title: Simulations of microdosimetric quantities with the Monte Carlo code FLUKA for carbon ions at therapeutic energies.
abstract: OBJECTIVE
  Microdosimetric quantities can be used to estimate the biological effectiveness of radiation fields. This study evaluates the capability of the general-purpose Monte Carlo code FLUKA to simulate microscopic patterns of energy depositions for mixed radiation fields which are created by carbon ions at therapeutic energies in phantoms.
  
  
  METHODS
  Measured lineal energy spectra and linear energy transfer (LET) spectra produced by carbon ions of about 300 MeV/n at different depths in phantoms representing human tissue were chosen from published literature and were compared with results from simulations of the measurement set-ups with FLUKA.
  
  
  RESULTS
  Simulations of the dose-weighted lineal energy spectra yd(y) and dose-weighted LET spectra describe the main features of the respective measured spectra. All simulated frequency mean and dose mean lineal energy values are, respectively, within 21% and 11% of the measured ones. A slight underestimation of fragment fluences is notable. It is shown that the simultaneous detection of several charged fragments in the TEPC ('V effect') has considerable impact on the measured lineal energy spectra of fragments.
  
  
  CONCLUSIONS
  Agreement between measurements and FLUKA results is encouraging and shows that FLUKA can predict microdosimetric spectra of mixed radiation fields created by therapeutic carbon ions in phantoms reasonably well.
authors.affiliation: European Organization for Nuclear Research CERN, CH-1211, Geneva 23, Switzerland. Till.Tobias.Boehlen@cern.ch
authors.forename: Till T
authors.initials: TT
authors.lastname: Böhlen
authors.forename: Manjit
authors.initials: M
authors.lastname: Dosanjh
authors.forename: Alfredo
authors.initials: A
authors.lastname: Ferrari
authors.forename: Irena
authors.initials: I
authors.lastname: Gudowska
mesh_terms: D002244:Carbon / Q000627:therapeutic use*; D006801:Humans; D018499:Linear Energy Transfer; D055616:Microtechnology / Q000379:methods*; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011874:Radiometry
chemical_list: D002244:Carbon