  In their article published in Phys. Med. Biol. 60 (2015) 4149-4168, Lin et al
studied the radiosensitizing effect of gold nanoparticles (GNPs) using
radiation transport simulations and a biological model for the survival of
irradiated cells. This comment points out several 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 radiation effects of gold nanoparticles.
The two main caveats are the high mass fraction of gold considered and a
potential problem with the modified local effect model used to predict cell
survival.
