Variation in Measurements Between Calibrated Photometers for Mammography Diagnostic Workstation Monitors
Presentations
(Saturday, 3/26/2022) [Central Time (GMT-5)]
Purpose: To investigate and demonstrate variation between luminance values reported by vendor-calibrated photometers.
Methods: We tested 7 photometers from three manufacturers. Four different models were represented. All meters had been recently calibrated by the vendor, with stated luminance ranges that cover the mammography range used clinically. In order to test the variation in measurements between these meters in a clinical setting, three mammography diagnostic workstations were tested; both dual-screen grayscale monitors and widescreen color monitors were included. Using the monitor vendor’s QC software, a set of five the AAPM TG-18 luminance patterns (# 1, 8, 11, 15, 18) were displayed and measured, and standard deviation was measured for a single pattern (# 11) with five measurements. The patterns were chosen to cover representative gray levels across the maximum range of luminance.
Results: The standard deviation for luminance readings was minimal, with values ranging from 0.07 to 0.4 for the wide monitor setup and 0.2 to 1.5 for the dual-monitor setup. The measured luminance values were similar for the darkest gray levels, but diverged markedly for the higher luminance patterns (range 581 to 962 for pattern 18).
Conclusion: Even though the photometers were all recently calibrated, the values were not close to each other at the brighter luminance levels. This could be attributed to the reference meters or light sources used by the vendors. In clinical practice, physicists should be aware of the potential impact of meter selection on diagnostic workstation compliance testing.
Keywords
Calibration, Mammography, Quality Assurance
Taxonomy
IM- Breast X-Ray Imaging: Display Technology & Evaluation
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