  Muon imaging is one of the most promising non-invasive techniques for density
structure scanning, specially for large objects reaching the kilometre scale.
It has already interesting applications in different fields like geophysics or
nuclear safety and has been proposed for some others like engineering or
archaeology. One of the approaches of this technique is based on the well-known
radiography principle, by reconstructing the incident direction of the detected
muons after crossing the studied objects. In this case, muons detected after a
previous forward scattering on the object surface represent an irreducible
background noise, leading to a bias on the measurement and consequently on the
reconstruction of the object mean density. Therefore, a prior characterization
of this effect represents valuable information to conveniently correct the
obtained results. Although the muon scattering process has been already
theoretically described, a general study of this process has been carried out
based on Monte Carlo simulations, resulting in a versatile tool to evaluate
this effect for different object geometries and compositions. As an example,
these simulations have been used to evaluate the impact of forward scattered
muons on two different applications of muon imaging: archaeology and
volcanology, revealing a significant impact on the latter case. The general way
in which all the tools used have been developed can allow to make equivalent
studies in the future for other muon imaging applications following the same
procedure.
