Comment on “A simple empirical forward model for combined nuclear and multiple Coulomb scattering in proton radiography of thick objects”

A recent paper presents the view “a deterministic forward model that includes the essential physics of all of the elements of the radiographic chain is required to extract volume density distributions and material interface surface positions from proton transmission radiographs by iterative nonlinear fitting of parametric forward models” and presents a model that includes nuclear absorption, multiple Coulomb scattering, coherent nuclear elastic scattering and quasi-elastic nuclear scattering. In this note we point out that the data used in the above paper is not consistent with all of the points mentioned above. Specifically the quasi-elastic scattering term is not required to explain the data if the experimental setup is correctly modeled. Results from Monte Carlo modeling are presented verifying this point.