Figure 6. NPS plotted both as the total NPS and with the fixed-pattern noise removed. Data were measured with 70 kVp, 0.5 mm of added copper filtration, 0.3-mR (8 x 10-8 C/kg) incident exposure, with the grid removed. These curves are virtually identical above about 0.2 cycles per millimeter, indicating little residual structured noise after the pixel-by-pixel calibration procedure.