Detectability criteria

For the RT technique, the interpretation of results depends on human eyes. The difficulty is that the interpretation can vary from one person to another depending on perception. In order to help the user and allow automatic measures (for POD calculations for example), three criteria were implemented in CIVA to evaluate the detectability of defects. Those criteria are based on comparisons of contrast to noise ratio on the images with and without flaw.

The first one, “Pseudo Rose”, is inspired from the work of Albert Rose, and is adapted for roughly circular flaws. The second one, “Ellipse”, was developed for silver film; and the third one, “Fushia”, is based on the “Pseudo Rose” criterion and is adapted for elongated defects.

To use those criteria, don’t forget to tick the “Simulate images without flaws” option from the “Options” menu, “Computing” tab before launching your calculation.

In the analysis page, select the “Response detector noise” image, then select the “Detectability” menu (bottom of the analysis window).

 

 

Then click on the “+” button and select an area of measure.

 

 

By default, the Rose criterion will be displayed. This can be changed by clicking in the “Detectability” menu.

 

 

 

With the Rose criterion, a defect is considered as detected when it has a value above 7.

You will find more information about those criteria in articles available on our website and in the CIVA user manual.