Two ultrasound systems were studied to investigate the effects of positional and volumetric prostate variations on dosimetry over the course of external radiation therapy. A 2D system, currently used at the Montreal General Hospital for patient repositioning, was compared to a 3D system invented recently. Prostate variations were quantified from ultrasound images acquired daily during a 2003 clinical study. A method was devised to introduce ultrasound information in a Monte Carlo Treatment Planning System previously developed at McGill. Patient repositioning was evaluated for both systems using dose-volume histograms of Voxel Monte Carlo dose calculation. Repositioning with the 3D system, neglecting volume changes, was found to bring the target dose to within 1 % of the planned dose, rather than the 12 % of the clinical 2D system. However, when considering the varying 3D volumes, the dose could only be corrected to within 7 %. These results indicate that the 3D system provides not only a more accurate assessment of prostate displacements, but also volumetric information that significantly affects the dosimetry.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.98761 |
| Date | January 2005 |
| Creators | Mark, Clarisse Ildikó. |
| 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 | © Clarisse Ildikó Mark, 2005 |
| Relation | alephsysno: 002332458, proquestno: AAIMR24733, Theses scanned by UMI/ProQuest. |
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