Examinando por Autor "Leyva Rojas, José Alfonso"
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Ítem Aproximación computacional a través de Geant4 de la interacción de 7Li procedentes de la captura de neutrones en células biológicasMedina Martínez, Robinson Steven; Munévar Espitia, Edwin; Leyva Rojas, José AlfonsoThe Boron Neutron Capture Therapy (BNCT) is a therapy that allows tumoral cells selection to later eradicate them without generating great damage in normal tissue. The capture neutron nuclear reaction produces two high-LET particles (α and 7Li) with limited ranges to diameter single cell. Motivated in this approach we have carried out a Geant4 simulation to characterize the reaction 10B(n, α)7Li and study the energy deposited in brain tissue by the 7Li nuclei produced in the final state of that reaction. The results estimated that roughly 64% of events correspond to boron neutron capture. Finally, the simulation with tissue showed that the total energy deposited by 7Li nuclei were approximately 330 MeV.Ítem Aproximación computacional de la interacción de la radiación gamma procedente de la captura de neutrones en biomoléculas a través de Geant4Tellez Ardila, Diego Alexander; Munévar Espitia, Edwin; Leyva Rojas, José AlfonsoNeutron capture therapy for cancer with 157-Gd carrier (GdNCT) has become promising because of the type of nuclear reaction and the products that occur in this capture process, the products of the reaction are given by different types of phenomena with different ranges of energy; 158-Gd nucleus, gamma rays, internal conversion electrons, auger electrons, and x-rays. A computational study for the characterization of the reaction is performed with the help of the Geant4 tool and we compare the particles and their emitted energies with other computational studies, focusing on the gamma photons emitted in the simulation to estimate the energy and dose deposited in the brain tissue of NIST ICRP. The data obtained in this work are a contribution for the validation of the reaction of GdNCT in Geant4 and to the studies of GdNCT by the results of the energy and dose deposited by the gamma photons rarely studied in this type of therapy as possible agents causing damage to the tumor tissues.Ítem El cáncer : una mirada biofísica a través de la membrana celularOrtega Rozo, Leidy Camila; Munévar Espitia, Edwin; Leyva Rojas, José AlfonsoThe cell membrane is mainly composed of a lipid bilayer, which ultimately determines its biophysical properties, since lipids are important elements that regulate several cellular functions, i.e., they serve to protect the cell and regulate the traffic of substances inside and outside it. This regulation is carried out through a complex system of processes that occur through interactions of the membrane components with their surrounding environment, from the molecular point of view, some of the main theories, currently accepted about cancer, indicate that it starts due to the accumulation of alterations in essential genes in the control of cell proliferation and cell death. Cancer affects the cell membrane and these properties are altered, resulting in an imbalance in its initial structure. The fundamental purpose of this work is to study the implications on the cell membrane due to the fundamental purpose of this work is to study the implications on the cell membrane due to the affectations that cancer generates at the cellular level according to these theories with the help of molecular dynamics methods. For this purpose, a computational simulation will be implemented in the Gromacs suite, where we will focus essentially on the characterization of the biomechanics of the membrane due to the changes that are generated in the cell caused by cancer.Ítem Caracterización de la interacción de radiación ionizante neutra a nivel celular mediante una simulación computacional con Geant4Domínguez Castaño, Thalía Vanessa; Munévar Espitia, Edwin; Leyva Rojas, José AlfonsoThis work provides information about the effects that occur in biological tissue models when photons affect them, based on the characterization of the reactions that occur physically. The energy deposited and the absorbed dose in samples of water, brain tissue and skeletal muscle tissue are determined by means of the Geant4 free distribution computational tool. As a result, it can be seen that as the photons of higher energy (hard X-rays) pass through the material, their energy decreases. That is, the characteristic attenuation of the X-rays used for radiotherapy is observed. In tissue, photons with higher energy pass through more easily than photons with low energy, so the deeper it is, the greater the attenuation of the incident beam. The probability that a photon is absorbed or scattered and consequently a certain effect occurs will depend on the incident energy of the photon and the material it passes through.Ítem Diseño preliminar de un prototipo de un acelerador de iones ligeros para BNCT.Diaz Gómez, Víctor Alfonso; Munévar Espitia, Edwin; Leyva Rojas, José Alfonso; Munévar Espitia, Edwin; Munévar Espitia, Edwin [0000-0002-0578-7717]Currently, the use of medium- and low-energy particle accelerators has been extended to basic research laboratories in materials science, biomedical sciences, among others, and in terms of applications the main ones are in the generation of particle beams for imaging and therapy in different areas of medicine; in the industry they are in the characterization and optimization of materials. In this work, the physical foundations of linear accelerators have been studied, in particular different geometries and configurations of the electrodes for the acceleration system. A specific design was chosen in terms of configuration and geometry of electrodes, for its optimization through computational modeling of the acceleration system. Finally, a preliminary design for a compact linear acceleration column is obtained. Through a combination of experimental data taking and computational modeling, with the help of MATLAB-type calculation platforms, we study the equipotential lines, electric field vectors, and field lines to establish the different trajectories to be followed by deuterium ions, for the particular acceleration lines, given the different configurations and geometries of the electrodes that make up the accelerator column. To model the flow and acceleration of deuterium ions in an accelerating column. The purpose of this work is to determine whether the plasma meniscus and the beam interface can be properly modeled with MATLAB R2020a and thus, successfully predict the deuteron trajectory and beam shape over a wide range. Using MATLAB R2020a and based on experimental measurements of the electrostatic potential for a specific configuration and geometry of the accelerator column electrodes, a matrix of 6000 data characterized in electrostatic potential in 2d, i.e., V = V (x, y) was measured, which was taken as a basis to solve for the electric field: E = −∇V, using a central difference algorithm that allows one to find point by point each component of the electric field (Ex, Ey). Based on the above, we characterized the accelerating column in terms of the equipotential lines and the E field vector in the three acceleration zones, the trajectory of the particles (deuterons) accelerated in the extraction zone, the deuteron motion in the saturation zone, the kinetic energy of the ionized deuterium beam, and a 3D design based on the different columns studied. From the results obtained in this investigation, it is verified that the selected column and its electrode configuration fulfills the conditions to be used in medical application of BNCT. The column is characterized and the blueprint and three-dimensional designs are finally obtained, describing each of its parts and materials for its future construction.