Investigation of the use of Ge-doped optical fibre for in vitro IMRT prostate dosimetry

In this study, the thermoluminescence (TL) yield of Ge-doped optical fibres for in vitro dosimetry has been investigated for the verification of Intensity Modulated Radiation Therapy (IMRT) three-dimensional (3D) dose distributions. Ge-doped optical fibres offer many advantages over conventional dosimetry systems including high sensitivity, minimal fading, and cost effectiveness. IMRT verification plans using the Varian Eclipse treatment planning system for two prostate cancer patients were created using Alderson Rando Anthropomorphic Phantom CT data-sets. Measurements were performed using the Rando phantom at nominal energies of 6 MV and 15 MV. Ge-doped optical fibre TL yields were compared with dose determined through use of the treatment planning system and also with the well-established TL lithium fluoride (LiF) dosimetry system (Harshaw TLD-100 and TLD-700). Results show the Ge-doped optical fibre to verify in vitro doses within 3% of the Eclipse predicted doses and LiF TLDs for the particular high energy photon beams used.