EGS4 Code Research Articles

Calculation of The Effects of Fly Ash in Concrete Samples Used as Construction Materials on Radiation Shielding Efficiency Using EGS4 Code

The aim of this study is to determine the effects of reducing cement and replacing it with fly ash in concrete samples used as construction materials on the radiation shielding efficiency. The radiation shielding effect of concrete samples was determined using the EGS4 code. By contrasting the outcomes with XCOM data, theoretical discussion was conducted. At gamma ray energies between 59.5 and 1332 keV, the mass attenuation coefficients (μ/ρ) of concrete samples mixed with fly ash were theoretically investigated using WinXCOM and EGS4. Then, several shielding parameters, including mean free path (MFP), half value layer (HVL), radiation protection efficiency (RPE), effective atomic number (Zeff), and gamma-ray kerma coefficients (kγ), were found using the mass attenuation coefficients. It has been noted that the parameters governing radiation shielding performance of concrete samples used as building materials are altered when cement is reduced and fly ash is substituted.

Calculation of radiation shielding parameters of YBa2Cu3O7 and Y3Ba5Cu8O18 superconductors for the energies from 122 to 1332 keV using EGS4 code

This Study aims to evaluate the radiation shielding efficiency of YBa2Cu3O7 and Y3Ba5Cu8O18 superconducting ceramics. In the current study, the radiation shielding efficiency of YBa2Cu3O7 and Y3Ba5Cu8O18 superconducting ceramics were calculated using the EGS4 code and discussed experimentally and theoretically by comparing with XCOM data. The mass attenuation coefficients (μ/ρ) for YBa2Cu3O7 and Y3Ba5Cu8O18 superconductors and their contents was investigated theoretically (EGS4 and WinXcom) and experimentally at gamma-ray energies from 122 to 1332 keV. The theoretical values have been computed in the energy range from 1 keV to 100 MeV using WinXcom program. Then, using the mass attenuation coefficients, it was determined some shielding parameters such as mean free path (MFP), half value layer (HVL), effective atomic number (Zeff), radiation protection efficiency (RPE) and gamma–ray kerma coefficients ((kγ). It has been seen that the theoretical and the empirical results were in agreement. The data and findings from this study can guide further research and development of shielding materials for gamma-ray and neutron shielding applications.

Calculation of the Effects of Silver (Ag) Dopant on Radiation Shielding Efficiency of BiPbSrCaCuO Superconductor Ceramics Using EGS4 Code

In the current study, the effects of silver (Ag) additive on the radiation shielding efficiency of BiPbSrCaCuO superconducting ceramics was calculated using the EGS4 code and discussed theoretically by comparison with XCOM data. The mass attenuation coefficients (µ/ρ) for BiPbSrCaCuO superconductor ceramics and their contents were investigated theoretically (WinXcom and EGS4) at gamma-ray energies ranging from 59.5 to 1332 keV. The theoretical values were computed in the energy range from 1 keV to 100 MeV using the WinXcom program. Then, using the mass attenuation coefficients, some shielding parameters were determined, such as the mean free path (MFP), the half value layer (HVL), the effective atomic number (Zeff), the radiation protection efficiency (RPE), the macroscopic fast neutron removal cross-sections (ΣR, cm−1) and the gamma-ray kerma coefficients (kγ). Theoretically, the results obtained with XCOM and EGS-4 were found to be in good agreement. The radiation shielding efficiency (RPE), neutron removal cross-section (ΣR, cm−1), maximum and semi-valent layer (HVL), and mean free path (MFP) values were found to be smaller for BiPbSrCaCuO superconducting ceramics as the silver (Ag) contribution was increased. Data from this study can guide further research and development of shielding materials for gamma-ray and neutron shielding.

