The phantom is cast from a uniform material. The design sets aside areas to be used in uniformity measurements which are seen in the above image as two yellow circles. The material’s pixel value is designed to be uniform over the local region. These areas are used for measurements of spatial uniformity, mean pixel number and noise standard deviation values. The mean pixel value and standard deviation of a large number of points, (say 1000 for example), in a given ROI of the scan, is determined for central and peripheral locations of the region for each type of exposing protocol. Inspect the data for changes from previous scans and for correlation between neighboring slices. From the uniformity areas, several parameters can be calculated including signal-tonoise ratio (SNR), and noise power spectrum (NPS).