New thermoluminescence dosimetric characteristics of Cu-doped Li₂B₄O₇ phosphors with X-rays, gamma, and proton beams

The utilization of thermo-luminescence (TL) dosimetry is prevalent in the field of radiation protection, the assessment of absorbed dose in patients undergoing diagnostic radiology and radiotherapy is notably crucial. The primary objective of this research was to evaluate the thermoluminescence properties of Li₂B₄O₇:Cu phosphors subsequent to exposure below 10 Gy doses of therapeutic γ-rays, X-rays, and proton beams. Cu-doped Li₂B₄O₇ phosphors were fabricated through solid-state synthesis with varying Cu concentrations. The most effective radiation sensitivity was observed at 0.5 mol% Cu. In order to examine the thermoluminescence output concerning radiation quality, powder samples weighing around 10 mg were exposed to Co-60 γ-rays, 15.2 MeV protons, and 225 kV X-rays. The precise measurement of dosages was achieved by utilizing ion chambers. An examination was conducted on the TL characteristics, like glow curve, order of kinetics, heating rate, fading, and reusability. The results showed that the Li₂B₄O₇:Cu sample, which was irradiated with X-rays doses between 0.3 and 1.5 Gy, demonstrated a significant TL peak at around 261 °C. The linear response of the glow curve to absorbed dose, along with the presence of a single glow curve structure, suggests a simple distribution of luminescence traps. The reusability test involved ten consecutive irradiations, readings, and annealing cycles, revealing strong TL intensity stabilization. Over the course of 60 days, signal fading measurements on irradiated samples showed an approximate signal loss rate of 0.13% per day.