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Recent developments in data processing allow transformation of video frames into digital information. This makes it possible to perform computerised analysis of endoscopic ENT-videos. Two simple pilot systems ("Genlock Computer with Superimposer" and "Videodigitizer") are shown to discuss the advantages and drawbacks of these methods.

We determined the quality of digital radiographs delivered by a large image intensifier (diameter 54 cm) and by a conventional fluoroscopic unit with a 33 cm image intensifier, and compared them to that of 100 mm spot films obtained from the same units. A special image processor was available allowing 25 images/s using a 512/512 matrix or 7.5 images/s with a 1024 X 1024 matrix. The spatial resolution of digital radiographs was well below that of the spot films, while no difference was found in contrast resolution. Images of colon specimens and gastrointestinal studies demonstrate that digital radiography does not imply a loss in diagnostic information inspite of the lower spatial resolution. Gastrointestinal studies using digital radiographs will reduce the amount of irradiation exposure of the patient and could represent an additional use for an existing equipment for DSA.

Digital radiography is a generally accepted term comprising all x-ray image systems producing a projected image which resembles the conventional x-ray film image, and which are linked to any type of digital image processing. Fundamental criteria of differentiation are based on the production and detection method of the x-ray image. Various systems are employed, viz. the single-detector, line-detector or fanbeam detector and the area-beam or area-detector image converters, which differ from one another mainly in the manner of conversion of the radiation produced by the x-ray tube. The article also deals with the pros and cons of the various principles, the multitude of systems employed, and the varying frequency of their use in x-ray diagnosis work.

The use of dual energy methods in digital radiography allows selective imaging of soft tissues or calcified structures and contrast media. The value of this method is demonstrated on the basis of 400 patient examinations. The isolated imaging of soft tissues without skeletal superposition gives particular advantages in diagnosis of the chest and the cranio-cervical region. Soft tissue calcifications and calcium-containing concrements in the bile ducts and in the urinary tract are well demonstrated without soft tissue superposition. The disadvantages and the limits of the method are discussed, its potential and possible future developments are shown.

Preliminary examinations with digital subtraction myelography revealed the possibility of saving up to 70% of water soluble contrast medium compared with usual myelographic procedures, thereby reducing the risk of neurotoxic adverse reactions.

Intravenous digital subtraction angiography using Fuji computed radiography system (FCR-DSA) was used to evaluate 57 preoperative patients with clinical manifestations of peripheral vascular disease of lower extremity. With its high contrast resolution and good special resolution, image of FCR-DSA could offer optimal information of vascular abnormality in lower extremity distal to midfoot for the diagnosis and the choice of management.

In addition to computed tomography which presents actually the most important processing and transfer procedure of digital X-ray images, application of real time addition and subtraction of X-ray images in a digital mode has found considerable interest. An estimation of the information contents of both digital and analog images is made in close relation to applications. As example of an image processing system on digital base a recently developed system for intravenous arteriography is described: the Philips-DVI.