Impact of coking plant to heavy metal characteristics in groundwater of surrounding areas: Spatial distribution, source apportionment and risk assessments.

Coking industry is a potential source of heavy metals (HMs) pollution. However, its impacts to the groundwater of surrounding residential areas have not been well understood. This study investigated the pollution characteristics and health risks of HMs in groundwater nearby a typical coking plant. Nine HMs including Fe, Zn, Mo, As, Cu, Ni, Cr, Pb and Cd were analyzed. The average concentration of total HMs was higher in the nearby area (244.27 µg/L) than that of remote area away the coking plant (89.15 µg/L). The spatial distribution of pollution indices including heavy metal pollution index (HPI), Nemerow index (NI) and contamination degree (CD), all demonstrated higher values at the nearby residential areas, suggesting coking activity could significantly impact the HMs distribution characteristics. Four sources of HMs were identified by Positive Matrix Factorization (PMF) model, which indicated coal washing and coking emission were the dominant sources, accounted for 40.4%, and 31.0%, respectively. Oral ingestion was found to be the dominant exposure pathway with higher exposure dose to children than adults. Hazard quotient (HQ) values were below 1.0, suggesting negligible non-carcinogenic health risks, while potential carcinogenic risks were from Pb and Ni with cancer risk (CR) values > 10-6. Monte Carlo simulation matched well with the calculated results with HMs concentrations to be the most sensitive parameters. This study provides insights into understanding how the industrial coking activities can impact the HMs pollution characteristics in groundwater, thus facilitating the implement of HMs regulation in coking industries.

Mobilization mechanisms and spatial distribution of arsenic in groundwater of western Bangladesh: Evaluating water quality and health risk using EWQI and Monte Carlo simulation.

Arsenic (As) contamination in groundwater is emerging as a significant global concern, posing serious risks to the safety of drinking water and public health. To understand the release mechanisms, mobilization processes, spatial distribution, and probabilistic health risks of As in western Bangladesh, forty-seven samples were collected and analyzed using an atomic absorption spectrometer (AAS). The As concentrations in groundwater ranged from 1.97 to 697.4 µg L⁻1 (mean: 229.9), significantly exceeding recommended levels. The dominant hydrochemistry of As-enriched groundwater was Ca-Mg-HCO3, with the primary sources of arsenic in groundwater being the dissolution of arsenic-bearing minerals in sediment and the recharge of aquifers from the Ganges River Basin. The assessment using the Entropy Water Quality Index revealed that the groundwater is unsuitable for drinking, with 89.36% (n = 42) of the samples surpassing the WHO's limit for arsenic. Rock-water interactions, including calcite dissolution and silicate weathering within the confined aquifer, predominantly influenced hydrochemical properties. The significant relationships among Fe, Mn, and As indicate that the reductive dissolution of FeOOH and/or MnOOH considerably contributes to the release of As from sediment into groundwater. Geochemical modeling analysis revealed that siderite and rhodochrosite precipitate into aquifer solids, suggesting a weak to moderate relationship among As, Fe, and Mn. The long residence time of groundwater, combined with the presence of a clayey aquitard, likely controls the mobilization of arsenic in the aquifer. For the first time, Monte Carlo simulations have been used in arsenic-prone areas to assess the severity of arsenic contamination in western Bangladesh. The analysis indicates that out of 100,000 people, 10 may develop cancer as a result of drinking arsenic-contaminated water, with children being more susceptible than adults.

A Monte Carlo study comparing dead-time losses of a gamma camera between tungsten functional paper and lead sheet for dosimetry in targeted radionuclide therapy with Lu-177.