Dosimetry of positrons from PET radiotracers using Monte Carlo simulations and measurements

Positrons, the anti-particle of electrons, are broadly used in medicine and materials science. Thus, understanding how free positrons interact with soft biological matter is important for medical diagnostic procedures as well as for safety. Most research in this regard focuses on positron transport in the context of image quality; however, scholars lack knowledge regarding radiation dose exposure. Too little attention has been paid to the full analysis of positron internal dosimetry.In this paper we examine the quality of positron transport using EGS5 Monte Carlo (MC) code, comparing it to GAMOS Monte Carlo code. To validate the suitability of EGS5 and GAMOS codes for positron dose evaluations, an experiment with a concentrate FDG syringe was performed. Dose rate was measured using a mobile MOSFET device and compared to MC simulation results obtained by EGS5 and GAMOS. In this study simulations of the transport of mono-energetic positron beams from 100 keV to 1.2 MeV were performed, in addition to two practical radionuclide isotopes through two different tissue layers: 5 mm and 0.07 mm thickness. The results of the simulations using ESG5 Monte Carlo code were compared to the GAMOS Monte Carlo code results. The simulations were performed to obtain detailed energy deposition from interactions of positrons and secondary electrons induced by positron sources along tissue layers.The EGS5 code dose results demonstrate good agreement with the MOSFET measured results. The GAMOS code results yielded a difference of more than twice the measured dose. Differences between the EGS5 and the GAMOS codes resulting from the tissue layer simulations are presented in this paper.

Calculation of the effects of lead (Pb)-doped eyeglass lenses on radiation shielding efficiency Using Monte Carlo EGS4 code and WinXCOM

Calculation of the effects of lead (Pb)-doped eyeglass lenses on radiation shielding efficiency Using Monte Carlo EGS4 code and WinXCOM

Specific absorbed fractions of electrons and photons for Digimouse voxelized phantom using GATE/GEANT4 Monte-Carlo simulation

Knowledge of SAF at different energies is crucial for internal dosimetry. For this purpose, a set of calculated SAF values for a mouse voxelized phantom's selected organs are presented below. Values of SAF were calculated for mono-energetic photons and electrons with energy varying from 10 keV to 4 MeV using the Monte Carlo simulation via GATE/GEANT4 code (GEANT4 Application for Emission Tomography). The heart, liver, lungs, kidneys, and spleen were considered as the source organs from which the particles were released. Then, the estimated results were compared to those calculated in a previous study using EGS4 code. It is indicated that the obtained results are in good agreement with the reference values for all energies of photons and electrons, with discrepancies less than 9% and 5% for self-irradiation and cross-irradiation, respectively.

Enhancement of the EGSnrc code egs_chamber for fast fluence calculations of charged particles

PurposeSimulation of absorbed dose deposition in a detector is one of the key tasks of Monte Carlo (MC) dosimetry methodology. Recent publications (Hartmann and Zink, 2018; Hartmann and Zink, 2019; Hartmann et al., 2021) have shown that knowledge of the charged particle fluence differential in energy contributing to absorbed dose is useful to provide enhanced insight on how response depends on detector properties. While some EGSnrc MC codes provide output of charged particle spectra, they are often restricted in setup options or limited in calculation efficiency. For detector simulations, a promising approach is to upgrade the EGSnrc code egs_chamber which so far does not offer charged particle calculations. MethodsSince the user code cavity offers charged particle fluence calculation, the underlying algorithm was embedded in egs_chamber. The modified code was tested against two EGSnrc applications and DOSXYZnrc which was modified accordingly by one of the authors. Furthermore, the gain in efficiency achieved by photon cross section enhancement was determined quantitatively. ResultsElectron and positron fluence spectra and restricted cema calculated by egs_chamber agreed well with the compared applications thus demonstrating the feasibility of the new code. Additionally, variance reduction techniques are now applicable also for fluence calculations. Depending on the simulation setup, considerable gains in efficiency were obtained by photon cross section enhancement. ConclusionThe enhanced egs_chamber code represents a valuable tool to investigate the response of detectors with respect to absorbed dose and fluence distribution and the perturbation caused by the detector in a reasonable computation time. By using intermediate phase space scoring, egs_chamber offers parallel calculation of charged particle fluence spectra for different detector configurations in one single run.

