Statistical assessment of natural radioactivity, radon activity, and associated radiological exposure due to artisanal mining in Atiwa West district of the Eastern region, Ghana.

The activity concentration of natural radionuclides, radon activity concentration, mass and area exhalation rates have been studied in soils from gold mining communities in Atiwa West district. The natural radionuclides were determined by gamma ray spectrometry method while radon concentrations were measured using CR-39 detectors. The mean activity concentrations were found to be 26.9 ± 1.7 Bq/kg, 57.5 ± 3.6 Bq/kg, 237.5 ± 17.6 Bq/kg and 560.0 ± 54 Bq/m3 for Ra-226, Th-232, K-40 and Rn-222 respectively. The evaluated mass exhalation rates ranged from 2.8 ± 0.3 to 6.5 ± 0.7 × 10-5 Bq/kg/h while the area exhalation rates were from 0.8 ± 0.09 to 2.0 ± 0.21 × 10-3 Bq/m2/h. Some mining and farming areas recorded high exhalation rates indicating that the use of soils as building materials from such areas could pose a level of radiation hazard to the population. The evaluated radiological risks were below reference levels. A good linear correlation was observed between Ra-226 and Rn-222 activity concentrations and in the investigated soils. The Pearson correlation coefficient, cluster analysis and principal component analysis were used to study the relationship between the determined parameters of the study.

Cell-cycle dependence on the biological effects of boron neutron capture therapy and its modification by polyvinyl alcohol.

Boron neutron capture therapy (BNCT) is a unique radiotherapy of selectively eradicating tumor cells using boron compounds (e.g., 4-borono-L-phenylalanine [BPA]) that are heterogeneously taken up at the cellular level. Such heterogenicity potentially reduces the curative efficiency. However, the effects of temporospatial heterogenicity on cell killing remain unclear. With the technical combination of radiation track detector and biophysical simulations, this study revealed the cell cycle-dependent heterogenicity of BPA uptake and subsequent biological effects of BNCT on HeLa cells expressing fluorescent ubiquitination-based cell cycle indicators, as well as the modification effects of polyvinyl alcohol (PVA). The results showed that the BPA concentration in the S/G2/M phase was higher than that in the G1/S phase and that PVA enhances the biological effects both by improving the uptake and by canceling the heterogenicity. These findings might contribute to a maximization of therapeutic efficacy when BNCT is combined with PVA and/or cell cycle-specific anticancer agents.

Comparison of linear energy transfer measurement for therapeutic carbon beam using CR-39 and TLD.

The measurement of linear energy transfer (LET) is crucial for the evaluation of the radiation effect in heavy ion therapy. As two detectors which are convenient to implant into the phantom, the performance of CR-39 and thermoluminescence detector (TLD) for LET measurement was compared by experiment and simulation in this study. The results confirmed the applicability of both detectors for LET measurements, but also revealed that the CR-39 detector would lead to potential overestimation of dose-averaged LET compared with the simulation by PHITS, while the TLD would have a large uncertainty measuring ions with LET larger than 20 keVµm-1. The results of this study were expected to improve the detection method of LET for therapeutic carbon beam and would finally be benefit to the quality assurance of heavy ion radiotherapy.

Estimation of alpha exposure on CR-39 detector using a UV-VIS spectrophotometer.

This work is dedicated to study the possibility of using UV-VIS spectrophotometer, a non-invasive technique with a versatile applications that is being used to determine the optical properties of matter, to estimate the CR-39 exposure to alpha particles. CR-39 detectors were exposed to alpha particles from two different alpha sources: 241Am and radon gas. Tracks densities on CR-39 were determined using the traditional counting method by an optical microscope. The transmittances of CR-39 detectors were measured using UV-VIS spectroscopy in the range of 400-1000 nm, and results were correlated with measured tracks densities. The comparison showed that this method is effective in estimating exposure of CR-39 to alpha particles, and that its efficiency has increased by increasing the etching time of the detectors.

The impact of the broad range of gamma doses on follow-up fission fragment track parameters in CR-39 radiation detector.

