title: Technical Note: Monte Carlo study of106Ru/106Rh ophthalmic plaques including the106Rh gamma spectrum.
abstract: OBJECTIVE
  To assess the influence of the106Rh gamma spectrum on the Monte Carlo simulation of106Ru/106Rh ophthalmic plaques, which has been neglected without a quantitative estimation in all previous publications.
  
  
  METHODS
  Simulations were run with the penelope 2014 Monte Carlo code for radiation transport. Depth-dose distributions in water were simulated for the plaque models CCA, CCC, CCX and CIA. In addition to the106Rh beta spectrum, all gamma components from the106Rh gamma spectrum were included in the simulations. Depth-dose curves were compared with those obtained without considering the106Rh gamma spectrum. Moreover, half-value (HVL) and tenth-value layers (TVL) were estimated for the106Rh gamma spectrum in water, PMMA, stainless steel and lead. Some practical radiation protection applications were discussed. Parallel computing was implemented to reduce computing time.
  
  
  RESULTS
  The contribution of the106Rh gamma spectrum on the depth-dose curves is negligible at depths of clinical interest. The HVL and TVL of the106Rh gamma spectrum were found to be similar to those of137Cs. The air-kerma rate at 1 m for a CCA plaque in typical clinical conditions was about 0.4μGym2h-1, resulting in equivalent doses at that point elow 0.05 mSv during a treatment. The air-kerma rate would be underestimated by a factor of 5 if the106Rh gamma spectrum were not considered. Also, a freely available software tool was developed to ease parallelization of penelope 2014 simulations that use penmain as steering main program.
  
  
  CONCLUSIONS
  The influence of the106Rh gamma spectrum is not relevant for clinical purposes, thus validating the common assumption from the literature. However, for simulations at large distances from the plaques, such as for radiation shielding assessment and estimation of dose to personnel, the gamma spectrum from106Rh must be taken into account to obtain accurate results.
authors.affiliation: NCTeam, Strahlenklinik, Universitätsklinikum Essen, Hufelandstraße 55, D-45122, Essen, Germany.|Servei de Física i Protecció Radiològica, Hospital Universitari Vall d'Hebron, Institut de Recerca (VHIR), Universitat Autònoma de Barcelona Pg. Vall d'Hebron, 119-129, 08035, Barcelona, Spain.
authors.forename: Marcelino
authors.initials: M
authors.lastname: Hermida-López
authors.affiliation: NCTeam, Strahlenklinik, Universitätsklinikum Essen, Hufelandstraße 55, D-45122, Essen, Germany.
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Brualla
mesh_terms: D003198:Computer Simulation; D006801:Humans; D009010:Monte Carlo Method; D011835:Radiation Protection; D011874:Radiometry; D012984:Software; D014867:Water
chemical_list: D014867:Water
keywords: 
  penelope
  ; MUSIMAN; ruthenium plaques