Year

2014

Degree Name

Master of Science - Research

Department

Faculty of Engineering

Abstract

Eye plaque brachytherapy is a radiation treatment modality, currently used to treat ocular malignancies. To date, there are no dosimeters used clinically which are capable of determining the dose rate in real time from brachytherapy eye plaques. This research aims to progress the implementation of a new dosimetry technique, spectroscopic dosimetry, clinically, and involved the development and verification of a dose map for eye plaque brachytherapy through three experimental dosimetric methods as well as theoretical calculations.

MOSFET based surface dosimeters were used to determine the surface and scleral dose in close proximity to the eye plaque. These were calibrated using TG-43 specifications, and gained results within the expected range. To determine the dose rate at depths from the plaque, Gafchromic film was used. Using the TG-43 guidelines to calibrate the film, dose rates were determined and used for comparison with the spectroscopic dosimeter. The film results were found to agree with the TG- 43 calculated doses. As TG-43 is held as the gold standard for brachytherapy dosimetry, it is used as the benchmark for all other dosimeters in this research.

A silicon detector based real time dosimeter was developed specifically for quality assurance measurements in eye plaque brachytherapy, using a method of spectroscopic dosimetry. A comparison was made between TG-43 predicted results and the spectroscopic detector. These results were accurate and in close agreement, showing that the spectroscopic probe is an accurate method of dosimetry for ROPES eye plaques.

With the MOSFET based dosimeters obtaining accurate scleral dose measurements and the spectroscopic detector obtaining fast doses at depths, it can be stated that solid state devices may be used to obtain a complete dose map during eye plaque brachytherapy.

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