Thermoluminescence properties of Cr, Si, and Mg co-doped Al2O3 ceramics plates under proton beam irradiation

This study evaluates the thermoluminescence (TL) properties of Cr, Si, and Mg co-doped Al₂O₃ (Al₂O₃:Cr,Si,Mg) ceramic plates under 200 MeV proton beam irradiation, aiming to assess their potential for high-resolution two-dimensional dosimetry in proton therapy. Spectral measurements revealed a dominant TL emission peak at 693 nm, corresponding to the ²E → ⁴A₂ transition of Cr³⁺ ions. The glow curves exhibited consistent peak temperature and shape regardless of dose and linear energy transfer (LET), indicating the stability of the trap and recombination centers. The TL response showed excellent linearity with absorbed dose, agreeing within ±1.5 % with ionization chamber measurements, and demonstrated minimal dependence on LET. Furthermore, large-area (200 mm × 200 mm) TL ceramic plates were used to obtain two-dimensional dose distribution maps. The off-axis ratio and percent depth dose distributions measured using TL imaging were in good agreement (within ±1–6 %) with those obtained from standard dosimeters, and the spatial resolution reached 156 μm. These results suggest that Al₂O₃:Cr,Si,Mg ceramics are suitable for accurate, reusable, and high-resolution proton dosimetry, offering a promising alternative to conventional film- or ionization-based detectors for quality assurance in particle therapy.