Response characterization of an Y2O3:Eu-based radioluminescence probe under 60Co irradiation

P MOLINA; M SOMMER; F KATTNER; J HENNIGER

Halle

Congreso; 8th International Conference on Luminescent Detectors and Transformers of Ionizing Radiation - LUMDETR 2012; 2012

Centre for Innovation Competence SiLi-nano

In the last years the fiberoptic dosimetry (FOD) technique has become an attractive method to measure real-time dose rate in radiation treatments. The FOD technique is based on the use of scintillating materials coupled to the end of an optical fiber, which collects the light emitted (radioluminiscence, RL) by the scintillator during irradiation. Since usually the intensity of the emitted light is proportional to the dose-rate, the technique provides a reliable measuring method, which can be employed in radiotherapy treatments. The main drawback of the FOD technique is the luminescence generated by the radiation in the optical fiber itself (usually known as stem effect), which adds to the RL emission from the scintillator. The main contribution to the stem effect comes from the Cherenkov radiation generated in the fiber, which is particularly significant in the blue region of the visible spectrum. The intensity of the stem effect depends on the length and position of the irradiated portion of the optical fiber with respect to radiation beam. For this reason its contribution is not univocally related to the dose rate at the position of the scintillator. It is necessary to remove the contribution of the stem effect in order to have a precise estimation of the dose rate. Recently the feasibility of using europium-doped yttrium oxide (Y2O3:Eu) as FOD material has been investigated [1]. High RL efficiency, emission in the red region of the electromagnetic spectrum, and practically no afterglow make this material suitable to be used as scintillator in the framework of FOD technique [1]. In this work, the response of an Y2O3:Eu-based FOD probe irradiated with cobalt 60 gamma rays in different conditions has been investigated for the first time. Measurements of depth dose profile (DDP) in a water phantom with the Y2O3:Eu-based probe have been compared with similar measurements obtained with a standard ionization chamber. In particular, dependence of DDP with respect to irradiation field size and scintillator size have been investigated. [1] Molina, P. ,et al., Radioluminescence of red-emitting Eu-doped phosphors for fiberoptic dosimetry. Appl. Radiat. Isotopes (2012), doi:10.1016/j.apradiso.2012.01.005