Specular Beamforming

Acoustically hard objects, such as bones, needles, or catheters, are poorly visualized in conventional ultrasound images. These objects behave like acoustic mirrors and reflect sound in specific directions. Soft tissue and diffusive reflectors scatter sound in a broad range of directions. Conventional delay-and-sum beamforming is based on the assumption of a purely scattering domain with relatively weak reflectivity. We present an adaptive beamforming technique that takes into account the physics of specular reflection. Patterns predicted by the law of reflection are detected across the pool of received data and used to enhance the visualization of specular energy. This technique can be applied to any synthetic imaging sequence. Here, it is applied to synthetic transmit aperture imaging. In vitro experiments show a clear improvement in target visibility and an increase of 30 to 60 dB in signal-to-noise ratio.