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dc.contributor.supervisorMcCurdy, Boyd M. C. (Physics and Astronomy)en_US
dc.contributor.authorChytyk-Praznik, Krista
dc.date.accessioned2012-04-10T22:09:46Z
dc.date.available2012-04-10T22:09:46Z
dc.date.issued2006en_US
dc.date.issued2009en_US
dc.identifier.citationK. Chytyk and B. M. C McCurdy, “Investigation of tilted dose kernels for portal dose image prediction in electronic portal images,” Med Phys, 2006. 33 (9): p. 3333-3339.en_US
dc.identifier.citationK. Chytyk and B. M. C. McCurdy, “Comprehensive fluence model for absolute portal dose image prediction,” Med Phys, 2009. 36 (4): p. 1389-98en_US
dc.identifier.urihttp://hdl.handle.net/1993/5287
dc.description.abstractRadiation therapy is continuously increasing in complexity due to technological innovation in delivery techniques, necessitating thorough dosimetric verification. Comparing accurately predicted portal dose images to measured images obtained during patient treatment can determine if a particular treatment was delivered correctly. The goal of this thesis was to create a method to predict portal dose images that was versatile and accurate enough to use in a clinical setting. All measured images in this work were obtained with an amorphous silicon electronic portal imaging device (a-Si EPID), but the technique is applicable to any planar imager. A detailed, physics-motivated fluence model was developed to characterize fluence exiting the linear accelerator head. The model was further refined using results from Monte Carlo simulations and schematics of the linear accelerator. The fluence incident on the EPID was converted to a portal dose image through a superposition of Monte Carlo-generated, monoenergetic dose kernels specific to the a-Si EPID. Predictions of clinical IMRT fields with no patient present agreed with measured portal dose images within 3% and 3 mm. The dose kernels were applied ignoring the geometrically divergent nature of incident fluence on the EPID. A computational investigation into this parallel dose kernel assumption determined its validity under clinically relevant situations. Introducing a patient or phantom into the beam required the portal image prediction algorithm to account for patient scatter and attenuation. Primary fluence was calculated by attenuating raylines cast through the patient CT dataset, while scatter fluence was determined through the superposition of pre-calculated scatter fluence kernels. Total dose in the EPID was calculated by convolving the total predicted incident fluence with the EPID-specific dose kernels. The algorithm was tested on water slabs with square fields, agreeing with measurement within 3% and 3 mm. The method was then applied to five prostate and six head-and-neck IMRT treatment courses (~1900 clinical images). Deviations between the predicted and measured images were quantified. The portal dose image prediction model developed in this thesis work has been shown to be accurate, and it was demonstrated to be able to verify patients’ delivered radiation treatments.en_US
dc.language.isoengen_US
dc.publisherAmerican Institute of Physics Publishingen_US
dc.publisherAmerican Institute of Physics Publishingen_US
dc.rightsinfo:eu-repo/semantics/openAccess
dc.subjectradiation therapyen_US
dc.subjectportal dosimetryen_US
dc.subjecta-Si EPIDen_US
dc.subjectdosimetric verificationen_US
dc.subjectin vivo verificationen_US
dc.subjectMonte Carlo simulationen_US
dc.subjectcomputational modelingen_US
dc.titleDosimetric verification of radiation therapy including intensity modulated treatments, using an amorphous-silicon electronic portal imaging deviceen_US
dc.typeinfo:eu-repo/semantics/doctoralThesis
dc.typedoctoral thesisen_US
dc.degree.disciplinePhysics and Astronomyen_US
dc.contributor.examiningcommitteePistorius, Stephen (Physics and Astronomy) Fiege, Jason (Physics and Astronomy) Sherif, Sherif (Electrical and Computer Engineering) Butler, Jim (Radiology)Schreiner, John (Queen's University, Cancer Centre of Southestern Ontario)en_US
dc.degree.levelDoctor of Philosophy (Ph.D.)en_US
dc.description.noteMay 2012en_US


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