Comment on "Comparing gold nano-particle enhanced radiotherapy with protons, megavoltage photons and kilovoltage photons: A Monte Carlo simulation" by Lin et al [Phys. Med. Biol. 59 (2014) 7675-7689]

In their article published in Phys. Med. Biol. 59 (2014) 7675-7689, Lin et al studied the dose enhancement of of gold nanoparticles (GNPs) for proton therapy, which they compared with the case of photon irradiation. This comment points out two caveats to the methodlogy used by Lin et al that may not be evident to readers and may contribute to confusion in the literature about the dose enhancement by gold nanoparticles.