Ítem El Efecto Casimir en un sistema de bicapas lipídicasRondón Ramírez, Fidel Leonardo; Rey Ramírez, Jose David; Munévar Espitia, Edwin; Leyva Rojas, José AlfonsoThe Casimir Effect is a phenomenon studied in different branches of physics like nanotechnology, astrophysics and biophysics systems. This work was focused in a bi-layer lipid system upon which a theoretical recompilation of the manifestation of the Casimir Effect on a cellular membrane was performed and to achieve that, it was necessary to breakdown the harmonic oscillator paradigm in the classic regime and shift into the quantic regime. This was done to understand the way in which the electromagnetic field quantizes in the vacuum and then obtain a mathematical expression that correlates the Casimir Effect applying interface conditions. Lastly, alternating the interface conditions it is possible to explain the interaction in the cellular membrane as a consequence of the Casimir Effect.Ítem Estudio computacional en Gate de la interacción de protones con tejidos biológicos y con yoduro de sodio dopado con talioSantana Gil, Johan Sebastian; Munevar Espitia, Edwin; Leyva Rojas, José AlfonsoThe physics of ionizing radiation plays a fundamental role in the development of dosimetry, since it deals strictly with the measurement of the absorbed dose as a result of the interaction between ionizing radiation and matter. To carry out such dose measurement, in some cases materials with a crystalline structure are implemented, such as scintillator material (sodium iodide doped with thallium), which can be adapted as dosimeters. The scintillation counter is based on the principle that light is emitted when the scintillator material is exposed to radiation, this occurs because part of the energy deposited by the incident radiation is absorbed by the material: this implies that the molecular structure is excites by ionizing the compound, showing a change in its electronic configuration. As the material is ionized, the electrons acquire energy but after a certain time they return to their fundamental state, emitting radiation (photons). Assuming that the crystalline material to be handled is thallium-doped sodium iodide, a simulation will be implemented in a Geant4 extension called Gate; in order to determine the dose delivered to sodium iodide with thallium impurities [NaI(Tl)]. Similarly, a biological tissue (pancreas) will be irradiated with protons in the Gate computational tool, to determine its respective dose. Once these dose values are obtained, they will be compared in order to establish whether sodium iodide is a material that resembles the response to radiation with respect to the response of a biological tissue such as the pancreas. The development of this work will aimed at carrying out the corresponding computational simulations in the Gate extension with the purpose of grounding the comparisons between the inorganic material [NaI(Tl)] and the organic material (pancreas), that is, to study the response of sodium iodide doped with thallium and the pancreas by exposing them to radiation from a proton beam.Ítem Estudio computacional en Geant 4 de la interacción de protones con tejidos biológicos y con fluoruro de litio dopado con manganesoAgudelo Mora, Álvaro Jair; Munevar Espitia, Edwin; Leyva Rojas, José AlfonsoThe thermoluminescence phenomenon is caused by the interaction between a doped chemical compound and incident radiation; said compound is ionized by changing its electronic configuration. After that, this material is heated to a certain temperature so that the electrons return to their initial configuration, emitting radiation in the form of photons. In particular, there is special interest in Lithium Fluoride as a thermoluminescent material, due to its possible uses and applications in various areas, such as dosimetry and medical physics, among others. In such a way, that studies for this type of crystals are required, in this work a computational simulation will be carried out in Geant4, in order to determine the dose received by Lithium Fluoride (LiF) doped with impurities of Manganese (Mn), when irradiated with Protons at certain energy ranges. A biological tissue (skin) will also be irradiated with protons in Geant4 and the corresponding dose will be determined. This in order to compare the doses obtained in both cases and thus be able to establish whether LiF is a material that resembles the response to radiation similar to that of soft tissue such as skin. In this work we want to carry out the respective computational simulations in Geant4, in order to establish comparisons between the inorganic and biological systems, ie, study the response of Lithium Fluoride (LiF) doped with Manganese (Mn) impurities and of the biological tissue (SKIN) when irradiated with protons.Ítem Evaluación computacional de la dinámica estructural de una biomolécula, luego de su interacción con partículas cargadas.Rubio Cepeda, Luis Miguel; Munevar Espitia, Edwin; Leyva Rojas, José AlfonsoIn the field of research on the interaction of radiation and matter, a space has been opened for computational simulations, Which has turned into an important tool in the development of an investigation and in the approximation to the possible results that can be obtained when experimenting. This work presents the results of the effects of charged particles in the three dimensional structure of a biomolecule based on an simulation (pdb4dna) of the geant4 toolset, modified for the purpose of evaluating some parameters after the interaction of a biomolecule (1bb3.pdb) with radiation,These results were obtained during the internship development. On the other hand, the data was obtained by throught a new simulation, which was detached from the base code, where it obtains from deposited energy values. The analysis shown was done through ROOT software in order to compare the partial similarities among the two codes.