scholarly journals Study of Tissue Inhomogeneity Effects on Central Axis Radiation Beam Parameters using Monte Carlo Methods

2020 ◽  
Vol 8 (5) ◽  
pp. 352-362
Author(s):  
Dr. Santhosh VS ◽  
◽  
Dr. Anand RK ◽  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Methods ◽  
Homogeneous Medium ◽  
Central Axis ◽  
Beam Parameter ◽  
Monte Carlo Code ◽  
X Rays ◽  
Radiation Beam ◽  
Beam Parameters ◽  
Tissue Inhomogeneity

Introduction: The central axis radiation beam parameters are used for the dose calculations inradiotherapy and usually measured in a homogeneous medium. Human body is not homogeneous innature and the incident beam has to travel through different medium such as bone tissue air etc toreach the tumor. Objective: The objective of the present work is to study the effects of tissueInhomogeneity on central axis beam parameter such as percentage Depth Dose using Monte CarloMethods Materials and Methods: The Monte Carlo simulation is a virtual experiment and can beconducted with the Monte Carlo software tool installed in a PC. Input files are written as per thespecification of the Monte Carlo code. Two radiation beams beans commonly used for radiationtreatment such as Cobalt 60 and 6MV X ray were used for the simulation. Results: Depth Dosecharacteristics in homogeneous tissue medium for Cobalt60 and 6MV X rays beams were studied andis consistent with the published experimental values.In the second case, at the interface betweentissue and bone the PDD pattern changed as reported by the previous works. And the absorbed doseat bone layer is higher than the dose value predicated in a homogeneous condition. In the nextsimulation we conducted the simulation for a tissue air tissue medium. Conclusion: The presentstudy clearly demonstrate that Monte Carlo methods simulation can be used as a tool for estimationof dose in tissue Inhomogeneity where measurements are seldom possible.

MCVM: MONTE CARLO MODELING OF PHOTON MIGRATION IN VOXELIZED MEDIA

2010 ◽  
Vol 03 (02) ◽  
pp. 91-102 ◽  
Author(s):  
TING LI ◽  
HUI GONG ◽  
QINGMING LUO
Keyword(s):  
Monte Carlo ◽  
Refractive Index ◽  
High Precision ◽  
Heterogeneous Media ◽  
Homogeneous Medium ◽  
Software Tool ◽  
Light Transport ◽  
Photon Migration ◽  
Monte Carlo Code ◽  
Monte Carlo Modeling

The Monte Carlo code MCML (Monte Carlo modeling of light transport in multi-layered tissue) has been the gold standard for simulations of light transport in multi-layer tissue, but it is ineffective in the presence of three-dimensional (3D) heterogeneity. New techniques have been attempted to resolve this problem, such as MCLS, which is derived from MCML, and tMCimg, which draws upon image datasets. Nevertheless, these approaches are insufficient because of their low precision or simplistic modeling. We report on the development of a novel model for photon migration in voxelized media (MCVM) with 3D heterogeneity. Voxel crossing detection and refractive-index-unmatched boundaries were considered to improve the precision and eliminate dependence on refractive-index-matched tissue. Using a semi-infinite homogeneous medium, steady-state and time-resolved simulations of MCVM agreed well with MCML, with high precision (~100%) for the total diffuse reflectance and total fractional absorption compared to those of tMCimg (< 70%). Based on a refractive-index-matched heterogeneous skin model, the results of MCVM were found to coincide with those of MCLS. Finally, MCVM was applied to a two-layered sphere with multi-inclusions, which is an example of a 3D heterogeneous media with refractive-index-unmatched boundaries. MCVM provided a reliable model for simulation of photon migration in voxelized 3D heterogeneous media, and it was developed to be a flexible and simple software tool that delivers high-precision results.

scholarly journals A comprehensive Monte Carlo study to design a novel multi-nanoparticle loaded nanocomposites for augmentation of attenuation coefficient in the energy range of diagnostic X-rays

2021 ◽  
Vol 27 (4) ◽  
pp. 279-289
Author(s):  
Elahe Sayyadi ◽  
Asghar Mesbahi ◽  
Reza Eghdam Zamiri ◽  
Farshad Seyyed Nejad
Keyword(s):  
Monte Carlo ◽  
Energy Range ◽  
Radiation Protection ◽  
Experimental Studies ◽  
Rubber Matrix ◽  
Photon Flux ◽  
Monte Carlo Code ◽  
X Rays ◽  
Wide Range ◽  
Shielding Properties

