title: Impact of photon cross section uncertainties on Monte Carlo-determined depth-dose distributions.
abstract: This work studies the impact of systematic uncertainties associated to interaction cross sections on depth dose curves determined by Monte Carlo simulations. The corresponding sensitivity factors are quantified by changing cross sections by a given amount and determining the variation in the dose. The influence of total and partial photon cross sections is addressed. Partial cross sections for Compton and Rayleigh scattering, photo-electric effect, and pair production have been accounted for. The PENELOPE code was used in all simulations. It was found that photon cross section sensitivity factors depend on depth. In addition, they are positive and negative for depths below and above an equilibrium depth, respectively. At this depth, sensitivity factors are null. The equilibrium depths found in this work agree very well with the mean free path of the corresponding incident photon energy. Using the sensitivity factors reported here, it is possible to estimate the impact of photon cross section uncertainties on the uncertainty of Monte Carlo-determined depth dose curves.
authors: Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Brazil.
authors: E
authors: E
authors: Aguirre
authors: Laboratório de Ciências Radiológicas, Universidade do Estado do Rio de Janeiro, Brazil.
authors: M
authors: M
authors: David
authors: Laboratório de Ciências Radiológicas, Universidade do Estado do Rio de Janeiro, Brazil.
authors: C E
authors: CE
authors: deAlmeida
authors: Instituto de Física Gleb Wataghin, Universidade Estadual de Campinas, Brazil. Electronic address: mbernalrod@gmail.com.
authors: M A
authors: MA
authors: Bernal
mesh_terms: D000465:Algorithms; D001918:Brachytherapy / Q000379:methods; D003037:Cobalt Radioisotopes / Q000737:chemistry; D003198:Computer Simulation; D015233:Models, Statistical; D009010:Monte Carlo Method; D017785:Photons; D011336:Probability; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D015203:Reproducibility of Results; D012984:Software; D035501:Uncertainty
chemical_list: D003037:Cobalt Radioisotopes
keywords: Dose distribution; Monte Carlo; Photon cross sections; Systematic uncertainty