title: Studying Effects of Gold Nanoparticle on Dose Enhancement in Megavoltage Radiation.
abstract: BACKGROUND
  Gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated as drug carriers, photothermal agents, contrast agents and radiosensitisers.
  
  
  OBJECTIVE
  The aim of this study is to understand characteristics of secondary electrons generated from interaction of gold nanoparticles GNPs with x-rays as a function of nanoparticle size and beam energy and thereby further understanding of GNP-enhanced radiotherapy.
  
  
  METHODS
  Effective range, defection angle, dose deposition, energy, and interaction processes of electrons produced from the interaction of x-rays with a GNP were calculated by Monte Carlo simulations. The MCNPX code was used to simulate and track electrons generated from 30 and 50 nm diameter GNP when it is irradiated with a cobalt-60 and 6MV photon and electron beam in water.
  
  
  RESULTS
  When a GNP was present, depending on beam types used, secondary electron production increased by 10- to 2000-fold compared to absence of a GNP.
  
  
  CONCLUSIONS
  GNPs with larger diameters also contributed to more doses.
authors.affiliation: Master of Nuclear Physics, Babol University of Medical Science, Paramedical School, Babol, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Khadem Abolfazli
authors.affiliation: Assistant Professor of Medical Physics, Iran university of medical science, Tehran, Iran.
authors.forename: S R
authors.initials: SR
authors.lastname: Mahdavi
authors.affiliation: Master of Biophysics, Babol University of Medical Science, Paramedical School, Babol, Iran.
authors.forename: Gh
authors.initials: G
authors.lastname: Ataei
keywords: Dose Enhancement; Gold Nanoparticle; MCNPX Code; Megavoltage Radiotherapy