FLUKA Monte Carlo Simulations Research Articles

Influence of V2O5 on the optical properties and radiation shielding performance of borate glass system containing Li2O and ZnO

It is significant to investigate the photon transmission resilience of different glasses in order to identify the role played by each chemical unit therein and identify the radiation protection functionality of such glass systems. The role of V2O5 in dictating the optical and radiation transmission ability of (15-x)Li2O-70B2O3-15ZnO-xV2O5 glasses is investigated in this report. Extensive optical parameters which include: molar refractivity (Rmol.), metallization criterion (M), molar polarizability (αMol.), optical transmission (TOpt.), static dielectric constant, εstatic, reflection loss (RLoss), and optical dielectric constant, εoptical of the studied glasses were theoretically calculated. The mass attenuation coefficient MACg of the investigated glasses for 15 keV to 15 MeV photons was simulated through the FLUKA Monte Carlo simulation code and XCOM. Also, the fissile neutron removal cross section ΣR was estimated theoretically using the partial density method. Obtained results indicated that he Rmol. and αMol. of the LBZV glasses were enhanced with increment in V2O5 concentration; increasing from 16.892 to 19.869 cm2/mol and 6.703 × 10−24 to 7.885 × 10−24 cm3 respectively. Other estimated optical constants showed variations that appear to be strongly dictated by the amount of V2O5 in the glass chemistry. MACgdata from FLUKA simulations and XCOM calculations resonate well with each other. The MACg lies in the limits of 0.02–13.418 cm2/g, 0.018–13.848 cm2/g, 0.020–14.182 cm2/g, 0.02–14.367 cm2/g, and 0.019–14.772 cm2/g for increasing V2O5 concentration. The absorption parameters show that the V2O5 plays a positive role in the ability of the glasses to absorb gamma photons.

Optical transmission, polarizability, and photon/neutron shielding properties of Bi2O3/MnO/B2O3 glass system

The Bi2O3/MnO/B2O3 glass system was successfully investigated for their optical and radiation protection features. The optical characterization of the glasses was achieved by estimating and analysing important optical parameters such as molar volume, refractive index, and molar refractivity using standard equations. The photon mass attenuation coefficient MAC of the glasses was estimated by FLUKA Monte Carlo simulation and validated by XCOM computation for energies 0.015 – 15 MeV. Further, the fast neutron removal cross section of the glasses was estimated theoretically. The optical and radiation shielding parameters showed strong dependence on the chemical composition. The molar volume of the BMB-Ax glasses decreased from 40.658 to 36.895 cm3/mole as the molar concentration of B2O3 increased relative to Bi2O3 and MnO. In addition, the refractive index of BMB-Ax reduced from 2.60 to 2.34 while the molar refractivity reduced from 26.73 to 22.05 × 10−24 cm3 for BMB-A1 –A3 accordingly. The MAC ranged from 89.629 to 0.039, 76.162–0.037, and 67.414–0.036 cm2g−1 for BMB-A1, and BMB-A2, and BMB-A3. The effective atomic number of the glasses was within the range: 24.62 – 78.05, 18.27 – 76.60, and 15.41 – 75.49 while the fast neutron removal cross section was estimated to be equal to 0.1002, 0.0972, and 0.0967 cm−1 for B2O3 molar concentration of 3, 4, and 6 respectively. The BMB-Ax glasses showed good optical and radiation shielding properties that makes them potentially useful in optical and radiation protection applications such as photonics and shielding respectively.

Thick target neutron yields from Beryllium, Carbon, Tungsten, and Lead targets irradiated by 26.7 MeV/nucleon [formula omitted] ions

The angular and energy distributions of secondary neutrons produced from 26.7 MeV/nucleon 4He ions, stopping in thick Be, C, W and Pb targets are measured by the time of flight method. The GEANT4, PHITS, and FLUKA Monte Carlo simulation codes with different physics models are employed to simulate the neutron yields and the results are compared with the experimental data. For the thick Be and C targets, GEANT4 with INCL++ reproduces the experimental data reasonably well. Whereas PHITS with JQMD-2.0 overestimates the neutron yields at intermediate energies and FLUKA with PEANUT underestimated the neutron yields at intermediate energies. For W and Pb targets, FLUKA with PEANUT physics model agree with experimental data best. PHITS with JQMD-2.0 overestimates the neutron yield at intermediate energies at 0°, and GEANT4 with INCL++ underestimates the neutron yield at intermediate energies at three angles.

