The resolution of a film or film — screen combination is essential for characterizing the radiographic system. The conventional methods for measuring the resolution in radiography, based on the Image Quality Indicators (IQI) and Penetrameters, are not applicable for high energy radiation (in the MV range) due to the high penetration. In addition, the IQI and Penetrameters do not measure only the spatial resolution but rather an undefined combination of the spatial and thickness resolution. Another approach used for analyzing the film resolution is based on the measurement of the radiographic response to a step function input.