OBJECTIVE: Dead-time loss is reported to be non-negligible for some patients with a high tumor burden in Lu-177 radionuclide therapy, even if the administered activity is 7.4 GBq. Hence, we proposed a simple method to shorten the apparent dead time and reduce dead-time loss using a thin lead sheet in previous work. The collimator surface of the gamma camera was covered with a lead sheet in our proposed method. While allowing the detection of 208-keV gamma photons of Lu-177 that penetrate the sheet, photons with energies lower than 208 keV, which cause dead-time loss, were shielded. In this study, we evaluated the usefulness of tungsten functional paper (TFP) for the proposed method using Monte Carlo simulation. METHODS: The count rates in imaging of Lu-177 administered to patients were simulated with the International Commission on Radiological Protection (ICRP) 110 phantom using the GATE Monte Carlo simulation toolkit. The simulated gamma cameras with a 0.5-mm lead sheet, 1.2-mm TFP, or no filter were positioned closely on the anterior and posterior sides of the phantom. The apparent dead times and dead-time losses at 24 h after administration were calculated for an energy window of 208 keV ± 10%. Moreover, the dead-time losses at 24-120 h were analytically assessed using activity excretion data of Lu-177-DOTATATE. RESULTS: The dead-time loss without a filter was 5% even 120 h after administration in patients with a high tumor burden and slow excretion, while those with a lead sheet and TFP were 0.22 and 0.58 times less than those with no filter, respectively. The count rates with the TFP were 1.3 times higher than those with the lead sheet, and the TFP could maintain primary count rates at 91-94% of those without a filter. CONCLUSIONS: Although the apparent dead time and dead-time loss with the lead sheet were shorter and less than those with TFP, those with TFP were superior to those without a filter. The advantage of TFP over the lead sheet is that the decrease in primary count rates was less.

Determination of soil environmental criteria for high-risk trace metals in urban park soils using improved CLEA model.

The trace metals (TMs) accumulated in urban park soils can pose potential threats to human health, making the management of soil quality based on health risks critically important. Based on the human health risk assessment (HHRA) model coupled with Monte Carlo Simulation, this study improved the contaminated land exposure assessment (CLEA) model. Combined with local parameters, the Soil Environmental Criteria (SEC) for high-risk trace metals (TMs) in urban park soils were calculated. Results indicated that all the mean TCR (Total carcinogenic risk) values of seven TMs exceeded the risk threshold of 1E-06, suggesting a higher likelihood of carcinogenic risks for all populations. As and Cr presented the highest potential carcinogenic risks, and were identified as high-risk TMs in the study area. The traditional CLEA model was enhanced by incorporating region-specific data, optimizing exposure parameter calculations, and addressing parameter sensitivity and uncertainty. Using the improved CLEA model, the SEC values for high-risk TMs were calculated, revealing that the SEC values gradually increased from ages 1 to 18, while significantly decreased for individuals over 80 years old. This study effectively addresses issues of parameter uncertainty and sensitivity in the CLEA model, offering new insights for the development of soil environmental quality standards.

Development of a novel tool for high-precision focal irradiation using a clinical brachytherapy system.

PURPOSE: This study aims to emphasize the necessity of a focal irradiation tool for small animals and compare the beam characteristics of a tool developed using a brachytherapy system with a linear accelerator (LINAC)-based tool. METHODS: A 1-mm tungsten collimator was designed for a Ir-192 brachytherapy system. The percent depth dose (PDD) and horizontal profile of the collimator were measured and compared with a 4-mm commercial cone in the LINAC. Monte Carlo simulations validated all the measurements. Mouse brains were irradiated using a focal irradiation tool, and immunohistochemistry was performed on the brain samples to assess the dose accuracy. RESULTS: PDD showed that the maximum dose (dmax) for Ir-192 was at the surface in both measurements and simulations. At a depth of 1 mm, the collimator measured doses of 25.6 % and 21.0 %, respectively. At 6 MV in the LINAC, the dmax was observed at depths of 0.7 and 0.8 cm in measurements and simulations, respectively. The full width at half maximum (FWHM) at a depth of 1 mm was 1.0 and 1.1 mm for Ir-192 in the measurements and simulations, respectively. For small cone sizes at dmax, FWHM was 4.0 and 4.1 mm for the measurements and simulations, respectively. Immunohistochemistry results indicated that focal irradiation with Ir-192 affected small superficial brain areas while sparing the contralateral side and subventricular zone. CONCLUSION: The focal irradiation tool accurately delivered doses to small regions and shallow depths in the mouse brain, making it valuable for precise radiotherapy during small animal experiments.

Prediction of refraction error after toric lens implantation with biometric input data uncertainties and power labelling tolerances.

