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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Improvements to the Efficiency of the Radiotherapy Treatment Planning Process

Lee, Chieh-Hsiu Jason 26 July 2012 (has links)
Radiotherapy is one method of treating di erent diseases like cancer. It requires a treatment plan that clearly delineates target and non-target volumes, and the beams and their intensities to deliver the prescribed dose. Historical treatment plans often contain volume names that are unaccounted for. An approach is applied where desired volumes are detected and renamed to conform to current search standards. The mapped names provide an avenue for searching historical plans when performing outcomes analysis in the future to help improve quality in radiation therapy. A specific form known as intensity modulated radiation therapy is applied to total marrow irradiation, a method to remove all marrow in the body prior to bone marrow transplant. A set-covering approach is used, solved using heuristics and commercial packages to compare outcomes. Constraint programming is used in an attempt to better and to improve on the heuristic solutions.
2

Improvements to the Efficiency of the Radiotherapy Treatment Planning Process

Lee, Chieh-Hsiu Jason 26 July 2012 (has links)
Radiotherapy is one method of treating di erent diseases like cancer. It requires a treatment plan that clearly delineates target and non-target volumes, and the beams and their intensities to deliver the prescribed dose. Historical treatment plans often contain volume names that are unaccounted for. An approach is applied where desired volumes are detected and renamed to conform to current search standards. The mapped names provide an avenue for searching historical plans when performing outcomes analysis in the future to help improve quality in radiation therapy. A specific form known as intensity modulated radiation therapy is applied to total marrow irradiation, a method to remove all marrow in the body prior to bone marrow transplant. A set-covering approach is used, solved using heuristics and commercial packages to compare outcomes. Constraint programming is used in an attempt to better and to improve on the heuristic solutions.
3

Optimisation automatique des incidences des faisceaux par l'algorithme du simplexe et optimisation des contrôles qualité par la Maîtrise Statistique des Processus (MSP) en Radiothérapie Conformationnelle par Modulation d'Intensité (RCMI) / Automatic optimisation of beam orientations using the simplex algorithm and optimisation of quality control using statistical process control (SPC) for intensity modulated radiation therapy (IMRT)

Gérard, Karine 07 November 2008 (has links)
La Radiothérapie Conformationnelle par Modulation d’Intensité (RCMI) est aujourd’hui reconnue comme une technique de référence permettant d’augmenter le contrôle local de la tumeur tout en réduisant la dose reçue par les organes à risques avoisinants. Cependant, son développement est freiné par l’étape de préparation du traitement du patient qui nécessite une charge de travail considérable. Dans le but d’augmenter l’efficience de la mise en œuvre d’un traitement, deux axes de travail ont été déterminés. Le premier axe concernait l’optimisation automatique des incidences des faisceaux. Nous avons pour cela mis en œuvre un algorithme (le simplexe) qui a été intégré dans le système de planification de traitement. Il permet, à partir des objectifs dosimétriques fixés par l’utilisateur, de déterminer automatiquement les incidences de faisceaux optimales : irradiant suffisamment le volume cible tout en épargnant les organes à risques avoisinants. En plus d’un gain en temps, les résultats du simplexe ont montré – sur trois patients atteints d’un cancer de l’oropharynx – un gain en qualité par rapport à une sélection manuelle des faisceaux. En effet, pour une couverture du volume cible équivalente voire meilleure, il permet de réduire la dose reçue par les organes à risques. Le second axe concernait l’optimisation des contrôles pré-traitement. Nous avons pour cela utilisé une méthode industrielle : la Maîtrise Statistique des Processus (MSP) afin d’analyser rétrospectivement les résultats des contrôles de la dose absolue effectués avec la chambre d’ionisation au Centre Alexis Vautrin (CAV). Cette étude a montré l’intérêt de la MSP pour renforcer la sécurité des traitements grâce à la mise en place de cartes de contrôle. Elle a également montré que notre processus de délivrance de la dose était stable et statistiquement capable pour les traitements de la prostate, ce qui implique qu’une réduction du nombre de contrôles peut être envisagée pour ce type de traitement au CAV / Intensity Modulated Radiation Therapy (IMRT) is currently considered as a technique of choice to increase the local control of the tumour while reducing the dose to surrounding organs at risk. However, its routine clinical implementation is partially held back by the excessive amount of work required to prepare the patient treatment. In order to increase the efficiency of the treatment preparation, two axes of work have been defined. The first axis concerned the automatic optimisation of beam orientations. We integrated the simplex algorithm in the treatment planning system. Starting from the dosimetric objectives set by the user, it can automatically determine the optimal beam orientations that best cover the target volume while sparing organs at risk. In addition to time sparing, the simplex results of three patients with a cancer of the oropharynx, showed that the quality of the plan is also increased compared to a manual beam selection. Indeed, for an equivalent or even a better target coverage, it reduces the dose received by the organs at risk. The second axis of work concerned the optimisation of pre-treatment quality control. We used an industrial method: Statistical Process Control (SPC) to retrospectively analyse the absolute dose quality control results performed using an ionisation chamber at Centre Alexis Vautrin (CAV). This study showed that SPC is an efficient method to reinforce treatment security using control charts. It also showed that our dose delivery process was stable and statistically capable for prostate treatments, which implies that a reduction of the number of controls can be considered for this type of treatment at the CAV

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