Precision Analysis of the Noise Power Spectrum Estimate in Radiography Imaging

The noise power spectrum (NPS) is usually measured to quantitatively evaluate the detector noise performance. In this paper, Bartlett's method is employed to estimate the NPS values, in which the NPS estimate is the sample mean of periodograms. The precision of the NPS estimate is then derived and equal to the inverse of the square root of the sample size. It can be noticed that the precision is independent of the NPS values and the spectral resolution. We conducted a Monte Calro simulation on the precision and compared the precisions for a general radiography detector. We could observe the sample-size dependency on the NPS estimate precision through extensive experiments and derived a system uncertainty, which is dependent on the radiation of the x-ray, readout circuits, etc. The theoretical and numerical analyses on the NPS estimate precision will be a good guideline in designing high-precision detectors.