BACKGROUND: The purpose of this study was to simulate the impact of biometric measure uncertainties, lens equivalent and toric power labelling tolerances and axis alignment errors on the refractive outcome after cataract surgery with toric lens implantation. METHODS: In this retrospective non-randomised cross sectional Monte-Carlo simulation study we evaluated a dataset containing 7458 LenStar 900 preoperative biometric measurements. The biometric uncertainties from literature, lens power labelling according to ISO 11979, and axis alignment tolerances of a modern toric lens (Hoya Vivinex) were taken to be normally distributed and used in a Monte-Carlo simulation with 100 000 samples per eye. The target variable was the defocus equivalent (DEQ) derived using the Castrop (DEQC) and the Haigis (DEQH) formulae. RESULTS: Mean/median / 90% quantile DEQC was 0.22/0.21/0.36 D and DEQH was 0.20/0.19/0.32 D. Ignoring the variation in lens power labelling and toric axis alignment the respective DEQC was 0.20/0.19/0.32 D and DEQH was 0.18/0.17/0.29 D. DEQC and DEQH increased with shorter eyes, steeper corneas, equivalent lens power and highly with toric lens power. CONCLUSIONS: According to our simulation results, uncertainties in biometric measures, lens power labelling tolerances, and axis alignment errors are responsible for a significant part of the refraction prediction error after cataract surgery with toric lens implantation. Additional labelling of the exact equivalent and toric power on the lens package could be a step to improve postoperative results.

Monte Carlo-based simulation of virtual 3 and 4-dimensional cone-beam computed tomography from computed tomography images: An end-to-end framework and a deep learning-based speedup strategy.

Background and purpose: In radiotherapy, precise comparison of fan-beam computed tomography (CT) and cone-beam CT (CBCT) arises as a commonplace, yet intricate task. This paper proposes a publicly available end-to-end pipeline featuring an intrinsic deep-learning-based speedup technique for generating virtual 3D and 4D CBCT from CT images. Materials and methods: Physical properties, derived from CT intensity information, are obtained through automated whole-body segmentation of organs and tissues. Subsequently, Monte Carlo (MC) simulations generate CBCT X-ray projections for a full circular arc around the patient employing acquisition settings matched with a clinical CBCT scanner (modeled according to Varian TrueBeam specifications). In addition to 3D CBCT reconstruction, a 4D CBCT can be simulated with a fully time-resolved MC simulation by incorporating respiratory correspondence modeling. To address the computational complexity of MC simulations, a deep-learning-based speedup technique is developed and integrated that uses projection data simulated with a reduced number of photon histories to predict a projection that matches the image characteristics and signal-to-noise ratio of the reference simulation. Results: MC simulations with default parameter setting yield CBCT images with high agreement to ground truth data acquired by a clinical CBCT scanner. Furthermore, the proposed speedup technique achieves up to 20-fold speedup while preserving image features and resolution compared to the reference simulation. Conclusion: The presented MC pipeline and speedup approach provide an openly accessible end-to-end framework for researchers and clinicians to investigate limitations of image-guided radiation therapy workflows built on both (4D) CT and CBCT images.

Assessment of drinking water quality and identifying pollution sources in a chromite mining region.

Water sources near mining regions are often susceptible to contamination from toxic elements. This study employs machine learning (ML) techniques to evaluate drinking water quality and identify pollution sources near a chromite mine in Iran. Human health risks were assessed using both deterministic and probabilistic approaches. Findings revealed that concentrations of calcium (Ca), chromium (Cr), lithium (Li), magnesium (Mg), and sodium (Na) in the water samples exceeded international safety standards. The Unweighted Root Mean Square water quality index (RMS-WQI) and Weighted Quadratic Mean (WQM-WQI) categorized all water samples as 'Fair', with average scores of 67.95 and 67.19, respectively. Of the ML models tested, the Extra Trees (ET) algorithm emerged as the top predictor of WQI, with Mg and strontium (Sr) as key variables influencing the scores. Principal component analysis (PCA) identified three distinct clusters of water quality parameters, highlighting influences from both local geology and anthropogenic activities. The highest average hazard quotient (HQ) for Cr was 1.71 for children, 1.27 for adolescents, and 1.05 for adults. Monte Carlo simulation for health risk assessment indicated median hazard index (HI) of 4.48 for children, 3.58 for teenagers, and 2.98 for adults, all exceeding the acceptable threshold of 1. Total carcinogenic risk (TCR) exceeded the EPA's acceptable level for 99.38 % of children, 98.24 % of teenagers, and 100 % of adults, with arsenic (As) and Cr identified as the main contributors. The study highlights the need for urgent mitigation measures, recommending a 99 % reduction in concentrations of key contaminants to lower both carcinogenic and non-carcinogenic risks to acceptable levels.

