| Título: | MR based frickle-gelatin dosimetry : uncertainty evaluation and computerised analysis of measured dose distributions |
| Autores: | Belanger, Philippe. |
| Fecha: | 2001 |
| Publicador: | McGill University - MCGILL |
| Fuente: |
 |
| Tipo: | Electronic Thesis or Dissertation |
| Tema: |
Health Sciences, Radiology. Physics, Radiation. Biophysics, Medical. |
| Descripción: | Dynamically delivered intensity modulated beams (IMBs) pose unique verification problems that may be addressed with the use of integrating continuous 3D dosimeters such as gel based Fricke dosimeters. Accurate knowledge of the ability of these dosimeters to measure adequately and precisely the delivered dose is a prerequisite for their clinical use. The magnetic properties of the ferrous and ferric ions present in the gel based Fricke dosimeter after its irradiation are the basis for the use of magnetic resonance imaging (MRI) in the measurement of dose. This thesis presents the investigation of a 3D gel based Fricke dosimetry system (Fricke-gel). A software system is developed and spin-lattice relaxation rate (R1) images are computed from MR images of irradiated Fricke-gel phantoms in order to quantify the dosimetric uncertainties resulting from the MR imaging system, from the gel itself, as well as from the external parameters. The sensitivity and the minimum detectable dose of the Fricke-gel dosimeter are determined. Validation of the dosimeter's capacity to measure dose distributions is made through measurement of percent depth dose curves (PDD's), and field profiles (open and wedged). An example of clinical utilisation of the Fricke-gel dosimeter is presented. Dose distributions are evaluated visually by 3D software tools and quantitatively analyzed by dose-volume histograms. Results show a good correlation between the Fricke-gel measured dose distributions and treatment planning software dose calculations. |
| Idioma: | en |
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