title: The alanine detector in BNCT dosimetry: dose response in thermal and epithermal neutron fields.
abstract: OBJECTIVE
  The response of alanine solid state dosimeters to ionizing radiation strongly depends on particle type and energy. Due to nuclear interactions, neutron fields usually also consist of secondary particles such as photons and protons of diverse energies. Various experiments have been carried out in three different neutron beams to explore the alanine dose response behavior and to validate model predictions. Additionally, application in medical neutron fields for boron neutron capture therapy is discussed.
  
  
  METHODS
  Alanine detectors have been irradiated in the thermal neutron field of the research reactor TRIGA Mainz, Germany, in five experimental conditions, generating different secondary particle spectra. Further irradiations have been made in the epithermal neutron beams at the research reactors FiR 1 in Helsinki, Finland, and Tsing Hua open pool reactor in HsinChu, Taiwan ROC. Readout has been performed with electron spin resonance spectrometry with reference to an absorbed dose standard in a (60)Co gamma ray beam. Absorbed doses and dose components have been calculated using the Monte Carlo codes fluka and mcnp. The relative effectiveness (RE), linking absorbed dose and detector response, has been calculated using the Hansen & Olsen alanine response model.
  
  
  RESULTS
  The measured dose response of the alanine detector in the different experiments has been evaluated and compared to model predictions. Therefore, a relative effectiveness has been calculated for each dose component, accounting for its dependence on particle type and energy. Agreement within 5% between model and measurement has been achieved for most irradiated detectors. Significant differences have been observed in response behavior between thermal and epithermal neutron fields, especially regarding dose composition and depth dose curves. The calculated dose components could be verified with the experimental results in the different primary and secondary particle fields.
  
  
  CONCLUSIONS
  The alanine detector can be used without difficulty in neutron fields. The response has been understood with the model used which includes the relative effectiveness. Results and the corresponding discussion lead to the conclusion that application in neutron fields for medical purpose is limited by its sensitivity but that it is a useful tool as supplement to other detectors and verification of neutron source descriptions.
authors.affiliation: Institute for nuclear chemistry, Johannes Gutenberg-University, Mainz D-55128, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Schmitz
authors.affiliation: Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, Aarhus C, Aarhus 8000, Denmark.
authors.forename: N
authors.initials: N
authors.lastname: Bassler
authors.affiliation: AIT Austrian Institute of Technology GmbH, Vienna A-1220, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Blaickner
authors.affiliation: AIT Austrian Institute of Technology GmbH, Vienna A-1220, Austria and TU Wien, Vienna University of Technology, Vienna A-1020, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Ziegner
authors.affiliation: Insitute of Nuclear Engineering and Science, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China.
authors.forename: M C
authors.initials: MC
authors.lastname: Hsiao
authors.affiliation: Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu 30013, Taiwan, Republic of China.
authors.forename: Y H
authors.initials: YH
authors.lastname: Liu
authors.affiliation: Department of Physics, University of Helsinki, POB 64, FI-00014, Finland and HUS Medical Imaging Center, Helsinki University Central Hospital, FI-00029 HUS, Finland.
authors.forename: H
authors.initials: H
authors.lastname: Koivunoro
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland.
authors.forename: I
authors.initials: I
authors.lastname: Auterinen
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Serén
authors.affiliation: VTT Technical Research Centre of Finland, Espoo, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Kotiluoto
authors.affiliation: National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW, United Kingdom and Medical Physics Group, EBG MedAustron GmbH, Wiener Neustadt A-2700, Austria.
authors.forename: H
authors.initials: H
authors.lastname: Palmans
authors.affiliation: National Physical Laboratory, Acoustics and Ionising Radiation Division, Teddington TW11 0LW, United Kingdom.
authors.forename: P
authors.initials: P
authors.lastname: Sharpe
authors.affiliation: Department of Pharmacy and Toxicology, University of Mainz, Mainz D-55128, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Langguth
authors.affiliation: Institut für Kernchemie, Johannes Gutenberg-Universität, Mainz D-55128, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Hampel
mesh_terms: D000409:Alanine / Q000528:radiation effects*; D016754:Boron Neutron Capture Therapy / Q000295:instrumentation* / Q000379:methods; D003037:Cobalt Radioisotopes / Q000627:therapeutic use; D003198:Computer Simulation; D004307:Dose-Response Relationship, Radiation; D004578:Electron Spin Resonance Spectroscopy; D005720:Gamma Rays / Q000627:therapeutic use; D008962:Models, Theoretical; D009010:Monte Carlo Method; D009502:Neutrons / Q000627:therapeutic use*; D017785:Photons; D011522:Protons; D011874:Radiometry / Q000295:instrumentation* / Q000379:methods
chemical_list: D003037:Cobalt Radioisotopes; D011522:Protons; D000409:Alanine