A comparative photon shielding properties of protective Window materials by using EGS5 code

For an X-ray room, there is a special window for radiation workers to monitor the patient during an irradiation procedure. Lead glass commonly used as protective window materials for diagnostic X-rays even it is known for its toxicity due to the lead oxide in the air which could be inhaled either during manufacturing or recycled process. Monte Carlo simulation (EGS5 code) was used to study several other types of available protective windows for its radiation shielding efficiency. In this study, the practicability of acrylic glass, plate glass and Pyrex glass systems with respect to lead glass were studied for protective window materials. The photon attenuation coefficients (μ), the percentage of transmitted and reflected photon energy spectra and half-value layer (HVL) were investigated by using simulation. Three photon source energies of 59.5 keV, 150 keV, and X-ray 150 kVp were calculated via EGS5 code to study the capability of these four glass systems as low energy photons radiation shielding materials. A thickness of 7 cm plate glass, 8 cm pyrex glass and more than 10 cm acrylic glass are adequate as a non-lead shielding material for 150 kVp X-ray to have a similar lead-glass equivalency. The use of plate glass as radiation protecting material to replace lead glass can reduce expenses as plate is way cheaper than lead but the increase thickness of plate will need special framing and concerns of its increased weight needs to be considered. However, given that the X-ray primary beam will not be directed towards the protective windows, therefore the findings are appropriate, with less thickness of plate glass could be used.

Monte Carlo Study on Dose Distributions Around 192Ir, 169Yb, and 125I Brachytherapy Sources Using EGSnrc-based egs_brachy User-code.

As per the recommendations of the American Association of Physicists in Medicine Task Group 43, Monte Carlo (MC) investigators should reproduce previously published dose distributions whenever new features of the code are explored. The purpose of the present study is to benchmark the TG-43 dosimetric parameters calculated using the new MC user-code egs_brachy of EGSnrc code system for three different radionuclides 192Ir, 169Yb, and 125I which represent high-, intermediate-, and low-energy sources, respectively. Brachytherapy sources investigated in this study are high-dose rate (HDR) 192Ir VariSource (Model VS2000), 169Yb HDR (Model 4140), and 125I -low-dose-rate (LDR) (Model OcuProsta). The TG-43 dosimetric parameters such as air-kerma strength, S k, dose rate constant, Λ, radial dose function, g(r) and anisotropy function, F(r,θ) and two-dimensional (2D) absorbed dose rate data (along-away table) are calculated in a cylindrical water phantom of mass density 0.998 g/cm3 using the MC code egs_brachy. Dimensions of phantom considered for 192Ir VS2000 and 169Yb sources are 80 cm diameter ×80 cm height, whereas for 125I OcuProsta source, 30 cm diameter ×30 cm height cylindrical water phantom is considered for MC calculations. The dosimetric parameters calculated using egs_brachy are compared against the values published in the literature. The calculated values of dose rate constants from this study agree with the published values within statistical uncertainties for all investigated sources. Good agreement is found between the egs_brachy calculated radial dose functions, g(r), anisotropy functions, and 2D dose rate data with the published values (within 2%) for the same phantom dimensions. For 192Ir VS2000 source, difference of about 28% is observed in g(r) value at 18 cm from the source which is due to differences in the phantom dimensions. The study validates TG-43 dose parameters calculated using egs_brachy for 192Ir, 169Yb, and 125I brachytherapy sources with the values published in the literature.

Possible Neutrino-Antineutrino Production during Gamma Ray e−e+ Pair Production: Monte Carlo Simulation Study

An alternative Feynman diagram for electron-positron pair production, in which neutrino and antineutrino are also produced on the same pathway, is introduced here. In the proposed pair production process, a portion of the momentum is carried by neutrinos and antineutrinos, allowing the rest of the momentum for the electron-positron pair. Simulations to inspect the proposed pair production process were conducted in this research using the EGS5 code system while modifying its subroutine “PAIR”. Liquid Xenon detector was then positioned in the path of various mono-energetic photon beams ranging from 2.6 to 12 MeV. These simulations were intended to inspect the detectability of the alternative pair production effects on radiation measurements in order to assess the detection conditions. Simulation results provided a comparison between the original pair production process and the proposed pair production process. Spectral results showed that changes in the region around 1 - 2 MeV and in the photopeak region were remarkable, therefore detectable. Further experimental research is recommended based on simulation findings. The alternative pair production process, firstly introduced in this paper, led to production of a larger flux of neutrinos from gamma radiation. This additional neutrino production and its contribution to non-baryonic dark matter are discussed.

