Monte Carlo Simulation Program Research Articles

Performance Analysis of Automated Parcel Lockers in Urban Delivery: Combined Agent-Based–Monte Carlo Simulation Approach

Background: The habitat structure, the environmental impact, the market acceptance, the changes in consumers’ preferences, and the pandemic urged for innovative solutions in urban last-mile delivery. Parcel lockers are among the most preferred solutions by customers due to their home proximity, time availability, and cost efficiency. Methods: This paper introduces an agent-based model (ABM) and a Monte Carlo simulation program to analyze in detail the activity of parcel locker points. The ABM describes the behavior of the agents (customers, parcels, lockers, delivery agents). The simulation is realized using ARENA 12 software. Two scenarios are created based on the number of daily delivery shifts; for each scenario, 300 simulation experiments with various input data are conducted. Results: Three measures of performance (MOPs) are selected to assess the system activity: the number of daily delivered parcels, the delivery time of an order, and the daily delayed orders. The simulation outputs reveal significant predictors of MOPs and disclose moments when actions need to be taken to increase system capacity or change customer behavior. Conclusions: The versatility of the simulation model in terms of input variables makes it a useful decision support tool for planning by highlighting quantitative assessments, organizing delivery activity, along with influences due to customer behavior changes.

An optimization design for fiber-optic neutron detector based on 6LiF/ZnO:Ga and wavelength shifting fibers

The fiber-optic neutron detector consists principally of a neutron-sensitive scintillator, optical fiber, and photomultiplier tube. It has features such as small size, real-time online measurement capability, and high resistance to electromagnetic interference. This detector is excellent for neutron detection in areas with limited space and strong electromagnetic interference. However, its small size results in a comparatively low neutron sensitivity. The goal of this study is to look into the relationship between detector parameters and performance in order to improve the detector design. The research begins with the development of a detector model using Monte Carlo simulation programs to investigate the relationship between the 6LiF/ZnO:Ga mass ratio, thickness, wavelength-shifting fiber length, and detector performance. The 6LiF/ZnO:Ga mass ratio was then used as the test parameter to create equivalent detector samples for experimental validation. The results show that the detector has the highest neutron sensitivity when the mass ratio of 6LiF/ZnO:Ga is 1:1. This pattern is consistent with theoretical simulation results, indicating that the optimization strategy for detector parameters is feasible. The results of this work give a theoretical foundation for the development and practical implementation of the fiber-optic neutron detector.

A Deep-Learning-Based Partial-Volume Correction Method for Quantitative 177Lu SPECT/CT Imaging.

With the development of new radiopharmaceutical therapies, quantitative SPECT/CT has progressively emerged as a crucial tool for dosimetry. One major obstacle of SPECT is its poor resolution, which results in blurring of the activity distribution. Especially for small objects, this so-called partial-volume effect limits the accuracy of activity quantification. Numerous methods for partial-volume correction (PVC) have been proposed, but most methods have the disadvantage of assuming a spatially invariant resolution of the imaging system, which does not hold for SPECT. Furthermore, most methods require a segmentation based on anatomic information. Methods: We introduce DL-PVC, a methodology for PVC of 177Lu SPECT/CT imaging using deep learning (DL). Training was based on a dataset of 10,000 random activity distributions placed in extended cardiac-torso body phantoms. Realistic SPECT acquisitions were created using the SIMIND Monte Carlo simulation program. SPECT reconstructions without and with resolution modeling were performed using the CASToR and STIR reconstruction software, respectively. The pairs of ground-truth activity distributions and simulated SPECT images were used for training various U-Nets. Quantitative analysis of the performance of these U-Nets was based on metrics such as the structural similarity index measure or normalized root-mean-square error, but also on volume activity accuracy, a new metric that describes the fraction of voxels in which the determined activity concentration deviates from the true activity concentration by less than a certain margin. On the basis of this analysis, the optimal parameters for normalization, input size, and network architecture were identified. Results: Our simulation-based analysis revealed that DL-PVC (0.95/7.8%/35.8% for structural similarity index measure/normalized root-mean-square error/volume activity accuracy) outperforms SPECT without PVC (0.89/10.4%/12.1%) and after iterative Yang PVC (0.94/8.6%/15.1%). Additionally, we validated DL-PVC on 177Lu SPECT/CT measurements of 3-dimensionally printed phantoms of different geometries. Although DL-PVC showed activity recovery similar to that of the iterative Yang method, no segmentation was required. In addition, DL-PVC was able to correct other image artifacts such as Gibbs ringing, making it clearly superior at the voxel level. Conclusion: In this work, we demonstrate the added value of DL-PVC for quantitative 177Lu SPECT/CT. Our analysis validates the functionality of DL-PVC and paves the way for future deployment on clinical image data.

