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This study aims to formulate semi-empirical processing applied to analyze simulated and experimental scattering spectra on pipeline samples for estimating the intensity of the single scattering component for the Compton scattering technique. Firstly, a procedure has been developed based on probability density functions of each scattering component, which are obtained by GEANT4. Secondly, sixteen targets are simulated with MCNP6 to validate the proposed procedure. It is shown that the relative deviation for all samples is under 3%. Thirdly, the nine calculated thickness of pipeline samples is determined with a maximum relative deviation lower than 5% in comparing to calibration thickness. [ABSTRACT FROM AUTHOR]

The structural and electronic properties of Cd1−xZnxTe and Cd1–xMnxTe compound semiconductors are investigated by using the first-principles pseudopotential plane-wave method based on the density functional theory (DFT). The generalized gradient approximation (GGA) and the local density approximation (LDA) are used. The calculated lattice parameters, the bulk modulus and the electronic band structures of different alloys are found to be in good agreement with the literature data. Absolute, photopeak and intrinsic detection efficiencies, in the 511–1332.5 keV gamma-ray energy range, are investigated using a stochastic approach, which is the Monte Carlo method as implemented in the Geant4 code. The calculated parameters are analyzed in the light of the available data. [ABSTRACT FROM AUTHOR]

The role of the nuclear interaction channel in the formation of unusually shaped tracks so-called "syringes" in olivine crystals from meteorites by galactic cosmic ray nuclei is considered. [ABSTRACT FROM AUTHOR]

We present the results concerning the development in Geant4 of a new data driven library, called here the ANSTO HF library. This X-ray fluorescence library is based on an approach of particular interest for PIXE simulation applications; however, it can be used in any Geant4 applications where X-ray fluorescence needs to be described. The X-ray fluorescence transition probabilities were calculated within the Hartree-Fock (HF) approach, which is recognised to better reproduce PIXE experimental values compared with the Hartree-Slater approach, adopted in the current default Geant4 EADL data library. These HF X-ray fluorescence transition probabilities were integrated into a new Geant4 library and will be released within Geant4 in the near future. In this paper, we compare the fluorescence X-ray spectra generated by the ANSTO HF library and by the currently available library (EADL-1991 [1]) within Geant4, for targets irradiated with protons and α particles with energies up to 10 MeV, a range of interest for PIXE applications. The comparisons were performed for a large set of sample materials spanning a broad range of target atomic numbers. These two approaches were compared to existing experimental measurements performed at the ANSTO heavy ion microprobe beamline using 2 MeV and 3 MeV proton and 10 MeV He2+ ion beams. This work represents a useful upgrade to the Geant4 atomic de-excitation package. [ABSTRACT FROM AUTHOR]

• Neutron beam characteristics were calculated by different reference physics lists. • Other physic lists underestimated the neutron yield except for QGSP_BIC_AllHP. • QGSP_BIC_AllHP is recommended for simulating low-energy proton hadronic interactions. • Two equations were obtained to predict the neutron yield for 9Be/7Li below 20 MeV. 9Be(p,xn) and 7Li(p,xn) are two reactions for the accelerator-based compact neutron source at low energy protons conditions, especially for BNCT facilities and it is necessary to simulate the beam characteristics accurately. The different reference physics lists recommended by GEANT4 have been used to calculate the neutron beam characteristics for the 9Be and 7Li targets bombarded by proton beams of 5 ∼ 10 MeV and the accuracy of GEANT4 simulations has been discussed. By comparing with the reference data such as experimental data, MCNP6 simulations and numerical calculations, the results calculated by QGSP_BIC_AllHP show good agreement with a relative error of less than 10%. The neutron yields level out and have a tendency to move forward, when the thickness is greater than the range of protons in targets. However, the neutron yields are significantly underestimated by other physics lists except for QGSP_BIC_AllHP. In addition, two fitted curve equations are acquired to quickly estimate the neutron yield for 9Be and 7Li targets below 20 MeV. Therefore, due to the limitation of the particle type and energy range in this study, GEANT4 with QGSP_BIC_AllHP is recommended to calculate hadronic interactions of protons with matter below 20 MeV. [ABSTRACT FROM AUTHOR]

ELIMED has been developed and installed at ELI beamlines as a part of the ELIMAIA beamline to transport, monitor, and use laser-driven ion beams suitable for multidisciplinary applications, including biomedical ones. This paper aims to investigate the feasibility to perform radiobiological experiments using laser-accelerated proton beams with intermediate energies (up to 30 MeV). To reach this goal, we simulate a proton source based on experimental data like the ones expected to be available in the first phase of ELIMED commissioning by using the G4-ELIMED application (an application based on the Geant4 toolkit that simulates the full ELIMED beamline). This allows the study of transmission efficiency and the final characteristics of the proton beam at the sample irradiation point. The Energy Selector System is used as an active energy modulator to obtain the desired beam features in a relatively short irradiation time (around 6 min). Furthermore, we demonstrate the capability of the beamline to filter out other ion contaminants, typically co-accelerated in a laser-plasma environment. These results can be considered as a detailed feasibility study for the use of ELIMED for various user applications such as radiobiological experiments with ultrahigh dose rate proton beams. [ABSTRACT FROM AUTHOR]

A comprehensive understanding of the lunar radiation environment is essential in preparing for future human exploration of the Moon. The radiation environment on the Moon includes primary space radiation and secondary radiation, which is induced in the lunar soil. Both primary and secondary radiation may pose severe health issues to future crews on the Moon. In this work, we build a detailed radiation environment model "Radiation Environment and Dose at the Moon (REDMoon)" for the lunar surface and subsurface. We use the GEANT4 (GEometry ANd Tracking) Monte‐Carlo code and "response function" approach to calculate type‐, energy‐, angular‐, depth‐, and time‐dependent particle spectra induced by galactic cosmic rays at the surface and subsurface of the Moon. Calculated radiation particle fluxes on and beneath the surface are in good agreement with previous experimental and numerical results while offering more details on the lunar radiation fields, such as angular and depth information. The depth profile of secondary particle spectra in the lunar soil has a maximum between 0.5 and 1 m below the surface, depending on particle type and energy. The angular distribution of secondary particles (in particular neutron, γ‐rays, electrons) with energy ≲1 MeV is mostly isotropic, while higher energy particles preferentially propagate downward. Our model provides full coverage of the spatial, directional, and energy information of the radiation field at the surface and subsurface of the Moon, which can serve for designing future human bases on the Moon. Plain Language Summary: Interplanetary space is filled with energetic particles that can affect astronauts' health, causing long‐term diseases or acute radiation poisoning. Our Moon lacks a magnetosphere and an atmosphere and is directly exposed to space radiation. Besides, energetic particles can also generate secondary particles in the lunar soil, which are transported therein or scattered to the surface of the Moon. This mixed radiation field poses considerable threats to future human exploration of the Moon. Future lunar bases are likely to use surface material to mitigate space radiation; thus, it is important to find optimized shielding depths as shielding could be counter‐productive if not carefully evaluated. In this work, we build and validate a detailed model to describe the radiation environment on the lunar surface and in the lunar soil. As a first iteration of the model, we provide the particle flux and its dependence on particle type, energy, zenith angle, soil depth, and solar cycle. Our model can be used to evaluate the radiation exposure for future humans on the Moon and design lunar habitats. Key Points: We model the radiation field on the surface and subsurface (down to 10 m) of the MoonWe obtain energy spectra of albedo and secondary particles at different depths and anglesThe results are comparable with previous studies while providing more details on the lunar radiation field [ABSTRACT FROM AUTHOR]