Monte Carlo calculations of target fragments from helium and carbon ion interactions with water.

When high energetic heavy ions interact with any target, short range, high linear energy transfer (LET) target fragments are produced. These target fragments (TFs) can give a significant dose to the healthy tissue during heavy ion cancer therapy, and when cosmic radiation interacts with astronauts. This paper presents Monte Carlo simulations, using the Particle and Heavy Ion Transport code System (PHITS), to characterize target fragments from reactions of helium and carbon ions with water. The calculated ranges, LET, doses, and production cross sections are presented. It is shown that protons, deuterons, tritons, alpha particles, 3He, 6He, nitrogen, oxygen, and fluorine ions are the most probable target fragments when carbon and helium ions collide with water. Among the produced target fragments, alpha particles and nitrogen ions give the highest dose to the targets, since the combination of fluence and LETs of these TFs are highest among the produced fragments. The production cross sections of proton and oxygen are the highest among the target fragments cross sections when helium and carbon ions imping on water, because these TFs can be produced through more reaction channels compared to other fragments. These findings are helpful for accurate dose measurement during heavy ion cancer therapy and for shielding of space radiation.

Optimizing number of Raman spectra using an artificial neural network guided Monte Carlo simulation approach to analyze human cortical bone.

This study presents a novel methodology for optimizing the number of Raman spectra required per sample for human bone compositional analysis. The methodology integrates Artificial Neural Network (ANN) and Monte Carlo Simulation (MCS). We demonstrate the robustness of ANN in enabling prediction of Raman spectroscopy-based bone quality properties even with limited spectral inputs. The ANN algorithms tailored to individual sex and age groups, which enhance the specificity and accuracy of predictions in bone quality properties. In addition, ANN guided MCS systematically explores the variability and uncertainty inherent in different sample sizes and spectral datasets, leading to the identification of an optimal number of spectra per sample for characterizing human bone tissues. The findings suggest that as low as 2 spectra are sufficient for biochemical analysis of bone, with R2 values between real and predicted values of v1/PO4/Amide I and ∼I1670/I1640 ratios, ranging from 0.60 to 0.89. Our results also suggest that up to 8 spectra could be optimal when balancing other factors. This optimized approach streamlines experimental workflows, reduces data and acquisition costs. Additionally, our study highlights the potential for advancing Raman spectroscopy in bone research through the innovative integration of ANN-guided probabilistic modeling techniques. This research could significantly contribute to the broader landscape of bone quality analyses by establishing a precedent for optimizing the number of Raman spectra with sophisticated computational tools. It also sets a novel platform for future optimization studies in Raman spectroscopy applications in biomedical field.

Nanoscale dosimetry for a radioisotope-labeled metal nanoparticle using MCNP6.2 and Geant4.

