American Society for Nondestructive Testing (ASNT) Radiographic Testing Practice Test

Increasing the source-to-film distance primarily affects the geometric characteristics of the radiographic image. When this distance is increased, the radiation diverges more before it reaches the film. This divergence leads to a reduction in the intensity of the radiation that reaches the film per unit area, which can cause the overall exposure to be lower.

However, at the same time, this increased distance can allow for a decrease in distortion and increased sharpness of the image. The quality of the radiograph can remain equivalent if the exposure is adjusted appropriately, typically by increasing the source intensity or exposure time to account for the reduced radiation reaching the film. Therefore, it is possible to maintain an acceptable level of quality in the radiograph despite changes in exposure conditions. This balance allows for maintaining detail while reducing the potential for issues like geometric distortion.

Ultimately, achieving an equivalent quality radiograph is feasible through careful calibration of the exposure settings in relation to the new source-to-film distance.