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dc.contributor.advisor Oldham, Mark en_US
dc.contributor.author Niebanck, Michael Henry en_US
dc.date.accessioned 2012-05-25T20:17:37Z
dc.date.available 2012-05-25T20:17:37Z
dc.date.issued 2012 en_US
dc.identifier.uri http://hdl.handle.net/10161/5526
dc.description Thesis en_US
dc.description.abstract <p><bold>Purpose:</bold> Radiosurgery has become a widely used procedure in the treatment of both solid tumors and secondary metastases in the brain. In cases with multiple brain lesions, isocenters are typically set up for each target, a process which can take hours and become very uncomfortable for the patient. Recently, multifocal treatments with a single isocenter have emerged as a solution. With the high doses delivered to small regions during radiosurgery, the importance of treatment verification is paramount, especially when delivering high doses to regions off isocenter. </p><p><bold>Methods:</bold> A 5-arc RapidArc radiosurgery plan with a single isocenter and 5 targets was used to treat a dosimeter placed within a RPC-type head and neck phantom. The treatment was delivered five times at varying prescription doses, depending on the sensitivity of the PRESAGE dosimeter used. The delivered dose distribution was measured using an in-house optical-CT system and compared to the Eclipse-planned dose distribution using dose volume histograms and Gamma analysis.</p><p><bold>Results:</bold> Reasonable dose agreement was measured between the majority of the dosimeters and the Eclipse plan (80-85% pass rate at 5%/3 mm Gamma critera). The failing voxels were located on the periphery of the dosimeter at regions of extremely high or low dose, suggesting a dose dependent stability of the PRESAGE formulation. The formulation with the best temporal stability had a much higher Gamma pass rate of 98% at 3%/2mm criteria.</p><p><bold>Conclusions:</bold> The potential of accurate delivery of the complex radiosurgery plan was demonstrated with one of the three formulations of PRESAGE. While agreement was worse in the other formulations, the problem seemed to be an easily-fixable stability issue, resulting in improper scaling of doses. Replication of the most stable formulation would provide an excellent tool for verification of radiosurgery treatment delivery and other complex procedures.</p> en_US
dc.subject Medical imaging and radiology en_US
dc.subject Oncology en_US
dc.subject Optical-CT en_US
dc.subject PRESAGE en_US
dc.subject QA en_US
dc.subject radiosurgery en_US
dc.subject RapidArc en_US
dc.title A Novel Comprehensive Verification Method for Multifocal RapidArc Radiosurgery Treatments en_US
dc.type Thesis en_US
dc.department Medical Physics en_US

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