BASIC IMAGING PROPERTIES OF A NEW SCREEN-FILM SYSTEM FOR CHEST RADIOGRAPHY

To evaluate the potential clinical usefulness of a new screen-film sys tem (advanced screen-film system; AD system) for chest radiography, it s fundamental imaging properties compared with a conventional screen-f ilm system (HR-4/HR-S) were investigated. The basic imaging properties were evaluated by measuring characteristic (H&D) curves, relative spe eds, MTFs (modulation transfer functions), WS (Wiener spectra), and x- ray attenuations of screens. The detail visibilities and pathological details of various diseases in chest radiographs of patients were eval uated subjectively. The film gradient of the AD system was slightly lo wer at low radiographic density, and higher at high density, as compar ed with a conventional screen-film system. The screen speed of the AD system was 212% greater than that of the conventional system and the f ilm speed was 53% that of the conventional film. As the result the tot al speed of the AD system was slightly higher compared with the conven tional system. The spatial resolution of the AD system was comparable to or slightly lower than that of the conventional system. The noise l evel of the AD system was considerably lower than that of the conventi onal system at low (D=0.5) and middle (D=1.0) radiographic density lev els. However, it was high at high radiographic density (D=1.8). The ra diographic densities in the underpenetrated areas with the AD system w ere greater than those of the conventional system when the lung densit ies are matched comparable. Improvement in noise level with the AD sys tem at low and middle density levels may be useful for detection of va rious diseases in chest radiographs. (C) 1996 American Association of Physicists in Medicine.