Using the EN584-1 film characterization in radiographic modelling

One of the problems in modelling radiographic inspections concerns the film characteristics as the last step in the radiographic modelling chain, throughout which the energy deposited by the incoming radiation is to be converted to a grey value. This conversion depends not only on the total dose absorbed by the film, but also on the radiation’s spectrum and to a lesser extent also on the incidence angle of the incoming radiation. Models trying to take all or most of these influential parameters into account inevitably lead to complex and proprietary film characterizations, and in particular require information generally not available in the film data sheets provided by the manufacturers. The recent EN584 standard for the classification of film systems for industrial radiography proposes a pragmatic and in many cases sufficient classification in terms of the dose required to obtain optical density 2, and the gradient of an optical density vs. required dose at optical densities 2 and 4. In this paper, we discuss different ways to implement an EN584-compliant film model.