The influence of ambient lighting on the detection of small contrast elements in digital dental radiographs

摘要

Objectives: The aim of this study was to evaluate the effect of ambient light on the detection of contrast elements in digital dental radiographs. Materials and methods: A high-contrast standardized digital radiograph of an aluminum step wedge containing 32 boreholes of different depth was cut into 40 isometric images. Images were presented at random on a 17-in cathode ray tube (CRT) monitor at different ambient background illuminations of 0, 50, 200, and 500 lx. Twenty observers stated twice their blinded decision whether or not they could perceive a dark spot on a five-point confidence scale. Areas (Az) under receiver operating characteristic curves were calculated and compared between the four different ambient illuminations using the Friedman test. Statistical significance was set at p < 0.05. Overall agreement was estimated determining the intraclass correlation coefficient. Results: The Az values (0.735 for 0 lx, 0.728 for 50 lx, 0.735 for 200 lx, and 0.788 for 500 lx) did not significantly differ (p = 0.796) between the four ambient lighting levels. Conclusions: The detection of small contrast features in digital dental radiographs on a CRT monitor seems to be comparable over a wide range of ambient background illumination. Clinical relevance: The ambient light in dental offices of <500 lx may not negatively impact the diagnostic performance of digital dental radiographs.