What letter is placed on the back of the film to check back scatter?

• A. A
• B. B
• C. C
• D. D

Answer: (B)

In radiographic film testing, you use a marker on the back of the film to identify backscatter effects. The letter placed there is chosen to stand for Backscatter, giving a clear, quick cue to anyone reading the film that density around that mark may be influenced by radiation scattering from materials behind the film. By marking the back of the film with this indicator, inspectors can distinguish densities caused by the primary exposure from those due to backscatter, improving interpretation and consistency across films and tests. This marker is specifically placed on the film’s back so its presence and position consistently signal backscatter conditions, making the marking an accepted, standardized reference in QA checks.