Monte Carlo simulation and optimization of neutron ray shielding performance of related materials

Polymers have become widely used substrate materials for shielding neutron rays because of their high hydrogen content and easy processing procedures. Rare-earth materials are also being gradually adopted as neutron absorbers because of their considerable thermal neutron absorption cross-sections. This paper utilizes the FLUKA Monte Carlo simulation program to compare the shielding effects of various polymers and rare-earth oxides on neutron rays across different energy ranges. The study investigates the superior shielding materials for neutron radiation in each energy range. Subsequently, a series of materials are simulated by combining the preferred shielding materials for neutron rays in each energy range, exploring the influence of material composition and composite structure on the effectiveness of neutron ray shielding. It is revealed that the preferred material for shielding neutron rays changes for different energy ranges. For low-energy neutron rays, rare-earth oxides such as Sm2O3 and Gd2O3 demonstrate the most effective shielding, whereas for high-energy neutron rays, polyethylene (PE) provides the best shielding performance. Materials with different compositions show varying preferred structures when dealing with a 252Cf neutron source. However, in mitigating the secondary gamma rays generated during the neutron shielding process, stacked-type materials exhibit the most effective shielding performance.

Investigation of charged particles interaction with CeBr3 scintillator by Monte Carlo simulation programs

This work aims to investigate the interaction of charged particles (alpha and proton) with the CeBr3 scintillator by using Monte Carlo simulation. The total mass stopping power (TMSP), projected range, ion distributions, and ion ranges in the CeBr3 at an energy range of 0.01 - 10,000 , were computed by SRIM and FLUKA programs. The simulation results show that the TMSP of CeBr3 obtained by both programs is in good agreement. The alpha particle has a higher TMSP of the CeBr3 than the proton. The projected range of alpha and proton particles increases with increasing energy. The projected range of the proton is higher than that of the alpha particle when compared at the same energy. Finally, the 2D visualization of ion distributions and ion ranges for alpha and proton particles was reported.
 
 

IMPROVING THE QUANTIFICATION ACCURACY OF Tc-99m MIBI DUAL-PHASE PARATHYROID SPECT/CT: A MONTE CARLO SIMULATION STUDY

Objective: Quantitative parathyroid SPECT imaging is a technique used to assess Primary hyperparathyroidism that may have potential in the identification and differentiation of parathyroid lesions as well as the estimation of disease severity. Studying the effect of data acquisition parameters on the quantification error is important for maximizing the accuracy of this diagnostic technique. In this study we examine the effects of different data acquisition parameters, namely the type of collimator, scatter correction status and reconstruction iteration number on the quantification accuracy using computer simulation. Methods: The SIMIND Monte Carlo Simulation and CASToR iterative reconstruction program was used to simulate a commercially available SPECT camera (Siemens Symbia Intevo Gamma Camera) with a crystal size of 29.55cm and 128x128 matrix size. A digital cylindrical phantom filled with water was constructed. A 0.36 cm radius spherical adenoma filled with a uniform 1MBq radioactivity is placed within the phantom. Low-Energy High Resolution (LEHR) and Low Energy Ultra High Resolution (LEUHR) collimator models are tested. Along with the presence of Scatter correction and differing iteration numbers (x16, x32). An image FOV based calibration method was used to gather quantitative information and checked against the input radioactivity. Results: The presence of scatter correction caused a 15-20% relative improvement in quantification accuracy. The optimal number of iterations produced a 10% relative improvement. Overall, accuracies as good as 7% in estimated activity concentration could be observed. Conclusion: The optimization of parameters can provide a significant improvement in quantification accuracy.

