'Undercut' or 'burned out' edges on a test piece film image can be caused by what?

Scattered radiation leads to undercut or burned out edges on a test piece film image because it can create an illusion of density or exposure in areas that should remain lighter or unexposed. When scattered radiation interacts with the film, it can hit regions that are not directly in the path of the primary beam to create an unwanted density on the radiographic film, resulting in those characteristic edges.

This phenomenon is particularly evident around the edges of a test piece where the exposure gradient is not uniform. When the primary X-ray beam is partially blocked or scattered, the film might receive additional radiation indirect exposure, causing these edges to appear darker than the intended evaluation area.

The other options, while related to radiography, do not cause the specific issue of undercut or burned out edges as clearly as scattered radiation does. Insufficient exposure time would lead to overall underexposure rather than specific edge effects, improper film development may cause various overall image quality issues but would not specifically produce the characteristic undercut or burned out edges, and lack of proper shielding might cause general background density increase rather than targeted edge effects.