Synchrotron X-ray Irradiation of a Rat’s Head Model: Monte Carlo Study of Chromatic Gel Dosimetry

Accurate treatment planning in radiotherapy essentially decreases damage to healthy tissue surrounding the tumor. Due to plans to use a direct, highly collimated, narrow beam with high intensity to treat small area tumors, researchers have studied microbeam radiation therapy extensively. Using a synchrotron beam as the radiation source may help to limit damage, but treatment planning using computerized simulations and dosimetry is still necessary to achieve optimal results. For this purpose, PDA-gel dosimeters were developed and their sensitivity around a 150 keV induced synchrotron X-ray radiation beam was examined via Monte Carlo simulations using the EGS5 code system. The microbeam development is now at the animal study stage. In this study, we simulate the irradiation of a rat’s brain. The simulation results obtained spectra for two types of PDA-gel dosimeters that were compared with the spectrum obtained in a modelized brain tumor of a rat. Additionally, percentage depth dose curves were calculated for the brain tissue and the two gels. Correction equations for the dosimeters were obtained from the dose-difference plots. For further references, these equations can be used to calculate the actual dose in a brain tumor in a rat. The Monte Carlo simulations demonstrate that PDA-gel dosimeters can be used for treatment planning using synchrotron irradiations.

Design, fabrication and characterization of neutron irradiation facility using accelerator-based photoneutron source

In this paper we describe the design of a neutron generator assembly using an electron accelerator. We have carried out design calculations for this assembly by optimizing neutron source strength and maximizing output neutron flux at a reasonable L/D ratio keeping in view the radiography applications. For this purpose, detailed Monte Carlo calculation using EGS-4 code was carried out to estimate photon flux. The results of EGS4 calculations are used in source definition card of MCNP simulation to compute neutron source strength from Beryllium in order to arrive at an optimum design. The parameters such as neutron source strength; collimation ratio etc. were optimized. The thermal neutron flux at each position of this assembly including those at the end of collimator, Cd ratio, neutron-to-gamma ratio has been estimated. Experimental measurements of these parameters are in good agreement with simulation results.

The determination of correction factors for free-air ionization chamber calculation using monte carlo method

A free-air ionization chamber is used as the primary standard instrument for absolute measurement of air kerma for of X-ray beams. The evaluation of correction factors is a key importance for establishing the standard. Photon-scattering, and diaphragm transmission and scattering were taken into the accounts to reduce some photon phenomena. On the other hand, electron-loss factor which scatter from an electrode were used for electron compensates. In this research, Correction factors were calculated for each mono-energetic photon from 2 to 60 keV for low energy x-rays and 10 to 320 keV for medium energy x-rays by EGS5 code. The calculated corrections from a mono-energetic photon of W/Mo mammography x-rays were compared between effective energy and spectrum method. There is no significant difference between two methods.

Investigation of gamma ray shielding capability of fabricated clay-polyethylene composites using EGS5, XCOM and Phy-X/PSD

Gamma radiation shielding capability (GRSC) of the fabricated clay-polyethylene composites designated A, B, C, D, E, F and G containing 0, 5, 10, 15, 20, 25 and 30 wt %, respectively of recycled low density polyethylene (LDPE) were investigated. This was done by evaluating their radiation shielding parameters: the linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half value layer (HVL), tenth value layer (TVL) and mean free path (mfp) using a Monte Carlo simulation (EGS5 code) and Phy-X/PDS software. The values obtained for each parameter through each method are in good agreement. The effective atomic number (Zeff) of the composites was also estimated. Furthermore, the ambient dose rate and corresponding photon spectra at a distance of 20 cm for Am-241 source with 1 cm thickness ofthe selected Sample A and B were calculated. Though, the GRSC of the composites reduced as LDPE wt. % is increasing in the clay matrix yet the shielding effectiveness of the composites are found comparable or better, which indicates the suitability of the composites for gamma ray shielding applications.