Monte Carlo Simulation and N-XCOM Software Calculation of the Neutron Shielding Parameters for the NCRP Report 144 Recommended Conventional Concretes

Purpose: Radiation shielding requires deep knowledge about the shielding materials properties. Additionally, the interaction between the radiation and materials should be well understood.
 Materials and Methods: Monte Carlo (MC) simulation, NXCOM, and WinXCOM computational programs were utilized for the concrete shielding properties against 1.5 MeV neutron beam and 137Cs emitted γ-ray. In a simulated “good geometry” using MCNP5 MC code, NXCOM and WinXCOM, radiation attenuation factor (µ), microscopic neutron removal cross-section ( Half and Tenth Value Layers (HVL and TVL) of the studied concretes were derived. Obtained results by the methods were compared and discussed.
 Results: For 137Cs emitted γ-ray, mass attenuation factor (µ/ρ) obtained as 0.026 cm2/g, 0.025 cm2/g, and 0.025 cm2/g for the Serpentine concrete as the minimum factors by MCNP5 code, WinXCOM and NXCOM software, respectively. Good agreement was seen in the results derived by the use of the applied calculation methods. Maximum values for the µ/ρ were calculated as 0.03 cm2/g, 0.029 cm2/g and 0.029 cm2/g by MCNP5 code, WinXCOM and NXCOM, respectively. For the neutron attenuation factor, calculations were conducted for the concretes and the highest and lowest ΣR/ρ were derived for Serpentine and Ordinary concretes. MCNP5 MC code was calculated ΣR/ρ for the Serpentine and Ordinary concretes as 0.039 cm2/g and 0.030 cm2/g, respectively. ΣR/ρ for the Serpentine and Ordinary concretes as 0.039 cm2/g and 0.030 cm2/g, respectively.
 Conclusion: It was concluded that the calculated results showed N-XCOM program can be applied for the shielding calculations for the conventional concretes studied in this work.

Field output correction factors of small static field for IBA razor nanochamber

Purpose. The goal of this work is present results of field output factors (OF) using an IBA CC003 (Razor NanoChamber) and compare these results with PTW 60019 (MicroDiamond) and IBA Razor Diode. The experimental results for IBA CC003 were also compared with Monte Carlo (MC) Simulation, using Penelope and Ulysses programs. In addition, field output correction factors () for IBA CC003 were derived with three different methods: (1) using PTW 60019 and IBA Razor as reference detectors; (2) comparison between MC and experimental measurements; and (3) using only MC.Material and Methods. The beam collimation included in this study were (1) square field size between 10 × 10 and 0.5 × 0.5 cm2 defined by the MLC and jaws and (2) cones of different diameters. For IBA CC003 it was determined the polarity and ion collection efficiency correction factors in parallel and perpendicular orientation.Results. The results indicate (1) the variation of polarity effect with the field size is relevant for the determination of OF using IBA CC003, especially for parallel orientation; (2) there is no significant variation of the ion collection efficiency with the field size using IBA CC003 in parallel orientation; (3) OF differences between IBA CC003 and PTW 60019/IBA Razor, and experimental and MC results, increase with decreasing field size;The results indicate (1) using the first and second method, increase with decreasing field size, which can be related with the influence of the volume effect and (2) using the third method, decrease with decreasing field size, which can be explained by the perturbation effect.Conclusions. Our results demonstrate the need of applying for IBA CC003 for 1 cm, to compensate for volume averaging and perturbations effects.

MATOQ: a Monte Carlo simulation of electron transport in environmental-friendly gas mixtures for Resistive Plate Chambers

The increasing interest in environmental-friendly gas mixtures for gaseous particle detectors, especially tetrafluoropropene-based gas mixtures for Resistive Plate Chambers (RPCs), has prompted in recent years the need for simulating electron transport coefficients and reaction rates in these mixtures. MATOQ is a Monte Carlo simulation program that calculates electron transport parameters, specifically designed for studying and optimizing environmental-friendly gas mixtures for RPCs. Unlike other existing codes, MATOQ allows for the simulation of electron avalanches by including the effect of space charge electric field, which can significantly impact the avalanche evolution in gaseous detectors such as RPCs. After the validation of the MATOQ simulation in the temporal and spatial growth configurations, we present the electron transport coefficients and the reaction rates in tetrafluoropropene-based gas mixtures, which may represent a valid alternative to the standard gas mixtures currently used for RPCs.

