Date of Award

1-1-2018

Thesis Type

masters

Document Type

Thesis

Divisions

medic

Department

Faculty of Medicine

Institution

University of Malaya

Abstract

The purpose of this study was to characterize specific dosimetric properties of Gafchromic HD-V2 film and to investigate its feasibility in the dosimetric verification for Stereotactic Radiosurgery (SRS). Basic dosimeter properties including energy and dose rate dependencies were investigated and HD-V2 film showed energy and dose rate dependencies of less than 9.5% and 4.94% respectively. The HD-V2 film has very low dependency on scanning orientation in portrait versus landscape as well as “face-up” versus “face-down” scanning orientation. The percentage differences recorded were less than 2.7% for portrait versus landscape and less than 2.5% for “face-up” versus “facedown” orientation. In terms of angular dependency, there was no significant influence on net optical density, with deviations less than 4.3% for films irradiated at selected gantry angles ranging from 0° (which film is perpendicular to the irradiation beam) to 180°. Two treatment plans using SRS technique were created and irradiated using HD-V2 film for dosimetric verification. The dose distributions were calculated using a treatment planning system to obtain point doses at specified positions within a phantom. The calculated doses from TPS were compared to dose distributions delivered to HD-V2 film. The results of the point dose measurements for SRS treatment irradiations showed that the deviations between the TPS predicted dose and HD-V2 film measurements were less 4% which were within the recommended values by ICRU. This study shows that Gafchromic HD-V2 film can be used as dosimetric verification for SRS and for radiotherapy clinical practices that involves high range of doses of 10 to 1000 Gy

Note

Dissertation (M.A.) – Faculty of Medicine, University of Malaya, 2018.

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