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 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. [ABSTRACT FROM AUTHOR]

A considerable fraction of incident high energy photons from astrophysical transients such as Gamma Ray Bursts (GRBs) is Compton scattered by the Earth’s atmosphere. These photons, sometimes referred to as the “reflection component”, contribute to the signal detected by space-borne X-ray/γ-ray instruments. The effectiveness and reliability of source parameters such as position, flux, spectra and polarization, inferred by these instruments are therefore highly dependent on the accurate estimation of this scattered component. Current missions use dedicated response matrices to account for these effects. However, these databases are not readily adaptable for other missions, including many upcoming transient search and gravitational wave high-energy electromagnetic counter part detectors. Furthermore, possible systematic effects in these complex simulations have not been thoroughly examined and verified in literature. We are in the process of investigation of the effect with a detailed Monte Carlo simulations in GEANT4 for a Low Earth Orbit (LEO) X-ray detector. Here, we discuss the outcome of our simulation in form of Atmospheric Response Matrix (ARM) and its implications of any systematic errors in the determination of source spectral characteristics. We intend to apply our results in data processing and analysis for AstroSat-CZTI observation of such sources in near future. Our simulation output and source codes will be made publicly available for use by the large number of upcoming high energy transient missions, as well as for scrutiny and systematic comparisons with other missions. [ABSTRACT FROM AUTHOR]

The noted Design of a new and effective radiation shielding material is a growing demand to reduce the harmful effects of ionizing radiation in medical and nuclear applications. In this research article, three silver nitrate (AgNO3) doped PVA polymers were reported to serve as potential shielding materials against gamma ray. These polymers were tested in terms of their polarizability, optical transmission, and metallization properties. Furthermore, the radiation shielding performance of the involved polymers was assessed by Geant4 simulations based on Monte Carlo approach over a large range of energies up to 15 MeV. The results indicate that the density of the present polymers increased from 1.19 g/cm3 for pure-PVA to 1.41 g/cm3 for 5% AgNO3 doped PVA sample. At high energies, exceeding 150 keV, LAC values of all investigated samples become almost independent of their chemical composition. For Pure-PVA polymer, the LAC values start from its highest values of 1.358 cm−1 at 15 keV then decrease with increasing energy to be 0.022 cm−1 at 15 MeV. At all penetration depths and energies, EABF values were higher for Pure-PVA than those of other polymers. The AgNO3 addition has a positive impact to improve the shielding performance of the polymer to be close to that of ordinary concrete (standard radiation shield). [ABSTRACT FROM AUTHOR]

At the moment, there is no method that allows the user to calculate the dose of UV radiation during the liquid nitrogen (LN2) sterilization process while complying with quality control regulations. This article describes a simulating method using Geant4 to obtain the dose of UV radiation in real-time with a cryogenic Silicon PhotoMultipliers (SiPM) inside the LN2 container. The results present the zone of minimum UV radiation and the estimation of the radiation dose with a cryogenic SiPM, located in the minimum zone to certify the absence of microorganisms in the LN2. • A dosimetry system is necessary to monitor the dose of UV radiation during the sterilization of LN 2. • The distribution of UV photons inside a container of LN 2 was analyzed using Geant4 toolkit. • The zone of minimum UV radiation is defined from the radius and height of a LN2 container. • The cryogenic silicon photomultiplier is suitable for obtaining the dose of UV radiation inside the LN 2. [ABSTRACT FROM AUTHOR]

CdZnTe detectors play an important role in international astronomy research. In this paper, the spectra response of CdZnTe planar detector for γ-ray was numerically simulated using GEANT4 Monte-Carlo simulation toolkit, and the influence of the factors, such as transport properties of electrons and holes, applied bias voltage, thickness of detector and other factors were studied. The calculated results show that when the charge collection efficiency ( CCE) of electron is high, the dependence of energy resolution on the ratio of electron and hole mobility-lifetime product ((μτ)e/ (μτ)h) is strong, and the resolution increases with the decrease of the ratio. The energy resolution and CCE of carrier can be improved by raising up the bias. When the CCE of electron is high, increasing thickness can weaken the hole signal contribution to the total induced charge, and improve the energy resolution. The value of (μτ)eE /d can be used to evaluate CCE of planar CdZnTe detectors for rays of low energy, and the corresponding relationship was calculated. [ABSTRACT FROM AUTHOR]

• Benchmark comparison of Geant4 and MCNP6 in characterisation of fast neutron beam. • SOI Bridge microdosimeter measured experimentally and compared with the two codes. • Neutron capture products from p+ B-implanted regions of the Bridge was investigated. In this study, Monte Carlo codes, Geant4 and MCNP6, were used to characterize the fast neutron therapeutic beam produced at iThemba LABS in South Africa. Experimental and simulation results were compared using the latest generation of Silicon on Insulator (SOI) microdosimeters from the Centre for Medical Radiation Physics (CMRP). Geant4 and MCNP6 were able to successfully model the neutron gantry and simulate the expected neutron energy spectrum produced from the reaction by protons bombarding a 9Be target. The neutron beam was simulated in a water phantom and its characteristics recorded by the silicon microdosimeters; bare and covered by a 10B enriched boron carbide converter, at different positions. The microdosimetric quantities calculated using Geant4 and MCNP6 are in agreement with experimental measurements. The thermal neutron sensitivity and production of 10B capture products in the p+ boron-implanted dopant regions of the Bridge microdosimeter is investigated. The obtained results are useful for the future development of dedicated SOI microdosimeters for Boron Neutron Capture Therapy (BNCT). This paper provides a benchmark comparison of Geant4 and MCNP6 capabilities in the context of further applications of these codes for neutron microdosimetry. [ABSTRACT FROM AUTHOR]

