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The Influence of Monitor Periodic GSDF Calibration On Luminance Measurements

A Ruuge*, Y Erdi , Memorial Sloan Kettering Cancer Center, New York, NY


(Sunday, 7/29/2018) 4:30 PM - 5:00 PM

Room: Exhibit Hall | Forum 9

Purpose: This work evaluates the repeatability of the primary diagnostic monitor (PDM) luminance measurements performed with an external photometer.

Methods: Ten PDMs (Barco model MDCC-6130) were included in the evaluation. The monitors were located at three different radiology reading rooms. Luminance measurements were performed for each PDM weekly for a period of 12 weeks. All PDMs were calibrated using BarcoMediCalQA software. Four PDMs were calibrated each time before the luminance measurements were taken. Six PDMs were calibrated only once before the first luminance measurement. TG-18 LN1-18 and TG-18 UNL80 test patterns were used for luminance measurements with an external photometer (RaySafe Solo) by the same operator. Ambient light was checked with the probe attached to the same photometer and was kept constant during all measurements. For each set of measurements, the repeatability of luminance values and variations of PDM non-uniformity along with deviation from the expected GSDF curve were evaluated.

Results: For all tested PDMs the largest variation was for luminance values above 300 cd/m², with a maximum standard deviation of 7.2 cd/m² for non-calibrated PDMs and 3.4 cd/m² for calibrated PDMs. The ambient light measurements showed 0.2 cd/m² for each tested PDM. The maximum change in deviation from the expected GSDF curve was between 1.3 and 4.2% for non-calibrated PDMs and between 1.2 and 5.6% for calibrated PDMs. Change in monitor non-uniformity was within 3% for all tested PDMs.

Conclusion: Although it is expected that PDM luminance values will decrease over time, there is a variation in PDM luminance measurements that is due to biannual calibration of the monitors. The PDMs calibrated immediately before the measurements showed less variation in luminance when compared with those calibrated on a semiannual cycle.


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