Neural-network–based algorithm for the inverse problem of measuring K-shell ionization cross-sections of Si induced by 3–25 keV electrons and 4.5–9 keV positrons using the thick-target method

In this study, a neural network method is proposed for solving the inverse problem in the measurement of inner-shell ionization cross-sections using the thick-target method. It was applied to calculate the K-shell ionization cross-section of silicon (Si) from positron impacts in the energy range from 4.5 to 9 keV, using a Monte Carlo simulation program called PENELOPE to construct a comprehensive characteristic X-ray yield and cross-section database, serving as a foundation for training the neural network. The experimental values are compared with those obtained using regularization, yield differential, and distorted-wave Born approximation (DWBA) theoretical models. Our findings reveal that the cross-section results obtained from all three algorithms are in good agreement with the theoretical DWBA values within the error range. Moreover, our study highlights the superiority of the neural network algorithm in solving ill-posed problems, compared with traditional regularization algorithms and the yield differential method. Furthermore, we re-analyse the experimental data of electron-induced ionization cross-sections on a pure thick Si target in the energy range from 3 to 25 keV, which were originally obtained by Zhu et al. who used a regularization method. The reprocessed cross-sections obtained in this study exhibit good agreement with the reported results within the error range. To the best of our knowledge, this is the first experimental report of the K-shell ionization cross-sections of Si from positron impact.

Analyzing the influence of oblique incidence on quantitative backscattering tissue polarimetry: a pilot ex vivo study.

Among the available polarimetric techniques, backscattering Mueller matrix (MM) polarimetry provides a promising non-contact and quantitative tool for in vivo tissue detection and clinical diagnosis. To eliminate the surface reflection from the sample cost-effectively, the non-collinear backscattering MM imaging setup always has an oblique incidence. Meanwhile, for practical organ cavities imaged using polarimetric gastrointestinal endoscopy, the uneven tissue surfaces can induce various relative oblique incidences inevitably, which can affect the polarimetry in a complicated manner and needs to be considered for detailed study. The purpose of this study is to systematically analyze the influence of oblique incidence on backscattering tissue polarimetry. We measured the MMs of experimental phantom and ex vivo tissues with different incident angles and adopted a Monte Carlo simulation program based on cylindrical scattering model for further verification and analysis. Meanwhile, the results were quantitatively evaluated using the Fourier transform, basic statistics, and frequency distribution histograms. Oblique incidence can induce different changes on non-periodic, two-periodic, and four-periodic MM elements, leading to false-positive and false-negative polarization information for tissue polarimetry. Moreover, a prominent oblique incidence can bring more dramatic signal variations, such as phase retardance and element transposition. The findings presented in this study give some crucial criterions of appropriate incident angle selections for in vivo polarimetric endoscopy and other applications and can also be valuable references for studying how to minimize the influence further.

Photoelectrically detected magnetic resonance on sulfur doped NV centers

The compatibility of the method of photoelectrically detected magnetic resonance with the technique of nitrogen vacancy (NV) yield enhancement by sulfur doping has been demonstrated. For this purpose, ensembles of nitrogen vacancy centers of different area densities were generated in undoped, medium doped, and heavily doped areas of a diamond sample. The implantation depths for the dopants and the nitrogen atoms were matched in advance using the Monte Carlo simulation program “Stopping and Range of Ions in Matter.” A comparison of the pulsed photoelectrically detected magnetic resonance spectra of the NV ensembles also revealed a moderate enhancement of the signal to noise ratio for the doped areas. A connection with the increase of the NV− to NV0 ratio in the doped areas observed in optical measurements is suggested by us.

Monte Carlo Simulation of Alkaline Earth Metal Oxides Protective Layers Bombarded With Ne+ or Xe+ in Plasma Display Panels

One of the major components of commercial plasma display panel (PDP) cells is the magnesium oxide (MgO) protective layer. In order to obtain both lower discharge breakdown voltage and higher energy efficiency in the cells, other alkaline Earth metal oxides have been extensively studied as alternatives to MgO. Another important factor in the life-extending of PDP is resistance to ion sputtering. In this article, the Monte Carlo simulation program Stopping and Range of Ions in Matter (SRIM)-2013 was applied to study the behavior of the sputtering yield, vacancies/ions, backscattered ions, ion range, lateral and radial projection, energy loss due to ionization, vacancies, and phonons, of MgO, calcium oxide (CaO), SrO, and barium oxide (BaO) as a function of incident angle for Ne <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{+}$ </tex-math></inline-formula> and Xe <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{+}$ </tex-math></inline-formula> ion beam. It is discovered that CaO, SrO, and BaO protective layers increase the number of backscattered ions from surfaces when they are hit by noble gas ions. They resist sputtering and vacancies better than the MgO protective layer.