CATANA (Centro di AdroTerapia ed Applicazioni Nucleari Avanzate) was the first Italian protontherapy facility dedicated to the treatment of ocular neoplastic pathologies. It is in operation at the LNS Laboratories of the Italian Institute for Nuclear Physics (INFN-LNS) and to date, 500 patients have been successfully treated. Even though proton therapy has demonstrated success in clinical settings, there is still a need for more accurate models because they are crucial for the estimation of clinically relevant RBE values. Since RBE can vary depending on several physical and biological parameters, there is a clear need for more experimental data to generate predictions. Establishing a database of cell survival experiments is therefore useful to accurately predict the effects of irradiations on both cancerous and normal tissue. The main aim of this work was to compare RBE values obtained from in-vitro experimental data with predictions made by the LEM II (Local Effect Model), Monte Carlo approaches, and semi-empirical models based on LET experimental measurements. For this purpose, the 92.1 uveal melanoma and ARPE-19 cells derived from normal retinal pigmented epithelium were selected and irradiated in the middle of clinical SOBP of the CATANA proton therapy facility. The remarkable results show the potentiality of using microdosimetric spectrum, Monte Carlo simulations and LEM model to predict not only the RBE but also the survival curves. [ABSTRACT FROM AUTHOR]

In the treatment of the tumors using proton therapy, the synchrotron emits a monoenergetic beam that transports most of its energy in a special position after entering the target. There are two approaches to invading the entire tumor tissue. One of these methods, which the present work deals with, is known as passive scattering. The proton beam should be passed through a rotating scatterer, called modulation wheel, to cover the total volume of the tumor. This scattering device, in its turning, places different thicknesses of materials on the path of the proton and converts this monoenergetic beam to a spectrum with lower energy. This beam is absorbed in the lower depth of the tissue. The goal of this approach is to achieve an energy absorption curve with a maximum flat area in the tumor volume and a fast reduction to zero after passing through the tumor. Investigating the effect of materials and the geometric changes of the dispersive components in the path of the proton beam is a significant issue affecting the shape of the absorption curve. Using the Geant4 toolkit which is based on the Monte Carlo method, this dispersive system was simulated. The calculation of the geometric characteristics of the range modulator wheel, which leads to a flattened absorption curve in the tumor area, has been studied in the literature. In the present work, a Python program with an iterative algorithm has been written to design an acceptable plane curve.

nline elemental analysis of irradiated tissue in proton therapy is a major part of this treatment, since it leads to accurate estimation of the depth of Bragg peak, proton range, and distribution of stopping power of irradiated tissue. Given the fact that each element has unique characteristic prompt gamma (PG) spectrum, recording and analyzing of the emitted gamma-ray spectra is one of the methods used for online elemental analysis of irradiated tissue. In the present study, the PG lines of most abundant elements of human tissues (12C, 16O, 20Ca, and 14N) are obtained using Geant4 toolkit. Moreover, the linear dependency of 7.12, 3.91 and 2.31 MeV PG counts to the mass of 16O, 20Ca, and 14N are investigated in five phantoms. The gamma lines of 2.31, 3.91 and 7.12 MeV are selected to determine the mass of nitrogen, calcium, and oxygen in the irradiated volume. Furthermore, for two test phantoms, the mass of elements is estimated using linear fitting and is compared with predefined mass of these elements in the test phantoms. The results showed that the relative errors of estimated mass of calcium, nitrogen, and oxygen are less than 6%, which leads to the range estimation deviation of about 1 mm.

The aim of this work is to develop a Geiger-Muller (GM) detector system for robot to look for a radioactive source in case of a nuclear emergency or in a high radiation environment. In order to find a radiation source easily, a detector system, including 3 detectors, was designed to search γ-ray radiation sources autonomously. First, based on GEANT4 simulation, radiation dose rates in 3 Geiger-Muller (GM) counters were simulated at different source-detector distances, distances between detectors and angles. Various sensitivity analyses were performed experimentally to verify the simulated designed detector system. A mono-energetic C137s γ-ray source with energy 662 keV and activity of 1.11 GBq was used for the observation. The simulated results were compared with the experimental dose rate values and good agreements were obtained for various cases. Only based on the dose rates in three detectors, the radiation source with a specific source activity and angle was localized in the different location. A method was adopted with the measured dose rates and differences of distances to find the actual location of the lost γ-ray source. The corresponding angles of deviation and detection limits were calculated to determine the sensitivity and abilities of our designed detector system. The proposed system can be used to locate radiation sources in low and high radiation environments.

Background: Various factors effecting deposited energy and dose enhancement ratio (DER) in the simplified model of cell caused by the interaction of a cluster of gold nanoparticles (GNPs) with electron beams were assessed, and the results were compared with other sources through Geant4 Monte Carlo simulation toolkit. Method: The effect of added GNPs on the DNA strand breaks level, irradiated to electron, proton, and alpha beams, is assessed. Results: Presence of GNPs in the cell makes DER value more pronounced for low-energy photons rather than electron beam. Moreover, the results of DER values did not show any significant increase in absorbed dose in the presence of GNP for proton and alpha beam. Moreover, the results of DNA break with GNPs for proton and alpha beam were negligible. It is demonstrated that as the sizes of the GNPs increase, the DER is enlarged until a certain size for 40 keV photons, while there is no striking change for 50 keV electron beam when the size of the GNPs changes. The results indicate that although energy deposited in the cell for electron beam is more than low-energy photon, DER values are low compared to photon. Conclusion: Larger GNPs do not show any preference over smaller ones when irradiated through electron beams. It is proved that GNPs do not significantly increase single-strand breaks (SSBs) and double-strand breaks during electron irradiation, while there exists a direct relationship between SSB and energy.

