THE DETERMINATION OF NEUTRON FLUENCE TO ABSORBED DOSE CONVERSION COEFFICIENTS AND RELATIVE BIOLOGICAL EFFECT BASED ON MICRODOSIMETRY MEASUREMENTS

2019 ◽  
Vol 187 (2) ◽  
pp. 262-267
Author(s):  
Weihua Zhang ◽  
Chunjuan Li ◽  
Yisheng Zou ◽  
Yina Liu ◽  
Hailong Luo
Keyword(s):  
Biological Effect ◽  
Absorbed Dose ◽  
Neutron Radiation ◽  
Electron Multiplier ◽  
Lineal Energy ◽  
Radiation Fields ◽  
Empirical Procedure ◽  
Tissue Equivalent ◽  
Conversion Coefficients ◽  
Tissue Equivalent Proportional Counter

Abstract A tissue-equivalent proportional counter (TEPC) is a reference detector to measure microdosimetric quantities. A conventional spherical TEPC and a novel TEPC based on a ceramic thick gas electron multiplier (THGEM) foil were developed to carry out microdosimetric measurements of lineal energy spectra in monoenergetic and 252Cf/241Am-Be neutron radiation fields, and the absorbed dose values had been derived. In order to go further in radiobiology and therapy, the fluence to absorbed dose conversion coefficients in neutron fields were also determined. According to the dose distribution in lineal energy, the neutron relative biological effect (RBE) values were also calculated using an empirical procedure applying biological weighting functions.

On Some Methodological Issues of Studying Cytogenetic Effects in Cancer Patients Treated with Neutron Therapy Using U-120 Cyclotron

2018 ◽  
Vol 63 (2) ◽  
pp. 47-54
Author(s):  
В. Лисин ◽  
V. Lisin
Keyword(s):  
Radiation Field ◽  
Chromosome Aberrations ◽  
Absorbed Dose ◽  
Neutron Radiation ◽  
The Body ◽  
Beam Intensity ◽  
Whole Body ◽  
Γ Radiation ◽  
Cytogenetic Effect ◽  
Tissue Equivalent

Purpose: To study dosimetric characteristics of neutron radiation field, to determine their role in the formation of the total cytogenetic effect in the patient’s body and to assess the cytogenetic dosimetry capabilities in improving the quality of NT. Material and methods: A therapeutic beam with the average neutron energy of ~6.3 MeV was obtained from the V-120 cyclotron. The radiation field of the beam was investigated with the help of two ionization chambers with different sensitivity to neutrons. Chamber with high and low sensitivities were made of polyethylene and graphite, respectively. To exclude the uncertainty associated with the change in beam intensity in time, a dosimeter monitor operating in the integral mode was used. Results: The dependence of the monitor factor on the irradiated area was measured. The distributions of the absorbed dose of neutrons and γ-radiation over the depth of the tissue-equivalent medium were found. The contribution of γ-radiation to the neutron dose was increased from ~10 % at the entry to the medium to ~30 % at a depth of 16 cm. Dose distributions of scattered neutron and γ-radiation in the plane of the end face of the forming device were obtained. The contribution of these radiations to the dose received by the patient’s body was estimated. This contribution was shown to be comparable with that from the therapeutic beam. The analysis of the influence of NT on the estimation of the frequency of chromosome aberrations in the blood of patients was carried out. Conclusion: The frequency of chromosome aberrations in the blood of patients was determined by the whole-body dose, including dose due to scattered radiation. When using equal focal doses, the cytogenetic effect was found to be dependent on the area of the irradiated field and the depth of the tumor in the patient’s body. The differences in the RBE of neutrons and γ-radiation as well as the instability of the therapeutic neutron beam intensity create uncertainties that do not allow for the necessary control over the doses using the cytogenetic dosimetry. Therefore, cytogenetic dosimetry should be combined with an effective instrument dosimetry method. The use of biodosimetry based on the assessment of the frequency of chromosome aberrations is promising for controlling the average whole-body dose, on which the overall radiation response of the body depends.

scholarly journals High-sensitive colour indicator of absorbed dose of epithermal neutrons radiation

2022 ◽  
Vol 2155 (1) ◽  
pp. 012032
Author(s):  
G A Kulabdullaev ◽  
A A Kim ◽  
G T Djuraeva ◽  
A F Nebesniy ◽  
G A Abdullaeva ◽  
...  
Keyword(s):  
Absorbed Dose ◽  
High Sensitivity ◽  
Neutron Radiation ◽  
Arsenazo Iii ◽  
Indicator Solution ◽  
Tissue Equivalent ◽  
Epithermal Neutrons ◽  
Delayed Measurement ◽  
Artificial Illumination ◽  
Error Of Measurement

Abstract In our study, the high-sensitivity colour indicator of the absorbed dose of radiation of epithermal neutrons with energy 0 to 10 keV for dosimetry of low-energy neutrons was developed. We had been developed an indicator on the basis of the dye solution of arsenazo III and gadopentetic acid, allowing precisely define of absorbed dose in the range 2 to 103 Gy. The properties of arsenazo III as metallic indicator, which changes colour after binding of free ions of metals, were used. Colour of the indicator solution before irradiation and after it is stable enough in time at storage in the dark, at artificial illumination or at scattered sunlight. The developed indicator, consisting of a solution of arsenazo III and gadopentetic acid, allows estimating the absorbed dose of epithermal neutron irradiation with good accuracy and reduces the error of measurement related to changing colour of dye under the influence of other factors (light, temperature etc.) Dosimeter is tissue-equivalent and possesses a high-sensitivity neutron radiation due to the content of gadolinium in solution, which has great neutron capture cross-section. The developed dosimeter persists spectrophotometric characteristics after irradiaion within few weeks that allows to use it for measurement of the absorbed dose, both in real time mode and with the delayed measurement within few weeks.

scholarly journals Experimental investigation on radiation shielding of high performance concrete for nuclear and radiotherapy facilities

2016 ◽  
Vol 22 (2) ◽  
pp. 41-47 ◽  
Author(s):  
Szymon Domański ◽  
Michał A. Gryziński ◽  
Maciej Maciak ◽  
Łukasz Murawski ◽  
Piotr Tulik ◽  
...  
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Absorbed Dose ◽  
Nuclear Research ◽  
Neutron Radiation ◽  
Radiation Shielding ◽  
Transmitted Radiation ◽  
Radiation Fields ◽  
Shielding Properties ◽  
Set Up

Abstract This paper presents the set of procedures developed in Radiation Protection Measurements Laboratory at National Centre for Nuclear Research for evaluation of shielding properties of high performance concrete. The purpose of such procedure is to characterize the material behaviour against gamma and neutron radiation. The range of the densities of the concrete specimens was from 2300 to 3900 kg/m3. The shielding properties against photons were evaluated using 137Cs and 60Co sources. The neutron radiation measurements have been performed by measuring the transmitted radiation from 239PuBe source. Scattered neutron radiation has been evaluated using the shadow cone technique. A set up of ionization chambers was used during all experiments. The gamma dose was measured using C-CO2 ionization chamber. The neutron dose was evaluated with recombination chamber of REM-2 type with appropriate recombination method applied. The method to distinguish gamma and neutron absorbed dose components in mixed radiation fields using twin detector method was presented. Also, recombination microdosimetric method was applied for the obtained results. Procedures to establish consecutive half value layers and tenth value layers (HVL and TVL) for gamma and neutron radiation were presented. Measured HVL and TVL values were linked with concrete density to highlight well known dependence. Also, influence of specific admixtures to concrete on neutron attenuation properties was studied. The results confirmed the feasibility of approach for the radiation shielding investigations.

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