Detecting perturbations of a radiation field inside a head-sized phantom exposed to therapeutic carbon-ion beams through charged-fragment tracking.

Noninvasive methods to monitor carbon-ion beams in patients are desired to fully exploit the advantages of carbon-ion radiotherapy. Prompt secondary ions produced in nuclear fragmentations of carbon ions are of particular interest for monitoring purposes as they can escape the patient and thus be detected and tracked to measure the radiation field in the irradiated object. This study aims to evaluate the performance of secondary-ion tracking to detect, visualize, and localize an internal air cavity used to mimic inter-fractional changes in the patient anatomy at different depths along the beam axis. In this work, a homogeneous head phantom was irradiated with a realistic carbon-ion treatment plan with a typical prescribed fraction dose of 3Gy(RBE). Secondary ions were detected by a mini-tracker with an active area of 2 cm2 , based on the Timepix3 semiconductor pixel detector technology. The mini-tracker was placed 120mm behind the center of the target at an angle of 30 degrees with respect to the beam axis. To assess the performance of the developed method, a 2-mm thick air cavity was inserted in the head phantom at several depths: in front of as well as at the entrance, in the middle, and at the distal end of the target volume. Different reconstruction methods of secondary-ion emission profile were studied using the FLUKA Monte Carlo simulation package. The perturbations in the emission profiles caused by the air cavity were analyzed to detect the presence of the air cavity and localize its position. The perturbations in the radiation field mimicked by the 2-mm thick cavity were found to be significant. A detection significance of at least three standard deviations in terms of spatial distribution of the measured tracks was found for all investigated cavity depths, while the highest significance (six standard deviations) was obtained when the cavity was located upstream of the tumor. For a tracker with an eight-fold sensitive area, the detection significance rose to at least nine standard deviations and up to 17 standard deviations, respectively. The cavity could be detected at all depths and its position measured within 6.5 ± 1.4mm, which is sufficient for the targeted clinical performance of 10mm. The presented systematic study concerning the detection and localization of small inter-fractional structure changes in a realistic clinical setting demonstrates that secondary ions carry a large amount of information on the internal structure of the irradiated object and are thus attractive to be further studied for noninvasive monitoring of carbon-ion treatments.

Synthesis, physical, optical, structural and radiation shielding characterization of borate glasses: A focus on the role of SrO/Al2O3 substitution

In a bid to expand the amount of information available on glass systems and their potential applications for radiation shielding design, glass samples with the compositions (30-x)SrO-xAl 2 O 3 –68B 2 O 3 –2V 2 O 5 (x = 5, 7.5, 10, 12.5&15 mol %) coded as SABV0 - 4 were prepared by the melt-quenching technique and analyzed for their optical, structural, physical, and radiation shielding features. The glassy (amorphous) nature of the SABV glass samples was affirmed by broad peaks of X-ray diffraction spectra. Calculated values of density and molar volume shown opposite behavior and the variation of these values were discussed as structural modifications in the glass matrix. From recorded optical absorption spectra optical band gap energy (Eg)-indirect transition, Urbach energy and optical basicity were estimated. FTIR spectra were recorded for all the samples in the range 400 cm −1 to 4000 cm −1 . The FTIR absorbance spectra unveiled the SABV network structure mainly incorporating of BO 3 and BO 4 units. Raman spectroscopy is achieved to detect the structural changes and at higher wavenumber, B–O stretching modes in [BO 3 ] observed with one or two NBO's. The results of ESR spectra of glasses have indicated the highly covalent environment of vanadium ions. Analysis of the photon shielding parameters of the glasses which were obtained primarily from FLUKA Monte Carlo simulations and XCOM computations revealed photon energy and glass chemical composition dependence. The mass attenuation coefficient and effective atomic number ranged from 0.2668 to 0.3385 cm 2 g -1 and 12.98–15.93 accordingly as the weight fraction of Sr increased from 16.06 to 26.72% in the glasses. Generally, photon shielding ability of the SABV glasses follows the trend: SABV0 > SABV1 > SABV2 > SABV3 > SABV4. The thermal neutron total cross section follows the same trend with values fluctuating between 71.9553 and 80.6268 cm −1 . However, SABV1 showed superior fast neutron moderating capacity among the glasses. The present SABV glasses showed outstanding photon shielding ability compared to common shields. The prepared glasses are thus suitable candidates for radiation protection applications.