Abstract Introduction: The present study aimed to investigate the radiation protection properties of silicon-based composites doped with nano-sized Bi2O3, PbO, Sm2O3, Gd2O3, WO3, and IrO2 particles. Radiation shielding properties of Sm2O3 and IrO2 nanoparticles were investigated for the first time in the current study. Material and methods: The MCNPX (2.7.0) Monte Carlo code was utilized to calculate the linear attenuation coefficients of single and multi-nano structured composites over the X-ray energy range of 10–140 keV. Homogenous distribution of spherical nanoparticles with a diameter of 100 nm in a silicon rubber matrix was simulated. The narrow beam geometry was used to calculate the photon flux after attenuation by designed nanocomposites. Results: Based on results obtained for single nanoparticle composites, three combinations of different nano-sized fillers Sm2O3+WO3+Bi2O3, Gd2O3+WO3+Bi2O3, and Sm2O3+WO3+PbO were selected, and their shielding properties were estimated. In the energy range of 20-60 keV Sm2O3 and Gd2O3 nanoparticles, in 70-100 keV energy range WO3 and for photons energy higher than 90 keV, PbO and Bi2O3 nanoparticles showed higher attenuation. Despite its higher density, IrO2 had lower attenuation compared to other nanocomposites. The results showed that the nanocomposite containing Sm2O3, WO3, and Bi2O3 nanoparticles provided better shielding among the studied samples. Conclusions: All studied multi-nanoparticle nanocomposites provided optimum shielding properties and almost 8% higher attenuation relative to single nano-based composites over a wide range of photon energy used in diagnostic radiology. Application of these new composites is recommended in radiation protection. Further experimental studies are suggested to validate our findings.

scholarly journals Observing Galaxy Clusters with eROSITA: Simulations

10.14311/1466 ◽  
2011 ◽  
Vol 51 (6) ◽  
Author(s):  
J. Hölzl ◽  
J. Wilms ◽  
I. Kreykenbohm ◽  
Ch. Schmid ◽  
Ch. Grossberger ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Dark Matter ◽  
Dark Energy ◽  
Galaxy Clusters ◽  
Cosmological Parameters ◽  
Mass Function ◽  
Angular Diameter ◽  
Monte Carlo Code ◽  
X Rays ◽  
Sky Survey

The eROSITA instrument on board the Russian Spectrum Roentgen Gamma spacecraft, which will be launched in 2013,will conduct an all sky survey in X-rays. A main objective of the survey is to observe galaxy clusters in order to constrain cosmological parameters and to obtain further knowledge about dark matter and dark energy. For the simulation of the eROSITA survey we present a Monte-Carlo code generating a mock catalogue of galaxy clusters distributed accordingto the mass function of [1]. The simulation generates the celestial coordinates as well as the cluster mass and redshift. From these parameters, the observed intensity and angular diameter are derived. These are used to scale Chandra cluster images as input for the survey-simulation.

TH-C-AUD-08: Comparison of Tomotherapy Dose Distributions for 6MV X-Rays and Different Cobalt-60 Source Designs Using Monte Carlo Methods

2007 ◽  
Vol 34 (6Part23) ◽  
pp. 2628-2628 ◽  
Author(s):  
Chandra P Joshi ◽  
Johnson Darko ◽  
Sandeep K Dhanesar ◽  
P B Vidyasagar ◽  
L John Schreiner
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Methods ◽  
X Rays ◽  
Dose Distributions

An Effective Method of Simulation for the Leksell Gamma Knife Perfexion by Rotating Particles in the Phase Space File

2020 ◽  
Vol 65 (1) ◽  
pp. 54-58
Author(s):  
T. Medjadj ◽  
A. Ksenofontov ◽  
A. Dalechina
Keyword(s):  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Phase Space ◽  
Gamma Knife ◽  
Homogeneous Medium ◽  
Planning System ◽  
Monte Carlo Code ◽  
Output Factors ◽  
Gamma Knife Perfexion ◽  
Conical Form

Purpose: To develop an effective method of Monte Carlo simulation of the GammaKnife Perfexion system by rotating particles in the phase space file (PSF). This method does not require simulating of all 192 sources that are distributed in the conical form of the Perfexion collimator. The simulation was performed only for 5 out of 192 sources for each collimator size. Material and methods: Monte Carlo simulation of dose distribution for previous models of GammaKnife system requires phase space file for only one source, since this phase space is identical for all the 201 sources. The Perfexion model is more complex due to the non-coaxial positions of the sources and the complexity of the collimator system itself. In this work, we present an effective method to simulate the Perfexion model using a phase space file. Penelope Monte Carlo code was used to perform this simulation. In this method, the PSF was obtained for one source in each ring, resulting in five files for each collimator size. PSF for other sources were created by azimuthal redistribution of particles, in the obtained PSF, by rotation around the Z-axis. The phase space files of the same ring were then stored together in a single file. Results: The paper presented MC simulation using the azimuthal redistribution of particles in the phase space file by rotation around the Z-axis. The simulation has been validated comparing the dose profiles and output factors with the data of the algorithm TMR10 planning system Leksell Gamma Plan (LGP) in a homogeneous environment. The acceptance criterion between TMR10 and Monte Carlo calculations for the profiles was based on the gamma index (GI). Index values more than one were not detected in all cases, which indicates a good agreement of results. The differences between the output factors obtained in this work and the TMR10 data for collimators 8 mm and 4 mm are 0.74 and 0.73 %, respectively. Conclusion: In this work successfully implemented an effective method of simulating the Leksell Gamma knife Perfexion system. The presented method does not require modeling for all 192 sources distributed in the conical form of the Perfexion collimator. The simulation was performed for only five sources for each collimator and their files PSF were obtained. These files were used to create the PSF files for other sources by azimuthal redistribution of particles, in these files, by rotation around the Z-axis providing correct calculations of dose distributions in a homogeneous medium for 16, 8 and 4 mm collimators.

