Validación de un modelo de cálculo de dosis producida por electrones. / Evaluation of a dose calculation algorithm produced by electrons.

Rodríguez Hernández, Andrea P. (2017) Validación de un modelo de cálculo de dosis producida por electrones. / Evaluation of a dose calculation algorithm produced by electrons. Maestría en Física Médica, Universidad Nacional de Cuyo, Instituto Balseiro.

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Resumen en español

El objetivo del presente trabajo es evaluar el algoritmo de cálculo de dosis electrón Monte Carlo (eMC), el cual es el algoritmo que utiliza Eclipse para la plani cación de tratamiento con haces de electrones. La evaluación del algoritmo se realizo en dos etapas de valoración: desempeño en medios homogéneos y en medios heterogéneos para las energías de 6, 9, 12 y 15 MeV. El algoritmo permite variar parámetros de cálculo tales como tamaño de la grilla, incerteza, tipo y nivel de suavizado. Se realizó un análisis de la influencia de modificar los mismos en las distribuciones de dosis obtenidas. Se concluyo que al aplicar una grilla de 2 mm, incerteza 2% y suavizado Gaussiano con nivel de intensidad medio, se obtienen resultados clínicamente aceptables, tanto en tiempo como en precisión de dosis. Para la valoración del desempeño en medios homogéneos se efectuaron diferentes pruebas en las que se evalúo el modelado ante situaciones de DFS extendida, incidencia oblicua del haz, campos conformados, superficies irregulares, entre otros. Se adquirieron perfiles, planos de dosis y PDDs lo cuales fueron analizados aplicando diferentes criterios de evaluación gamma demostrándose de modo general que el algoritmo satisface el criterio 3% 3mm en mas del 95% de los puntos analizados. La segunda etapa consistió en evaluar el algoritmo en medios heterogéneos, para esto se utilizaron láminas de agua sólida y diversos materiales como corcho, aire y PMMA simulando alguna región del cuerpo. Se obtuvieron planos de dosis y se estableci o como criterio de comparación 4% 4mm el cual permitió obtener resultados satisfactorios. Para la medición de los perfiles y planos de dosis se utilizaron diversos dispositivos tales como un fantoma de exploración automática 3D SCANNER TM, un detector microDiamond tipo 60019, un arreglo bidimensional de diodos MapCHECK R 2 y laminas de material equivalente a agua. Se considera que el algoritmo electrón Monte Carlo es adecuado para el uso en el ámbito clínico, simulando de manera aceptable la distribución de dosis en configuraciones complejas, tomando precauciones en su implementación con bajas energías.

Resumen en inglés

The aim of the present work is to evaluate the electron Monte Carlo algorithm (eMC), which is the algorithm used by Eclipse for electron beam treatment planning. The evaluation of the algorithm was carried out in two evaluation stages: performance in homogeneous media and in heterogeneous media for the energies of 6, 9, 12 and 15 MeV. The algorithm allows varying calculation parameters such as grid size, uncertainty, type and level of smoothing. An analysis of the influence on the calculated dose distributions by modifying such parameters, was made. It was concluded that when a 2 mm grid, 2% uncertainty and Gaussian smoothing with medium intensity level are applied, clinically acceptable results are obtained, both in time and in dose precision. For the performance evaluation in homogeneous media, different tests were carried out in which the modeling was evaluated simulating situations of extended DFS, oblique beam incidence, shaped fields, irregular surfaces, and others. Proles, dose planes and PDDs were acquired and analyzed applying diefferent criteria of gamma evaluation, demonstrating that the algorithm satises the criterion 3% 3mm in more than 95% of the analyzed points. The second stage consisted of evaluating the algorithm in heterogeneous media, for this, solid water slabs and various materials such as cork, air and PMMA were used to simulate some region of the body. Dose planes were obtained and a 4% 4mm comparison criterion was established, which allowed to obtain satisfactory results. Different devices were used for the measurement of the proles and dose planes, such as 3D SCANNER TM automatic scan phantom, 60019 microDiamond detector, 2D diodes array MapCHECK R 2 and slabs of material equivalent to water. It was concluded that the electron Monte Carlo algorithm is suitable for use in clinical environment, simulating in an acceptable manner the dose distribution in complex congurations. Precautions should be taken with low energies implementation.

Tipo de objeto:Tesis (Maestría en Física Médica)
Palabras Clave:Electrons; Electrones; Algorithms; Algoritmos;[Electron Monte Carlo; Heterogeneous media; Medios heterogéneos; Homogeneous media; Medios homogéneos]
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Materias:Medicina > Radioterapia
Divisiones:Centro de Medicina Nuclear y Molecular de Entre Ríos (CEMENER)
Código ID:692
Depositado Por:Tamara Cárcamo
Depositado En:30 Jul 2018 16:03
Última Modificación:30 Jul 2018 16:03

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