Secondary fluorescence effect quantification of EPMA analyses of olivine grains embedded in basaltic glass

Trace element analysis of olivine is challenging but vital, since trace elements in olivine can potentially record crystallization conditions and, correspondingly, conditions of magma generation, evolution, and transport dynamics. Electron microprobe analysis (EPMA) is one of the most widely used methods for trace element analysis in olivine for many reasons including but not limited to high-spatial resolution and high precision. EPMA protocols with high-beam currents and long-counting times provide accurate trace element concentrations with low-detection limits. However, these protocols neglect the effect of secondary fluorescence (SF) across phase boundaries, which may lead to fictitious analytical results when analyses are performed near other phases. In these cases, obtaining accurate EPMA data requires correction of SF effects from the adjacent or surrounding phase. In this study, the contents of olivine trace elements Ca, Ni, Mn, Ti, Cr, and Al have been measured in run products of experimental high-temperature studies on mafic magmatic systems consisting of olivine grains embedded in basaltic glass. Olivine grain fragments with known composition, were embedded in basaltic powder, and heated to 1250 °C in 1-atm vertical gas-mixing furnace for a few minutes and quenched. EPMA analyses of the olivine grains before and after the experiments were used to quantify the effect of SF, which was found to be most significant for Ca and Ti, and to a lesser extend for Al, and to depend on the distance from the interface, olivine grain geometry, accelerating voltage, and olivine and glass compositions. By combining our experimental results with systematic SF calculations performed with the Monte Carlo simulation program PENEPMA, analytical expressions that give the apparent Ca, Ti, and Al concentrations due to SF in equant olivine grains embedded in basaltic glass were derived. These equations, which allow for a rapid correction of SF effects, are used to assess the average overestimation due to SF of olivine analyses included in current experimental databases, which might be the source of major discrepancies observed in petrological tools utilizing trace element contents in olivine.

Comparison of Experimental and Monte Carlo Efficiencies of 0.5g/cc Epoxy Matrix Marinelli Source with Multiple Radioactive Nuclides

Using the gamma spectroscopy system, it can be determined whether environmental samples or standard radioactive sources are radioactive, and from which elements their radioactivity originates. The purpose of Monte Carlo (MC) simulation is to model a real-life system with its inputs and evaluate the outputs with real results. This study calculates the experimental efficiency of a p-type HPGe detector using a 0.5 g/cc Epoxy Matrix Marinelli beaker and compares these results with GESPECOR and PHITS MC Simulation programs. Thus, the thickness of the dead layer, which thickens over time and affects the detector efficiency, was determined from the most compatible result of the MC calculations made repeatedly at various alternative thicknesses to the experimental results. For 1.5 mm dead layer thickness, less than 2 % error was found between the test and MC results, especially at energies above 165 keV. As a result, it was determined that the dead layer thickness of the detector reached 1.5 mm with an increase of 114 % after its production. The current value of the dead layer thickness of each detector should be checked, as the efficiency affects the determination of the activity.

Attenuation Effect of Sample Container in Radioactivity Measurement by Gamma-ray Spectroscopy

The measurement of radioactivity in environmental samples containing natural radionuclides such as 238U, 232Th, and 40K in gamma-ray spectrometry is the most common application. One of the most widely used sample containers for environmental radioactivity measurements is volumetric sample containers of certain sizes in cylindrical geometry. These cylindrical containers can be made of materials with different densities and thicknesses. In this intention, in this study, the effect of the sample container, which is one of the many parameters affecting the detector efficiency, was investigated. For this purpose, acrylic and polypropylene materials with of different densities were examined. IAEA RGU-1, IAEA-RGTh-1 and IAEA-RGK-1 standards containing uranium, thorium and potassium environmental radionuclides analyzed in gamma-ray spectrometric measurements were used as samples for these sample containers with different densities. Additionally, since the spectra in cylindrical geometry are taken by placing them on the detector endcap, the effect of the bottom thickness was investigated by changing the bottom thickness of these materials. Different material and bottom thickness evaluations were made using PHITS and GESPECOR Monte Carlo simulation programs. Compatible results were obtained with a difference of &amp;lt;5% between the PHITS and GESPECOR programs. From the outcome of this study, it can be concluded that when choosing the container material, the density should be as low as possible and especially the bottom thickness should be thin.