In this study, the effect of high γ-doses on the track parameters, structure as well as optical properties of pristine and γ-irradiation CR-39 nuclear track detector (NTD) were investigated. CR-39 detectors were exposed to γ-doses from 50 up to 500 kGy and then irradiated by fission ions (F.F) of fluence from 252CF source. The track diameter (D), bulk etch rate (VB), etch induction time (EIT), cut-off or saturated time (tcut-off) for saturated diameters and projected track length (Lo) of normally and inclined incident fission tracks were estimated for different removal layers (h). A linear relationship between D and γ-doses (Dγ) up to 500 k Gy was obtained. The VB for pristine and for γ-irradiated CR-39 was determined. A linear behaviour of VB was obtained up to 300 kGy. Etch induction time (EIT) and saturated time (tcut-off) of pristine and γ-irradiated detectors for normal and inclined fission ions tracks were evaluated respectively up to 500 kGy. Each EIT and tcut-off decreased exponentially fast with increasing γ-doses but the inclined incidence appeared earlier than normal case. Pristine and γ-irradiated CR-39 detectors were examined using FTIR and UV-Vis spectrophotometer. From this study, a linear relation of band gap energies (Egap) as a function of γ-doses, Dγ, was obtained. The value of (Egap) decreased when increasing γ-doses for direct and indirect transitions, respectively. In addition, a systematic increase of Urbach energy (EU) was recorded together with the Dγ increase. Moreover, a linear behavior of the refractive index (n) along with γ-irradiated CR-39 plastic detector was observed via direct and indirect methods.

The contribution of high-LET track to DNA damage formation and cell death for Monoenergy and SOBP carbon ion irradiation.

Carbon ion radiotherapy (CIRT) is a heavy ion charge particle therapy with 29 years of prominent use. Despite advantages like high relative biological effectiveness (RBE), improved quality of life, and reduced treatment time, challenges persist, especially regarding heavy nuclear fragments. Our research addresses these challenges in horizontal irradiation, aiming to comprehend Monoenergetic and Spread-Out Bragg peak (SOBP) carbon ion beam trajectories using cell survival analysis and visualizing biological effects through DNA damage (γ-H2AX). This reveals repair-related protein foci near the Bragg peak. CR-39, a plastic nuclear track detector, was explored to understand high-linear energy transfer (LET) tracks and radiation quality near the Bragg peak. Findings unveil high-LET DNA damage signatures through aligned γ-H2AX foci, correlating with LET values in SOBP. CR-39 visualized high-LET particle exposure, indicating comet-type etch-pits at the Bragg peak and suggesting carbon ion fragmentation. Unexpectedly, dot-type etch-pits in irradiated and post-Bragg peak regions indicated high-LET neutron production. This investigation highlights the intricate interplay of carbon ion beams, stressing the importance of understanding LET variations, DNA damage patterns, and undesired secondary exposure.

Assessment of radiological risk associated with thoron gas at primary schools in Al-Najaf city, Iraq.

Children spend considerable time at home and school, so school is likely to be a second source of natural radionuclide exposure after home. This study evaluates the radiological risk associated with thoron gas in the air within the building of one hundred primary schools in Al-Najaf City, Iraq, using a CR-39 detector. The results of the average value of thoron concentration detector, the annual effective dose (AED), Excessive Lifetime Cancer Risk (ELCR) × 10-3, and Lung Cancer Case (LCC) × 10-9 measured in the building of the schools were 7.47 ± 2.85 Bq/m3, 0.03 ± 0.01 mSv/y, 0.11 ± 0.04, and 0.54 ± 0.20, respectively. All the results of indoor thoron were below the global average limit. The results of the radiological survey due to thoron concentrations for studied primary schools suggest that the radionuclides and their radiological hazard indexes in all studied schools in AL Najaf city, Iraq, do not impose a health hazard.

Assessment of 222Rn, 226Ra, 238U, 218Po, and 214Po activity concentrations in the blood samples of workers at selected building material factories in Erbil City.

The objective of this research is to assess the impact of radon concentration on workers at certain construction material industries in Erbil, Kurdistan Region of Iraq. The CR-39 solid-state track detector was used in this experiment to monitor radon levels and their daughters. For this purpose, as a case study group, 70 workers were divided into seven subgroups (gypsum, cement plant, lightweight block, marble, red brick 1, crusher stone, and concrete block 2), and 20 healthy volunteers were selected as a control group. The findings demonstrate that the mean concentrations of radon, radium, uranium, and radon daughters deposited on the detector face (POS) and chamber walls (POW) for the case study group were 9.61 ± 1.52 Bq/m3, 0.33 ± 0.05 Bq/Kg, 5.39 ± 0.86 mBq/Kg, 4 ± 0.63, and 16.62 ± 2.64 mBq/m3, whereas for the control group, they were 3.39 ± 0.58 Bq/m3, 0.117 ± 0.03 Bq/Kg, 1.91 ± 0.32 mBq/Kg, 1.41 ± 0.24, and 5.88 ± 1 mBq/m3, respectively. The statistical analysis revealed that radon, radium, uranium, and POW and POS concentrations were statistically significant (p ≤ 0.001) in the samples for the case study groups of cement, lightweight block, red brick 1, marble, and crusher stone factories in comparison to the control group; however, the results for gypsum and concrete block 2 factories were not statistically significant in comparison to the control group. Intriguingly, the radon levels in every blood sample examined were far lower than the 200 Bq/m3 limit established by the International Atomic Energy Agency. Hence, it may be argued that the blood is devoid of contaminants. These results are crucial for determining whether or not an individual is exposed to substantial quantities of radiation and for demonstrating a link between radon, its daughter, uranium, and the prevalence of cancer among workers in the Kurdish region of Iraq.