Examination of the Run-Time Differences between the EGSnrc and the EGS5 Monte Carlo Codes

EGS5 Monte Carlo code is a general-purpose code for calculating photons and electrons transport for complex geometries in a wide range of energies. EGSnrc Monte Carlo code (BEAMnrc enclosed) was specially developed for medical physics usage, in particular for Linac modeling and dose calculations. Both EGS5 an EGSnrc were developed based on the former EGS4 code. For each of the codes, changes were made in the electron transport methods and in the geometrical utilities. Conformity between EGS5 calculation results and EGSnrc code results for Linac modelling was shown in recent work in our group. However, a large simulation run-time difference was found for the same conditions and statistical precision between these two codes. The EGS5 code took a longer period to obtain the same results compared to the EGSnrc code for Linac modelling. The electron transport in EGSnrc is based on the ESTEPE parameter, which is the maximum fractional energy loss per electron step. We investigated the ESTEPE parameter influence on the run-time and on the results accuracy. A set of variety simulations were performed using both codes in order to inspect the codes performance. We found that the EGSnrc run-time is strongly influenced by choosing different ESTEPE parameter values. While setting larger fractional energy losses per step, reduced simulation run-time was achieved. Hence, for optimal dose, one should define the optimal ESTEPE step-size parameter to achieve the desired dose results resolution. The use of the EGS5 code, based on the electron transport method improvements, is automatically adapted to the desired dose results quality without any user interference. Choosing the proper ESTEPE parameter for the use of EGSnrc for a given simulation resulted in similar run-time duration as with the use of EGS5. In conclusion, some cases that were tested in this study on the EGS5 and on the EGSnrc showed that the EGS5 is faster and more fluent to use between these two codes.

Calculation of the effects of electric fields on ionization by electrons emitted in a parallel plate ionization chamber irradiated with 60Co γ-rays

The effects of applied voltage on a parallel plate ionization chamber irradiated with 60Co γ-rays were investigated by performing calculations using EGS5 code, which incorporates the electromagnetic field. It was confirmed that the signal current from the chamber increases or decreases linearly beyond the recombination region, when positive or negative voltage is applied to the polarizing electrode, respectively, which is in agreement with the existing measurements. It was also confirmed that the voltage dependence is due to the stopping power of air, which increases or decreases as the secondary electrons are decelerated or accelerated in the electric field, respectively, because the electrons are emitted forward more than backward. The calculated rate of increase in the signal current was smaller than the experimental ones, and the calculated rate of decrease was larger than the experimental ones. Numerical calculations were performed to investigate the effects of the electric field on the number of ion pairs produced by electrons with energy less than 1 keV, which are emitted in the ionization chamber; this effect is not accounted for by the EGS5 code. It was revealed that the number of ion pairs increases with an increase in the electric field strength. The increase cannot be attributed to the Townsend primary ionization mechanism and takes place even at very low electric field strength. This theoretical correction improves the agreement of the calculation with experiment for both the positive and negative applied voltages. The contribution of the charge of secondary electrons which exit and alive at electrodes or the ionization volume on the signal current from the ionization chamber was also discussed.

