Optical fibre dosimetry in external beam radiotherapy: Measurements and Monte Carlo simulation
Date
2020-02-28Author
Alharbi, Majed
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Abstract
The introduction of new radiation therapy treatment techniques such as
intensity modulated radiotherapy and volumetric modulated arc therapy
cause well established dosimetry systems to be extended to their capability
limits. Optical fibre dosimetry systems offer several advantages over
conventional dosimeters for real time dosimetry. This thesis considered
the use of a novel inorganic scintillation detector based on a terbium
doped gadolinium oxysulphide inorganic scintillator. Essential dosimetry
characterisation of the inorganic scintillation detector system for external
beam radiotherapy was evaluated. Results obtained demonstrated promising
characteristics when used in external beam radiation therapy settings.
However, the system overestimated the dose when measuring percentage
depth dose and lateral dose profiles. The contribution of Cerenkov radiation
and the absorbed-dose energy dependence to the overall signal measured with
the inorganic scintillation detector system was also considered in this work. To
achieve this, an accurate Cerenkov removal technique using the hyperspectral
approach and accurate Monte Carlo model of the linear accelerator was
used. Results obtained suggest mechanisms other than the stem effect and
the absorbed-dose energy dependence influence the response of the inorganic
scintillation detector system at depth.