Studies of Radiation-Induced Conductivity (RIC) in the Teflon film of a radiation-charged electret ionization chamber (EIC) are discussed. An EIC measures dose from the amount of electret surface charge neutralized by ions created in the chamber's sensitive volume. A semi-empirical equation is presented for the calculation of prompt time-dependent RIC as a function of air-kerma rate and electric field. Measurements showing the dependence of radiation-induced current on electrode material show a tenfold difference in current between aluminum and graphite electrodes. RIC permits charge migration through the polymer which can cause an overestimation of dose. Intermittently heating and charging the electret will cause surface charges to be deposited at deep energy levels and therefore improving electret charge retention. This study demonstrates the influence of radiation induced currents on the performance of the radiation-charged RIC.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.56620 |
| Date | January 1992 |
| Creators | Markovic, Alexander |
| 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: 001307203, proquestno: AAIMM80384, Theses scanned by UMI/ProQuest. |
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