Real-time 3-D ultrasound imaging using sparse synthetic aperture beamforming

Abstract

A method for real-time three-dimensional (3-D) ultrasound imaging using a mechanically scanned linear phased array is proposed. The high frame rate necessary for real-time volumetric imaging is achieved using a sparse synthetic aperture beamforming technique utilizing only a few transmit pulses for each image. Grating lobes in the two-way radiation pattern are avoided by adjusting the transmit element spacing and the receive aperture functions to account for the missing transmit elements. The signal loss associated with fewer transmit pulses is minimized by increasing the power delivered to each transmit element and by using multiple transmit elements for each transmit pulse. By mechanically rocking the array, in a way similar to what is done with an annular array, a 3-D set of images can be collected in the time normally required for a single image.

On the Applications of the Frequency-Response Masking Technique in Array Beamforming

“…Hence, unlike for the passive array, one can come up with the same effective aperture function with different combinations of {h t (n)} and {h r (n)}. This was investigated in detail in the context of designing sparse linear arrays suitable for imaging systems [3], [16], [17]. We now briefly review a design method for sparse linear arrays [16].…”

“…Note that all the existing methods for designing an active array using the concept of effective aperture [2], [3], [16], [17] tried to either avoid the grating lobes by eliminating the periodicity of the sparse arrays or attenuate the grating lobes by introducing nulls in the effective aperture functions. Using the FRM technique, it will be shown next that instead of suppressing all the grating lobes completely, some of them can be integrated in mainlobe synthesis by exploiting the complementary property of {h a (n)} and {h c (n)} and by properly designing the masking filters.…”

Synthetic aperture focusing for a single-element transducer undergoing helical motion

“…Sparse SNR increase by different SAF methods for simulated and measured scatterers. sampling can be applied intelligently to reduce the impact on side-lobes [22] or an increased F # can be used at the expense of resolution. This section will only estimate the processing requirements for applying either two-step or direct 3D SAF, and not ways to reduce this.…”

Forward-backward generalized sidelobe canceler beamforming applied to medical ultrasound imaging

“…Applying apodization calculations, using fixed and data-independent weights can reduce the sidelobe level at the cost of the loss of lateral resolution. 4 Adaptive beamformers have been studied in other array signal processing fields, e.g. antenna, sonar and radar, the core of adaptive beamformer is calculate weights from the collected echo data.…”