Current brachytherapy dosimetry protocols assume that a physical source may be approximated by a point source. A new brachytherapy dosimetry protocol, recently proposed by the American Association of Physicists in Medicine Task Group 43, has the advantage of using functions derived solely from measurements performed in the medium and uses a more realistic source geometry than the point source approximation. The aim of this work is to obtain the dosimetric functions required by this new protocol for both a low and a high dose-rate Iridium-192 brachytherapy source through dose measurements in a water-equivalent phantom. / Dose measurements have been performed using lithium fluoride thermoluminescent detectors positioned in a polystyrene phantom at distances from the source that vary from 1 cm to 10 cm, with 1-cm intervals, and at angles that vary from 0$ sp circ$ to 170$ sp circ$ with 10$ sp circ$ intervals. / Our experimental results have clearly shown that the point-source approximation model can overestimate the dose to water, especially for the high dose-rate source, where we have found that differences between point-source estimates and exact measured values can differ by almost 30% for points along the longitudinal axis of the source.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.28232 |
| Date | January 1997 |
| Creators | Anctil, Jean-Claude. |
| Contributors | Clark, Brenda G. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Master of Science (Department of Medical Radiation Physics.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001601795, proquestno: MQ37088, Theses scanned by UMI/ProQuest. |
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