  An empirical numerical model that includes nuclear absorption, multiple
Coulomb scattering, and energy loss is presented in this work to calculate the
transmission of the thick objects in high energy proton radiography, and in
this numerical model the angular distributions are treated as Gaussians in the
laboratory frame. A Monte Carlo program based on Geant4 toolkit was developed
using for the high energy proton radiography experiment simulation, and
verifying the empirical numerical model. The two models are used to calculate
the transmission fraction of the step-wedge of carbon and lead in proton
radiography at 24GeV/c. The two models can reproduce the experiment data, and
the differences are analyzed.