Set up of a gamma spectrometry mobile unit equipped with LaBr3(Ce) detectors for radioactivity monitoring

This paper presents the development, calibration and testing of a mobile unit for radioactivity monitoring. A 4 × 4 vehicle was equipped with a GPS and two 2″×2″ LaBr3(Ce) scintillation detectors. It was modelled using MC simulations with the EGS5 code to obtain efficiency curves for different source term scenarios. The attenuation produced by the car structure was determined using MC and experimental measurements. A self-developed software was used to acquire and analyse the gamma spectra. In addition, Minimum Detectable Activity Concentrations were calculated for 137Cs and 131I.During standard operation, the mobile unit will create a radiological map of Catalonia (Spain), calculating in real time the ambient dose equivalent H*(10) and the activity concentration of natural and anthropogenic radionuclides. After its set up and calibration, the system was tested on the field and provided adequate results. Therefore, the mobile unit is available to assist in the event of a nuclear emergency tracking radioactive plumes and participating in radioisotope mapping surveys. It is also ready to obtain the required data to build the radiological map of Catalonia.

Full-energy peak efficiency and response function of 1 cm3 CdZnTe detectors

The energy dependence of the full-energy peak (FEP) efficiency and response function of 1 cm3 CdZnTe detectors that use gamma rays were investigated in the present study. Specifically, full-energy peaks from 60 keV to 1.3 MeV were evaluated. 214Am, 133Ba, 137Cs, 54Mn, and 60Co radionuclides with good source activities were employed. The results showed that the absolute peak efficiencies decreased at higher energies, and the calculated (EGS5 code) efficiencies were nearly 70% greater than the experimental values when above 100 keV photon. Below 100 keV, disagreement is within 35%. The measured and calculated peak efficiencies peak agreed within 5% in a wide energy range when the “effective” of the crystal area was down to 0.8 x 0.8 cm2. Agreement corresponding to response function curve at the region of interest (full-energy peak) and Compton plateau region for 137Cs achieved once considering the 0.8 x 0.8 cm2 effective area of the crystal and the source plastic casing. The results of the present study provided important insights on the calibration of the FEP efficiency as a function of the gamma ray energy. The detectors must be individually calibrated to obtain reliable results.

Monte Carlo study of the relationship between skin dose and optically stimulated luminescence dosimeter dose in Pd-103 permanent breast seed implant brachytherapy

PurposeTo establish a method for estimating skin dose for patients with permanent breast seed implant based on in vivo optically stimulated luminescence dosimeters (OSLDs) measurements. Methods and MaterialsMonte Carlo simulations were performed in a simple breast phantom using the EGSnrc user code egs_brachy. Realistic models of the IsoAid Advantage Pd-103 brachytherapy source and Landauer nanoDot OSLD were created to model in vivo skin dose measurements where an OSLD would be placed on the skin of a patient with permanent breast seed implant following implantation. Doses to a 0.2 cm3 volume of skin beneath the OSLD and to the sensitive volume within the OSLD were calculated, and the ratio of these values was found for various seed positions inside the breast phantom. The maximum value of this ratio may be used as a conversion factor that would allow skin dose to be estimated from in vivo OSLD measurements. ResultsConversion factors of 0.5 and 1.44 are recommended for OSLDs calibrated to dose to Al2O3 and water, respectively, at the point of measurement in the OSLD. These factors were not significantly affected by the addition of extra seeds in the dose calculations. ConclusionsA method for estimating skin dose from OSLD measurements was proposed. Individual institutions should calibrate OSLDs to Pd-103 seeds to apply the results of this work clinically.

SIMULATION OF PHOTON ATTENUATION THROUGH ALUMINIUM USING E-RADIATION SIMULATOR (EGS5 CODE)

Radiation education is necessary for a wide variety of people, such as radiation workers and students of medical imaging. In order to understand radiation behaviour inside the material, we have developed an e-radiation simulator by using Monte Carlo simulation programme (EGS5 code). Anyone who has no programming knowledge will able to simulate photons in a material through this easy to use web-based environment radiation simulator. To validate our simulator, we calculate photon linear attenuation coefficient (µ) of an aluminium material which commonly used as a filter in diagnostic radiology. For the sake of comparison, we calculate at high energy photon of 662 keV to compare our results of µ with the XCOM database and literature. Consequently, the results from the developed simulator comparable with the database and literature for the case of photon attenuation study.