RT – Backscatter;
The backscatter is the radiation that reflects the obstacles or the background and falls onto the back of the film during radiation tests. (Radiographic Testing, RT). The Backscatter will reduce the contrast and sharpness of the RT film, which may not be visible. Discontinuity or defects that appear on the film. Therefore , too much backscatter is not acceptable for RT.
RT – Backscatter Detection;
How to detect a backscatter or the reflected rays behind the film According to ASME Section V regulations, this can be done by placing the lead letter “B” on the back of the film holder during the RT process. If after making the RT , it appears that there is a white letter “B” . Appeared on film Then it means that the film has too many backscatter and has to reject the film.
AMARINE 
What if the “B” placed for the back scatter comes out dark ?
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If the letter B is blur or white, the film is rejectable. If the letter B is black (darker), it can be consider acceptable with certain guarantee from film maker (due the the lack of lead screening in the film) and with consultant of NDT expert.
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