THE ABSORPTION OF HIGH-ENERGY RADIATION, A MONTE CARLO STUDY: III. DENSITY AND TRANSPARENCY DISTRIBUTIONS

1963 ◽  
Vol 41 (12) ◽  
pp. 2206-2240
Author(s):  
N. R. Steenberg ◽  
W. P. Crofts
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
High Energy ◽  
Matter Distribution ◽  
Monte Carlo Data ◽  
Rigid Spheres ◽  
High Energy Radiation ◽  
Geometric Origin ◽  
Strong Surface ◽  
Spherical Arrays

Random spherical arrays of rigid spheres are being studied as a model for a nucleus under high-energy bombardment. This paper reports on the distribution of sphere centers, the matter distribution, and the transparency for such arrays. Low (12.5%) and high (42.2%) nominal densities are treated for arrays numbering 27 and 216 spheres. At high densities a strong surface correlation of geometric origin is observed. Analytic formulas are presented which in general adequately represent the Monte Carlo data.

THE ABSORPTION OF HIGH-ENERGY RADIATION, A MONTE CARLO STUDY: II. SPHERICAL GEOMETRY

1963 ◽  
Vol 41 (4) ◽  
pp. 651-663
Author(s):  
N. R. Steenberg
Keyword(s):  
Cross Section ◽  
Spherical Geometry ◽  
Monte Carlo Study ◽  
Nuclear Data ◽  
High Energy ◽  
Rare Gas ◽  
Nuclear Radius ◽  
Rigid Spheres ◽  
High Energy Radiation ◽  
The Individual

The absorption of radiation in a spherical obstacle composed of rigid spheres has been studied. The result is the absorption cross section of such an obstacle as a function of the free cross section and the number A of the individual spheres and of packing density. It is found that the usual rare-gas formula represents the cross section adequately. The analysis is applied to nuclear data for the absorption of 25-Bev/c protons by nuclei. It is found that for a nuclear radius R = r0A1/3 + δ, where δ is the radius of the nucleon, r0 = 1.17 fermi, δ = 1.05 fermi, and an average nucleon transparency a2 = 0.30 is consistent with the data.

THE ABSORPTION OF HIGH-ENERGY RADIATION, A MONTE CARLO STUDY: I. RECTANGULAR GEOMETRY

1963 ◽  
Vol 41 (4) ◽  
pp. 632-650 ◽  
Author(s):  
N. R. Steenberg ◽  
W. Van Iterson
Keyword(s):  
Monte Carlo ◽  
Cross Section ◽  
Effective Cross Section ◽  
Monte Carlo Study ◽  
High Energy ◽  
Rare Gas ◽  
High Energy Radiation ◽  
Energy Radiation ◽  
Alternative Formula ◽  
Random Array

As part of an investigation of the scattering of high-energy radiation by nuclei a Monte Carlo study has been made of the attenuation of radiation by a rectangular barrier composed of a moderately dense random array of rigid semiopaque spheres. It is found that the attenuation is much more rapid than that predicted by the rare-gas formula usually assumed and is well described by an alternative formula which is derived on probabilistic grounds. A corollary is that an effective cross section which is substantially larger than the free cross section must be assumed inside such a medium.

ON THE RELATION BETWEEN THE WIDTH OF CHARGE BALANCE FUNCTION AND HADRONIZATION TIME IN RELATIVISTIC HEAVY ION COLLISION

2007 ◽  
Vol 16 (10) ◽  
pp. 3355-3362
Author(s):  
DU JIAXIN ◽  
LI NA ◽  
LIU LIANSHOU
Keyword(s):  
Monte Carlo ◽  
Strong Dependence ◽  
Monte Carlo Study ◽  
Heavy Ion ◽  
High Energy ◽  
Relativistic Heavy Ion Collisions ◽  
Heavy Ion Collision ◽  
Balance Function ◽  
Charge Balance ◽  
Ion Collision

