scholarly journals Multi-scale Monte Carlo simulations of gold nanoparticle-induced DNA damages for kilovoltage X-ray irradiation in a xenograft mouse model using TOPAS-nBio

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Alexander P. Klapproth ◽  
Jan Schuemann ◽  
Stefan Stangl ◽  
Tianwu Xie ◽  
Wei Bo Li ◽  
...  
Keyword(s):  
Dna Damage ◽  
Monte Carlo ◽  
Mouse Model ◽  
Hybrid Nanoparticles ◽  
Mouse Tumor ◽  
Dna Damages ◽  
Microscopic Scale ◽  
X Ray ◽  
Multi Scale ◽  
The Individual

Abstract Background Gold nanoparticles (AuNPs) are considered as promising agents to increase the radiosensitivity of tumor cells. However, the biological mechanisms of radiation enhancement effects of AuNPs are still not well understood. We present a multi-scale Monte Carlo simulation framework within TOPAS-nBio to investigate the increase of DNA damage due to the presence of AuNPs in mouse tumor models. Methods A tumor was placed inside a voxel mouse model and irradiated with either 100-kVp or 200-kVp X-ray beams. Phase spaces were employed to transfer particles from the macroscopic (voxel) scale to the microscopic scale, which consists of a cell geometry including a detailed mouse DNA model. Radiosensitizing effects were calculated in the presence and absence of hybrid nanoparticles with a $$\text{Fe}_2\text{O}_3$$ Fe 2 O 3 core surrounded by a gold layer (AuFeNPs). To simulate DNA damage even for very small energy tracks, Geant4-DNA physics and chemistry models were used on microscopic scale. Results An AuFeNP-induced enhancement of both dose and DNA strand breaks has been established for different scenarios. Produced chemical radicals including hydroxyl molecules, which were assumed to be responsible for DNA damage through chemical reactions, were found to be significantly increased. We further observed a dependency of the results on the location of the cells within the tumor for 200-kVp X-ray beams. Conclusion Our multi-scale approach allows to study irradiation-induced physical and chemical effects on cells. We showed a potential increase in cell radiosensitization caused by relatively small concentrations of AuFeNPs. Our new methodology allows the individual adjustment of parameters in each simulation step and therefore can be used for other studies investigating the radiosensitizing effects of AuFeNPs or AuNPs in living cells.

MONTE CARLO CODE FOR STUDY OF THE RESPONSE FUNCTION OF Si(Li) DETECTORS FOR X-RAYS

1999 ◽  
Vol 09 (03n04) ◽  
pp. 135-141
Author(s):  
KÁROLY TŐKÉSI ◽  
TAKESHI MUKOYAMA
Keyword(s):  
Monte Carlo ◽  
Present Model ◽  
Monte Carlo Code ◽  
X Rays ◽  
Model Calculations ◽  
X Ray ◽  
Line Shapes ◽  
Calculated Line ◽  
The Individual ◽  
Good Agreement

For more detailed understanding of the line shape of X-ray peaks observed with Si ( Li ) detectors, a new Monte Carlo code was developed and tested in the range of incident X-ray energy less than 5 keV. In our simulation the individual elastic and inelastic processes in the solid and the charge collection probabilities in the different region of detectors are taken into account. The results of our model calculations are compared with experimental data. In general, good agreement is found between the experimental and calculated line shapes. This fact demonstrates the validity of the present model.

