Hybrid beamforming and steering with reconfigurable arrays.

Reconfigurable arrays offer an advantage over traditional ultrasound arrays because of their flexibility in channel selection. To improve ultrasound beamforming and coverage through beam steering, we propose a hybrid beamforming technique to elongate the depth of focus of transmit beams and a method of element selection that improves steering capabilities that take advantage of array reconfigurability using annular rings. A local minimization technique to optimize the hybrid aperture is discussed in this paper. The chosen hybrid apertures covering four focal zones result in improved range in depth of focus when compared with pure spherical beams via point spread functions (PSF) and lesion signal-to-noise ratio (LSNR) calculations. Improvements were statistically significant at focal depth extremes. Our method of beam steering utilizing a quantized phase delay selection to minimize delay errors indicated better performance by removing an artifact present with traditional ringed element selection.