Cosmic-ray flux predictions and observations for and with Metis on board Solar Orbiter

Context.The Metis coronagraph is one of the remote sensing instruments hosted on board the ESA/NASA Solar Orbiter mission. Metis is devoted to carry out the first simultaneous imaging of the solar corona in both visible light (VL) and ultraviolet (UV). High-energy particles can penetrate spacecraft materials and may limit the performance of the on-board instruments. A study of the galactic cosmic-ray (GCR) tracks observed in the first VL images gathered by Metis during the commissioning phase is presented here. A similar analysis is planned for the UV channel.Aims.We aim to formulate a prediction of the GCR flux up to hundreds of GeV for the first part of the Solar Orbiter mission to study the performance of the Metis coronagraph.Methods.The GCR model predictions are compared to observations gathered on board Solar Orbiter by the High-Energy Telescope in the range between 10 MeV and 100 MeV in the summer of 2020 as well as with the previous measurements. Estimated cosmic-ray fluxes above 70 MeV n−1have been also parameterized and used for Monte Carlo simulations aimed at reproducing the cosmic-ray track observations in the Metis coronagraph VL images. The same parameterizations can also be used to study the performance of other detectors.Results.By comparing observations of cosmic-ray tracks in the Metis VL images with FLUKA Monte Carlo simulations of cosmic-ray interactions in the VL detector, we find that cosmic rays fire only a fraction, on the order of 10−4, of the whole image pixel sample. We also find that the overall efficiency for cosmic-ray identification in the Metis VL images is approximately equal to the contribution ofZ ≥ 2 GCR particles. A similar study will be carried out during the whole of the Solar Orbiter’s mission duration for the purposes of instrument diagnostics and to verify whether the Metis data and Monte Carlo simulations would allow for a long-term monitoring of the GCR proton flux.

A thermal neutron source for the CERN radiation Calibration Laboratory

This work presents the design, construction and experimental characterisation of a lightweight and low-cost thermal neutron assembly, to be used with the existing Am–Be source irradiator of CERN radiation Calibration Laboratory (Cal Lab). The assembly consists of a cylindrical moderator (18 cm diameter, 25.5 cm height and 5.5 kg weight) and an optional reflector box (5 cm thick walls, 20 kg weight). The moderator is tailored to fit on the Am–Be source in its irradiation position, while the box encloses the detector under test during the irradiation. The exposure volume delimited by the box is 30 × 30 × 30 cm3. The thermal neutron fluence at the exposure location, i.e., 30 cm from the source, was optimized by FLUKA Monte Carlo (MC) simulations. The simulations were validated with measurements performed with a bare 3He proportional counter. The thermal neutron fluence at the nominal irradiation position is 7.43 × 102 cm−2s−1 with the cylindrical moderator only, and 5.75 × 103 cm−2s−1 with the cylinder and the reflector box, with the detector placed at the centre of the box. The thermal neutron fluence inside the box is rather uniform (variation <5%).

