Fig 2.

Effects of tube voltage, filtration, and dose rate on the color difference of the indicator. A, Indicators were irradiated at the dose of 1 Gy by using 4 tube voltages (50, 75, 100, and 125 kV) and 4 types of filtration (2.2 mm of aluminum, 5.2 mm of aluminum, 3.7 mm of aluminum + 0.1 mm of copper; and 3.7 mm of aluminum + 0.4 mm of copper) with a 20-mA tube current. The difference in the color difference was within 2.20. B, The effect of the dose rate was also evaluated by using 2 tube currents (5 and 20 mA) for the 4 types of filtration at the dose of 1 Gy with tube voltage of 75 kVp. For each filtration, the difference in the color between the 2 dose rates was within 0.79. Al indicates aluminum; Cu, copper.