Real-time 3D ultrasound imaging is based on volumetric beam steering and sweeping. Transducer capable to perform volumetric beamforming for medical imaging are typically two dimensional arrays of thousands of active elements. Electronic multiplexing and pre-beamforming is necessary in order to interface such arrays to conventional ultrasound scanners. This paper describes an alternative approach for volumetric beamforming based on a particular two dimensional array of a reduced number of elements obtained by superimposing two linear arrays on the same area. Capacitive Micromachined Ultrasonic Transducer (cMUT) technology is mentioned as a good candidate to approach the problem due to the possibility given by micromachining to fabricate arbitrarily shaped electrode patterns which define the array elements. The beamforming strategy is illustrated and assessed by means of beampattern calculations and synthetic 3D imaging formation. The resulting array is directly connectable to a standard imaging system.
Savoia, A.S., V., B., Caliano, G., Caronti, A., Carotenuto, R., Gatta, P., et al. (2007). Crisscross 2D cMUT array: beamforming strategy and synthetic 3D imaging results. In Ultrasonics Symposium, 2007. IEEE (pp.1514-1517) [10.1109/ULTSYM.2007.381].