scholarly journals Dosimetric Algorithm to Reproduce Isodose Curves Obtained from a LINAC

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Julio Cesar Estrada Espinosa ◽  
Segundo Agustín Martínez Ovalle ◽  
Cinthia Kotzian Pereira Benavides
Keyword(s):  
Monte Carlo ◽  
Absorbed Dose ◽  
Numerical Data ◽  
Radiation Beam ◽  
Calculation Time ◽  
Water Phantom ◽  
Percentage Depth Dose ◽  
Dose Profile ◽  
Depth Dose ◽  
Mcnpx Code

In this work isodose curves are obtained by the use of a new dosimetric algorithm using numerical data from percentage depth dose (PDD) and the maximum absorbed dose profile, calculated by Monte Carlo in a 18 MV LINAC. The software allows reproducing the absorbed dose percentage in the whole irradiated volume quickly and with a good approximation. To validate results an 18 MV LINAC with a whole geometry and a water phantom were constructed. On this construction, the distinct simulations were processed by the MCNPX code and then obtained the PDD and profiles for the whole depths of the radiation beam. The results data were used by the code to produce the dose percentages in any point of the irradiated volume. The absorbed dose for any voxel’s size was also reproduced at any point of the irradiated volume, even when the voxels are considered to be of a pixel’s size. The dosimetric algorithm is able to reproduce the absorbed dose induced by a radiation beam over a water phantom, considering PDD and profiles, whose maximum percent value is in the build-up region. Calculation time for the algorithm is only a few seconds, compared with the days taken when it is carried out by Monte Carlo.

scholarly journals Benchmarking of Siemens Linac in Electron Modes: 8-14 MeV Electron Beams

2018 ◽  
Vol 8 (2) ◽  
Author(s):  
H Dowlatabadi ◽  
A A Mowlavi ◽  
M Ghorbani ◽  
S Mohammadi ◽  
F Akbari
Keyword(s):  
Monte Carlo ◽  
Radiation Treatment ◽  
Electron Beams ◽  
Dose Profile ◽  
Depth Dose ◽  
Mcnpx Code ◽  
Gamma Index ◽  
Simulation Results ◽  
Mc Simulation ◽  
Good Agreement

Introduction: Radiation therapy using electron beams is a promising method due to its physical dose distribution. Monte Carlo (MC) code is the best and most accurate technique for forespeaking the distribution of dose in radiation treatment of patients.Materials and Methods: We report an MC simulation of a linac head and depth dose on central axis, along with profile calculations. The purpose of the present research is to carefully analyze the application of MC methods for the calculation of dosimetric parameters for electron beams with energies of 8–14 MeV at a Siemens Primus linac. The principal components of the linac head were simulated using MCNPX code for different applicators. Results: The consequences of measurements and simulations revealed a good agreement. Gamma index values were below 1 for most points, for all energy values and all applicators in percent depth dose and dose profile computations. A number of states exhibited rather large gamma indices; these points were located at the tail of the percent depth dose graph; these points were less used in in radiotherapy. In the dose profile graph, gamma indices of most parts were below 1. The discrepancies between the simulation results and measurements in terms of Zmax, R90, R80 and R50 were insignificant. The results of Monte Carlo simulations showed a good agreement with the measurements. Conclusion: The software can be used for simulating electron modes of a Siemens Primus linac when direct experimental measurements are not feasible.

scholarly journals Measurement of Percentage Depth Dose (PDD) for 6 MeV in water phantom and homogenous actual planning

2018 ◽  
Vol 16 (37) ◽  
pp. 1-6
Author(s):  
Samar I. Essa
Keyword(s):  
Ionizing Radiation ◽  
Clinical Medicine ◽  
Absorbed Dose ◽  
Field Size ◽  
X Ray ◽  
Water Phantom ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Different Depths ◽  
The Relationship

Radiotherapy is the branch of clinical medicine concerned with the application of ionizing radiation in the treatment of disease. And it is used to killing of cancer cells in a tissue using ionizing radiation while keeping the sparing of healthy cells at acceptable level. X-ray beams are used to deposit absorbed dose at depth within a patient at the site of the tumor. The aim of this work is studying the relationship between the depth dose and the field size in water phantom and homogenous actual planning. In our work, the dose distribution at different depths (zero-18 cm) deep at1cm interval treated with field size (10×10 and 20×20) cm2 were studied.Results show that high similarity between water phantom and actual planning for this reason water is taken as phantom for Quality Assurance (QA) and calculation the depth dose. When increasing the field size, the percentage of surface dose increases that this could be caused by an increase of the amount of scattering in the larger fields.Conclusion: There is almost no difference in depth dose between homogenous planning and water phantom.