We have explored the effectiveness of Geant4 by using it to simulate phonon conduction in Sn Host with Si Nanowire Interface. Our Monte Carlo Simulation shows that the effectiveness of the phonon conduction Geant4 simulation increases when the system attained a steady state of 100 time steps. We have simulated phonon conduction in Sn host with Si nanowire interface using a Geant4Condensed Matter Physics Monte Carlo simulation toolkit in a low cost and less powerful processing computer machine. In the simulation, phonons were displaced inside a computation domain from their initial positions with the velocities and direction vectors assigned to them. A time step was selected so that a phonon can move at most the length of one sub-cell in one time step. Our phonon conduction analysis of SiSn based alloy using Geant4 showed performance enhancement and reasonable predicted thermal values. Numerical predictions of the thermal profile simulations of the values of the temperature in each cell were all within ten percent of the average temperature of Silicon – Tin.

BackgroundIn recent years, lead halide perovskite scintillators have received extensive attention in the field of X-ray imaging. Hard X-ray medical imaging in energy range of 20~120 keV using scintillator detectors, sensitivity and imaging spatial resolution are important performance indicators.PurposeThis study aims to explore X-ray imaging property of halide lead perovskite scintillators by simulation.MethodsFirst of all, 3D MAPbBr3 quantum dots/polystyrene and 2D PEA2PbBr4 quantum dots/polystyrene scintillators were taken as research objects. Then, simulation code Geant4 was employed to establish detector model and simulate the X-ray relative detection efficiency and imaging spatial resolution of lead halide perovskite quantum dots/polymer composite scintillators. Finally, the effect of energy and the ratio of perovskite quantum dot occupation on the resolution were explained by secondary electron motion.ResultsThe results show that increasing the thickness of the composite scintillator and the proportion of perovskite quantum dots can improve the relative detection efficiency whilst reducing the thickness and increasing the proportion of perovskite quantum dots can improve the spatial resolution. When the absorption efficiency reaches 99.5%, 80% of 3D MAPbBr3 quantum dots/polystyrene excited by 20 keV X ray obtain the same spatial resolution of 10 lp·mm-1 as CsI. When the incident energy increases to 50 keV, the spatial resolution of CsI is 8 lp·mm-1, while that of lead halide perovskite scintillators is less than 4 lp·mm-1.ConclusionsIt is shown by this study that lead halide perovskites have certain application potential in 20 keV low-energy X-ray medical imaging.

Mammography machines must meet high requirements to ensure the quality of the generated images. On the other hand, due to the use of ionizing radiation, there is a need to minimize the dose received by patients. To optimize both of these parameters (dose and image quality), the response characteristics of image detectors and, depending on the composition of the breasts, the physical contrast of the examined structures should be considered. This study aimed to determine the optimal voltage values for a given breast thickness during imaging with the use of a selenium image detector. Analysis was carried out using the Monte Carlo simulation method with the GEANT4 code. Our results reveal that the combination of Mo anode together with Mo filtration (the system recommended in analog mammography) was the least favorable combination among those used in digital mammography machines with a selenium detector. Moreover, the use of Rh filtration instead of Mo was advantageous regardless of the thickness of the breast and resulted in a significant improvement in image quality with the same dose absorbed in the breast. The most advantageous solution was found to be an X-ray tube with a W anode. The highest values of the image quality-to-dose ratio were observed for breasts with dimensions ranging from 53 mm to 60 mm in thickness. Lower image quality was observed for breasts with smaller dimensions due to high breast glandularity, resulting in the deterioration of the physical contrast.

Gadolinium-159 (159Gd) is a beta emitter with appropriate energy for therapeutic application. However, this radioisotope additionally emits gamma rays, enabling the distribution of 159Gd to be detected by a gamma camera after each therapeutic administration. The current research is innovative in the investigation of 159Gd as a theranostic radioisotope in the radioembolization of HCC using Monte Carlo (MC) simulation. For 159Gd therapeutic investigation, various patient scenarios including varying tumour involvement (TI), tumour-to-normal liver uptake ratio (T/N), and lung shunting (LS) were simulated using Geant4 MC to estimate the absorbed doses to organs at risk. For 159Gd planar imaging investigation, the SPECTHead example from GATEContrib (GitHub) was utilized, and inside a liver a tumour was created and placed inside a torso phantom and simulated using GATE MC simulation. The majority of 159Gd absorbed doses by normal liver and lungs were less than the maximum dose limitations of 70 Gy and 30 Gy, respectively. Absorbed doses to other organs were observed to be below 1 Gy. The utilization of 58 keV and 363.54 keV photopeaks in combination produced optimal planar imaging of 159Gd. This research gives new insights into the use of 159Gd as a theranostic radioisotope, with the potential to be used as an Yttrium-90 (90Y) alternative for liver radioembolization.

Background: Gold nanoparticles (GNPs) accumulated within tumor cells have been shown to sensitize tumors to radiotherapy. From a physics point of view, the observed GNP-mediated radiosensitization is due to various downstream effects of the secondary electron (SE) production from internalized GNPs such as GNP-mediated dose enhancement. Over the years, numerous computational investigations on GNP-mediated dose enhancement/radiosensitization have been conducted. However, such investigations have relied mostly on simple cellular geometry models and/or artificial GNP distributions. Thus, it is at least desirable, if not necessary, to conduct further investigations using cellular geometry models that properly reflect realistic cell morphology as well as internalized GNP distributions at the nanoscale., Purpose: The primary aim of this study was to develop a nanometer-resolution geometry model of a GNP-laden tumor cell for computational investigations of GNP-mediated dose enhancement/radiosensitization. The secondary aim was to demonstrate the utility of this model by quantifying GNP-induced SE tracks/dose distribution at sub-cellular levels for further validation of a nanoscopic dose point kernel (nDPK) method against full-fledged Geant4 Monte Carlo (MC) simulation., Methods: A transmission electron microscopy (TEM) image of a single cell showing cytoplasm, cellular nucleus, and internalized GNPs in the cellular endosome was segmented into sub-cellular levels based on pixel value thresholding. A corresponding material density was allocated to each pixel, and, by adding a thickness, each pixel was transformed to a geometric voxel and imported as a Geant4-acceptable input geometry file. In Geant4-Penelope MC simulation, a clinical 6 MV photon beam was applied, vertically or horizontally to the cell surface, and energy deposition to the cellular nucleus and cytoplasm, due to SEs emitted by internalized GNPs, was scored. Next, nDPK calculations were performed by generating virtual electron tracks from each GNP voxel to all nucleus and cytoplasm voxels. Subsequently, another set of Geant4 simulation was performed with both Penelope and DNA physics models under the geometry closely mimicking in vitro cell irradiation with a clinical 6 MV photon beam, allowing for derivation of nDPK specific to this geometry and further comparison between Gean4 simulation and nDPK method., Results: The Geant4-calculated SE tracks and associated energy depositions showed significant dependence on photon incidence angle. For perpendicular incidence, nDPK results showed good agreement (average percentage pixel-to-pixel difference of 0.4% for cytoplasm and 0.5% for nucleus) with Geant4 results, while, for parallel incidence, the agreement became worse (-1.7%-0.7% for cytoplasm and -5.5%-0.8% for nucleus). Under the 6 MV cell irradiation geometry, nDPK results showed reasonable agreement (pixel-to-pixel Pearson's product moment correlation coefficient of 0.91 for cytoplasm and 0.98 for nucleus) with Geant4 results., Conclusions: The currently developed TEM-based model of a GNP-laden cell offers unprecedented details of realistic intracellular GNP distributions for nanoscopic computational investigations of GNP-mediated dose enhancement/radiosensitization. A benchmarking study performed with this model showed reasonable agreement between Geant4- and nDPK-calculated intracellular dose deposition by SEs emitted from internalized GNPs, especially under perpendicular incidence - a popular cell irradiation geometry and when the Geant4-Penelope physics model was used., (© 2024 American Association of Physicists in Medicine.)