A Monte Carlo study on the charge balance function in high energy hadron-hadron and relativistic heavy ion collisions are carried out using the Monte Carlo generators PYTHIA and AMPT, respectively. A strong dependence of the width of balance function on multiplicity is found in both cases. Using the mean parton-freeze-out time of a heavy-ion-collision event as the characteristic hadronization time for the event, it is found that for a fixed multiplicity interval the width of balance function is consistent with being independent of hadronization time.

scholarly journals The Influence of Brass Compensator Thickness and Field Size on Neutron Contamination Spectrum in 18MV Elekta SL 75/25 Medical Linear Accelerator with and without Flattening Filter: A Monte Carlo Study

2018 ◽  
Vol 8 (3Sep) ◽  
Author(s):  
A S Talebi ◽  
M Maleki ◽  
P Hejazi ◽  
M Jadidi ◽  
R Ghorbani
Keyword(s):  
Monte Carlo ◽  
Linear Accelerator ◽  
Monte Carlo Study ◽  
High Energy ◽  
Nonparametric Tests ◽  
Primary Electron ◽  
Field Size ◽  
Dose Ratio ◽  
Medical Linear Accelerator ◽  
Flattening Filter

BackgroundOne of the most significant Intensity Modulated Radiation Therapy treatment benefits is a high target to normal tissue dose ratio. To improve this advantage, an additional accessory such as a compensator is used to delivering doses. Compensator-based IMRT treatment is usually operated with an energy higher than 10 MV. Photoneutrons, which have high linear energy transfer and radiobiological effectiveness, are produced by colliding high-energy photon beams with linear accelerator structures, then they deliver the unwanted doses to patients and staff. Therefore, the neutron energy spectra should be determined in order to calculate and reduce the photoneutron risk.Objective: We have conducted a comprehensive and precise study on the influence of brass compensator thickness and field size on neutron contamination spectrum in an Elekta SL 75/25 medical linear accelerator with and without the flattening filter by Monte Carlo method.Materials and Methods: MCNPX MC Code version 2.6.0 was utilized to simulate the detailed geometry of Elekta SL 75/25 head components based on Linac’s manual. This code includes an important feature to simulate the photo-neutron interactions. Photoneutrons spectrum was calculated after the Linac output benchmarking based on tuning the primary electron beam.Results and Conclusion: Based on the Friedman and Wilcoxon nonparametric tests results (P<0.05), photoneutron fluence directly depends on the field size and compensator thickness. Moreover, the unflattened beam provides lower photoneutron fluence than the flattened beam. Photoneutrons fluence is not negligible in compensator-based IMRT treatment. However, in order to optimize treatment plans, this additional and unwanted dose must be accounted for patients.

scholarly journals A Monte Carlo Study on Dose Enhancement in the Presence of Nanoparticles by Photon Source: A Comparison between Various Concentration and Material of Nanoparticles

2021 ◽  
Author(s):  
Arezoo Kazemzadeh ◽  
Habiballah Moradi
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
High Energy ◽  
Energy Sources ◽  
Photon Beams ◽  
Treatment Efficiency ◽  
Dose Enhancement ◽  
Gold Silver ◽  
Photon Source ◽  
Energetic Photon

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.

scholarly journals A Monte Carlo study of high-energy photon transport in matter: application for multiple scattering investigation in Compton spectroscopy

2016 ◽  
Vol 23 (1) ◽  
pp. 244-252 ◽  
Author(s):  
Marek Brancewicz ◽  
Masayoshi Itou ◽  
Yoshiharu Sakurai
Keyword(s):  
Monte Carlo ◽  
Multiple Scattering ◽  
Monte Carlo Study ◽  
High Energy ◽  
X Rays ◽  
Simulation Algorithm ◽  
Energy Photon ◽  
Restricted Geometry ◽  
First Results ◽  
Photon Splitting

The first results of multiple scattering simulations of polarized high-energy X-rays for Compton experiments using a new Monte Carlo program,MUSCAT, are presented. The program is developed to follow the restrictions of real experimental geometries. The new simulation algorithm uses not only well known photon splitting and interaction forcing methods but it is also upgraded with the new propagation separation method and highly vectorized. In this paper, a detailed description of the new simulation algorithm is given. The code is verified by comparison with the previous experimental and simulation results by the ESRF group and new restricted geometry experiments carried out at SPring-8.

