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

The lead symbol "B" on the back of the film holder is an indication of whether excessive backscatter is present. In radiographic testing, backscatter refers to the radiation that is deflected back towards the film after interacting with materials. The presence of backscatter can compromise the quality of the radiographic image by creating fog or reduced contrast, which can obscure fine details in the image.

The "B" marking serves as a warning or informational cue for the technician, signaling them to be cautious of potential backscatter effects during imaging processes. If excessive backscatter is indicated, the technician may need to take additional measures, such as adjusting the setup or using additional shielding, to ensure that the radiographic results are reliable and accurate.

The incorrect choices do not align with the purpose of the "B" symbol. For example, it does not specify the type of film used or provide information about when the film expires. Additionally, it is not indicative of radiation presence in a general sense but rather focused specifically on the concern of backscatter, which directly affects the quality of the final radiographic image.