title: Impact of Various Beam Parameters on Lateral Scattering in Proton and Carbon-ion Therapy.
abstract: BACKGROUND
  In radiation therapy with ion beams, lateral distributions of absorbed dose in the tissue are important. Heavy ion therapy, such as carbon-ion therapy, is a novel technique of high-precision external radiotherapy which has advantages over proton therapy in terms of dose locality and biological effectiveness.
  
  
  METHODS
  In this study, we used Monte Carlo method-based Geant4 toolkit to simulate and calculate the effects of energy, shape and type of ion beams incident upon water on multiple scattering processes. Nuclear reactions have been taken into account in our calculation. A verification of this approach by comparing experimental data and Monte Carlo methods will be presented in an upcoming paper.
  
  
  RESULTS
  Increasing particle energies, the width of the Bragg curve becomes larger but with increasing mass of particles, the width of the Bragg curve decreases. This is one of the advantages of carbon-ion therapy to treat with proton. The transverse scattering of dose distribution is increased with energy at the end of heavy ion beam range. It can also be seen that the amount of the dose scattering for carbon-ion beam is less than that of proton beam, up to about 160mm depth in water.
  
  
  CONCLUSIONS
  The distortion of Bragg peak profiles, due to lateral scattering of carbon-ion, is less than proton. Although carbon-ions are primarily scattered less than protons, the corresponding dose distributions, especially the lateral dose, are not much less.
authors.affiliation: Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran.
authors.forename: M
authors.initials: M
authors.lastname: Ebrahimi Loushab
authors.affiliation: Physics Department, School of Sciences, Hakim Sabzevari University, Sabzevar, Iran ; ICTP, Associate Federation, Medical Physics Section, Trieste, Italy.
authors.forename: A A
authors.initials: AA
authors.lastname: Mowlavi
authors.affiliation: Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran.
authors.forename: M H
authors.initials: MH
authors.lastname: Hadizadeh
authors.affiliation: Physics Department, Faculty of Sciences, Ferdowsi University of Mashhad, Mashhad, Iran.
authors.forename: R
authors.initials: R
authors.lastname: Izadi
authors.affiliation: Physics Department, University of Bojnord, Bojnord, Iran.
authors.forename: S B
authors.initials: SB
authors.lastname: Jia
keywords: Bragg Peak; Carbon-ion Therapy; Geant4; Hadronic Interaction; Lateral Dose; Multiple Scattering; Proton Therapy