The alanine detector in BNCT dosimetry: Dose response in thermal and epithermal neutron fields. Issue 1 (30th December 2014)

• Record Type: Journal Article
• Authors: Schmitz, T.; Bassler, N.; Blaickner, M.; Ziegner, M.; Hsiao, M. C.; Liu, Y. H.; Koivunoro, H.; Auterinen, I.; Serén, T.; Kotiluoto, P.; Palmans, H.; Sharpe, P.; Langguth, P.; Hampel, G.
• Is Part Of: Medical physics. Volume 42:Issue 1(2015)
• Page Start: 400
• Page End: 411
• Publication Date: 2014-12-30
• Subjects: biomedical equipment -- dosimetry -- Monte Carlo methods -- neutron capture therapy -- neutron sources -- organic compounds -- paramagnetic resonance; Therapeutic applications, including brachytherapy -- Monte Carlo methods -- Probability theory, stochastic processes, and statistics -- Dosimetry/exposure assessment; Radiation therapy -- Production or acceleration of neutral particle beams, e.g. molecular or atomic beams -- Scintigraphy -- Neutron sources; dosimetry -- neutrons -- mixed fields -- alanine -- Monte Carlo modeling; Neutrons -- Photons -- Dosimetry -- Protons -- Monte Carlo methods -- Acids -- Neutron radiation effects -- Particle beam detectors -- Boron -- Graphite; Medical physics -- Periodicals; Medical physics; Geneeskunde; Natuurkunde; Toepassingen; Biophysics; Periodicals; Periodicals; Electronic journals; 610.153
• DOI: 10.1118/1.4901299
• Languages: English
• ISSNs: 0094-2405

Abstract

Abstract : Purpose: 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 codesfluka andmcnp . 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.