This thesis proposes models for the calculation of upper and lower limiting values to the backscatter factor (BSF) that can be used to evaluate measured and modelled BSF values. The upper limit to the BSF is obtained from a Monte Carlo simulation of an infinite parallel beam incident on a semi-infinite phantom in which the dose contribution from all orders of photon scatter is considered. The lower limit is calculated using an analytical photon transport model which considers only the primary dose and the scatter dose from photons that have undergone a single scattering interaction in the phantom. A parametrization of the limiting values in terms of photon energy and irradiation field size is presented and comparisons are made with BSF's from the literature. To further illustrate the utility of the limiting BSF's, comparisons are also made with current TLD-measured BSF's and Monte Carlo simulations of the BSF.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.69520 |
| Date | January 1993 |
| Creators | Patrocinio, Horacio Jose |
| Contributors | Schreiner, L. John (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: 001327790, proquestno: AAIMM87813, Theses scanned by UMI/ProQuest. |
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