Measurement of radioactive concentration in different foodstuffs consumed in Jazan region.

This study is concerned with measuring and analyzing all the parameters that affect the increase of radioactive forcing values within foodstuffs. Radon gas and radioactive doses of various foodstuffs collected from the markets of the Jazan region were measured using the nuclear track detector (CR-39). The results showed that agricultural soils and food processing methods influence increasing the concentration of radon gas. The highest concentration of radon gas was recorded in the milk sample S11 with a value of 1204.65±108.00 Bq/m3, while the lowest value was in the sugar sample S31 with a value of 78.77±4.15 Bq/m3. The radon gas concentration results for flour, rice, sugar, and salt were all within the recommended limit, while 33% of the results of tea and 84% of the results of powdered milk were higher than the recommended limit. The average effective dose for different foodstuffs ranged from 14.82±1.92 to 2.61±0.25 mSv/y. There was a strong correlation between exhalation rates and radium values. All studied foods are safe for use, except for powdered milk, so it is recommended to reduce it.

Radon mapping, correlation study of radium, seasonal indoor radon and radon exhalation levels in communities around Ghana atomic energy commission.

Radon mapping and seasonal radon studies have been carried out within the communities around the Ghana Atomic Energy Commission (GAEC), using ArcMap geostatistical interpolation tool. The correlation analysis was done using Pearson's correlation tools. Average seasonal indoor radon variations for CR (rainy) and CD (dry) with mean values ranging from 28.9 to 177.2 Bq/m3 (78.1 ± 38.7 Bq/m3) and 24.4-125.5 Bq/m3 (69.9 ± 24.2 Bq/m3). Average seasonal soil radon exhalation for ER (rainy) and ED (dry) with mean values ranging from 39.6 to 100.3 (68.9 ± 24.2 µBq/m2 h) and 55.2 to 111.9 (77.1 ± 18.7 µBq/m2 h). Radium concentrations ranged from 8.1 to 42.2 Bq/kg (21.3 ± 9.9 Bq/kg). Annual effective dose and resultant effective dose to lungs were found to be 0.9 to 2.9 (1.9 ± 0.8 mSv/yr), 2.1 to 9.2 (4.6 mSv/yr). The study recorded the highest and lowest positive correlation coefficient was found in the study with higher and lower coefficient values of 0.81 and 0.47 recorded in radium concentration with radon exhalation and indoor radon concentration within the dry season respectively. Pearson correlation result recorded values 0.81 and 0.47 as the highest and lowest positive coefficient values for the radium concentration correlation between radon exhalation and indoor radon concentration. One directional principal component was observed in radium concentration, seasonal radon exhalation, and indoor radon concentration. Two clusters originated from radium and seasonal radon concentrations present in dwellings as well as soils. Pearson's correlation results were in agreed with the principal component and cluster factor analysis. The study obtained the highest and lowest indoor radon concentrations with radon exhalation in rainy and dry seasons. Radium concentration was found to have a considerable effect on indoor radon and radon exhalation in dwellings and soils.

The first indoor radon mapping in the Campania region, Italy.

For the first time, a map of the 222Rn gas has been produced in the Campania region, the southern part of Italy, based on the activity concentration measured in indoor environments. This work is part of the radon mitigation policy and complies with the recent Italian Legislative Decree 101/2020, which implements the European Basic Safety Standards, Euratom Directive 59/2013, where Member States must declare areas with elevated levels of indoor radon concentration. The obtained map, divided by Campania municipalities, identifies priority areas with activity concentration values exceeding the reference level of 300 Bq m-3. In addition, an effective statistical analysis of the dataset has been carried out.

Determination of uranium and thorium contents in various material samples of Morocco using a new Monte Carlo code for evaluating the mean critical angle of etching of the CR-39 and LR-115 type II SSNTDs.

