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Soft-Copy Reading of Digital Chest Radiographs: Effect of Ambient Light and Automatic Optimization of Monitor Luminance

Uffmann, Martin MD*; Prokop, Mathias MD; Kupper, Walter MSc; Mang, Thomas MD*; Fiedler, Volker MD§; Schaefer-Prokop, Cornelia MD*

doi: 10.1097/01.rli.0000153658.15272.91
Original Article

Objective: We sought to evaluate whether soft-copy reading of simulated pulmonary chest lesions is influenced by ambient light and automatic optimization of cathode ray tube (CRT) monitor luminance.

Materials and Methods: Four types of simulated lesions (nodules, lines, micronodules, and patchy opacities) were superimposed over an anthropomorphic chest phantom. Lesion detection with soft-copy reading was assessed using a high-contrast grayscale 2K CRT monitor under the following conditions: (1) subdued lighting (<50 lux); (2) normal lighting conditions (450 lux) without, and (3) with a sensitivity modulation to automatically adjust the CRT luminance to the increased amount of ambient light. Reading data were analyzed according to receiver operating curve. Significance of differences was tested using an analysis of variance for repeated measures.

Results: Ambient room light of 450 lux did not significantly influence the detection of nodules and patchy opacities. However, bright ambient light significantly decreased detection of micronodules (0.60 vs. 0.74) and lines (0.52 vs. 0.66) relative to subdued lighting conditions. Automatic luminance adjustment could compensate the effect of ambient light for the micronodules (0.77) but not for the lines (0.53).

Conclusion: Bright ambient light significantly decreases detection of small low-contrast structures. This may be partially but not completely compensated by an automatic luminance adaptation.

From the *Department of Diagnostic Radiology, Medical University Vienna, Vienna, Austria; †Institute of Diagnostic Radiology, Utrecht University Medical Center, Utrecht, The Netherlands; ‡Siemens AG, Display Technologies, Karlsruhe, Germany; and §Klinikum Krefeld, Krefeld, Germany.

Received September 12, 2004 and accepted for publication, after revision, November 15, 2004.

Reprints: Martin Uffmann, MD Department of Diagnostic Radiology, Medical University Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria. E-mail:

© 2005 Lippincott Williams & Wilkins, Inc.