REAL-TIME DIGITAL X-RAY SUBTRACTION IMAGING

摘要

ABSTRACTA method and apparatus for producing visible differenceimages derived from an X-ray image of an anatomical subject,comprising the steps of producing an X-ray image, convertingit into television fields comprising trains of on-going videosignals, digitally storing and integrating the on-going videosignals over a time interval corresponding to a plurality ofsuccessive television fields and thereby producing stored andintegrated video signals, recovering the stored and integratedvideo signals from storage and thereby producing integratedvideo signals, producing video difference signals by performinga subtraction between the integrated video signals and the on-going video signals outside the time interval, and convertingthe video difference signals into visible television differenceimages representing on-going changes in the X-ray image. Thesubtraction may be performed digitally or on ananalog basis.The time interval is preferably at least on the order of onecomplete cardiac cycle. One embodiment involves digitallystoring and integrating the on-going video signals over aseries of additional time intervals each corresponding to aplurality of successive television fields, preferably on theorder of four television fields, and carrying out a series ofsubtractions between each of the additional successive inte-grated video signals and the first mentioned integrated videosignals serving as integrated mask video signals, and therebyproducing a series of successive digital difference videosignals.