Energy calibration of the GEMPix in the energy range of 6 keV to 2 MeV

The GEMPix is a small gaseous detector with a highly pixelated readout, consisting of a drift region, three Gas Electron Multipliers (GEMs) for signal amplification, and four Timepix ASICs with 55 μm pixel pitch and a total of 262,144 pixels (512×512 pixels). A continuous flow of a gas mixture (here propane-based tissue equivalent gas) is supplied externally at a rate of 5 L/h. By placing a sealed 241Am source outside of the detector and varying the source-detector distance, the residual energy of alpha particles entering the sensitive volume of the GEMPix through a thin Mylar window is varied. An alpha spectrometry measurement was performed to determine the emission spectrum of the source, and this spectrum was then used as an input to a FLUKA Monte Carlo simulation to obtain the residual energy of the alpha particles. Thus, a calibration curve from 5.9 keV (from an 55Fe source) up to more than 2 MeV was obtained, which is needed for future applications of the detector, in particular for microdosimetry.

Radiotherapy dosimetry parameters intercomparison among eight gel dosimeters by Monte Carlo simulation

Dosimetry in radiotherapy is extremely important to guarantee effectiveness of the treatment, as described by quality assurance procedures. The main dosimeter framework proposed by International Protocols is commonly based on determinations of in-water absorbed dose. Gel dosimetry, mainly based on liquid water, offers the unique characteristic that the phantom constitutes itself the radiosensitive material. This study reports on the suitability of gel dosimetry formulations, typically implemented for clinical purposes, evaluating dosimetry outputs by means of PENELOPE and FLUKA Monte Carlo simulations, along with experimental data. The effects on the absorbed dose distributions due to variation in the mass density and the mean excitation energy are calculated for BANG®, Fricke, ITABIS, MAGIC, NBT-Pluronic, NIPAM, PAGAT, and PRESAGE formulations at irradiations with 6 and 15 MV photon and 6 MeV electron beams. Dosimetry parameters for photon and electron beams are calculated, and effects due to variations in mass density and mean excitation energy are carefully investigated. According to the results obtained from Monte Carlo simulations, along with dose profile comparisons with simulations of in-water irradiations, and comparisons with experimental data, all studied gel dosimetry formulations are capable of assessing reliable dosimetry outputs extracted from 3D dose distributions, even with uncertainties in their mass density or mean excitation energy of ±10%.

Enhancing the understanding of fragmentation processes in hadrontherapy and radioprotection in space with the FOOT experiment

During proton and carbon ions cancer treatment, nuclear interactions of the beam nuclei with the patient tissues always occur: the former leads to target fragmentation only, the latter to both projectile and target fragments production. In proton therapy the low-energy, high-charge and therefore short-range fragments produced along the beam path in the target fragmentation process may have higher biological effectiveness compared to protons, resulting in a not negligible effect on the delivered dose in a region before the tumor site. In carbon treatments the long range of projectile fragments results in a dose deposition in the healthy tissues behind the tumor site. Therefore, precise fragmentation cross section data would be of great importance to further optimize treatments. At the same time, such data would help improving the design of the shielding of spaceships, especially in view of long distance travels (i.e. Mars human exploration). In fact, nuclear fragmentation occurring between the space background radiation and spacecrafts materials changes the composition of the radiation field and thus the dose received by the astronauts. The FOOT (FragmentatiOn Of Target) experiment has been designed to investigate nuclear fragmentation processes of interest for particle therapy and space radiation protection with a precision in the cross section measurements around 5%. In this work the physics motivations of FOOT and the final design of the experiment will be presented. A performances study of the electronic setup based on FLUKA Monte Carlo simulations and a preliminary analysis of experimental data are reported as well.

FLUKA and Geant4 Monte Carlo Simulations of a Desktop, Flat Panel Source Array for 3D Medical Imaging

FLUKA and Geant4 Monte Carlo Simulations of a Desktop, Flat Panel Source Array for 3D Medical Imaging

Physical characterization of 3He ion beams for radiotherapy and comparison with 4He