Simulation and analysis of the secondary-particle-induced background of the follow-up x-ray telescope onboard Einstein Probe

The Einstein Probe (EP) is a small scientific satellite committed to time-domain astronomy and high-energy astrophysics. One of the main payloads in the EP is the Follow-up X-ray Telescope (FXT). To get a quantity of in-orbit data as a reference, data from the Insight-Hard X-ray Modulation Telescope (Insight-HXMT) were adopted. The Insight-HXMT is dedicated to perform hard x-ray all-sky surveys, which has a parallel in-orbit environment with the EP. In this paper, we simulated the in-orbit background of an FXT by the Particle and Heavy-Ion Transport code System, which is the first general-purpose heavy ion transport Monte Carlo code, which has a simulated range from 0.01 meV to 1 TeV. The influence from protons in the EP orbital environment and the secondary rays caused by the shielding materials around the detector have been mainly considered. The Super Monte Carlo Simulation Program for nuclear and radiation Processes has been used to define the materials of the shielding structure. An isotropic source of protons and a complete shielding structure have been constructed in this simulation. First, the spectrum of background between 0.5 and 15 keV has been calculated. Second, we simulated the types of reactions and the fluxes of secondary particles, and all of them were calculated with the same model in the first step. Finally, we considered the effectiveness of the outermost shielding with different materials. Among the calculated spectra of background, we found two conspicuous energy responses with high counts, separately located in 7.345 keV (5 eV) and 8.045 keV (5 eV). Compared with the in-orbit data from the low energy x-ray telescope in the Insight-HXMT, the simulated results are credible. Considering the combination of the simulated types of reactions and fluxes of secondary particles, we could mostly judge that the secondary photons brought the photoelectric effects, which caused the two conspicuous responses in the spectrum of background. In addition, copper was the most suitable material for the outermost shielding in this simulation.

RESEARCH ON THE CONSTRUCTION OF A PHANTOM IN DOSE CALCULATION BY PHITS SIMULATION PROGRAM

In the field of medical physics, determining the dosage for organs is a very complex problem because it is impossible to directly measure the dosage inside a living person's body. Therefore, in order to estimate the dosage, one usually has to use phantoms. For dosage determination and safety assessment, Monte Carlo simulation programs and today's phantoms have become indispensable tools. There are already several standard phantoms in the world but they do not represent biological characteristics by region or for a specific object. Another method used to build characteristic phantoms is done through computed tomography (CT) images and the Hounsfield index. The method requires to convert the grayscale value of each pixel element into the Hounsfield index. As such, it can only be applied to CT imaging. To overcome this shortcoming, this study has developed a program based on a new process that can convert images to geometric format for MCNP\PHITS. The new procedure that we propose will allow researchers to describe the anatomical structures more accurately and be specific to each patient.

Upcgen: A Monte Carlo simulation program for dilepton pair production in ultra-peripheral collisions of heavy ions

