<title>Current Practice And Future Directions In Digital Subtraction Angiography</title>

Digital x-ray systems used thus far for non-film subtraction angiography may be divided into two main categories, those using image intensified video fluoroscopy apparatus and those using scanned linear detectors. On each type of system energy subtraction and time subtraction have been investigated. And, even if we limit ourselves to subtraction angiography, several types of energy and time subtraction algorithms have been tried.