EVALUATION OF AN ASYMMETRIC SCREEN-FILM SYSTEM FOR CHEST RADIOGRAPHY

To evaluate the potential utility of an asymmetric screen-film system for chest radiography, its image quality and detail visibility compare d with a conventional screen-film system are investigated. The basic i maging properties were evaluated by measuring Hurter and Driffield cur ves, resolution properties, and noise Wiener spectra. The visibility o f simulated anatomical and pathological derails in radiographs of a ch est phantom and normal anatomy in chest radiographs of patients were e valuated subjectively. The dynamic range of each system is comparable, though the asymmetric screen-film system can provide an advantage ove r the conventional System due to a relative dose reduction of approxim ately 35% and higher resolution properties at high optical densities. The noise level of the asymmetric screen-film system is slightly great er at low optical densities and much greater at high optical densities . However, the visibility of lung details with the asymmetric screen-f ilm system is slightly superior to the conventional screen-film system despite the increase in noise. Mediastinal and retrodiaphragmatic det ails are similar, though marginally superior with the asymmetric scree n-film system. It is concluded that the asymmetric screen-film system provided slightly superior image quality to the conventional screen-fi lm system for chest radiography, provided the average lung density is maintained at a higher level than is customary with conventional syste ms.