There is increasing interest in using helium ions for radiotherapy, complementary to protons and carbon ions. A large number of patients were treated with 4He ions in the US heavy ion therapy project and novel 4He ion treatment programs are under preparation, for instance in Germany and Japan. 3He ions have been proposed as an alternative to 4He ions because the acceleration of 3He is technically less difficult than 4He. In particular, beam contaminations have been pointed out as a potential safety issue for 4He ion beams. This motivated a series of experiments with 3He ion beams at Gesellschaft für Schwerionenforschung (GSI), Darmstadt. Measured 3He Bragg curves and fragmentation data in water are presented in this work. Those experimental data are compared with FLUKA Monte Carlo simulations. The physical characteristics of 3He ion beams are compared to those of 4He, for which a large set of data became available in recent years from the preparation work at the Heidelberger Ionenstrahl-Therapiezentrum (HIT). The dose distributions (spread out Bragg peaks, lateral profiles) that can be achieved with 3He ions are found to be competitive to 4He dose distributions. The effect of beam contaminations on 4He depth dose distribution is also addressed. It is concluded that 3He ions can be a viable alternative to 4He, especially for future compact therapy accelerator designs and upgrades of existing ion therapy facilities.

The impact of path estimates in iterative ion CT reconstructions for clinical-like cases

Ion computed tomography (CT) promises to mitigate range uncertainties inherent in the conversion of x-ray Hounsfield units into ion relative stopping power (RSP) for ion beam therapy treatment planning. To improve accuracy and spatial resolution of ion CT by accounting for statistical multiple Coulomb scattering deflection of the ion trajectories from a straight line path (SLP), the most likely path (MLP) and the cubic spline path (CSP) have been proposed. In this work, we use FLUKA Monte Carlo simulations to investigate the impact of these path estimates in iterative tomographic reconstruction algorithms for proton, helium and carbon ions. To this end the ordered subset simultaneous algebraic reconstruction technique was used and coupled with a total variation superiorization (TVS). We evaluate the image quality and dose calculation accuracy in proton therapy treatment planning of cranial patient anatomies. CSP and MLP generally yielded nearly equal image quality with an average RSP relative error improvement over the SLP of 0.6%, 0.3% and 0.3% for proton, helium and carbon ion CT, respectively. Bone and low density materials have been identified as regions of largest enhancement in RSP accuracy. Nevertheless, only minor differences in dose calculation results were observed between the different models and relative range errors of better than 0.5% were obtained in all cases. Largest improvements were found for proton CT in complex scenarios with strong heterogeneities along the beam path. The additional TVS provided substantially reduced image noise, resulting in improved image quality in particular for soft tissue regions. Employing the CSP and MLP for iterative ion CT reconstructions enabled improved image quality over the SLP even in realistic and heterogeneous patient anatomy. However, only limited benefit in dose calculation accuracy was obtained even though an ideal detector system was simulated.

The influence of beam delivery uncertainty on dose uniformity and penumbra for pencil beam scanning in carbon-ion radiotherapy.

The dose uniformity and penumbra in the treatment field are important factors in radiotherapy, which affects the outcomes of radiotherapy. In this study, the integrated depth-dose-distributions (IDDDs) of 190 MeV/u and 260 MeV/u carbon beams in the active spot-scanning delivery system were measured and calculated by FLUKA Monte Carlo simulation based on the Heavy Ion Medical Machine (HIMM). Considering the dose distributions caused by secondary particles and scattering, we also used different types of pencil beam (PB) models to fit and compare the spatial distributions of PB. We superposed a bunch of PB to form a 20×20 cm2 treatment field with the double Gaussian and double Gaussian logistic beam models and calculated the influence of beam delivery error on the field flatness and penumbra, respectively. The simulated IDDDs showed good agreement with the measured values. The triple Gaussian and double Gaussian logistic beam models have good fitness to the simulated dose distributions. There are different influences on dose uniformity and penumbra resulting from beam uncertainties. These results would be helpful for understanding carbon ion therapy, and physical therapists are more familiar with beam characteristics for active scanning therapy, which provides a reference for commissioning and optimization of treatment plans in radiotherapy.