In this paper an original Monte Carlo code for calculating the mean critical angle of etching of the CR-39 and LR-115 type II solid state nuclear track detectors SSNTD have been developed in order to determine the levels of uranium and thorium contents in a variety of natural material samples. We have also measured these concentrations via others techniques. Results obtained by the current method are more precise than those obtained by detection efficiency and isotope dilution mass spectrometry methods. The dependence of the SSNTDs means critical angles on the initial alpha particle energy and the density of the material have been investigated. A series of equations were used to calculate the mean critical angle of SSNTDs detectors and to estimate the concentrations of uranium and thorium inside studied materials.

A preliminary analysis of individual neutron dose monitoring with 6LiF-7LiF and CR39 / 中国辐射卫生

Objective To preliminarily compare 6LiF-7LiF and CR39 in individual neutron dose monitoring, and to provide a reference for improving individual neutron dose monitoring. Methods According to the GBZ 128-2019, 26 radiation workers from 7 institutions received individual neutron dose monitoring with 6LiF-7LiF and CR39 at the same time. The monitoring results were analyzed. Results For most of the workers, the personal neutron dose equivalent Hp(10) was less than the minimum detectable level. The results with the two monitoring methods differed in 6 of 26 workers. Conclusion Both 6LiF-7LiF and CR39 monitoring methods can be used for individual neutron dose monitoring for radiation workers, but the difference between 6LiF-7LiF and CR39 (in threshold energy, energy response, etc.) should be considered so that different types of radiation workers receive appropriate individual neutron dose monitoring.

Measuring uranium concentration in Um Qasr district, southern Iraq, in two different ways.

The current study uses ICP-MS (inductively coupled plasma mass spectrometry) and SSNTDs (solid-state nuclear track detectors) to measure uranium concentrations in 12 surface soil samples from selected locations in Um Qasr in the Southern Basrah governorate. In the ICP-MS technique, uranium concentrations ranged from 0.6 to 2.2 ppm, with an average value of 1.3 ppm. In the SSNTDs technique, uranium concentrations ranged from 1.4 ± 0.3 ppm to 1.6 ± 0.2 ppm, with an average value of 1.5 ± 0.2 ppm. The results obtained from the soil samples were within the permissible limits recommended by the UNSCEAR Committee of 11.7 ppm.

Evaluation of radon gas concentration in indoor air of spas and in spring water in the central Anatolia region of Turkey.

The present study aimed to determine the concentration of radon (222Rn) levels of indoor air of spas and of spring water sites in the Turkish cities of Nigde and Aksaray, both located in Cappadocia, Anatolia, which is a well-known tourist area. In this area there are a lot of spring water and thermal water sites providing both drinking water and water for spas, which are used for therapeutic treatments of diseases and for health services. Therefore, it is necessary to quantify radon gas concentrations in the air of sites that use geothermal waters and spring water. Consequently, radon measurements were carried out using CR-39 detectors placed at different locations within each investigated thermal spa and spring water site. The results obtained indicate that, in the air of spring water at Helvadere, there is a high radon concentration. The average radon concentrations obtained for the air of Ciftehan and Ziga thermal spas were 12.5 ± 1.4 Bq/m3 and 15.5 ± 2.1 Bq/m3, respectively, while in the air of Kemerhisar, Helvadere, and Okcu village spring water sites the average radon concentrations were 32 ± 4.2 Bq/m3, 265 ± 37.9 Bq/m3, and 35 ± 5.1 Bq/m3, respectively. The corresponding average effective doses were calculated both for patients and workers for Ciftehan and Ziga thermal spas, and for workers 0.09 and 0.11 mSv/year for Ciftehan and Ziga, respectively, were obtained. Doses for patients were 0.0007 and 0.0008 mSv/year for Ciftehan and Ziga, respectively. It is concluded that based on the measured radon concentrations and corresponding effective doses no radiation protection measures must be implemented.

RPL Neutron Dosimetry in n-γ Fields in Comparison with Polymer Detectors Type CR-39.

Previously we characterized radiophotoluminescent (RPL) detectors for measuring both fast and thermal neutrons for personal monitoring. The linear response and angular dependence, which satisfies the ISO 21909 standard makes their application possible in neutron dosimetry. The polymer CR-39 track detectors remain one of the most used dosimeters where neutron radiations are to be measured, but the visualization process is time consuming. The difference between results obtained by RPL and CR-39 has been discussed mainly for fast neutrons. The present study has also looked at thermal neutron dosimetry, where we found few results in the literature for CR-39. Our measurements demonstrate that RPL detectors can be advantageously incorporated into a dosimeter to measure thermal neutrons.

Radon surveys and effectiveness of remedial actions in spas on the Ischia island (Italy).

