computer Engineering
PI: Emad S. Ebbini
Wavefield Synthesis Using Dual-Mode Ultrasound Arrays
Image-guided noninvasive surgery using high-intensity focused ultrasound (HIFU) has recently been approved for the treatment of prostate cancer, uterine fibroids, and other tissue abnormalities. Ultrasound phased arrays are being increasingly utilized as HIFU applicators, both clinically and in research laboratories around the world. Phased arrays offer obvious advantages such as electronic scanning, which simplifies the machine-patient interface and allows for improved focusing by compensating for tissue aberration in the path of the HIFU beam. These researchers have introduced and recently demonstrated the concept of dual-mode ultrasound array (DMUA) systems for image-guided surgery. DMUAs offer unique advantages in the optimization of single- and multiple-focus HIFU wavefields due to the inherent registration between their imaging and therapy coordinate systems. This registration allows the physician to identify the target and/or critical structures on DMUA-generated images and immediately decide on the optimization parameters of the wavefield pattern that maximizes the power deposition at the target while minimizing the exposure to the critical structures, e.g. exposure to the ribs while targeting liver and kidney tumors.
Treatment planning for the use of DMUA systems in image-guided surgery presents several challenging computational problems requiring significant computational resources. For example, high-intensity ultrasound is inherently nonlinear with dynamic depletion and replenishment of harmonic components within the wavefield requiring specialized computationally intensive modeling. This is necessary due to the contribution of the higher harmonics to the therapeutic outcome at the target and the critical points. These researchers are interested in the synthesis of single- and multiple-focus HIFU wavefields that maximizes the energy in the higher harmonics at the target location(s) while minimizing the higher harmonic contribution at the critical points.
Mohamed Almekkawy, Graduate Student