What might cause mottling on a radiographic film?

Mottling on a radiographic film can occur due to backscatter from aged fluorescent screens. This phenomenon happens when the screen emits fluorescence that causes unwanted exposure on the film. Over time, the performance of fluorescent screens can degrade, leading to inconsistent light emission and hence uneven blackening or mottled areas on the film. The irregularities in exposure lead to a mottled appearance in the final radiograph, which detracts from the clarity needed for accurate interpretation.

In contrast, excessive exposure to radiation typically results in a uniform darkening of the entire film rather than a mottled appearance. Improper developing techniques might create a range of issues, such as streaks or spots, but they would not specifically cause the distinct mottled effect characteristic of backscatter. Contamination of the film surface may lead to artifacts or blemishes; however, these would not create the mottling pattern associated with scatter from degraded screens. Thus, backscatter from aged fluorescent screens is a well-recognized cause of mottling in radiographic films.