Radioluminescence properties of rare earth doped LiF–MgF2 compounds for fiber optic dosimetry

Abstract

This work investigates the radioluminescence (RL) properties of LiF–MgF2 compounds doped with rare earth (RE) ions (Eu, Ce, Lu, Tm) for their potential use in fiber optic dosimetry (FOD). Polycrystalline powders were synthesized via a two-step thermal treatment and tested under beta and clinical LINAC X-ray irradiation. Among all compositions, the Eu-doped sample at 0.4mol% (LiF–MgF2:Eu) showed the highest RL yield, excellent repeatability, and no significant signal afterglow, making it the most promising candidate. The RL spectrum of LiF–MgF2:Eu revealed broad emission bands attributed to intrinsic defects and Eu-related transitions. An FOD probe was constructed using this material and evaluated under clinical 6 MV LINAC irradiation. Time-resolved measurements confirmed the feasibility of the time-delayed readout method to suppress the Cherenkov stem effect. Percentage depth dose (PDD) curves obtained with the FOD probe showed good agreement with those measured using a reference ionization chamber and Monte Carlo simulations. These findings suggest that LiF–MgF2:Eu is a suitable, tissue-equivalent scintillator for real-time dosimetry in LINAC radiotherapy.