A multiplexed two-dimensional array for real time volumetric and B-mode imaging

Abstract

The Duke University real time volumetric imaging system employs receive mode parallel processing to increase image frame rate. This technique has an associated reduction in image resolution and contrast due to the requirement of a wide transmit beam. Since B-mode imaging can be accomplished in real time without this constraint. we propose a multiplexed 2-D array which has 2 sets of elements, one designed for volumetric imaging and one designed for B-mode imaging with improved resolution. Tbe interconnection of this array is challenging due to the large number of elements. We have developed a new technique for 2-D array interconnection which employs a thin multilayer flexible circuit The flex circuit element performance was comparable to hand wired 2-D arrays with greatly reduced fabrication time, regardless of the number of connections. METHODSVolumetric imaging can be performed in real time using receive mode parallel processing to increase image frame rate [ll . This requires a two-dimensional (2-D) array with transmit beam width sufficient to allow 4 x 4 parallel receive beams to be acquired simultaneously. The wide transmit beam is achieved by concentrating transmit elements in the center of the aperture. Unfortunately, this degrades lateral resolution and image contrast When the system is used for B-mode imaging, a real time frame mte is achieved without receive mode parallel processing, making the wide transmit beam and its associated loss in resolution and contrast unnecessary. Therefore, we propose a multiplexed sparse 2-D array which has 2 sets of elements, one with a wide transmit beam for volumetric imaging and one with a narrow transmit beam for B-mode imaging. Selection of the aperture would depend on the system imaging mode selected by the clinician.The multiplexed array element geometry is shown in Fig. 1. We employ sparse random 2-D arrays to improve resolution with a limited number of system channels [2]. The aperture for volumetric imaging is shown in Fig. 1(A) and the B-mode imaging aperture is shown in Fig 1(B). Each set of elements includes 192 transmit elements shown in black and 64 receive elements shown in white. Since the transmitters of both apertures 0-7803-3615-1/96/$5.00 0 1996 JEEE are highly sampled in the center of the array, it was necessary to share transmit elements between both apertures. In this design, 84 transmit elements are common to both apertmx resulting in a total of 428 active elements in the array. A B Fq. 1. Multiplexed apertures for (A) volumetric imaging and (B) B-mode imaging Multiplexing the 2-D apertures is accomplished using a relaxor ferroelectric material IBaTie -(Pb(Mgln Ntruj)o3-F'bTiO3))] (Lockheed-Martin, Baltimore MD)which has biased controlled sensitivity. The circuit diagram in Fig. 2 is used to select the aperture by applying a DC bias field of 0.75 W/m to activate elements while allowing passage of transient signals. We have previously reported a multiplexed 3 x 32 element 1.5-D relaxor ferroelectric transducer with expanding elevation aperture which...

Archives of Electrical Engineering

“…By using ( 7) and ( 8) the offspring of two parent arrays are obtained. Xi and X j are two parent arrays, the two offspring are obtained through a random parameter α which belongs to the interval [1,2]. The flow chart of the GA is illustrated in Fig.…”

“…To overcome these disadvantages, 2-dimensional (2D) matrix arrays can be used. The 2D array can be electronically controlled to steer the beams in both the elevation and lateral directions [2][3][4][5][6]. Unfortunately, the 2D array probe design must obey the spatial sampling condition (i.e.…”

Progress in Two-Dimensional Arrays for Real-Time Volumetric Imaging

“…1, [10][11][12][13][14][15][16] The very large number of elements (N X M) and the difficulty of electrically connecting to the very small elements has limited most 2-D arrays to operating frequencies of approximately 2.5 Mhz. For example, a conventional linear phased array consists of 128 operating channels with a tJ2 interelement spacing in a fully-sampled aperture.…”

Experimental results from an electrostrictive multiplexed 2-D array

“…A detachablc high density Bias circuits were inserted between the handle interconnection to the transducer was provide by a stack pitch flex circuit edge connectors (Precision Interconnect, of 6 double sided 2 x 36 = 72 position, 25 mil (.635 pm)PAC, Portland OR). The six connectors provided 432 connections within a 2.5 cm x 2.5 cm area[6]. Six double sided flex circuits located at the base of the multiplexed transducer mated with the PAC connectors.…”