Current dose photon calculation algorithms have shortcomings in calculating dose distributions accurately in complex, heterogeneous phantoms. In this work, using existing Monte Carlo (MC) algorithms, we implemented and validated a comprehensive MC treatment planning system (MCTPS). We compared MCTPS with the corrected pencil beam algorithm used in the commercial TPS, CadPlan (V2.7.3). The accuracy of dose distributions calculated by MCTPS was studied for six lung cancer patients in two modes: without correction for inhomogeneity (the clinically used method) and with the equivalent tissue air ratio (EgTAR) inhomogeneity correction switched on. Without the use of inhomogeneity corrections, absorbed dose estimated by CadPlan is in error by more than 10% in the planning target volume (PTV). With the EgTAR correction, good agreement was observed for the dose to the PTV, however, in regions close to an interface, where a significant density gradient occurs, the error is up to 10%. Dose errors in other organs were studied using differential dose volume histograms.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.29412 |
| Date | January 2002 |
| Creators | Al-Yahya, Khalid S. |
| Contributors | Seuntjens, Jan (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: 001945052, proquestno: MQ85764, Theses scanned by UMI/ProQuest. |
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