Regarding to their unique physical and mechanical features, glasses and glass-ceramics are suitable materials for shielding purposes. The present study evaluates the shielding properties of the CaF 2 -CaO-B 2 O 3 -P 2 O 5 -SrO-Ta 2 O 5 glass system using Monte Carlo GEANT4 and MCNPX codes for X-ray radiations with an energy range of 20 to 100 keV. MAC values of the Ta 0 , Ta 1 , Ta 2 , Ta 2.5 , and Ta 3 samples of the CaF 2 -CaO-B 2 O 3 -P 2 O 5 -SrO-Ta 2 O 5 glass were computed using Phy-X/PSD, GEANT4, and MCNPX codes and compared. According to the results, the programs have good compatibility with each other. For instance, in the energy of 40 keV and for the Ta 2 sample, GEANT4 and MCNP codes are 1.445765406 and 1.517801204 cm 2 /g, respectively, indicating 7.419529525 and 2.829628418% differences with 1.562 cm 2 /g obtained using the Phy-X/PSD software. According to recent estimations, the Ta 3 sample of the CaF 2 -CaO-B 2 O 3 -P 2 O 5 -SrO-Ta 2 O 5 glass system can be selected as the best shield compared with the other samples., (© 2024. The Author(s).)

Aging infrastructure is a threatening issue throughout the world. Long exposure to oxygen and moisture causes premature corrosion of reinforced concrete structures leading to the collapse of the structures. As a consequence, real-time monitoring of civil structures for rust becomes critical in avoiding mishaps. Muon scattering tomography is a non-destructive, non-invasive technique which has shown impressive results in 3D imaging of civil structures. This paper explores the application of advanced machine learning techniques in identifying a rusted reinforced concrete rebar using muon scattering tomography. To achieve this, we have simulated the performance of an imaging prototype setup, designed to carry out muon scattering tomography, to precisely measure the rust percentage in a rusted rebar. We have produced a 2D image based on the projected 3D scattering vertices of the muons and used the scattering vertex density and average deviation angle per pixel as the distinguishing parameter for the analysis. A filtering algorithm, namely the Pattern Recognition Method, has been employed to eliminate background noise. Since this problem boils down to whether or not the material being analyzed is rust, i.e., a classification problem, we have adopted the well-known machine learning algorithm Support Vector Machine to identify rust in the rusted reinforced cement concrete structure. It was observed that the trained model could easily identify 30% of rust in the structure with a nominal exposure of 30 days within a small error range of 7.3%.

X-ray fluorescence imaging (XFI) can localize diagnostic or theranostic entities utilizing nanoparticle (NP)-based probes at high resolution in vivo, in vitro, and ex vivo. However, small-animal benchtop XFI systems demonstrating high spatial resolution (variable from sub-millimeter to millimeter range) in vivo are still limited to lighter elements (i.e., atomic number Z≤45). This study investigates the feasibility of focusing hard X-rays from solid-target tubes using ellipsoidal lens systems composed of mosaic graphite crystals with the aim of enabling high-resolution in vivo XFI applications with mid-Z (42≤Z≤64) elements. Monte Carlo simulations are performed to characterize the proposed focusing-optics concept and provide quantitative predictions of the XFI sensitivity, in silico tumor-bearing mice models loaded with palladium (Pd) and barium (Ba) NPs. Based on simulation results, the minimum detectable total mass of PdNPs per scan position is expected to be on the order of a few hundred nanograms under in vivo conform conditions. PdNP masses as low as 150 ng to 50 ng could be detectable with a resolution of 600 μm when imaging abdominal tumor lesions across a range of low-dose (0.8 μGy) to high-dose (8 μGy) exposure scenarios. The proposed focusing-optics concept presents a potential step toward realizing XFI with conventional X-ray tubes for high-resolution applications involving interesting NP formulations.

The gamma mass (µm) and linear (µ) attenuation coefficients of polycarbonate-bismuth oxide composites (PC-Bi2O3) with different bismuth oxide weight factors were investigated theoretically using EpiXS and a Monte Carlo simulation-based toolkit and Geant4 within an energy range between 0.1 and 2 MeV. The wide energy ranges of gamma rays and neutrons were chosen to cover as many applications as possible. The attenuation coefficients were then used to compute the half-value layers. The effective atomic numbers and effective electron densities of the studied samples obtained by EpiXS were compared as well. In order to further evaluate the shielding effectiveness of the studied samples, the thicknesses of all the investigated samples equivalent to 0.5 mm lead at a gamma energy of 511 keV were compared using a Geant4 code simulating a female numerical phantom with a gamma source placed facing the chest and a cylinder-shaped shield wrapped around the trunk area. The fast neutron removal cross sections of the investigated samples were studied to evaluate the effect of the weight factor of nanocomposites on the neutron shielding capabilities of the polymer as well.

