[Radiographic magnification technique with a high-speed rare-earth screen-film system (author's transl)]

Abstract

The advantages of radiographic magnification technique - better detail recognition and improved contrast with an enlarged field of vision - should prove an important supplement to the properties of a high-speed rare-earth system - low-current intensity, low voltage, short exposure time and, consequently, lower irradiation dosage. Physical measurements of the Wiener spectral value, MTF and HD curve proved the superiority of the radiographic magnification technique in combination with a rare-earth screen-film system as compared with a conventional system (Dupont Par speed screen, RP films). Phantom radiographs confirmed these results. The clinical usefulness of this method was assessed with respect to the detection rate of gall-stones by means of oral cholecystography. Two out of 25 cases showed gallstones only following implementation of the radiographic magnification technique. This method seems to be particularly valuable in angiography. In 7 out of 18 abdominal angiograms and 4 out of 14 renal angiograms the number of visible vessel ramifications was greater with the magnification technique. In 5 cases valuable diagnostic information was revealed only by means of the magnification technique. Despite two-fold or 1.7-fold magnification, measurements of skin irradiation exposure showed a reduction of about half in comparison with conventional techniques. Reduced exposure to irradiation combined with improved detail resolution should ensure that this method receives an established place in routine radiodiagnosis.