Either you send xrays across the surface, using the curvature, or you place a detector on one side and an emitter on the other. Since you would know where you e

Either you send xrays across the surface, using the curvature, or you place a detector on one side and an emitter on the other. Since you would know where you expect the stress to have the greatest effect, you test the worst spots first, rather than scanning the whole thing.