Simulation of Absorbed Dose Distribution In Space Materials

2004 ◽  
Vol 851 ◽  
Author(s):  
Boris A. Briskman
Keyword(s):  
Dose Distribution ◽  
Radiation Spectrum ◽  
Space Vehicle ◽  
Absorbed Dose ◽  
Numerical Characteristic ◽  
Dose Profile ◽  
Depth Dose ◽  
Space Material ◽  
Test Adequacy ◽  
Material Tests

ABSTRACTThe problems of absorbed dose distribution simulation at on-ground space material tests are discussed. Several approaches to such simulation, oriented to increase the test adequacy and economy, are analyzed. Sometimes, it is possible to use quantitative criteria of absorbed dose distribution depending on the specific space vehicle orbit. The assessment of reliable simulation of the radiation spectrum may be made, for example, by introducing a special numerical characteristic of the depth dose profile in a material - depth dose criterion. For this purpose, it is recommended to use the ratio of the exponent index of the depth dose profile (μ) to the density of the material (ρ). In the simplest form, the depth dose profile can be represented as a sum of two exponents. The first depth dose profile applies to a near-the-surface layer of 5 to 10 μm in thickness, and the second to a layer of from 10 μm up to, as a minimum, 100 μm in thickness. The reference values of μ/ρ for typical spectra of ionizing radiation are calculated.

An investigation of the effect of gold nanoparticles with different concentrations on increasing absorbed dose: an empirical and simulation study

2018 ◽  
Vol 18 (02) ◽  
pp. 191-197
Author(s):  
Masoumeh Hoseinnezhad ◽  
Mohammad Mahdavi ◽  
Seyyed R. M. Mahdavi ◽  
Mobarake Mahdavizade
Keyword(s):  
Monte Carlo Simulation ◽  
Gold Nanoparticles ◽  
Monte Carlo ◽  
Absorbed Dose ◽  
Simulation Method ◽  
Dose Enhancement ◽  
Depth Dose ◽  
Optical Ct ◽  
Ct System ◽  
Monte Carlo Simulation Model

AbstractPurposeThe purpose of this study was to determine the dose enhancement factor (DEF) of gold nanoparticles in a dosimeter gel and construct percentage depth dose curves, using the Optical CT system and the Monte Carlo simulation model, to determine the effect of increasing the dose caused by increasing the concentration of gold nanoparticles at depths in the gel.Materials and methodsThe Magic-f Gel was made based on the relevant protocol in the physics lab. To determine the amount of the increase in the absorbed dose, the gold nanoparticles were added to the gel and irradiated. An increase in the dose after adding nanoparticles to the gel vials was estimated both with the Optical CT system and by the Monte Carlo simulation method.ResultsDose enhancement curves for doses of 2, 4 and 6 Gy were prepared for gel vials without adding nanoparticles, and nanoparticle gels at concentrations 0·17, 3 and 6 mM. Also, the DEF was estimated. For the 0·17 mM molar gel, the DEF for 2, 4 and 6 Gy was 0·7, 0·743 and 0·801, respectively. For the 3 mM gel, it was 1·98, 2·5 and 2·2, and for the 6 mM gel, it was 37·4, 4·24 and 4·71, respectively.ConclusionThe enhancement of the dose after adding gold nanoparticles was confirmed both by experimental data and by simulation data.

scholarly journals Monte Carlo simulations of EBT3 film dose deposition for percentage depth dose (PDD) curve evaluation

