Study on effect of source to film distance (SFD) on the radiographic images

Abstract

Radiographic testing is a Non-Destructive Testing (NDT) method that utilizes radiation rays. It was found that many radiographic operators do not follow the existing procedures in radiographic testing. One of the procedures that is often neglected is the minimal Source Film Distance (SFD). Therefore, this study aims to determine the effect of different SFDs on the quality of the resulting radiographic film by varying the SFDs. The specimens used are pipe and plate with different thickness. For both specimens, it was found that for SFDs that were less than the $\mathbf{SFD}_{\text{minimum}}$, the density values exceeded the ASME standards, the film was blackened, and the sensitivity values were lower. For the SFD values that were higher than $\mathbf{SFD}_{\text{minimum}}$, the density values were lower than the standards, the film was whitened, and more wires were measured in sensitivity. Thus, it can be concluded that the SFD greatly affects the quality of the resulting radiographic films.