A compact concave array for cardiac imaging

A novel prototype scanhead was developed specifically for cardiac imaging. The transducer used a concave geometry to steer and pivot the beam through a `keyhole´ acoustic window near the skin line between the ribs. A soft, compliant fluid-filled nose compartment was designed as an integral part of the probe. The array was built on a radius of curvature of 17.14 mm, a pitch of 0.422 mm, contained 80 active elements, and used an RTV lens to focus the short axis. The concave array performance is compared to that of the convex and classical phased arrays. The scanhead was judged to be superior to a convex 15-mm probe and was found to be comparable in performance to the phased array. A key technical problem that had to be resolved was the near-field clutter and reverberations encountered when doing cardiac imaging through ribs