Real-time rectilinear volumetric imaging using a periodic array.

Current real-time phased array volumetric scanners use a 2-D array to scan a pyramidal volume comprised of many sector scans stacked in the elevation direction. This scan format is primarily useful for cardiac imaging to avoid interference from the ribs. However, a real-time rectilinear volumetric scan with a wider field-of-view (FOV) close to the transducer could prove more useful for abdominal, breast or vascular imaging. In our previous work, a 94 x 94 Mills cross array operating at 5 MHz was fabricated, and the first real-time rectilinear volumetric images were made using a 2-D array and the Duke real-time 3-D scanner. The FOV for the Mills cross was 30 x 8 x 60 mm. Despite reasonable success with the Mills cross array, the array had limitations of poor off-axis sensitivity and a smaller FOV in one direction. To overcome these limitations, a new rectilinear array containing over 65,500 elements was developed with a periodic geometry to increase the FOV to 30 mm x 30 mm x 60 mm and improve the off-axis sensitivity. Images of tissue-mimicking phantoms and the carotid artery in vivo were obtained. In addition, spectral and color flow Doppler results from a pulsatile flow phantom were obtained.