“…However, since Φ is just the product of the fluence per exposure times exposure, a number of relative studies converted the output DN images to K a images based on the STP curve which is the plot of the output DN versus the input DAK level. In particular, they used linear regression model to fit the experimental data for DR systems (Ranger et al, 2007, Ghetti et al, 2008, Michail et al, 2010and Michail et al, 2011 or both linear and logarithmic regression models for DR and CR systems respectively (Monnin et al, 2005, Mackenzie and Honey, 2007, Marshall, 2007and Monnin et al, 2007. All these studies applied simple regression models without taking into account weighting factors or uncertainties on the measurements.…”