Phased subarrays for low cost C-Scan applications

Abstract

The performance of subarray processing as a means of reducing overall beamforming computational load for a low cost C-Scan imaging device is analyzed. Unlike the case encountered in B-Mode imaging, the C-Scan format is characterized by a large channel count (4096 in this case) and very short data record lengths. Additionally, unlike the case in B-Mode, there is no essential need for realtime processing of 'streaming' received channel data. Thus, the C-Scan image format benefits greatly from a subarray processing approach in which partial sums are 'reused' with modified differential delays to form multiple beamformed image pixels. For the design configuration considered here, a subarray aperture of 4x4 elements would be approximately optimal and yielded an approximately 12 - 15 fold reduction in overall beamforming computational load. The actual number of beamforming sums is also influenced by the selected pixel spacing and the range over which partially summed apertures can be steered. Keywords-; Beamforming; Ultrasound Imaging; 2D Array; Phased subarray