Primary DNA Damage Assessed With the Comet Assay and Comparison to the Absorbed Dose of Diagnostic X-rays in Children

2009 ◽  
Vol 28 (5) ◽  
pp. 405-416 ◽  
Author(s):  
Đurđica Milković ◽  
Vera Garaj-Vrhovac ◽  
Mária Ranogajec-Komor ◽  
Saveta Miljanić ◽  
Goran Gajski ◽  
...  
Keyword(s):  
Dna Damage ◽  
Comet Assay ◽  
Absorbed Dose ◽  
Peripheral Blood Lymphocytes ◽  
X Rays ◽  
X Ray ◽  
Before And After ◽  
The Individual ◽  
Dose Measurements ◽  
Posterior Anterior

The aim of this work is to assess DNA damage in peripheral blood lymphocytes of children prior to and following airway X-ray examinations of the chest using the alkaline comet assay and to compare data with the measured absorbed dose. Twenty children with pulmonary diseases, between the ages of 5 and 14 years, are assessed. Absorbed dose measurements are conducted for posterior–anterior projection on the forehead, thyroid gland, gonads, chest, and back. Doses are measured using thermoluminescent and radiophotoluminescent dosimetry systems. Differences between tail lengths, tail intensity, and tail moments as well as for the long-tailed nuclei before and after exposures are statistically significant and are dependent on the individual. The results demonstrate the usefulness of the comet assay as a measure of X-ray damage to lymphocytes in a clinical setting. Doses measured with both dosimeters show satisfactory agreement (0.01 mSv) and are suitable for dosimetric measurements in X-ray diagnostics.

scholarly journals Replica Exchange Monte Carlo Method for Proton and X-Ray Induced DNA Damage and Repair

2021 ◽  
Vol 120 (3) ◽  
pp. 290a
Author(s):  
Thienbao N. Carpency ◽  
Megan Cordone ◽  
Camila Quintero Hilsaca ◽  
Zachary Condon ◽  
Sarah Castro
Keyword(s):  
Dna Damage ◽  
Monte Carlo ◽  
Monte Carlo Method ◽  
Replica Exchange ◽  
Dna Damage And Repair ◽  
X Ray ◽  
Replica Exchange Monte Carlo

scholarly journals DNA damage in lens epithelial cells exposed to occupationally-relevant X-ray doses and role in cataract formation

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Ion Udroiu ◽  
Antonella Sgura ◽  
Agnese Chendi ◽  
Lorenzo Lasagni ◽  
Marco Bertolini ◽  
...  
Keyword(s):  
Dna Damage ◽  
Monte Carlo ◽  
Epithelial Cells ◽  
Lens Epithelial Cells ◽  
Eye Lens ◽  
Monte Carlo Code ◽  
Cataract Formation ◽  
X Ray ◽  
Radiation Induced ◽  
The Relationship

AbstractThe current framework of radiological protection of occupational exposed medical workers reduced the eye-lens equivalent dose limit from 150 to 20 mSv per year requiring an accurate dosimetric evaluation and an increase understanding of radiation induced effects on Lens cells considering the typical scenario of occupational exposed medical operators. Indeed, it is widely accepted that genomic damage of Lens epithelial cells (LEC) is a key mechanism of cataractogenesis. However, the relationship between apoptosis and cataractogenesis is still controversial. In this study biological and physical data are combined to improve the understanding of radiation induced effects on LEC. To characterize the occupational exposure of medical workers during angiographic procedures an INNOVA 4100 (General Electric Healthcare) equipment was used (scenario A). Additional experiments were conducted using a research tube (scenario B). For both scenarios, the frequencies of binucleated cells, micronuclei, p21-positive cells were assessed with different doses and dose rates. A Monte-Carlo study was conducted using a model for the photon generation with the X-ray tubes and with the Petri dishes considering the two different scenarios (A and B) to reproduce the experimental conditions and validate the irradiation setups to the cells. The simulation results have been tallied using the Monte Carlo code MCNP6. The spectral characteristics of the different X-ray beams have been estimated. All irradiated samples showed frequencies of micronuclei and p21-positive cells higher than the unirradiated controls. Differences in frequencies increased with the delivered dose measured with Gafchromic films XR-RV3. The spectrum incident on eye lens and Petri, as estimated with MCNP6, was in good agreement in the scenario A (confirming the experimental setup), while the mean energy spectrum was higher in the scenario B. Nevertheless, the response of LEC seemed mainly related to the measured absorbed dose. No effects on viability were detected. Our results support the hypothesis that apoptosis is not responsible for cataract induced by low doses of X-ray (i.e. 25 mGy) while the induction of transient p21 may interfere with the disassembly of the nuclear envelop in differentiating LEC, leading to cataract formation. Further studies are needed to better clarify the relationship we suggested between DNA damage, transient p21 induction and the inability of LEC enucleation.

