Experimental and Monte Carlo simulation study on potential new composite materials to moderate neutron-gamma radiation

Efficiency of tungsten-polymer composite shields on fetal dose reduction in chest CT scans

Given their desirable shielding properties, 5 polymer composite shields reinforced with tungsten were selected and their effects as gamma shields on fetal dose reduction were investigated. According to the results, the selected shields reduce the fetus brain, the fetus lungs, the fetus kidneys, and the total fetus dose almost 34.17%-41.19%, 20.47%-25.08%, 9.27%-12.13%, and 15.39%-18.69%, respectively, at tube voltage of 80 kVp. At the higher tube potentials, the values of dose reduction were smaller. Moreover, it was observed that polymers named PHEMA-WO3 and RS-U-30 had an excellent shielding ability among the other studied composites.

Investigation of radiation protective features of azadispiro derivatives and their genotoxic potential with Ames/Salmonella test system

PURPOSE

Five different types of synthesized azadispiro derivatives have been analyzed for radiation absorption capacity and determined their potential to be exploited as substances for a drug to be developed against radiation has been investigated.

MATERIAL AND METHODS

Fast neutron attenuation parameters like the effective mean free path, half-value layer (HVL), removal cross-sections, and neutron transmission number were found with the Monte Carlo simulation Geometry And Tracking (GEANT4) code. Gamma radiation absorption parameters, such as effective atom number (Z_eff), mean free path (MFP), mass attenuation coefficient (MAC), and half-value layer (HVL) were theoretically determined with WinXCom software. Besides, the exposure build-up factor (EBF) was calculated by using GP fitting parameters. Neutron absorption dose rate was experimentally calculated with ²⁴¹Am-Be fast neutron source which has 4.5 MeV of energy, 74 GBq activity, and portative BF₃ neutron detector. Ames/Salmonella test systems were used for the genotoxic potentials of the azadispiro derivatives.

RESULTS AND CONCLUSIONS

Experimental and theoretical results were checked with paraffin and High-Density Polyethylene. The results showed that Azadispiro derivatives have neutron radiation absorption capability close to paraffin and High-Density Polyethylene. The gamma radiation absorption properties for azadispiro derivatives have been investigated, and it has been observed that these materials can absorb gamma radiation. Ames/Salmonella assay was used to examine whether the derivatives had a genotoxic effect probability or not. The results showed that these derivatives were genotoxic and safe at test doses (up to 5 mM). Consequently, it has been understood that these azadispiro derivatives can be used as active and genotoxic safety ingredients in the production of a protective drug against both neutrons and gamma rays.

Determination of radioprotective and genotoxic properties of sulfamide derivatives

Some potential drug active substances with the ability to reduce the effects of radiation on human tissues and cells were investigated. For this purpose, eight different types of sulfamide derivatives were synthesized and nuclear radiation protection parameters were determined. Neutron radiation reduction parameters such as the half-value layer effective removal cross-sections, mean free path, and the number of particles passing through the sample were determined with GEANT4 code. Additionally, the gamma radiation attenuation parameters of the materials examined were determined using Phy-X/PSD software in the energy area of 0.015–15 MeV. These parameters are the half-value layer, mass attenuation coefficient, mean free path, exposure buildup factor and effective atomic number. Neutron radiation absorption experiments were applied using an 241Am-Be fast neutron source. All results obtained for neutron radiation were compared with paraffin and water. It has been found that the ability of sulfamide derivatives to absorb these radiations is superior to reference materials. To determine whether these derivatives could have adverse effects on human health, their genotoxic potential was determined using the Ames/Salmonella bacterial reversion test. The results showed that these derivatives can be considered genotoxically safe in tests at concentrations up to 5 mM. Thus, it is suggested that the derivative materials examined in this study can be used as active substances for a drug to be made for protection against both neutron and gamma radiation.

Evaluation of the Radiation Shielding Characteristics of Several Glass Systems Using the EPICS2017 Library

In this paper, the investigation of the Electron–Photon Interaction Cross Sections 2017 (EPICS2017) library on the shielding characteristics of several glasses under various chemical systems is presented. The EPICS2017 library of ENDF/B-VIII was interpolated to calculate the mass attenuation coefficients (MACs) of selected glass systems. Results from EPICS2017 have been compared with values from experimental and theoretical methods used to evaluate the photon shielding properties. The EPICS2017 estimations strongly agreed with experimental MAC results. The MAC values from several Monte Carlo codes (Geant4, MCNP4C, MCNP5, and FLUKA) based on EPDL97 or EPDL89 strongly agreed with EPICS2017-based interpolation, within reasonable deviations. The obtained results indicate that EPICS2017 can be used to evaluate the MACs for any glass system in which there are no experimental values available at various photon energies. It was demonstrated that the linear EPICS2017 library can be a considerable tool in future photon shielding research and developments of glass systems, as a recent alternative to the widely used XCOM by NIST.