Low-energy electromagnetic processes affecting free-falling test-mass charging for LISA and future space interferometers

Galactic cosmic rays and solar energetic particles charge gold-platinum, free-falling test masses (TMs) on board interferometers for the detection of gravitational waves in space. The charging process induces spurious forces on the test masses that affect the sensitivity of these instruments mainly below 10−3 Hz. Geant4 and FLUKA Monte Carlo simulations were carried out to study the TM charging process on board the LISA Pathfinder mission that remained into orbit around the Sun–Earth Lagrange point L1 between 2016 and 2017. While a good agreement was observed between simulations and measurements of the TMs net charging, the shot noise associated with charging fluctuations of both positive and negative particles resulted 3–4 times higher that predicted. The origin of this mismatch was attributed to the propagation of electrons and photons only above 100 eV in the simulations. In this paper, low-energy electromagnetic processes to be included in the future Monte Carlo simulations for LISA and LISA-like space interferometers TM charging are considered. It is found that electrons and photons below 100 eV give a contribution to the effective charging comparable to that of the whole sample of particles above this energy. In particular, for incident protons ionization contributes twice with respect to low energy kinetic emission and electron backscattering. The other processes are found to play a negligible role. For heavy nuclei only sputtering must be considered.

Development of SiO2 based doped with LiF, Cr2O3, CoO4 and B2O3 glasses for gamma and fast neutron shielding

Abstract In this study, the fast neutron and gamma-ray absorption capacities of the new glasses have been investigated, which are obtained by doping CoO,CdWO4,Bi2O3, Cr2O3, ZnO, LiF,B2O3 and PbO compounds to SiO2 based glasses. GEANT4 and FLUKA Monte Carlo simulation codes have been used in the planning of the samples. The glasses were produced using a well-known melt-quenching technique. The effective neutron removal cross-sections, mean free paths, half-value layer, and transmission numbers of the fabricated glasses have been calculated through both GEANT4 and FLUKA Monte Carlo simulation codes. Experimental neutron absorbed dose measurements have been carried out. It was found that GS4 glass has the best neutron protection capacity among the produced glasses. In addition to neutron shielding properties, the gamma-ray attenuation capacities, were calculated using newly developed Phy-X/PSD software. The gamma-ray shielding properties of GS1 and GS2 are found to be equivalent to Pb-based glass.

Prompt-Gamma Spatial Energy-Distribution in a Proton Therapy Plan for Beam Range Verification

Generating a 2D energy-spatial distribution of the Prompt Gamma emission through FLUKA Monte Carlo simulations (from a proton therapy plan developed in a treatment planning system). The PG 2D spatial distribution can be potentially included in the Treatment Planning System (TPS), to predict the proton beam range and fine tune the dose distributions. A breast proton plan was developed in the treatment planning system, and then simulated in FLUKA MC. The patient geometry in FLUKA consisted of the voxelized CT, where the clinical dose was scored. The incident proton beam was modelled according to (Fiorini, 2018). A PG slit Energy-Dispersive Pixelated (EPD) imaging detector (Vella, 2020) was added to the model at 90 degrees with the respect to gantry 0. The EPD detector is capable of simultaneously capturing energy-spectra and images of the gamma-ray emission. Pixelated images are captured at the detector through the slit (60mm thickness, 10mm aperture). Two PG energy-spatial distribution were estimated, one at the target from the secondary PG generated by the proton incident beams, and the other tracked from the target to the PG detector through the slit collimator. The two energy-distributions were compared to assess the efficiency of the detector and estimate the proton range. A 2D image of the beam was generated from the proton plan to assess the detector physical capabilities. The optimum number of PGs required to generate a 2D spatial distribution of the beam in water through a slit collimator is ∼106 (Vella, 2020). However, detecting the PG emission through the slit has 1% efficiency. The number of incident protons of the beam required to generate a PG image of the beam to assess the proton range should be at least 1010, which is equivalent to a PG spatial distribution of ∼108 in the tumor. Of those, 106 gamma-rays will then reach the detector through the slit, the emission at the maximum dose. Variance reduction techniques were applied to improve the efficiency of the simulations. Finally, proton range from the PG energy-spatial distribution was estimated and compared to the proton dose distribution which were found to be within 2% difference. We have shown that the prompt-gamma secondary emission from a proton treatment can generate a 2D energy-spatial distribution of the proton beam able to assess the proton range. The optimum number of PG necessary to generate a beam image was estimated. Energy-spatial distribution of the proton induced PG emission can be potentially included in the TPS to predict the beam range and fine tune the dose delivery plan. The next step is exploring alternative detector/collimator combination to improve the efficiency of the imaging system.

