Author: James Ward, Anzi Zhao 👨🔬
Affiliation: Northwestern Medicine 🌍
Purpose: This study investigates the correlation between the backlight runtime in diagnostic displays and their corresponding performance, which may aid in making informed decisions regarding the timing of proactive replacement.
Methods: Nineteen 12 mega-pixel diagnostic displays exclusively for mammogram interpretation and all identical in make and model were evaluated. The backlight hours of the displays range from approximately 5,000 to 50,000 hours. Luminance measurements were taken with two external photometers at calibrated maximum luminance and in a boost mode where the highest possible luminance of the display was enabled. Additionally, luminance measurements were obtained at 18 grayscale levels utilizing AAPM TG18 test patterns. A DICOM Grayscale Standard Display Function (GSDF) was generated and compared with the results from an automated GSDF compliance check performed on the display with the internal photometer. White point accuracy was assessed by comparing the results obtained from both external and internal photometers.
Results: The relationship between the backlight hours and the highest possible luminance of the display demonstrates an inverse linear correlation, with R² values of 0.92 and 0.89. The relationship between the backlight hours and the error of the internal photometer GSDF compared to those of the external photometers showed a linear correlation, with R2 values of 0.59 and 0.50. Internal photometer white point routinely measured as accurate with calibration, but external verification showed a linear correlation in deviation, with an R2 of 0.78.
Conclusion: External verification of internal photometer measurement of maximum luminance, GSDF, and white point combined with the backlight hours of the display can be used to predict the remaining effective lifespan of the display.