Thermoluminescence of zirconium oxide nanostructured to mammography X-ray beams

Synthesis and evaluation of thermoluminescence properties of ZrO2:Mg for radiotherapy dosimetry

This study aimed to investigate the thermoluminescent properties of ZrO₂:Mg irradiated with a 6 MV X-ray beam and its potential application in radiotherapy dosimetry. ZrO₂ powder was synthesized using the sol-gel method and Mg was used as a dopant. Irradiations were performed with ZrO₂:Mg chips located at the center of a 10 × 10 cm² radiation field at a source surface distance of 100 cm, below a stack of solid water slabs, at the depth of maximum absorbed dose. The investigated characteristics of the material included linearity with radiation dose, reproducibility, accuracy, sensitivity and fading. Regarding the intrinsic difference of the samples, the glow curves of the investigated ZrO₂:Mg chips exposed to 1 Gy of 6 MV X-rays exhibited three or four peaks. The ZrO₂:Mg samples showed a 47% fading at 24 h after irradiation, and the reproducibility of the thermoluminescence reading of ZrO₂:Mg for equal irradiation conditions was ± 21%. The thermoluminescence response of the investigated ZrO₂:Mg samples to various absorbed doses from 0.5 to 2.5 Gy showed a gentle increase of the thermoluminescence intensity with increasing absorbed dose. The obtained results show that ZrO₂:Mg is not an appropriate candidate for X-ray photons in radiotherapy, due to low thermoluminescence peak temperature, low reproducibility, low sensitivity to various absorbed doses and significant fading.

Thermoluminescence properties of micro and nano structure hydroxyapatite after gamma irradiation

The goal of this study is to compare the thermoluminescence properties of nano and micro structure hydroxyapatite. Nano structure hydroxyapatite was synthesized via hydrolysis method, while the micro structure one was from Merck Company. X-ray diffraction and fourier transform infrared spectroscopy were used to determine the crystal structure and chemical composition of the hydroxyapatite samples. Particles sizes of each sample were estimated using Scherer equation and transmission electron microscopy system. Thermoluminescence properties of the samples were investigated under gamma irradiation. The glow curves of micro and nano structure samples show a peak at 150 °C and 200 °C, respectively. Thermoluminescence responses of both the samples were linear in the range of 25 – 1 000 Gy where, nano structure sample show a greater slope and stronger linearity in comparison to the micro sample. The results show that the thermoluminescence response of micro sample faded rapidly in comparison to the nano sample due to the existence of the peak at higher temperature.