A platform for multi-point fiber optic base dosimetry

Radiotherapy is in a period of rapid scientific and clinical development and the increasing complexity of modern treatment modalities has also introduced a more comprehensive patient-specific quality assurance programme (QA) to verify an individual patient delivery. Optical fibers offer a solution for in vivo radiotherapy dosimetry with many advantages over currently employed clinical dosimetry systems. A new technology is based on the use of luminescent materials with a plastic optical fiber, acting as light guides, to create a multi-point dosimeter. In this study, two different types of optical fibers with a core diameter of 1 mm were used in all the characterization measurements. In both cases the inorganic radiation sensor is based on europium-doped yttrium oxide and emits light slightly above 600 nm. In both configurations, the fibers were connected to a small portable reader. Optical fibers were irradiated in a water equivalent slab phantom, at the nominal photon energy of a 6 MV clinical accelerator for a fixed dose of 1 Gy. Field Output Factors (OF) for photon small beams were measured using the two fibers and a ionization chamber. Several measurements of the signal were performed to test the stability over time and repeatability. The comparison of OF measurements between the two fibers and the ion chamber was performed. In our preliminary measurements optical fibers have been demonstrated to be able to perform accurate radiotherapy dosimetric measurements.