Interpretation of Digital Chest Radiographs: Comparison of Light Emitting Diode versus Cold Cathode Fluorescent Lamp Backlit Monitors

Objective: To compare the diagnostic performance of light emitting diode (LED) backlight monitors and cold cathode fluorescent lamp (CCFL) monitors for the interpretation of digital chest radiographs. Materials and Methods: We selected 130 chest radiographs from health screening patients. The soft copy image data were randomly sorted and displayed on a 3.5 M LED (2560 ${\times}$ 1440 pixels) monitor and a 3 M CCFL (2048 ${\times}$ 1536 pixels) monitor. Eight radiologists rated their confidence in detecting nodules and abnormal interstitial lung markings (ILD). Low dose chest CT images were used as a reference standard. The performance of the monitor systems was assessed by analyzing 2080 observations and comparing them by multi-reader, multi-case receiver operating characteristic analysis. The observers reported visual fatigue and a sense of heat. Radiant heat and brightness of the monitors were measured. Results: Measured brightness was 291 $cd/m^2$ for the LED and 354 $cd/m^2$ for the CCFL monitor. Area under curves for nodule detection were 0.721 ${\pm}$ 0.072 and 0.764 ${\pm}$ 0.098 for LED and CCFL (p = 0.173), whereas those for ILD were 0.871 ${\pm}$ 0.073 and 0.844 ${\pm}$ 0.068 (p = 0.145), respectively. There were no significant differences in interpretation time (p = 0.446) or fatigue score (p = 0.102) between the two monitors. Sense of heat was lower for the LED monitor (p = 0.024). The temperature elevation was $6.7^{\circ}C$ for LED and $12.4^{\circ}C$ for the CCFL monitor. Conclusion: Although the LED monitor had lower maximum brightness compared with the CCFL monitor, soft copy reading of the digital chest radiographs on LED and CCFL showed no difference in terms of diagnostic performance. In addition, LED emitted less heat.