Year

2014

Degree Name

Doctor of Philosophy

Department

Centre for Medical Radiation Physics

Abstract

This thesis presents research for the application of silicon dosimetry and microdosimetry for radiation protection and Quality Assurance (QA) in radiation therapy.

The first part of this thesis describes the development and characterisation of a charged particle silicon detector to assess the radioactivity of contaminated soil from nuclear power plant accidents.

The second part of the thesis is continuing research into the development of novel silicon on insulator (SOI) microdosimeter aimed at deriving relative biological effectiveness (RBE) in mixed radiation fields using microdosimetry which does not require any prior knowledge of the components of this field.

Different generations of CMRP SOI microdosimeters were investigated and tested in 12C heavy ion therapy, and the derived RBE10 values obtained by the SOI microdosimeters agreed with a Tissue Equivalent Proportional Counter (TEPC).

A novel 3D SOI microdosimeter was proposed in this thesis and the fabrication processes are described in detail. Using the GEANT4 Monte Carlo toolkit, simulations were developed to study the response of the new 3D microdosimeters in various radiation fields and optimize the design. A heavy ion microprobe was used to comprehensively study the charge collection properties of the silicon detectors using the Ion Beam Induced Charge Collection (IBICC) technique.

A monolithic ΔE-E telescope was evaluated in response to a 12C heavy ion therapy beam. Information about the radiation field was obtained by measuring the energy deposition coincidently in the ΔE and E stage in coincidence. The detector provides two-dimensional (2D) information of the LET of the particles as well as identifying the types of particles produced from the primary radiation field. An experimental and theoretical study was carried out and is presented in this thesis.

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