Thermoluminescence and optical characteristics of lithium potassium borate glass for radiation therapy dose measurement

Abstract

Radiosensitive glasses of lithium potassium borate (LKB) co-doped with CuO-MgO then with TiO2-MgO were prepared using melt-quenching technique. Present studies were carried out, seeking to improve upon the thermoluminescence (TL) signal of such glass systems. The overall aim of this thesis was to develop a radiosensitive glass that is suitable for thermoluminescence dosimetry (TLD). A glow curve with single prominent peak was produced at ~220 oC as a result of dopant activation (CuO/TiO2). An enhancement of about three times was shown as a result of adding MgO as a co-dopant activator (LKB: 0.1Cu, 0.1Mg and LKB: 0.5Ti, 0.25Mg- mol%). This enhancement was attributed to the ability of magnesium to create extra traps and consequently energy transfer to monovalent Cu+ and Ti3+ ions. A charge imbalance was predicted in the glass host by the addition of alkaline (Mg2+). Both LKB:Cu,Mg and LKB:Ti,Mg have low Z material (Zeff = 8.55 and 8.89, respectively), good reproducibility and low fading. The prepared glass showed 15 times less sensitive than that of LiF:Mg,Ti (TLD-100), but a promising dose response linearity was achieved over a long span of irradiation doses (up to 103 Gy). The trap parameters, including the order of kinetics (b), activation energy (E) and frequency factor (s) associated with LKB:Cu,Mg were also determined. Furthermore, a TolAnal software was used for glow curve deconvolution and analysis for the created peaks. The photoluminescence spectra (emission and excitation) for the prepared samples were studied. As new mixtures, a series of glass characterization and physical properties were discussed. The achieved results promise the use of these compositions in different dosimetric applications, particularly in medical dosimetry and high dose monitoring.