High-resolution real-time three-dimensional acoustic imaging system with a reflector

Purpose. We propose an acoustic real-time three-dimensional (3-D) diagnostic imaging system based on a hybrid array-reflector configuration that realizes high time and spatial resolutions with a modest computational load. Methods. All the elements on a small dense array were excited with proper time delays to transmit a broad beam similar to that of a single transmitter element. The echo was gathered by a concave reflector and received by the dense array. The image of the target was reconstructed by numerical back projection from the defocused image distributed on the array. With this scheme, images of the whole measurement area can be reconstructed from a single transmit and receive event. Results. The number of elements can be reduced to about 1/8.2 that of a dense 2-D array of a digital beamforming system having the same spatial resolution. By weighting individual elements, the sidelobe level could be suppressed to less than -21 dB. The maximum theoretical frame rate is 5000 3-D images/s. This method has a higher signal-to-noise ratio than that of defocused multi-element digital beamforming methods, overcoming conventional phased array performance. Conclusion. The proposed scheme is suited for purposes that require high time and spatial resolutions, such as cardiology.