BACKGROUND: Metal nanoparticles (MNPs) labeled with radioisotopes (RIs) are utilized as radio-enhancers due to their ability to amplify the radiation dose in their immediate vicinity. A thorough understanding of nanoscale dosimetry around MNPs enables their effective application in radiotherapy. However, nanoscale dosimetry around MNPs still requires further investigation. PURPOSE: This study aims to provide insight into the radio-enhancement effects of MNPs by elucidating nanoscale dosimetry surrounding MNPs labeled with Auger-emitting RIs. We particularly focus on distinguishing the respective dose contributions of photons and electrons emitted by Auger-emitting RIs in the context of dose enhancement. METHODS: A 50 nm diameter NP of silver (Ag) core and gold (Au) shell (Ag@Au NP) was assumed to emit mono-energetic electrons and photons (3, 5, 10, 20, and 30 keV), or the energy spectrum corresponding to one of three Auger-emitting RIs (103Pd, 125I, and 131Cs) from the Ag core. Nanoscale radial dose distributions around a single radioactive Ag@Au NP were evaluated in spherical shells of water. Monte Carlo simulations were conducted using single-event and track structure transport methods implemented in MCNP6.2 and Geant4-DNA-Au physics, respectively. To evaluate the extent of radio-enhancement by the Ag@Au NP, two scenarios were considered: Ag@Au NPs (Au shell included) and Ag@water NPs (Au shell replaced by water). RESULTS: The radial doses of 10, 20, and 30 keV electrons estimated by both codes were comparable. However, the radial doses of 3 and 5 keV electrons by MCNP6.2 were much larger near the NP surface than those by Geant4. There was a dose enhancement of a few % to tens % by the Au shell in the region of the NP surface to 10 µm, depending on the electron energy. The radial doses of photons with the Au shell were higher up to their secondary electron ranges than those without the Au shell. The maximum dose enhancement factor of photons occurred at 20 keV and was 63.4 by MCNP6.2 and 50.5 by Geant4. The overall radial doses of electrons were 1-2 orders of magnitude larger than those of photons. As a result, in cases of RIs emitting both electrons and photons, the radial doses up to electron ranges were dominantly governed by electrons. The dose enhancement estimated by both codes for the RIs ranged from a few % except in the immediate vicinity of the NP surface. CONCLUSION: Given the dominant contribution of electrons to radial doses of MNP labeled with Auger-emitting RIs, physical dose enhancement expected by interactions with photons was hindered. Since there are no available RIs emitting exclusively photons, achieving enhanced physical doses within a cell through a combination of MNPs and RIs appears currently unattainable. The radial doses of photons near the NP surface exhibited considerable discrepancies between the codes, primarily attributed to low-energy electrons. The difference may arise from higher cross-sections of Au inelastic scattering in Geant4-DNA-Au compared to MCNP6.2.

Monte Carlo Model Validation of 6MV Beam of OMID, the First Iranian Linear Accelerator.

Monte Carlo (MC) techniques are regarded as an accurate method to simulate the dose calculation in radiotherapy for many years. The present paper aims to validate the simulated model of the 6-MV beam of OMID linear accelerator (BEHYAAR Company) by EGSnrc codes system and also investigate the effects of initial electron beam parameters (energy, radial full width at half maximum, and mean angular spread) on dose distributions. For this purpose, the comparison between the calculated and measured percentage depth dose (PDD) and lateral dose profiles was done by gamma index (GI) with 1%-1 mm acceptance criteria. MC model validating was done for 3 cm × 3 cm, 5 cm × 5 cm, 8 cm × 8 cm, 10 cm × 10 cm, and 20 cm × 20 cm field sizes. To study the sensitivity of model to beam parameters, the field size was selected as 10 cm × 10 cm and 30 cm × 30 cm. All lateral dose profiles were obtained at 10 cm. Excellent agreement was achieved with a 99.2% GI passing percentage for PDD curves and at least 93.8% GI for lateral dose profiles for investigated field sizes. Our investigation confirmed that the lateral dose profile severely depends on the considered source parameters in this study. PDD only considerably depends on the initial electron beam energy. Therefore, source parameters should not be specified independently. These results indicate that the current model of OMID 6-MV Linac is well established, and the accuracy of the simulation is high enough to be used in various applications.

Systematic assessment of source identification and ecological and probabilistic health risks of potentially toxic elements (PTEs) in soils of a typical coal mining area in Guanzhong region.

Mining activities may cause the accumulation of potentially toxic elements (PTEs) in surrounding soils, posing ecological threats and health dangers to the local population. Therefore, a comprehensive assessment using multiple indicators was used to quantify the level of risk in the region. The results showed that the mean values of the nine potentially toxic elements in the study area were lower than the background values only for Cr, and the lowest coefficient of variation was 17.1 % for As, and the spatial distribution characteristics of the elements indicate that they are enriched by different factors. The elements Hg and Cd, which have substantial cumulative features, are the key contributors to ecological risk in the study region, which is overall at moderate risk. APCS-MLR model parses out 4 possible sources: mixed industrial, mining and transportation sources (53.98 %), natural sources (24.56 %), atmospheric deposition sources (12.60 %), and agricultural production sources (8.76 %). The probabilistic health risks show that children are more susceptible to health risks than adults; among children, the safety criteria (HI < 1 and CR < 10-4) were surpassed by 29.29 % of THI and 8.58 % of TCR. According to source-orientated health hazards, the element Ni significantly increases the risk of cancer. Mixed sources from industry, mining, and transportation are important sources of health risks. The results of this research provide some scientific references for the management and decrease of regional ecological and health risks.

