Simulation of a Modified Multielement Random Phased Array for Image Guidance and Therapy

Random phased arrays have been shown to produce single and multiple foci to ablate tumors deep in the body with out damaging the intervening tissues. Simulations are performed to improve element distribution of an existing random phased array to enhance its performance by minimizing grating and side lobes, increasing intensity at the focus and maximizing the steering range. Field distributions are calculated both in lateral and axial planes. Multiple simultaneous foci are generated and steered in 3D volume. It was observed that the therapeutic operating field is up to 4 cm in lateral and 6 cm in axial directions. Secondary hotspots having magnitude less than 15% of the main lobe appear when a single focus is steered more than 15 mm away from the axis. Improvements in terms of peak pressure amplitude and reduced sidelobes have been observed. Synthetic aperture beamforming was used to reconstruct images of interest to demonstrate that the modified array is suitable for image guidance having good spatial resolution near the geometric focus.