Design and characterization of a real-time angular scatter ultrasound imaging system.

A novel ultrasound imaging system has been implemented using two 32-element linear phased array transducers oriented at an angle of 40 degrees to one another. The system simultaneously acquires and displays, in real time, a conventional backscatter image and an angular scatter image formed using side-scattered echoes from the same region. The design of the system is shaped by the influence of the scatter angle on the spatial resolution and receive signal processing requirements of the instrument. The subtended scatter angles are restricted to values >90 degrees to ensure that the angular scatter receiver effectively tracks the transmitted pulse and that the spatial resolution in the two images is comparable. The system is sufficiently tolerant of small variations in the average acoustic velocity of the medium to guarantee reliable pulse tracking in biomedical applications. The angular scatter signal magnitude is significantly weighted by the directivity of the receive array. The imaging system will most effectively demonstrate angular variations in scattering at scatter angles between 125 and 145 degrees , where the angular response of the receiver is near its peak.