Wikipedia sez:

:Backscatter is the reflection of waves, particles, or signals back to the direction they came from. The term is used in several fields of physics, as well as in photography, Medical ultrasonography, telecommunication, and e-mail.

That Wikipedia entry also contains, as a section heading, the phrase

:Possible ways to reduce the scope of this problem

Which I am going to steal for the title of something, just you wait.