Theoretical Investigation of the Effects of Aldehyde Substitution with Pyran Groups in D-π-A Dye on Performance of DSSCs.

This work investigated the substitution of the aldehyde with a pyran functional group in D-π-aldehyde dye to improve cell performance. This strategy was suggested by recent work that synthesized D-π-aldehyde dye, which achieved a maximum absorption wavelength that was only slightly off the threshold for an ideal sensitizer. Therefore, DFT and TD-DFT were used to investigate the effect of different pyran substituents to replace the aldehyde group. The pyran groups reduced the dye energy gap better than other known anchoring groups. The proposed dyes showed facile intermolecular charge transfer through the localization of HOMO and LUMO orbitals on the donor and acceptor parts, which promoted orbital overlap with the TiO2 surface. The studied dyes have HOMO and LOMO energy levels that could regenerate electrons from redox potential electrodes and inject electrons into the TiO2 conduction band. The lone pairs of oxygen atoms in pyran components act as nucleophile centers, facilitating adsorption on the TiO2 surface through their electrophile atoms. Pyrans increased the efficacy of dye sensitizers by extending their absorbance range and causing the maximum peak to redshift deeper into the visible region. The effects of the pyran groups on photovoltaic properties such as light harvesting efficiency (LHE), free energy change of electron injection, and dye regeneration were investigated and discussed. The adsorption behaviors of the proposed dyes on the TiO2 (1 1 0) surface were investigated by means of Monte Carlo simulations. The calculated adsorption energies indicates that pyran fragments, compared to the aldehyde in the main dye, had a greater ability to induce the adsorption onto the TiO2 substrate.

Design Optimisation of a Flat-Panel, Limited-Angle TOF-PET Scanner: A Simulation Study.

In time-of-flight positron emission tomography (TOF-PET), a coincidence time resolution (CTR) below 100 ps reduces the angular coverage requirements and, thus, the geometric constraints of the scanner design. Among other possibilities, this opens the possibility of using flat-panel PET detectors. Such a design would be more cost-accessible and compact and allow for a higher degree of modularity than a conventional ring scanner. However, achieving adequate CTR is a considerable challenge and requires improvements at every level of detection. Based on recent results in the ongoing development of optimised TOF-PET photodetectors and electronics, we expect that within a few years, a CTR of about 75 ps will be be achievable at the system level. In this work, flat-panel scanners with four panels and various design parameters were simulated, assessed and compared to a reference scanner based on the Siemens Biograph Vision using NEMA NU 2-2018 metrics. Point sources were also simulated, and a method for evaluating spatial resolution that is more appropriate for flat-panel geometry is presented. We also studied the effects of crystal readout strategies, comparing single-crystal and module readout levels. The results demonstrate that with a CTR below 100 ps, a flat-panel scanner can achieve image quality comparable to that of a reference clinical scanner, with considerable savings in scintillator material.

Stress sensitivity analysis of vuggy porous media based on two-scale fractal theory.

Interparticle pore space and vugs are two different scales of pore space in vuggy porous media. Vuggy porous media widely exists in carbonate reservoirs, and the permeability of this porous media plays an important role in many engineering fields. It has been shown that the change of effective stress has important effects on the permeability of vuggy porous media. In this work, a fractal permeability model for vuggy porous media is developed based on the fractal theory and elastic mechanics. Besides, a Monte Carlo simulation is also implemented to obtain feasible values of permeability. The proposed model can predict the elastic deformation of the fractal vuggy porous media under loading stress, which plays a crucial role in the variations of permeability. The predicted permeability data based on the present fractal model are compared with experimental data, which verifies the validity of the present fractal permeability model for vuggy porous media. The parameter sensitivity analysis indicates that the permeability of stress-sensitivity vuggy porous media is related to the capillary fractal dimension, capillary fractal tortuosity dimension, Young's modulus, and Poisson's ratio.