A program for calculating the spectra and densities of neutron fluxes in the experimental channels of the research reactor WWR-M was developed. To do this, the reactor core was modeled. Irradiation of neutron activation detectors was performed. The obtained experimental rates of nuclear reactions are consistent with the calculated within 10 %. [ABSTRACT FROM AUTHOR]

Purpose: Designing and optimizing scintillator‐based gamma detector using Monte Carlo simulation is of great importance in nuclear medicine and high energy physics. In scintillation detectors, understanding the light transport in the scintillator and the light collection by the photodetector plays a crucial role in achieving high performance. Thus, accurately modeling them is critical. Methods: In previous works, we developed a model to compute crystal reflectance from the crystal 3D surface measurement and store it in look‐up tables to be used in the Monte Carlo simulation software GATE. The relative light output comparison showed excellent agreement between simulations and experiments for both polished and rough surfaces in several configurations, that is, without and with reflector. However, when comparing them at the irradiation depth closest to the photodetector face, rough crystals with a reflector overestimated the predicted light output. Investigating the cause of this overestimation, we optimized the LUT algorithm to improve the reflectance computation accuracy, especially for rough surfaces. However, optical Monte Carlo simulations carried out with these newly generated LUTs still overestimate the light output. Based on previous observations, one probable cause is the erroneous assumption of perfect couplings between the reflector and crystal and between the crystal and photodetector, which likely results in an important overestimation of the light output compared to experimental values. In practice, several factors could degrade it. Here, we investigated possible suboptimal optical experimental configurations that could lead to a degraded light collection when using Teflon or ESR reflectors coupled to the crystal with air or grease. We generated look‐up tables with a mixture of air and grease and showed the effect of three possible sources of light loss: the presence of a small gap between the crystal and the reflector edges close to the photodetector face, the infiltration of grease in the crystal–reflector coupling, and the presence of inhomogeneities in the photodetector–crystal interface. Results: The strongest effect is linked to the presence of a small gap of grease between the edges of the reflector material and the crystal (light loss of 10%–12% for 0.2 mm gap). The optical grease infiltrating the crystal–reflector air coupling decreases the light output, depending on the infiltration's extent and the amount of grease infiltrated. Five percent of air in the crystal–photodetector coupling can cause a light output decrease of 2% to 4%. The individual and combined effect of these advanced models can explain the discrepancy of the relative light output obtained with ESR in simulations and experiments. With Teflon, the study indicates that the light output loss strongly depends on the reflectance deterioration caused by grease absorption. Conclusions: Our results indicate that when studying scintillation detector performance with different finishes, performing simulations in ideal coupling conditions can lead to light output overestimation. To perform an accurate light output comparison and ultimately have a reliable detector performance estimation, all potential sources of practical limitations must be carefully considered. To broadly enable high‐fidelity modeling, we developed an interface for users to compute their own LUTs, using their surface, scintillator, and reflector characteristics. [ABSTRACT FROM AUTHOR]

Silica-based optical fibers presents a variety of applications used in radiation environments such as space, fusion facilities, accelerators and nuclear power plants. The radiation-induced displacement damage in optical fibers resulting in point defects may lead to attenuation signals that is a major concern for these applications. The present study proposes a computational approach to the calculation of the proton-induced displacement damage in vitreous silica. Therefore, Geant4 as a Monte Carlo particle transport code has been used to obtain the knock-on atom distributions caused by the interaction of space trapped proton with vitreous silica during an ISS mission. Moreover, molecular dynamics simulations using ReaxFF potential have been performed to produce the initial vitreous silica structure to evaluate the displacement damage cascades by LAMMPS package. The results show that ReaxFF has an appropriate potential to produce and evaluate the vitreous silica structure that provides better agreement with experimental data at both short-range and medium-range order. Furthermore, ODC(Si3) and NBOHC(O1) are dominant defect species created in the vitreous silica after trapped proton irradiation, where the total number of defects have increased on average by 94 for each keV increasing in PKA energy approximately. [ABSTRACT FROM AUTHOR]

The production, application, and/or measurement of polarised X-/gamma rays are key to the fields of synchrotron science and X-/gamma-ray astronomy. The design, development and optimisation of experimental equipment utilised in these fields typically relies on the use of Monte Carlo radiation transport modelling toolkits such as Geant4. In this work the Geant4 "G4LowEPPhysics" electromagnetic physics constructor has been reconfigured to offer a best set of electromagnetic physics models for studies exploring the transport of low energy polarised X-/gamma rays. An overview of the physics models implemented in "G4LowEPPhysics", and it's experimental validation against Compton X-ray polarimetry measurements of the BL38B1 beamline at the SPring-8 synchrotron (Sayo, Japan) is reported. "G4LowEPPhysics" is shown to be able to reproduce the experimental results obtained at the BL38B1 beamline (SPring-8) to within a level of accuracy on the same order as Geant4's X-/gamma ray interaction cross-sectional data uncertainty (approximately ± 5 %). [ABSTRACT FROM AUTHOR]

BACKGROUND: Pencil beam X-ray luminescence computed tomography (XLCT) imaging provides superior spatial resolution than other imaging geometries like sheet beam and cone beam geometries. However, the pencil beam geometry suffers from long scan times, resulting in concerns overdose which discourages the use of pencil beam XLCT. OBJECTIVE: The dose deposited in pencil beam XLCT imaging was investigated to estimate the dose from one angular projection scan with three different X-ray sources. The dose deposited in a typical small animal XLCT imaging was investigated. METHODS: A Monte Carlo simulation platform, GATE (Geant4 Application for Tomographic Emission) was used to estimate the dose from one angular projection scan of a mouse leg model with three different X-ray sources. Dose estimations from a six angular projection scan by three different X-ray source energies were performed in GATE on a mouse trunk model composed of muscle, spine bone, and a tumor. RESULTS: With the Sigray source, the bone marrow of mouse leg was estimated to have a radiation dose of 44 mGy for a typical XLCT imaging with six angular projections, a scan step size of 100 micrometers, and 106 X-ray photons per linear scan. With the Sigray X-ray source and the typical XLCT scanning parameters, we estimated the dose of spine bone, muscle tissues, and tumor structures of the mouse trunk were 38.49 mGy, 15.07 mGy, and 16.87 mGy, respectively. CONCLUSION: Our results indicate that an X-ray benchtop source (like the X-ray source from Sigray Inc.) with high brilliance and quasi-monochromatic properties can reduce dose concerns with the pencil beam geometry. Findings of this work can be applicable to other imaging modalities like X-ray fluorescence computed tomography if the imaging protocol consists of the pencil beam geometry. [ABSTRACT FROM AUTHOR]

