  Background: Calculating the characteristics of radiation emerging from
radiation shielding to determine the level of safety in protected areas has
been a widely studied topic in Radiation Protection due to its importance for
the protection of the public and professionals. Methods: This work provides
spatial distributions of energy spectra of emergent photons after shielding
barriers. These distributions are obtained through Monte Carlo simulations
using monoenergetic pencil photon beams incident on shielding barriers of
different materials and thicknesses. The obtained results are applied to
calculate the spectra of transmitted radiation in cases of polyenergetic beams
similar to those encountered in clinical practice. Results: The significant
contribution of secondary radiation in the radiation found behind shields is
demonstrated across a wide range of energies, barrier thicknesses and barrier
materials. Conclusion: It is shown that characterizing shields using their
response to monoenergetic pencil beams provides a useful tool for
characterizing radiation behind shields in a wide range of practical
situations.