Experimental comparison of clinically used ion beams for imaging applications using a range telescope

In particle therapy, the x-ray based treatment planning converting photon attenuation values to relative stopping power ratio (RSP) introduces clinically relevant range uncertainties. Recently, novel imaging technologies using transmission ion beams have been investigated to directly assess the water equivalent thickness (WET) of tissue, showing improved accuracy in RSP reconstruction, while potentially reducing the imaging dose. Due to their greater availability, protons have been mostly used for ion imaging. To this end, in this work, the influence of three ion species (protons, helium and carbon ions) on the image quality of radiographic WET retrieval has been explored with a dedicated experimental setup and compared to Monte Carlo (MC) simulations. Three phantom setups with different tissue interfaces and features have been irradiated with clinically validated proton, helium and carbon ion pencil beams under comparable imaging dose and beam settings at the Heidelberg Ion-Beam Therapy Center. Ion radiographies (iRADs) were acquired with an integration mode detector, that functions as a range telescope with 61 parallel plate ionization chambers. For comparison, experiments were reproduced in-silico with FLUKA MC simulations. Carbon ions provide iRADs with highest image quality in terms of normalized root mean square error, followed by helium ions and protons. All ions show similar capabilities of resolving WET for the considered phantoms, as shown by the similar average relative error < 3%. Besides for the slab phantom, MC simulations yielded better results than the experiment, indicating potential improvement of the experimental setup. Our results showed that the ability to resolve the WET is similar for all particles, intrinsically limited by the granularity of the detector system. While carbon ions are best suited for acquiring iRADs with the investigated integration mode detector, helium ions are put forward as a less technical challenging alternative.

Radiation shielding features of zirconolite silicate glasses using XCOM and FLUKA simulation code

This work aimed to investigate the ionizing radiation shielding features of zirconia silicate SiO2Na2OCaO —xZrO2 (SCNZ) glass system. The mass attenuation coefficients (μ/ρ) were generated by FLUKA Monte Carlo simulation code and the obtained data was verified via the calculated data from XCOM software over an extended photon energy range of 0.015 – 20 MeV. The obtained values of μ/ρ were used to evaluate several important shielding parameters such as half value layer (HVL), mean free path (MFP), effective atomic number (Zeff), and effective electron density (Neff). Results reveal that μ/ρ, MFP, HVL, Zeff, and Neff of the investigated glasses strongly depend on photon energy and chemical composition. Additionally, by using GP fitting parameters, the exposure buildup factor (EBF) of the investigated glasses were calculated. Results show that the greatest values of buildup factors exhibit at higher energies for all glass samples. Finally, the values of fast neutron removal cross section (ΣR) and the kinetic energy loss rate (Mass Stopping Power, MSP) of alphas and protons passing through the studied glasses were evaluated. Results display that the insertion of ZrO2 improves the nuclear shielding capability of SCNZ glasses. Especially, SCNZ7 glass owns superior shielding ability for charged particles as well as gamma radiation.

Low energy deposition patterns in irradiated phantom with metal artefacts inside: a comparison between FLUKA Monte Carlo simulation and GafChromic EBT2 film measurements

Standard radiotherapy treatment planning software is not able to properly account for the presence of metal artefacts in the irradiation field, thus resulting in reduced accuracy of the treatment delivery to the tumor. To overcome this, Monte Carlo (MC) codes are used for the simulation of energy deposition in the target.In this study the feasibility of MC code FLUKA for the evaluation of low energy X-ray deposition patterns/dose distributions in the irradiated 3D printed anthropomorphic head and neck phantom with integrated metal artefact (metal tooth in the lower jaw) has been assessed comparing FLUKA simulations with experimental results, obtained when evaluating energy distribution patterns on irradiated EBT2 films. A good agreement between experimental and simulation results was found in general, however in field specific cases discrepancies with ~5% uncertainty was estimated. This indicates potential of FLUKA simulations for orthovoltage therapy applications, however the need for more accurate adjustment of FLUKA simulations must be considered.