Study of suitability of Fricke-gel-layer dosimeters for in-air measurements to characterize epithermal/thermal neutron beams for NCT

The reliability of Fricke gel dosimeters in form of layers for measurements aimed at the characterization of epithermal neutron beams has been studied. By means of dosimeters of different isotopic composition (standard, containing 10B or prepared with heavy water) placed against the collimator exit, the spatial distribution of gamma and fast neutron doses and of thermal neutron fluence are attained. In order to investigate the accuracy of the results obtained with in-air measurements, suitable MC simulations have been developed and experimental measurements have been performed utilizing Fricke gel dosimeters, thermoluminescence detectors and activation foils. The studies were related to the epithermal beam designed for BNCT irradiations at the research reactor LVR-15 (Řež). The results of calculation and measurements have revealed good consistency of gamma dose and fast neutron 2D distributions obtained with gel dosimeters in form of layers. In contrast, noticeable modification of thermal neutron fluence is caused by the neutron moderation produced by the dosimeter material. Fricke gel dosimeters in thin cylinders, with diameter not greater than 3 mm, have proved to give good results for thermal neutron profiling. For greater accuracy of all results, a better knowledge of the dependence of gel dosimeter sensitivity on radiation LET is needed

Determination of Trace Concentration in TMD Detectors using PGAA

Transmutation detectors could be alternative to the traditional activation detector method for neutron fluence dosimetry at power nuclear reactors. This new method require an isotopically highly-sensitive, non-destructive in sense of compactness as well as isotopic content, precise and standardly used analytical method for trace concentration determination. The capability of Prompt Gamma-ray Activation Analysis (PGAA) for determination of trace concentrations of transmuted stable nuclides in the metallic foils of Ni, Au, Cu and Nb, which were irradiated for 21 days in the reactor core at the LVR-15 research reactor in Řež, is reported. The PGAA measurements of these activation foils were performed at the PGAA facility at Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRMII) in Garching

Fast-neutron dose evaluation in BNCT with Fricke gel layer detectors

Boron neutron capture therapy (BNCT) is a cancer radiotherapy that uses epithermal and thermal neutron beams.The determination of the absorbed dose in healthy tissue, separating the various dose contributions having different radiobiological effectiveness (RBE) is of great importance for therapy planning. However, a standard code of practice has not yet been established because suitable methods for dosimetry in BNCT are still in progress. A study about the characterization o fthe epithermal column of the LVR-15 research reactor in Rez (CZ) has been performed, in particular concerning the fast-neutron dose. This dose is no tnegligible and its determination is important owing to its high RBE. Fast-neutron and photon dose distributions in a water phantom have been measured by means of Frickegel layer dosimeters. Even if gel layer dosimetry is not yet standardized, it is presently the only method for obtaining images of each dose contribution in BNCT neutron fields. The results were compared with values measured with thermoluminescence detectors, twin ionization chambers, data taken from literature and MonteCarlo simulations

Determination of Trace Concentration in TMD Detectors using PGAA

Transmutation detectors could be alternative to the traditional activation detector method for neutron fluence dosimetry at power nuclear reactors. This new method require an isotopically highly-sensitive, non-destructive in sense of compactness as well as isotopic content, precise and standardly used analytical method for trace concentration determination. The capability of Prompt Gamma-ray Activation Analysis (PGAA) for determination of trace concentrations of transmuted stable nuclides in the metallic foils of Ni, Au, Cu and Nb, which were irradiated for 21 days in the reactor core at the LVR-15 research reactor in Řež, is reported. The PGAA measurements of these activation foils were performed at the PGAA facility at Forschungs-Neutronenquelle Heinz Maier-Leibnitz (FRMII) in Garching

Evaluation of all dose components in the LVR-15 reactor epithermal neutron beam using Fricke gel dosimeter layers

Fricke gel dosimeters in the form of layers are suitable to reconstruct bidimensional distributions of the absorbed dose; in accordance with their chemical composition and applying suitably developed algorithms, they can provide dose images of the different radiation components in a BNCT field. After the description of the applied method, this work presents the results obtained at the epithermal column of the BNCT facility at the NRI in \u158e\u17e (CZ). The measured dose distributions are shown in comparison with data taken by means of other dosimeters thermoluminescence dosimeters (TLDs) and with calculations carried out with the Monte Carlo code MCNP5. The agreement with the results obtained by means of the different techniques is satisfying

Fast Neutron Dose Evaluation in BNCT with Fricke Gel Detectors

Boron neutron capture therapy (BNCT) is a cancer radiotherapy that uses epithermal neutron beams. For therapy planning, a preliminary determination of the absorbed dose in healthy tissue is necessary, separating the various dose contributions having different biological effect. An experimental method, based on Fricke gel dosimeters, for imaging the dose due to the fast-neutron component of the beam has been developed and the results obtained with a BNCT epithermal beam are shown, supported by Monte Carlo simulations

LVR-15 Reactor Epithermal Neutron Beam parameters - results of measurements

The epithermal neutron beam of the LVR-15 reactor provides the appropriate conditions for varied BNCT activity. The principal parameters have been frequently determined. The following detectors has been used for the measurement: Set of activation monitors of different nuclides irradiated in free beam and in the water phantom, Si semiconductor detector with 6LiF converter, twin ionization chambers, thermoluminescence dosimeters, gel dosimeters used for imaging of separate part of dose, neutron spectrometer of Bonner type. Obtained results of measured parameters are presented in the paper