Two-Dimensional Random Arrays for Real Time Volumetric Imaging

Abstract

Two-dimensional arrays are necessary for a variety of ultrasonic imaging techniques, including elevation focusing, 2-D phase aberration correction, and real time volumetric imaging. In order to reduce system cost and complexity, sparse 2-D arrays have been considered with element geometries selected ad hoc, by algorithm, or by random process. Two random sparse array geometries and a sparse array with a Mills cross receive pattern were simulated and compared to a fully sampled aperture with the same overall dimensions. The sparse arrays were designed to the constraints of the Duke University real time volumetric imaging system, which employs a wide transmit beam and receive mode parallel processing to increase image frame rate. Depth-of-field comparisons were made from simulated on-axis and off-axis beamplots at ranges from 30 to 160 mm for both coaxial and offset transmit and receive beams. A random array with Gaussian distribution of transmitters and uniform distribution of receivers was found to have better resolution and depth-of-field than both a Mills cross array and a random array with uniform distribution of both transmit and receive elements. The Gaussian random array was constructed and experimental system response measurements were made at several ranges. Comparisons of B-scan images of a tissue mimicking phantom show improvement in resolution and depth-of-field consistent with simulation results.

Ultrasound three-dimensional velocity measurements by feature tracking

“…The transducer was diced into a grid with an interelement spacing of 0.4 mm. The 192 transmit elements are arranged randomly with a Gaussian spatial distribution, and the 64 receive elements have a spatially even random distribution similar to that described by Davidsen et al [14]. The transducer is fixed to a translation stage by a clamp that keeps its position constant relative to the mounting.…”

Adaptive near-field beamforming techniques for sound source imaging

“…[18][19][20][21][22][23][24][25][26] Optimal weights to minimize main lobe width or maximum side lobe level for an equally spaced linear array can be analytically calculated using Dolph-Chebyshev array weighting.…”

Beamforming of sound from two-dimensional arrays using spatial matched filters

“…Mills cross arrays, vernier arrays, and random 2D arrays have been studied. [1][2][3][4] Others have used various approaches such as simulated annealing 5 or linear programming 6 to arrive at an optimal solution given constraints of aperture size and channel counts. Still others have used the concept of the effective aperture or co-array to develop novel sparse 2D array configurations which provide a radiation pattern with low sidelobes and acoustic clutter.…”