2020 ◽  
Vol 21 (12) ◽  
pp. 314-324
Author(s):  
Spencer M. Robinson ◽  
Nolan Esplen ◽  
Derek Wells ◽  
Magdalena Bazalova‐Carter
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Dose Deposition

scholarly journals Dose profile evaluation of a 137Cs source using a solid water phantom

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Caio Fernando Teixeira Portela ◽  
Thêssa Cristina Alonso ◽  
Arnado Prata Mourão
Keyword(s):  
Visible Light ◽  
Beam Energy ◽  
Maximum Dose ◽  
Absorbed Dose ◽  
Radiochromic Film ◽  
Radiochromic Films ◽  
Water Phantom ◽  
Dose Profile ◽  
Cesium 137 ◽  
Solid Water

The precision in the dose values delivered in irradiation processes is essential for the efficiency and quality control of these processes. Radiochromic films can be used to record doses and the calibration of these films must be performed so that they can be used as dosimeters. The planning and control of the radiation released in a process allows to adjust the desired dose in the irradiated object. The photons in the primary beam interact with the matter of the object and the beam energy is attenuated due to these interactions. The attenuation depends on the characteristics of the beam and the composition of the irradiated matter. When a beam of photons propagates on an object, it tends to deposit more energy close to the surface and after reaching the maximum dose value, it decreases the dose values with depth. The films used in this work are of the Gafchromic External Beam Therapy (EBT) type, insensitive to visible light and can be prepared in places where sunlight and artificial light exists. Like many other dosimeters, which follow certain protocols, radiochromic films can provide an absolute dose measurement. Radiochromic films are characterized by their linearity, reproducibility, uniformity, sensitivity, and stability after irradiation. For the realization of the experiments, a part of the film to be irradiated was removed designated as background (BG). BG represents a piece of radiochromic film that will not change and reflects changes in film absorption in relation to environmental conditions such as temperature, visible light and scanning light, for example and that must be handled from it way that the film radiated. In this work, irradiations of a solid water phantom were performed using a source of cesium-137 with the deposition of a maximum absorbed dose value of 2.0 Gy. The phantom was placed 1,0 m far from the source collimator. Radiochromic films were placed inside the phantom to obtain the depth variation dose profile and axial dose profiles measured at 1.0 cm depth in the phantom. The dose variation profile in depth allowed to verify that the maximum dose value happened at a depth between 10 and 13 mm, very close to the surface due to the beam energy range (keV). The axial profiles presented a flatness of about 9.4 cm with a total field of 12 cm in diameter. 

scholarly journals Design and Analysis Effect of Gantry Angle Photon Beam 4 MV on Dose Distributions using Monte Carlo Method EGSnrc Code System

2016 ◽  
Vol 27 (1) ◽  
pp. 18-20
Author(s):  
Uum Yuliani ◽  
Ridwan Ramdani ◽  
Freddy Haryanto ◽  
Yudha Satya Perkasa ◽  
Mada Sanjaya
Keyword(s):  
Monte Carlo ◽  
Vertical Axis ◽  
Photon Beam ◽  
Field Size ◽  
Dose Calculations ◽  
Dose Distributions ◽  
Percentage Depth Dose ◽  
Depth Dose ◽  
Surface Field ◽  
Gantry Angle

Varian linac modeling has been carried out to obtain Percentage Depth Dose (PDD) and profiles using variations gantry angle 0o, 15o, 30o , 45o in the vertical axis of the surface, field size 10x10 cm2, photon beam 4 MV and Monte Carlo simulations. Percentage Depth Dose and profile illustrates dose distributions in a phantom water measuring 40x40x40 cm3, changes gantry is one of the factors that determine the distribution of the dose to the patient research shows changes in Dmax in the Percentage Depth Dose is affected by changes in the angle gantry resulted in the addition of the area build up so it can be used for therapy in the region and produce skin sparing effects that can be used to protect the skin from exposure to radiation. The graph result is profiles obtained show lack simetrisan in areas positive quadrant has a distribution of fewer doses than the quadrant of negative as well as the slope of the surface so that it can be used for some cases treatments that require a depth and a certain slope, dose calculations are more accurate and can minimize side effects.

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