• The yield of scintillation photons in high LET domain is suppressed. • This study proposed an alternative method for estimating the suppression of yields. • The new model uses sequential FRET calculations with Geant4. • The proposed computational model improved the prediction of suppressed yields. The yield of scintillation photons emitted from scintillators is considered to be proportional to the LET (linear energy transfer) which is energy distribution per unit length, in the low-LET domain, but not proportional in the high LET domain due to the suppression yield from the so-called quenching effect. Ogawa et al. proposed a computational method to estimate scintillation yield using Monte Carlo simulations considering the principle of the FRET (fluorescence resonance energy transfer) process, which is a phenomenon of energy transfer between fluorescent molecules. In their study, the track structure simulations could reproduce measured yields of scintillation. However, Ogawa et al.'s model was not suitable for estimating the scintillation yields when the particle energy was low when using condensed history simulations. Therefore, we propose a new method for estimating scintillation yields more accurately using Geant4 to improve the model calculations based on condensed history simulations. We simulated the local energy deposition pattern in a NE102A plastic scintillator to calculate the number of excitors in the microscopic volume for various nuclides (helium to argon ions). The suppressed scintillation yields were estimated using the model calculations of sequential FRET processes while considering the inactivation of the excitors selected as donors of the FRET process. The model calculations successfully reproduced the experimental scintillation yields within 10 % error for the lighter ions up to neon. However, when the analysis was repeated for silicon and argon, the maximum error in the scintillation yields increased up to 27 %. The proposed computational model for the evaluation of the suppressed scintillation yields emitted from NE102A scintillator irradiated with heavy ions using sequential FRET calculations with condensed history method returned simulated scintillation yields. [ABSTRACT FROM AUTHOR]

• GAMMORA is a tool that creates full Monte-Carlo simulations of the Varian TrueBeam. • It generates the files that can be executed with GATE for simple or complex cases. • It can be used for research or clinical applications (examples are presented). • Particle sources are generated by a pre-trained GAN neural network (gaga). • It is as a free and open-source tool validated and used for five years. Monte Carlo (MC) is the reference computation method for medical physics. In radiotherapy, MC computations are necessary for some issues (such as assessing figures of merit, double checks, and dose conversions). A tool based on GATE is proposed to easily create full MC simulations of the Varian TrueBeam STx. GAMMORA is a package that contains photon phase spaces as a pre-trained generative adversarial network (GAN) and the TrueBeam's full geometry. It allows users to easily create MC simulations for simple or complex radiotherapy plans such as VMAT. To validate the model, the characteristics of generated photons are first compared to those provided by Varian (IAEA format). Simulated data are also compared to measurements in water and heterogeneous media. Simulations of 8 SBRT plans are compared to measurements (in a phantom). Two examples of applications (a second check and interplay effect assessment) are presented. The simulated photons generated by the GAN have the same characteristics (energy, position, and direction) as the IAEA data. Computed dose distributions of simple cases (in water) and complex plans delivered in a phantom are compared to measurements, and the Gamma index (3%/3mm) was always superior to 98%. The feasibility of both clinical applications is shown. This model is now shared as a free and open-source tool that generates radiotherapy MC simulations. It has been validated and used for five years. Several applications can be envisaged for research and clinical purposes. [ABSTRACT FROM AUTHOR]

• New open source C++ platform based on Geant4 for radiation biology. • Modeling of 2D and 3D realistic cell populations. • Simulation of preclinical and clinical beam irradiating cell populations. • Evaluation of the impact of nanoparticles present in cell populations. Multicellular tumor spheroids are realistic in-vitro systems used in radiation biology research to study the effect of anticancer drugs or to evaluate the resistance of cancer cells under specific conditions. When combining the modeling of spheroids together with the simulation of radiation using Monte Carlo methods, one could estimate cell and DNA damage to be compared with experimental data. We developed a Cell Population (CPOP) modeler combined to Geant4 simulations in order to tackle how energy depositions are allocated to cells, especially when enhancing radiation outcomes using high-Z nanoparticles. CPOP manages to model large three-dimensional cell populations with independent deformable cells described with their nucleus, cytoplasm and membranes together with force law systems to manage cell–cell interactions. CPOP is an opensource platform written in C++. It is divided into two main libraries: a "Modeler" library, for cell geometry modeling using meshes, and a Multi Agent System (MAS) library, simulating all agent (cell) interactions among the population. CPOP is fully interfaced with the Geant4 Monte Carlo toolkit and is able to directly launch Geant4 simulations after compilation. We modeled a full and realistic 3D cell population from SK-MEL28 melanoma cell population cultured experimentally. The spheroid diameter of 550 ± 40 µm corresponds to a population of approximately 1000 cells having a diameter of 17.2 ± 2.5 µm and a nucleus diameter of 11.2 ± 2.0 µm. We decided to reproduce cell irradiations performed with a X-RAD 320 Biological Irradiator (Precision XRay Inc., North Branford, CT). We simulated the energy spectrum of secondary particles generated in the vicinity of the spheroid and plotted the different energy spectra recovered internally to the spheroid. We evaluated also the impact of AGuIX (Gadolinium) nanoparticles modeled into the spheroid with their corresponding secondary energy spectra. We succeeded into modeling cell populations and combined them with Geant4 simulations. The next step will be to integrate DNA geometrical models into cell nuclei and to use the Geant4-DNA physics and radiolysis modeling capabilities in order to evaluate early strand breaks induced on DNA. [ABSTRACT FROM AUTHOR]

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• The projectile range and fragmentation cross-section simulation study are performed for 20Ne ion beam on various elemental targets C, Al, Cu, Sn, Pb, and Ta. • The cross-section data are generated for heavy fragments (Z = 5–9) as well as for light fragments (Z = 2–4). • The Binary Cascade (BIC), the Liege Intranuclear cascade (INCL++), and the Quantum Molecular Dynamics (QMD) are used for the simulation study. • The simulation data are compared to the experimental results and nuclear fragmentation model data. • The QMD model produces the best result with an even–odd effect for all target materials. The computational study of projectile range and partial fragmentation cross-section (PFXS) has been executed for 20Ne ion using Geant4 Monte Carlo simulation toolkit. The interaction of heavy semi-symmetric system for energy range 290 MeV/n−670 MeV/n has been researched on various targets: carbon (C), aluminium (Al), copper (Cu), tin (Sn), lead (Pb), and tantalum (Ta). The range simulated via Geant4 and SRIM software shows an agreement of ~ 99%. The PFXS simulation has been conducted using three models of Geant4: the Binary Cascade (BIC), Liege Intranuclear cascade (INCL++), and Quantum Molecular Dynamics (QMD). The PFXS is computed for heavy (Z = 5–9) and light (Z = 2–4) fragments. These models have been validated by analysing simulation data with experimental and semi-empirical nuclear fragmentation model data. The QMD model provides the best data for PFXS following an odd–even effect for all targets. The BIC and the INCL++ behave in similar manner for high Z target. [ABSTRACT FROM AUTHOR]