Portal MV imaging with thin-film high-energy current X-ray detectors: A Monte Carlo study

2017 ◽  
Vol 44 (12) ◽  
pp. 6128-6137
Author(s):  
Bo Liu ◽  
Piotr Zygmanski ◽  
Erno Sajo
Keyword(s):  
Thin Film ◽  
Monte Carlo ◽  
Monte Carlo Study ◽  
High Energy ◽  
X Ray ◽  
Energy Current

scholarly journals Physics Contributions Evaluation of interpolation methods for TG-43 dosimetric parameters based on comparison with Monte Carlo data for high-energy brachytherapy sources

2010 ◽  
Vol 1 ◽  
pp. 28-32 ◽  
Author(s):  
Ma Carmen Pujades-Claumarchirant ◽  
Domingo Granero ◽  
Jose Perez-Calatayud ◽  
Facundo Ballester ◽  
Christopher Melhus ◽  
...  
Keyword(s):  
Monte Carlo ◽  
High Energy ◽  
Monte Carlo Data ◽  
Interpolation Methods

scholarly journals Evaluation of Iodine-123 and Iodine-131 SPECT Activity Quantification: A Monte Carlo Study

2021 ◽  
Author(s):  
Michaella Morphis ◽  
Johan A. van Staden ◽  
Hanlie du Raan ◽  
Michael Ljungberg
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Study ◽  
High Energy ◽  
Optimal Number ◽  
Detector Response ◽  
Reconstruction Process ◽  
Recovery Curves ◽  
Quantitative Accuracy ◽  
Projection Images ◽  
Iodine 131

Abstract Purpose: The quantitative accuracy of Nuclear Medicine images, acquired for both planar and SPECT studies, is influenced by the isotope-collimator combination as well as image corrections incorporated in the iterative reconstruction process. These factors can be investigated and optimised using Monte Carlo simulations. This study aimed to evaluate SPECT quantification accuracy for 123I with both the low energy high resolution (LEHR) and medium energy (ME) collimators, and 131I with the high energy (HE) collimator. Methods: Simulated SPECT projection images were reconstructed using the OS-EM iterative algorithm, which was optimised for the number of updates, with appropriate corrections for scatter, attenuation, and collimator detector response (CDR), including septal scatter and penetration compensation. An appropriate conversion factor (CF) was determined from four different source geometries (activity-filled: water-filled cylindrical phantom, sphere in water-filled (cold) cylindrical phantom, sphere in air and point-like source), investigated with different VOI diameters. Recovery curves were constructed from recovery coefficients to correct for partial volume effects (PVEs). The quantitative method was evaluated for spheres in voxel-based digital cylindrical and patient phantoms. Results: The optimal number of OS-EM updates was 60 for all isotope-collimator combinations. The CFpoint with a VOI diameter equal to the physical size plus a 3.0 cm margin was selected, for all isotope-collimator geometries. The spheres’ quantification errors in the voxel-based digital cylindrical and patient phantoms were less than 3.2% and 5.4%, respectively, for all isotope-collimator combinations. Conclusion: The study showed that quantification errors of less than 6.0% could be attained, for all isotope-collimator combinations, if corrections for; scatter, attenuation, CDR (including septal scatter and penetration) and PVEs, are performed. 123I LEHR and 123I ME quantification accuracies compared well when appropriate corrections for septal scatter and penetration were applied. This can be useful in departments that perform 123I studies and may not have access to ME collimators.

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