Visualization of spatial dose distribution for effective radiation protection education in interventional radiology: obtaining high-accuracy spatial doses.

In recent years, eye lens exposure among radiation workers has become a serious concern in medical X-ray fluoroscopy and interventional radiology (IVR), highlighting the need for radiation protection education and training. This study presents a method that can maintain high accuracy when calculating spatial dose distributions obtained via Monte Carlo simulation and establishes another method to three-dimensionally visualize radiation using the obtained calculation results for contributing to effective radiation-protection education in X-ray fluoroscopy and IVR. The Monte Carlo particle and heavy ion transport code system (PHITS, Ver. 3.24) was used for calculating the spatial dose distribution generated by an angiography device. We determined the peak X-ray tube voltage and half value layer using Raysafe X2 to define the X-ray spectrum from the source and calculated the X-ray spectrum from the measured results using an approximation formula developed by Tucker et al. Further, we performed measurements using the "jungle-gym" method under the same conditions as the Monte Carlo calculations for verifying the accuracy of the latter. An optically stimulated luminescence dosimeter (nanoDot dosimeter) was used as the measuring instrument. In addition, we attempted to visualize radiation using ParaView (version 5.12.0-RC2) using the spatial dose distribution confirmed by the above calculations. A comparison of the measured and Monte Carlo calculated spatial dose distributions revealed that some areas showed large errors (12.3 and 24.2%) between the two values. These errors could be attributed to the scattering and absorption of X-rays caused by the jungle gym method, which led to uncertain measurements, and (2) the angular and energy dependencies of the nanoDot dosimetry. These two causes explain the errors in the actual values, and thus, the Monte Carlo calculations proposed in this study can be considered to have high-quality X-ray spectra and high accuracy. We successfully visualized the three-dimensional spatial dose distribution for direct and scattered X-rays separately using the obtained spatial dose distribution. We established a method to verify the accuracy of Monte Carlo calculations performed through the procedures considered in this study. Various three-dimensional spatial dose distributions were obtained with assured accuracy by applying the Monte Carlo calculation (e.g., changing the irradiation angle and adding a protective plate). Effective radiation-protection education can be realized by combining the present method with highly reliable software to visualize dose distributions.

Monte Carlo calculated absorbed-dose energy dependence of EBT3 and EBT4 films for 5-200 MeV electrons and 100 keV-15 MeV photons.

PURPOSE: To use Monte Carlo simulations to study the absorbed-dose energy dependence of GAFChromic EBT3 and EBT4 films for 5-200 MeV electron beams and 100 keV-15 MeV photon beams considering two film compositions: a previous EBT3 composition (Bekerat et al.) and the final composition of EBT3/current composition of EBT4 (Palmer et al.). METHODS: A water phantom was simulated with films at 5-50 mm depth in 5 mm intervals. The water phantom was irradiated with flat, monoenergetic 5-200 MeV electron beams and 100 and 150 keV kilovoltage and 1-15 MeV megavoltage photon beams and the dose to the active layer of the films was scored. Simulations were rerun with the films defined as water to compare the absorbed-dose response of film to water, f - 1 ( Q ) = D f i l m D w a t e r $f^{-1}(Q)=\frac{D_{film}}{D_{water}}$ . RESULTS: For electrons, the Bekerat et al. composition had variations in f - 1 ( Q ) $f^{-1}(Q)$ of up to ( 1.9 ± 0.1 ) % $(1.9\,\pm \,0.1)\%$ from 5 to 200 MeV. Similarly, the Palmer et al. composition had differences in f - 1 ( Q ) $f^{-1}(Q)$ up to ( 2.5 ± 0.2 ) % $(2.5 \pm 0.2)\%$ from 5 to 200 MeV. For photons, f - 1 ( Q ) $f^{-1}(Q)$ varied up to ( 2.4 ± 0.3 ) % $(2.4 \pm 0.3)\%$ and ( 4.5 ± 0.7 ) % $(4.5 \pm 0.7)\%$ from 100 keV to 15 MeV for the Bekerat et al. and Palmer et al. compositions, respectively. The depth of films did not appear to significantly affect f - 1 ( Q ) $f^{-1}(Q)$ for photons at any energy and for electrons at energies > $>$  50 MeV. However, for 5 and 10 MeV electrons, decreases of up to ( 10.2 ± 1.1 ) % $(10.2 \pm 1.1)\%$ in f - 1 ( Q ) $f^{-1}(Q)$ were seen due to stacked films and increased beam attenuation in films compared to water. CONCLUSIONS: The up to ( 2.5 ± 0.2 ) % $(2.5 \pm 0.2)\%$ and ( 4.5 ± 0.7 ) % $(4.5 \pm 0.7)\%$ variations in f - 1 ( Q ) $f^{-1}(Q)$ for electrons and photons, respectively, across the energies considered in this study indicate the importance of calibrating films with the energy intended for measurement. Additionally, this work emphasizes potential issues with stacking films to measure depth dose curves, particularly for electron beams with energies ≤ $\le$ 10 MeV.

