A Modified Detectability Criterion for Conventional Radiography Simulation

For the conventional radiographic technique, X/gamma ray film interpretation is based on human eye perception. There is no criterion of "universal" visibility / detectability of flaws and IQIs for simulated radiography. However, at least one detectability criterion is required for an automatic analysis study of a given set-up. The Rose criterion, based on the contrast to noise ratio of the imaged flaw normalized to the spatial image resolution, is the current reference detectability measure. It is by definition well-adapted in the case of roughly circular flaws (e.g. flat bottom holes or step hole IQIs) but shows its limits for cracks with an elongated shape or close to the limit of spatial resolution as well as for wire IQIs. In this paper, we propose a modified detectability criterion to take into account the variability of flaw shape. This paper shows a performance comparison between human expertise and this new criterion, using a large flaw database and IQIs with associated operator evaluations developed in a prior work.