The possible damaging effects on human health of inhaled radon and its decay products are of interest to workers and the public. In particular, radon in thermal environments often occurs in high concentrations. Therefore, investigations and remedial actions are important to reduce activity concentration values and associated risk. This work concerns the analysis of two surveys of radon gas activity concentration carried out in 2006/2007 and 2019/2020 at twenty thermal spas on the island of Ischia (Italy). Annual measurements were carried out in workplaces located in the basement and ground floor using passive CR-39 detectors. In the spas involved in both surveys, the effectiveness of the remedial actions, implemented by the owners, was assessed obtaining an average percentage reduction of 74%. Considerations were made about the annual effective dose, and the location of the spas taking into account the geological setting of the volcanic nature of the island.

Measurement of neutron equivalent dose in the thyroid, chiasma, and lens for patients undergoing pelvic radiotherapy: A phantom study.

Radiotherapy is one of the most common methods for treating malignant diseases, whose ultimate goal is to deliver lethal doses to tumor cells. One of the unwanted consequences of radiotherapy is secondary radiation outside the treatment field, which imposes additional doses to healthy tissues and organs, specifically neutron doses, which we aim to evaluate. Therefore, this study aims to measure the fast neutron equivalent dose and the risk of secondary cancer in the thyroid, chiasm, and lenses in the treatment of the pelvic area. In this study, CR-39 detectors were used to measure the equivalent fast neutron dose in different sections of the RANDO Phantom (thyroid, chiasm, and lenses) and were irradiated by the energy of 18 MV on Varian Clinac 2100 C-D linear accelerator. CR-39 detectors were calibrated with predetermined doses by an Am-Be neutron source. Then, after etching and reading processes, the equivalent dose of fast neutrons was determined. According to the results, the fast neutron doses in the thyroid, right and left eye lenses, and chiasm were 0.613 ± 0.024, 0.835 ± 0.040, 0.866 ± 0.016, and 0.685 ± 0.045 mSv/Gy, respectively. Moreover, the secondary cancer risks in the unshielded organs are 0.004, 0.029, 0.030, and 0.025 for the thyroid, right and left eye lenses, and chiasm, respectively. In conclusion, the contribution of neutrons to the secondary doses in the out-of-field organs is significant and should not be ignored.

Changes of the linear energy transfer (LET) and beam width of therapeutic carbon ion beam in density heterogeneous phantoms.

This work aims to investigate the changes in the linear energy transfer (LET) spectra distribution and the beam spot width of a therapeutic carbon ion beam in density heterogeneous phantoms. Three different heterogeneous phantoms were fabricated using a combination of solid water, lung, and bone tissue slabs and irradiated by a single energy carbon beam (276.5 MeV u-1). CR-39 detectors were used for experimental measurements and the Monte Carlo toolkit Geant4 was employed for theoretical simulations. The results demonstrated that the measured LET spectra agree well with the simulation results. The lung and bone tissues displayed no obvious effect on the spectral distribution of LET. The dose-average LET was invariant and showed no obvious difference in the different materials, while the track-average LET increased in the lung and decreased in the bone materials. Similarly, the beam spot size increased in the lung, and decreased in the bone materials. Additionally, the fluence of the secondary fragments varied in different tissues. These findings are expected to provide cross-validation data for the quality assurance of carbon ion therapy and to be beneficial for validating the base data in treatment planning systems.

Simulation study on radiation fields around targets to apply CR-39 for photo-neutron measurement in electron accelerator near the threshold energy.

Photo-neutron production in electron accelerator near the threshold energy has been studied by Monte Carlo simulation using the FLUKA code. A pencil beam of 10 MeV electron was incident normally on W, Ta, Pb and Bi targets and a CR-39 detector attached to the target was used as scoring region. In the simulation, photon and neutron spectra, yield and their spatial distribution, fast neutron fluence above 100 keV, total dose and neutron dose deposition were estimated for these metallic targets. The photon emission was found to be forward peaked whereas the neutron emission was isotropic in nature. The photon yield was found to be 5 to 6 orders of magnitude higher than that of neutrons. In W and Ta, the photon yield is maximum for 1.5 mm thickness whereas for Pb and Bi, the photon yield is highest at 2 and 2.5 mm respectively. The total neutron yield was highest for W and lowest for Pb whereas highest number of fast neutrons above 100 keV was for W followed by Bi, Pb and Ta. Production of significant number of fast neutrons above 100 keV suggests the possibility of the use of CR-39 detector for measurement of these neutrons. The total dose deposition was found to be highest for Bi followed by Pb, Ta and W whereas the neutron dose equivalent was highest for W followed by Pb, Bi and Ta. This simulation study will be useful for neutron dosimetry, estimation of source term, implementation of CR-39 for measurement and other radiation protection aspects in the vicinity of an electron accelerator.