Design of a compact and portable space neutron spectrometer based on Monte Carlo.

With the rapid development of space exploration, the detection of space neutron radiation is becoming increasingly important. The currently widely used Bonner sphere spectrometer have drawbacks such as large size and weight, as well as low fault tolerance, when detecting space neutron spectra. This paper describes in detail a new type of space neutron spectrometer (SNS), which has two different specifications to adapt to the directional and non-directional neutron field environment, and can measure the directional neutron energy spectrum. For the directed neutron field, SNS integrates 12 3He thermal neutron counters (diameter 3 cm: 3, diameter 4 cm: 6, diameter 5 cm: 3) and uses cylindrical polyethylene as a moderator. For non-directed neutron fields, SNS integrates 9 3He thermal neutron counters (diameter 3 cm: 4, diameter 4 cm: 3, diameter 5 cm: 2) located in a single structure made of polyethylene, boron-containing polyethylene and gadolinium. The device is capable of providing a strong directional response in the energy range of thermal neutrons up to 20 MeV, with little sensitivity to neutrons coming from directions other than the axis of the cylinder. The Monte Carlo transport code FLUKA was used to determine the final configuration of the instrument, including the arrangement, number, and position of thermal neutron counters. In addition, the response matrix of the instrument was calculated using FLUKA code. This device can replace traditional Bonner sphere spectrometer for measuring space neutrons, and it also provides reference value for downsized and lightweight neutron spectrometers on the ground.

Pollution area identification, receptor model-oriented sources and probabilistic health hazards to prioritize control measures for heavy metal management in soil.

Identifying the primary source of heavy metals (HMs) pollution and the key pollutants is crucial for safeguarding eco-health and managing risks in industrial vicinity. For this purpose, this investigation was carried out to investigate the pollution area identification with soil static environmental capacity (QI), receptor model-oriented critical sources, and Monte Carlo simulation (MCS) based probabilistic environmental and human health hazards associated with HMs in agricultural soils of Narayanganj, Bangladesh. The average concentration of Cr, Ni, Cu, Cd, Pb, Co, Zn, and Mn were 98.67, 63.41, 37.39, 1.28, 23.93, 14.48, 125.08, and 467.45 mg/kg, respectively. The geoaccumulation index identified Cd as the dominant metal, indicating heavy to extreme contamination in soils. The QI revealed that over 99% of the areas were polluted for Ni and Cd with less uncertain regions whereas Cr showed a significant portion of areas with uncertain pollution status. The positive matrix factorization (PMF) model identified three major sources: agricultural (29%), vehicular emissions (25%), and industrial (46%). The probabilistic assessment of health hazards indicated that both carcinogenic and non-carcinogenic risks for adult male, adult female, and children were deemed unacceptable. Moreover, children faced a higher health hazard compared to adults. For adult male, adult female, and children, industrial operations contributed 48.4%, 42.7%, and 71.2% of the carcinogenic risks, respectively and these risks were associated with Ni and Cr as the main pollutants of concern. The study emphasizes valuable scientific insights for environmental managers to tackle soil pollution from HMs by effectively managing anthropogenic sources. It could aid in devising strategies for environmental remediation engineering and refining industry standards.