Recent Advances in Scintillating Optical Fibre Dosimeters

Scintillating optical fibres have shown interesting results for ionizing radiation monitoring. Since they may enable a remote, punctual and real-time dose assessment, their application in medical dosimetry is very promising. This work aims to summarize some recent progresses in the development and characterization of rare-earth doped silica optical fibres. The radioluminescent and dosimetric properties of Ce, Eu and Yb-doped fibres are presented and the advantages and challenges in the use of these sensors for radiation therapy dosimetry are discussed. For such application, an effective approach to deal with the stem effect, i.e. the spurious luminescent signal originated in the light guide as a consequence of its exposition to ionizing radiations (i.e. Cerenkov light and intrinsic fluorescence) must be considered. The stem effect mainly occurs in the UV-VIS region. We demonstrated that the use of a dopant emitting in the near infrared, like Yb, is suitable for an optical discrimination of the dosimetric signal. Indeed, through a characterization of the dosimetric properties of Yb-doped fibres in conjunction with an optical filter and an avalanche detector, we proved that the drawback due to the stem effect does not impair the system response even in the most challenging irradiation geometries, attesting to the robustness of the device in complex dosimetric scenarios.