Actual Time Scan Conversion and Image Processing in a Phased Array Ultrasound Imaging System

Abstract

A new on-line digital scan conversion and image processing system has been developed at Duke University. This new system provides simultaneous real- time digital scan conversion and multi-dimensional image processing. Operating at image frame rates comensurate with TV video tape r ecorders for image storage, this system simultaneously converts a random B-mode image into digital form and reads a sequence of the last four image frames recorded. These four s equential frames represent either a time sequence of the same image in which case image averaging or MTI can be readily accomplished or they may represent some other parametric variation in the images in which case the multi-dimensional aspect of the process- ing becomes even mre apparent and important. Ultrasound B-mode images obtained for medical diagnostic use are typically composed of a large number of more or less randomly oriented B-mode image lines. Static image scan converters using analog storage devices have found widespread acceptance since their introduction into B-mode ultrasonography in the early 1970~~~~. More recently, digital scan converters are coming into use for such static imaging and these are now commercially available. Although digital scan conversion for time varying or dynamic imaging has been employed for the conversion and distribution of radar imaees for aircraft surveilance and traffic control such techniques have not pre- viously been employed for diagnostic ultra- sound imaging. The widespread development of real-time or dynamic ultrasound imaging sys- tems has led t o the development at Duke Uni- versity of a high speed digital scan conver- sion system which also incorporates m ulti- dimensional forms of on-line image processing.