Publication: Estudio y caracterización de las incertidumbres geométricas presentes en el proceso radioterápico : manejo individualizado de las incertidumbres
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2022-04-20
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Universidad Complutense de Madrid
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Abstract
En el tratamiento radioterápico aparecen múltiples incertidumbres que limitan su precisión. Dependiendo del tipo de tratamiento y de la localización del mismo, las fuentes de incertidumbre y la manera de manejarlas diferirán. En tratamientos convencionales es posible la caracterización de la población de pacientes para obtener los márgenes necesarios entre el volumen blanco clínico (CTV en sus siglas en inglés) y el volumen blanco de planificación (PTV, en sus siglas en inglés) de cara a asegurar un correcto cubrimiento del tumor. Esta metodología realiza generalidades sobre nuestra población que implican sobreestimaciones en la cobertura obtenida. En el caso de tumores afectados por el movimiento respiratorio, la práctica general es utilizar un volumen intermedio entre el CTV y PTV, llamado volumen blanco interno (ITV en inglés), que representa la envolvente de todas las posiciones en las que se puede encontrar el tumor...
During a radotherapy treatment many uncertainties may arise leading to a loss of accuracy. The sources of uncertainty and the methods used to handle them will differ depending on the technique and the anatomical location of the treatment. In conventionally fractionated treatments it is possible to characterize the patient population to obtain proper margins between the Clinical Target Volume (CTV) and the Planning Target Volume (PTV) that assure enough tumor coverage. This methodology is based on simplifications that imply overestimations of the final coverage.When tumors are affected by breathing movement, an intermediate volume between the CTV and PTV is employed. This volume, called Internal Target Volume (ITV), represents the envelope off all the positions where the tumor might be during a breathing cycle. The ITV definition depends on the imaging systems available. In case it is not available a system capable of obtaining time-correlated images, the usual method is to perform CT images in inhale and exhale phases (inhale/exhale CT), which can lead to errors given the unnatural state of respiration to which the patient is subjected by having to maintain the two states of respiration during the duration of the scan...
During a radotherapy treatment many uncertainties may arise leading to a loss of accuracy. The sources of uncertainty and the methods used to handle them will differ depending on the technique and the anatomical location of the treatment. In conventionally fractionated treatments it is possible to characterize the patient population to obtain proper margins between the Clinical Target Volume (CTV) and the Planning Target Volume (PTV) that assure enough tumor coverage. This methodology is based on simplifications that imply overestimations of the final coverage.When tumors are affected by breathing movement, an intermediate volume between the CTV and PTV is employed. This volume, called Internal Target Volume (ITV), represents the envelope off all the positions where the tumor might be during a breathing cycle. The ITV definition depends on the imaging systems available. In case it is not available a system capable of obtaining time-correlated images, the usual method is to perform CT images in inhale and exhale phases (inhale/exhale CT), which can lead to errors given the unnatural state of respiration to which the patient is subjected by having to maintain the two states of respiration during the duration of the scan...
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Tesis inédita de la Universidad Complutense de Madrid, Facultad de Medicina, leída el 17-12-2021