A Linear Stepped Doppler Ultrasound Array for Real-Time Two-Dimensional Blood Flow Imaging

Abstract

Current Doppler ultrasound blood flow imaging systems which use transducers containing one or two crystals typically take 10 to 30 minutes to obtain a satisfactory carotid a rtery image. This long scanning time is due both to t he pulsatile nature of the flow and the fact t hat the transducer must be manually scanned over the artery. To effect a major reduction in scanning time, we have designed a linear stepped Doppler ultrasound array for real-time two dimensional imaging of blood flow through the carotid a rtery. The array consists of 32 crystals mounted on a staircase backing. To obtain sufficient resolution, a six crystal grouping is used, where the two middle crystals act as receivers and the four outer crystals act as properly phased transmitters. This arrangement of crystals interrogates a narrow beam of tissue at an angle of approximately 60O from the array axis. Scanning through the array provides one dimensional blood flow information, while the second dimension is achieved by rotating a mirror in front of the array.