A Large Aperture Real-Time Equipment for Imaging the Carotid Artery
This talk outlines the design and performance of a portable, real-time, high resolution ultrasound imaging system. The basic design consists of an imaging probe containing a large aperture transducer and a reflective scanning mechanism sealed in a water chamber with a transparent membrane at one end. The entire probe is portable. High resolutions are attained by the use of the large aperture transducer which may be dynamically focussed in depth and real-time operation is provided by the scanning mechanism which is capable of operation in excess of 30 frames/sec For preliminary testing, a prototype system of this design employing mechanical focussing was built and evaluated for applications in imaging the human carotid artery in-vivo. In this system the transducer aperture was F/4 to provide better than 0.5mm resolution in depth and about 1mm resolution in the transverse directions, and the scan rate was 4 frames/sec. The entire probe, together with the mechanical focussing arrangement for the transducer, weighed less than 9 lbs. and provides a field of view of about 5cm x 7cm. The probe weight may be further reduced by employing dynamic focussing. The equipment displays B-section views in sequences of four via commercially available gray scale storage display. Preliminary in-vivo images obtained by the prototype equipment are presented and discussed.