When viewing a radiograph, how would one identify an area that is not exposed to radiation?

An area on a radiograph that is not exposed to radiation will appear lighter or white in comparison to the surrounding areas. This occurs because radiographs capture differences in tissue density and how these densities interact with the X-ray beam. Areas that absorb less radiation—such as those that are highly dense (like bone) or those that have not been adequately exposed—will appear lighter on the film.

Unexposed areas provide little to no information because they do not interact with the X-rays that create the image. Thus, they maintain a lighter appearance compared to the more commonly exposed regions, which show varying levels of density based on the structures present.

Other options might suggest characteristics of exposure. A darker area would typically indicate higher radiation exposure or less dense material. Irregular borders could indicate certain pathologies but do not specifically indicate lack of exposure. A completely blank area suggests total lack of any radiographic data, but in practical terms, radiographers usually observe a lighter area as indicative of lack of exposure.