scholarly journals Characterization of laser-driven electron and photon beams using the Monte Carlo code FLUKA

2014 ◽  
Vol 32 (2) ◽  
pp. 233-241 ◽  
Author(s):  
F. Fiorini ◽  
D. Neely ◽  
R.J. Clarke ◽  
S. Green
Keyword(s):  
Monte Carlo ◽  
Electron Temperature ◽  
Spectral Characteristics ◽  
Simulation Method ◽  
Target Thickness ◽  
Monte Carlo Code ◽  
X Rays ◽  
Photon Beams ◽  
X Ray ◽  
Plasma Effects

AbstractWe present a new simulation method to predict the maximum possible yield of X-rays produced by electron beams accelerated by petawatt lasers irradiating thick solid targets. The novelty of the method lies in the simulation of the electron refiluxing inside the target implemented with the Monte Carlo code Fluka. The mechanism uses initial theoretical electron spectra, cold targets and refiluxing electrons forced to re-enter the target iteratively. Collective beam plasma effects are not implemented in the simulation. Considering the maximum X-ray yield obtained for a given target thickness and material, the relationship between the irradiated target mass thickness and the initial electron temperature is determined, as well as the effect of the refiluxing on X-ray yield. The presented study helps to understand which electron temperature should be produced in order to generate a particular X-ray beam. Several applications, including medical and security imaging, could benefit from laser generated X-ray beams, so an understanding of the material and the thickness maximizing the yields or producing particular spectral characteristics is necessary. On the other more immediate hand, if this study is experimentally reproduced at the beginning of an experiment in which there is an interest in laser-driven electron and/or photon beams, it can be used to check that the electron temperature is as expected according to the laser parameters.

SU-FF-T-271: Influence of Initial Pencil Beam Parameters On Large Non-Applicator Electron Field Profiles Calculated Using Monte Carlo Methods

2005 ◽  
Vol 32 (6Part11) ◽  
pp. 2012-2012
Author(s):  
R Weinberg ◽  
J Antolak ◽  
K Hogstrom ◽  
G Starkschall ◽  
R Kudchadker ◽  
...  
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Methods ◽  
Pencil Beam ◽  
Electron Field ◽  
Beam Parameters

Comparison of the Reactivity Effects Calculated by DRAGON and Serpent for a PHWR 37-Element Fuel Bundle

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Jawad Haroon ◽  
Leslie Kicka ◽  
Subhramanyu Mohapatra ◽  
Eleodor Nichita ◽  
Peter Schwanke
Keyword(s):  
Monte Carlo ◽  
Heavy Water ◽  
Monte Carlo Methods ◽  
Statistical Error ◽  
Natural Uranium ◽  
Monte Carlo Code ◽  
Fuel Temperature ◽  
Fuel Bundle ◽  
Deterministic Methods ◽  
Heavy Water Reactor

Deterministic and Monte Carlo methods are regularly employed to conduct lattice calculations. Monte Carlo methods can effectively model a large range of complex geometries and, compared to deterministic methods, they have the major advantage of reducing systematic errors and are computationally effective when integral quantities such as effective multiplication factor or reactivity are calculated. In contrast, deterministic methods do introduce discretization approximations but usually require shorter computation times than Monte Carlo methods when detailed flux and reaction-rate solutions are sought. This work compares the results of the deterministic code DRAGON to the Monte Carlo code Serpent in the calculation of the reactivity effects for a pressurized heavy water reactor (PHWR) lattice cell containing a 37-element, natural uranium fuel bundle with heavy water coolant and moderator. The reactivity effects are determined for changes to the coolant, moderator, and fuel temperatures and to the coolant and moderator densities for zero-burnup, mid-burnup [3750  MWd/t(U)] and discharge burnup [7500  MWd/t(U)] fuel. It is found that the overall trend in the reactivity effects calculated using DRAGON match those calculated using Serpent for the burnup cases considered. However, differences that exceed the amount attributable to statistical error have been found for some reactivity effects, particularly for perturbations to coolant and moderator density and fuel temperature.

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.

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