Using Monte Carlo techniques, the 18 MV accelerators CL2300 and CL21EX, 8 physical wedges and the enhanced dynamic wedge have been modeled and validated. The simulated PDDs, profiles, output factors and wedge factors are in good agreement with measured values. These models have been applied in the dose calculation of lung cancer patients to investigate the effect of tissue heterogeneity by comparing with the CADplan treatment planning system with and without heterogeneity correction. Plan I and plan II for 8 patients have been re-calculated with the Monte Carlo method. On average, the mean PTV dose calculated with the Monte Carlo method is 2.4% higher than that calculated with CADplan without correction but 2.5% lower than that with EqTAR correction. The Monte Carlo method predicts 13% higher mean lung dose than CADplan without heterogeneity correction. Because of this difference, the risk of radiation pneumonitis based on available NTCP models will be underestimated. A relationship of mean lung dose between two types of dose algorithms can be used to correct this underestimation.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.82214 |
| Date | January 2005 |
| Creators | Dai, Jinxian |
| 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: 002201509, proquestno: AAIMR12425, Theses scanned by UMI/ProQuest. |
Page generated in 0.0016 seconds