[Reduction of patient dose with maximum assurance of image quality].

Four methods of reducing the patient dose are reviewed. Without doubt, the patient dose can be considerably reduced by relatively simple means: With rare-earth screens by a factor of 2-4 compared with a CaWO4 universal screen (1 mR) and in some cases by a factor of 1.5-2 with prefiltration. A more complicated and expensive method is the 100 mm spotfilm technique. This permits a dose rate reduction by a factor of 10 compared with a CaWO4 universal screen or by a factor of 5 compared with a universal system with rare-earth screens. In the wide-ranging field of digital radiography, the possibilities of dose reductions by means of digital processing of conventional film screen exposures are investigated.