Fast Image Processing Systems For Evaluating The Clinical Potential Of Ultrasound Speckle Suppression And Parametric Imaging

Early experience of new forms of adaptive filtering for ultrasound speckle reduction and parametric imaging, using off-line conventional digital processing, has been sufficiently encouraging to warrant attempts to build fast on-line implementations for purposes of clinical trials. This paper describes the hardware under development. The feasibility of implementing specific algorithms in real-time (video rate) at low cost was demonstrated using a hybrid digital/analogue system in which the video signal (from any scanner) is sampled to 256 points per line and passed sequentially through a series of shift registers, in order to derive a 5 by 5 window of values which surrounds the image point to be processed. These 25 video signals are then used as inputs to an analogue processor, which provides the filtered output. For greater accuracy, flexibility, spatial resolution and freedom from image artefacts, a slower system has been constructed around a commercially available digital image processor. This system has been chosen to act as the main clinical test device. Whole images may be processed in a few tens of seconds and specified regions, if small enough, may be processed at rates approaching real-time.