Ultra-peripheral collisions (UPCs) of heavy ions can be used as a clean environment to study two-photon induced interactions such as dilepton pair photoproduction. Recently, precise data on lepton pair production in UPCs were obtained by the ATLAS experiment at the LHC where significant deviations, of up to 20%, from available theoretical predictions were observed. In this work, we present a Monte Carlo event generator, Upcgen, that implements a refined treatment of the photon flux allowing us to improve the agreement with ATLAS data at large dilepton rapidities. Besides, the new generator offers a possibility to study photon polarization effects and set arbitrary values of the lepton anomalous magnetic moment that can be used in the future studies of tau g−2 via ditau production measurements in UPCs. Program summaryProgram Title: UpcgenCPC Library link to program files:https://doi.org/10.17632/gbv9s729s9.1Developer's repository link:https://github.com/nburmaso/upcgenLicensing provisions: GPLv3Programming language:▪External routines/libraries: ROOT software toolkit; optionally: Pythia8 and (or) Pythia6 event generator, a compiler with OpenMP support.Nature of problem: In view of deviations between theoretical predictions and new experimental measurements of dilepton production cross sections in ultra-peripheral collisions of heavy ions, a more accurate calculation is needed. Precise predictions also become crucial for the studies related to tau anomalous magnetic moment measurements via ditau pair production in UPCs. We made an attempt to implement a dedicated Monte Carlo event generator with improved calculation of the photon flux that can be used to generate dilepton pairs in UPCs with a possibility to freely change the value of the anomalous magnetic moment.Solution method: Utilizing classes implemented in ROOT, the program calculates the dilepton pair production cross section AA→AA+ℓℓ by folding the elementary γγ→ℓℓ cross section and the two-photon luminosity. Computation of the elementary cross section with an arbitrary value of the anomalous magnetic moment is based on the generalized vertex formalism. The calculation of the two-photon luminosity is based on an improved photon flux treatment based on realistic nuclear form factors. Since the computation of the two-photon luminosity is a time-consuming operation, a corresponding 2D-histogram is cached in a ROOT-file. The dilepton pair production cross section is then used to generate lepton pairs via a Monte Carlo simulation process. For the decay of the taus, Pythia8 or Pythia6 can be used.Additional comments including restrictions and unusual features: The program is aimed on simulation of dilepton pair production in ultra-peripheral collisions of heavy ions in collider experiments. A user can set the energy of the colliding system, change species of incoming nuclei and also tune the anomalous magnetic moment of the lepton to be produced. A possibility to generate a realistic transverse momentum distribution of dilepton pairs is also taken into account.

Dose assessment for daily cone-beam CT in lung radiotherapy patients and its combination with treatment planning.

With the increased use of X-ray imaging for patient alignment in external beam radiation therapy, particularly with cone-beam computed tomography (CBCT), the additional dose received by patients has become of greater consideration. In this study, we analysed the radiation dose from CBCT for clinical lung radiotherapy and assessed its relative contribution when combined with radiation treatment planning for a variety of lung radiotherapy techniques. The Monte Carlo simulation program ImpactMC was used to calculate the 3D dose delivered by a Varian TrueBeam linear accelerator to patients undergoing thorax CBCT imaging. The concomitant dose was calculated by simulating the daily CBCT irradiation of ten lung cancer patients. Each case was planned with a total dose of 50-60Gy to the target lesion in 25-30 fractions using the 3DCRT or IMRT plan and retrospectively planned using VMAT. For each clinical case, the calculated CBCT dose was summed with the planned dose, and the dose to lungs, heart, and spinal cord were analysed according to conventional dose conformity metrics. Our results indicate greater variations in dose to the heart, lungs, and spinal cord based on planning technique, (3DCRT, IMRT, VMAT) than from the inclusion of daily cone-beam imaging doses over 25-30 fractions. The average doses from CBCT imaging per fraction to the lungs, heart and spinal cord were 0.52 ± 0.10, 0.49 ± 0.15 and 0.39 ± 0.08cGy, respectively. Lung dose variations were related to the patient's size and body composition. Over a treatment course, this may result in an additional mean absorbed dose of 0.15-0.2Gy. For lung V5, the imaging dose resulted in an average increase of ~ 0.6% of the total volume receiving 5Gy. The increase in V20 was more dependent on the planning technique, with 3DCRT increasing by 0.11 ± 0.09% with imaging and IMRT and VMAT increasing by 0.17 ± 0.05% and 0.2 ± 0.06%, respectively. In this study, we assessed the concomitant dose for daily CBCT lung cancer patients undergoing radiotherapy. The additional radiation dose to the normal lungs from daily CBCT was found to range from 0.15 to 0.2Gy when the patient was treated with 25-30 fractions. Consideration of potential variation in relative biological effectiveness between kilovoltage imaging and megavoltage treatment dose was outside the scope of this study. Regardless of this, our results show that the assessment of imaging dose can be incorporated into the treatment planning process and the relative effect on overall dose distribution was small compared to the difference among planning techniques.