Monte Carlo and practical study of a novel microdosimetric diamond detector

Abstract

Hadron therapy offers a higher dose conformity and increased radiobiological effectiveness, compared to conventional radiation therapy. The arrival of proton therapy in Belgium emphasises the importance of developing a way that could not only accurately represent the dose delivered to the patient, but that could also address the problem of radiobiological effectiveness in clinical conditions. Microdosimetry could provide an answer. Radiation quality can be specified in terms of spectra of the lineal energy, which can be measured by microdosimeters. This Master’s thesis aimed to investigate the possibilities of a prototype diamond detector as microdosimeter. The experimental setup (preamplifier, shaping amplifier and multichannel analyser) and appropriate working parameters were determined first. The microdosimeter was then calibrated in lineal energy (keV/μm). Next, the spectrum of a 241Am alpha source was acquired at multiple source-detector distances. A Bragg peak can be clearly recognised. Based on the microdosimetric spectra, the diamond microdosimeter offers a resolution of 10 keV/μm and a lower detection limit of 10 keV/μm. A Monte Carlo model of the diamond microdosimeter was developed as well. A good agreement between the experimental and simulation data was obtained. It is finally concluded that various improvements and extensions to the experiments can be achieved. These experiments represent the successful start of a new and promising research line concerning experimental microdosimetry at NuTeC, UHasselt.