This thesis presents an investigation of depth doses of 9-18 MeV electron beams measured with custom-built ionization chambers, film, and TLD in homogeneous solid water and bone-like phantoms as well as in a solid-water/bone heterogeneous phantom. Our measurement results show that dosimetry based on film and TLD corresponds well with ionization chamber dosimetry in both homogeneous and heterogeneous phantoms if appropriate methods for converting film or TLD responses to doses in phantom are used. We observed no clinically significant dose enhancement in relatively thin bone heterogeneities, however, we found dose enhancement in solid homogeneous bone phantoms. Work by previous investigators might have overestimated the dose in bone heterogeneities. We also found that the coefficient equivalent thickness (CET) method is suitable for estimating of dose in heterogeneous phantoms incorporating large uniform heterogeneities. / The thesis also presents an investigation of magnitudes, energies, and dose profiles of photon contaminations for 9-18 MeV electron beams with various field sizes used clinically. Our measurements show that the magnitude of photon contamination increases both with electron beam energy and with field size. The photon contamination dose profile is forward peaked and its energy decreases with an increase in field size.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.55403 |
| Date | January 1994 |
| Creators | Wang, Xiaofang, 1957- |
| 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: 001426105, proquestno: AAIMM00066, Theses scanned by UMI/ProQuest. |
Page generated in 0.0133 seconds