The Timepix chip has been exposed to the outer space for the first time with the Space Application of Timepix-based Radiation Monitor (SATRAM) instrument on Project for On-Board Autonomy Vegetation (Proba-V), a European Space Agency’s (ESA) satellite. The objective of this study is to develop a new technique to improve the separation of protons and electrons, which are detected by the single-layer Timepix detector in SATRAM. The current identification method proposed by Gohl et al. (2019) is based on pattern recognition and stopping power measurements. In this article, the limitations of this method are discussed. A new method based on neural network trained with Geant4 data is proposed. Its validation with SATRAM data is presented. Similarly, a neural network trained with Geant4 data is introduced. Its purpose is to deduce the particles’ incident energy using the energy deposited in the Timepix. [ABSTRACT FROM AUTHOR]

The last two decades have witnessed increasing use of X-ray imaging and, hence, the exposure of humans to potentially harmful ionizing radiation. Computed tomography accounts for the largest portion of medically-related X-ray exposure. Accurate knowledge of ionizing radiation dose from Cone-Beam CT (CBCT) imaging is of great importance to estimate radiation risks and justification of imaging exposures. This work aimed to review the published evidence on CBCT dose estimation by focusing on studies that employ Geant4-based toolkits to estimate radiation dosage. A systematic review based on a scientometrics approach was conducted retrospectively, from January 2021, for a comprehensive overview of the trend, thematic focus, and scientific production in this topic. The search was conducted using WOS, PubMed, and Scopus databases, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. In total, 93 unique papers were found, of which only 34 met the inclusion criteria. We opine that the findings of this study provides a basis to develop accurate simulations of CBCT equipment for optimizing the trade-off between clinical benefit and radiation risk. [ABSTRACT FROM AUTHOR]

This study investigates the characterization and calibration of the high‐energy electron experiments (HEP) instrument onboard the exploration of energization and radiation in geospace (ERG). Two detector modules, HEP‐L and HEP‐H, which employ stacks of multichannel silicon strip detectors, detect electrons in the energy ranges of 70 keV–1 MeV and 700 keV–2 MeV, respectively. The detector response to electron irradiation needs to be assessed to obtain accurate electron fluxes from these detectors. In this study, we perform Monte Carlo simulations using the Geant4 particle simulation tool to reconstruct incident electron fluxes from detected count rates. Based on the simulation results, we investigate the response characteristics of the detectors when electrons with a certain range of energy are irradiated onto them. A response function is constructed by combining the simulation results for different incident energies. A response matrix is calculated by binning the response function according to the energy channels of the detector, and an inverse matrix derived from the response matrix is used to calibrate the observational data. Compared with the data obtained from another electron instrument onboard the Arase satellite (MEP‐e), whose energy range overlaps with that of the HEP, the differential flux data for the overlapping energy range (85–95 keV) are consistent with each other. The basic characteristics of the HEP detectors are thus confirmed to provide well‐calibrated data. Key Points: Arase high‐energy electron instrument (HEP) observational data (70 keV–2 MeV) is calibrated using a Geant4 simulationA new "inverse matrix calibration" method is developed for this calibrationThe calibrated HEP data shows good agreement with the data from MEP‐e that is a lower energy electron instrument onboard Arase satellite [ABSTRACT FROM AUTHOR]

Purpose: Recently, the application of high atomic number nanoparticles is suggested in the field of radiotherapy to improve physical dose enhancement and hence treatment efficiency. Several factors such as concentration and material of nanoparticles and energy of beam define the amount of dose enhancement in the target in the presence of nanoparticles. Materials and Methods: In this approach, a spherical cell was simulated through the Geant4 Monte Carlo toolkit which contained a nucleus and nanoparticles distributed through the cell. To investigate the effect of the concentration of nanoparticles on the deposited dose, it ranged from 3 mg/g to 30 mg/g for different materials like gold, silver, gadolinium, and platinum. Also, various mono-energetic photon beams included low and high energy sources were applied. Results: The results proved that as the concentration increased, the Dose Enhancement Factor (DEF) enlarged. Overall, almost for all energy and material that were used in this study, the maximum of DEF values occurred in the concentration of 30 mg/g. Moreover, lower energy sources presented higher DEF compared to other sources. The results indicated that the highest amount of DEF transpired for 35 keV photon beams equal to 14.67. Also, the K-edge energy of each material affects DEF values. Conclusion: To obtain a better outcome in the use of nanoparticles in combination with radiotherapy, a higher concentration of nanoparticles and low-energy photons should be considered to optimize the DEF and thus the treatment ratio.

An individual albedo neutron dosimeter is simulated with the Geant4 toolkit. The simulation results are compared with results from an international intercomparison for Monte Carlo codes. The doses are obtained for thermoluminescent dosimeters irradiated free in the air and also on the surface of a water phantom for different neutron energy values. The Geant4 toolkit was not used by any of the participants in this intercomparison, so with these results we can infer the applicability of Geant4 in radiation protection for this type of simulation in neutron fields.

Patient specific quality assurance can be improved using an independent dose calculation system. In addition, the implementation of such a system may support light ion beam therapy facilities in reducing the needs for beam time, by substituting some of the experimental patient-specific quality assurance procedures by independent dose calculation. The GATE-RTion-based IDEAL system for light ion beam therapy was developed for this purpose. It was built in a DICOM-in, DICOM-out fashion, for easy integration into a state-of-the-art technology-based workflow for scanned ion beam therapy. This article describes the IDEAL system, followed by its clinical implementation at MedAustron for proton and carbon ion beams. Medical physics acceptance and commissioning steps are presented together with key results: for 3D proton and carbon ion reference boxes, 97% of the points agreed within 5% from the measurements. Experimental validation of stopping powers using real pig samples were between 1.8% and 3.8% for soft tissues. Finally, five clinical cases are described, i.e. two proton and three carbon ion treatments. Dosimetric benchmarking against TPS calculations are presented and discussed in details. As expected, the IDEAL software evidenced limitations arising from the pencil beam algorithm available in the TPS for carbon ions, especially in the presence of air cavities. The IDEAL system was found to satisfy the clinical requirements for independent dose calculation of scanned ion beam delivery systems and is being clinically implemented at MedAustron. The open-source code as well as the documentation was released on the OpenGATE collaboration website, thus allowing for long term maintenance and future upgrades based on a more widespread utilization.