title: Radiotherapy dose enhancement using BNCT in conventional LINACs high-energy treatment: Simulation and experiment.
abstract: OBJECTIVE
  To employ the thermal neutron background that affects the patient during a traditional high-energy radiotherapy treatment for BNCT (Boron Neutron Capture Therapy) in order to enhance radiotherapy effectiveness.
  
  
  BACKGROUND
  Conventional high-energy (15-25 MV) linear accelerators (LINACs) for radiotherapy produce fast secondary neutrons in the gantry with a mean energy of about 1 MeV due to (γ, n) reaction. This neutron flux, isotropically distributed, is considered as an unavoidable undesired dose during the treatment. Considering the moderating effect of human body, a thermal neutron fluence is localized in the tumour area: this neutron background could be employed for BNCT by previously administering (10)B-Phenyl-Alanine ((10)BPA) to the patient.
  
  
  METHODS
  Monte Carlo simulations (MCNP4B-GN code) were performed to estimate the total amount of neutrons outside and inside human body during a traditional X-ray radiotherapy treatment. Moreover, a simplified tissue equivalent anthropomorphic phantom was used together with bubble detectors for thermal and fast neutron to evaluate the moderation effect of human body.
  
  
  RESULTS
  Simulation and experimental results confirm the thermal neutron background during radiotherapy of 1.55E07 cm(-2) Gy(-1). The BNCT equivalent dose delivered at 4 cm depth in phantom is 1.5 mGy-eq/Gy, that is about 3 Gy-eq (4% of X-rays dose) for a 70 Gy IMRT treatment.
  
  
  CONCLUSIONS
  The thermal neutron component during a traditional high-energy radiotherapy treatment could produce a localized BNCT effect, with a localized therapeutic dose enhancement, corresponding to 4% or more of photon dose, following tumour characteristics. This BNCT additional dose could thus improve radiotherapy, acting as a localized radio-sensitizer.
authors.affiliation: Department of Physics, University of Turin, Via Pietro Giuria 1, 10126 Torino, Italy.
authors.forename: Katia
authors.initials: K
authors.lastname: Alikaniotis
authors.affiliation: Polytechnic of Turin, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Oscar
authors.initials: O
authors.lastname: Borla
authors.affiliation: Department of Physics, University of Turin, Via Pietro Giuria 1, 10126 Torino, Italy.
authors.forename: Valeria
authors.initials: V
authors.lastname: Monti
authors.affiliation: INFN of Turin, Via Pietro Giuria 1, 10126 Torino, Italy.
authors.forename: Gianna
authors.initials: G
authors.lastname: Vivaldo
authors.affiliation: INFN of Turin, Via Pietro Giuria 1, 10126 Torino, Italy.
authors.forename: Alba
authors.initials: A
authors.lastname: Zanini
authors.affiliation: Department of Physics, University of Trieste and INFN of Trieste, Via Valerio 2, 34127 Trieste, Italy.
authors.forename: Gianrossano
authors.initials: G
authors.lastname: Giannini
keywords: BNCT; Neutron; Photo-production; e-LINAC