  In this paper, we consider the imaging problem of terahertz (THz) tomography,
in particular as it appears in non-destructive testing. We derive a nonlinear
mathematical model describing a full THz tomography experiment, and consider
linear approximations connecting THz tomography with standard computerized
tomography and the Radon transform. Based on the derived models we propose
different reconstruction approaches for solving the THz tomography problem,
which we then compare on experimental data obtained from THz measurements of a
plastic sample.
