Interpretation of digital chest radiographs: comparison of light emitting diode versus cold cathode fluorescent lamp backlit monitors

Abstract

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 × 1440 pixels) monitor and a 3 M CCFL (2048 × 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 ± 0.072 and 0.764 ± 0.098 for LED and CCFL (p = 0.173), whereas those for ILD were 0.871 ± 0.073 and 0.844 ± 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℃ for LED and 12.4℃ 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.

Keywords: Diagnostic radiology; Diffuse pulmonary disease; Display; Images; Lung; Nodule; Radiography.

Fig. 1

Examples of selected chest radiographs and reference CT images. Those with nodue (A, B), increased interstitial markings (C, D) and neither abnormality (E, F), respectively.

Fig. 2

ROC curves for nodules (A, B) and ILD (C, D). X-axis value = false positive rate (1-specificity), Y-axis value = true positive rate (sensitivity), ROC = receiver operating characteristic, ILD = interstitial lung marking, CCFL = cold cathode fluorescent lamp, LED = light emitting diode

Fig. 3

Individual and mean ROC and AUC values for nodules (A) and ILD (B) using CCFL and LED monitor displays. Observers 1, 2, 3, and 4 were board certified radiologists and observers 5, 6, 7, and 8 were residents. AUC = area under curve, ROC = receiver operating characteristic, ILD = interstitial lung marking, CCFL = cold cathode fluorescent lamp, LED = light emitting diode