Observer performance using CRT monitors with different phosphors

The goal of this study was to compare observer performance on two monitors - one with a P45 and the other with a P104 phosphor. Phosphors have distinctly different physical properties that, among other things, affect the noise properties of the display. Differences in noise have an effect on the signal-to-noise ratio, and hence may have a significant affect on observer's detection performance. A complete physical analysis was done on the 2 monitors. A JND study was conducted to measure observer performance. A series of grating patterns was generated for display on the 2 monitors. Observers were instructed to report whether the pattern was vertical, horizontal or blank. Observer performance with the P45 was better than with the P104 phosphor. This result was supported those found in the physical evaluation, that showed poorer results on various parameters. The results indicate that the type of phosphor does affect the physical aspects, which in turn affects observer performance. Two clinical areas in particular that might be affected by phosphor differences are nodule detection in chest images and mass detection in mammograms, since low contrast targets will be most affected by the noise differences (SNR) in different monitor phosphors.