Monte Carlo simulations and measurement of DNA damage from x-ray-triggered Auger cascades in iododeoxyuridine (IUdR)

2001 ◽  
Vol 40 (3) ◽  
pp. 199-206 ◽  
Author(s):  
S. J. Karnas ◽  
V. V. Moiseenko ◽  
E. Yu ◽  
P. Truong ◽  
J. J. Battista
Keyword(s):  
Dna Damage ◽  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
X Ray

Determination of Stoichiometry of GaAs Component in (Gaas)Ge Epitaxially Grown Thin Films by Electron Microprobe X-Ray Analysis

1990 ◽  
Vol 48 (2) ◽  
pp. 264-265
Author(s):  
D. R. Liu ◽  
S. S. Shinozaki ◽  
R. J. Baird
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Compound Semiconductors ◽  
Energy Dispersive Analysis ◽  
X Ray ◽  
Metastable Alloys ◽  
Lower Voltage

The epitaxially grown (GaAs)Ge thin film has been arousing much interest because it is one of metastable alloys of III-V compound semiconductors with germanium and a possible candidate in optoelectronic applications. It is important to be able to accurately determine the composition of the film, particularly whether or not the GaAs component is in stoichiometry, but x-ray energy dispersive analysis (EDS) cannot meet this need. The thickness of the film is usually about 0.5-1.5 μm. If Kα peaks are used for quantification, the accelerating voltage must be more than 10 kV in order for these peaks to be excited. Under this voltage, the generation depth of x-ray photons approaches 1 μm, as evidenced by a Monte Carlo simulation and actual x-ray intensity measurement as discussed below. If a lower voltage is used to reduce the generation depth, their L peaks have to be used. But these L peaks actually are merged as one big hump simply because the atomic numbers of these three elements are relatively small and close together, and the EDS energy resolution is limited.

Low-voltage EDS of magnesium ferrite Dendrites in a FEG-SEM

1996 ◽  
Vol 54 ◽  
pp. 478-479
Author(s):  
Matthew T. Johnson ◽  
Ian M. Anderson ◽  
Jim Bentley ◽  
C. Barry Carter
Keyword(s):  
Monte Carlo ◽  
Quantitative Analysis ◽  
Monte Carlo Simulations ◽  
Cross Section ◽  
Spatial Resolution ◽  
Low Voltage ◽  
Magnesium Ferrite ◽  
X Ray ◽  
Interaction Volume ◽  
Ferrite Spinel

Energy-dispersive X-ray spectrometry (EDS) performed at low (≤ 5 kV) accelerating voltages in the SEM has the potential for providing quantitative microanalytical information with a spatial resolution of ∼100 nm. In the present work, EDS analyses were performed on magnesium ferrite spinel [(MgxFe1−x)Fe2O4] dendrites embedded in a MgO matrix, as shown in Fig. 1. spatial resolution of X-ray microanalysis at conventional accelerating voltages is insufficient for the quantitative analysis of these dendrites, which have widths of the order of a few hundred nanometers, without deconvolution of contributions from the MgO matrix. However, Monte Carlo simulations indicate that the interaction volume for MgFe2O4 is ∼150 nm at 3 kV accelerating voltage and therefore sufficient to analyze the dendrites without matrix contributions.Single-crystal {001}-oriented MgO was reacted with hematite (Fe2O3) powder for 6 h at 1450°C in air and furnace cooled. The specimen was then cleaved to expose a clean cross-section suitable for microanalysis.

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