Comment on 'Monte Carlo simulation on a gold nanoparticle irradiated by electron beams'

A recent paper by Chow et al (Phys. Med. Biol 57 3323-31) quantifies the dose due to secondary electrons created by gold nanoparticles when irradiated by electron beams. That paper fails to compare this dose to the overall dose from the electron beam. EGSnrc calculations are performed to show that, even for the unrealistically favourable case presented by Chow et al of a very narrow electron beam directed only at the nanoparticle, the dose outside the nanoparticle due to the secondary electrons generated by the nanoparticle is negligible compared to the dose from the primaries. Thus, it is irrelevant whether the dose from secondary particles is enhanced by the nanoparticles or not and there appears to be no advantage to using gold nanoparticles in electron beams, unlike the case for photon beams.