ABSTRACT
In the study, the passive multi-layer neutron spectrometer, based on thermoluminescence detectors, was tested in a calibration laboratory with 239Pu-Be and 252Cf isotopic sources. MCNP code was used for the calculation of the response functions for the neutron energy range from 1 meV to 100 MeV. It was also utilised for initial guess spectra calculations. Deconvolution was performed with MAXED and GRAVEL deconvolution codes resulting in the neutron spectra defined at the measuring point in the calibration laboratory.
Subject(s)
Plutonium , Radiometry , Radiometry/methods , Californium , Neutrons , Radiation DosageABSTRACT
Extremely important aspects of the boron neutron capture therapy are, first of all, administering to the patient a boron compound that selectively reaches the neoplastic cells, and in the second step, the verification of the irradiation process. This paper focuses on the latter aspect, which is the detailed dosimetry of the processes occurring after the reaction of thermal neutrons with the boron-10 isotope. The results of computer simulations with the use of a new type of human head phantom filled with a polymer dosimetric gel will be presented in this article.
Subject(s)
Boron Neutron Capture Therapy , Humans , Boron Neutron Capture Therapy/methods , Radiometry/methods , Neutrons , Radiotherapy Dosage , Phantoms, ImagingABSTRACT
The aim of the study is to show a method of real-time determination of the dose deposited in a tissue-like medium by α-particles emitted from the 10B(n,α)7Li reaction. The applied research method is to determine the correlation between the measured density of α-particle traces and measured in real time the 478 keV prompt-gamma rays derived from the 10B(n,α)7Li reaction. To achieve this aim, an appropriate construction of an experimental set-up is needed. The experimental set-up built for the purpose of the measurements carried out in the MARIA Reactor at the National Centre for Nuclear Research in Swierk, Poland, is presented. The main challenges related to obtaining optimal conditions for the measurement of the 478 keV gamma photons; the preliminary results of spectrometric measurements and further studies are also discussed.
Subject(s)
Alpha Particles , Boron Neutron Capture Therapy , Gamma Rays , Boron Neutron Capture Therapy/methods , Radiometry/methods , Spectrum AnalysisABSTRACT
The purpose of the manuscript is to provide a step-by-step protocol for performing immunofluorescence microscopy to study the radiation-induced DNA damage response induced by neutron-gamma mixed-beam used in boron neutron capture therapy (BNCT). Specifically, the proposed methodology is applied for the detection of repair proteins activation which can be visualized as foci using antibodies specific to DNA double-strand breaks (DNA-DSBs). DNA repair foci were assessed by immunofluorescence in colon cancer cells (HCT-116) after irradiation with the neutron-mixed beam. DNA-DSBs are the most genotoxic lesions and are repaired in mammalian cells by two major pathways: non-homologous end-joining pathway (NHEJ) and homologous recombination repair (HRR). The frequencies of foci, immunochemically stained, for commonly used markers in radiobiology like γ-H2AX, 53BP1 are associated with DNA-DSB number and are considered as efficient and sensitive markers for monitoring the induction and repair of DNA-DSBs. It was established that γ-H2AX foci attract repair proteins, leading to a higher concentration of repair factors near a DSB. To monitor DNA damage at the cellular level, immunofluorescence analysis for the presence of DNA-PKcs representative repair protein foci from the NHEJ pathway and Rad52 from the HRR pathway was planned. We have developed and introduced a reliable immunofluorescence staining protocol for the detection of radiation-induced DNA damage response with antibodies specific for repair factors from NHEJ and HRR pathways and observed radiation-induced foci (RIF). The proposed methodology can be used for investigating repair protein that is highly activated in the case of neutron-mixed beam radiation, thereby indicating the dominance of the repair pathway.
