The dosimetric characteristics of a standard Varian 52-leaf multileaf collimator (MLC) and BrainLAB m3 micro-multileaf collimator (micro-MLC) have been investigated for square, rectangular, and irregular fields for 6 MV and 18 MV photon beams provided by a Varian Clinac 2300 C/D linear accelerator (linac). The percentage depth dose data and the conventional collimator factor are unaffected by the addition of MLC or micro-MLC shaped field unless, in the latter case, the tertiary field is much less than the jaw setting. However, relative dose factors for a given MLC or micro-MLC field size depend on the jaw setting. The penumbra is generally sharpest for fields defined by the micro-MLC and the least sharp for fields defined by the MLC. Average transmission values were found to be between 1.5% and 2.5%. Comparison and evaluation of two treatments, one delivered using the MLC and the other using the micro-MLC, for the same radiosurgical target volume are described.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.31188 |
| Date | January 2001 |
| Creators | Barker, Jennifer. |
| Contributors | Podgorsak, E. B. (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: 001804160, proquestno: MQ70377, Theses scanned by UMI/ProQuest. |
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