ABSTRACT
The production of thermoluminescence (TL) dosimeters fabricated from B2O3-CaF2-Al2O3-SiO2 doped with Cu and Pr for use in diagnostic radiology is the main goal of this research. The TL samples were synthesized via the melt-quench technique processed by melting the mixture at 1200 °C for 1 h, and, after cooling, the sample thus created was divided into two samples and retreated by heating for 2 h (referred to as TLV30) and for 15 h (referred to as TLV17). SEM and EDS analyses were performed on the TL samples to confirm the preparation process and to investigate the effects of irradiation dosimetry on the TL samples. Furthermore, the TL samples were irradiated with γ-rays using a 450 Ci 137Cs irradiator and variable X-ray beams (5-70 mGy). Two important diagnostic radiology applications were considered: CT (6-24 mGy) and mammography (2.72-10.8 mGy). Important dosimetric properties, such as the glow curves, reproducibility, dose-response linearity, energy dependence, minimum dose detectability and fading, were investigated for the synthetized samples (TLV17 and TLV30), the results of which were compared with the Harshaw TLD-100. The TLV17 dosimeter showed higher sensitivity than TLV30 in all applied irradiation procedures. The dose-response linearity coefficients of determination R2 for TLV17 were higher than TLD-100 and TLV30 in some applications and were almost equal in others. The reproducibility results of TLV17, TLV30 and TLD-100 were less than 5%, which is acceptable. On the other hand, the results of the fading investigations showed that, in general, TLV17 showed less fading than TLV30. Both samples showed a significant decrease in this regard after the first day, and then the signal variation became essentially stable though with a slight decrease until the eighth day. Therefore, it is recommended to read the TL dosimeters after 24 h, as with TLD-100. The SEM images confirmed the existence of crystallization, whilst the EDS spectra confirmed the presence of the elements used for preparation. Furthermore, we noticed that TLV17 had grown dense crystals that were larger in size compared to those of TLV30, which explains the higher sensitivity in TLV17. Overall, despite the fading, TLV17 showed greater radiation sensitivity and dose-response linearity compared with TLD-100. The synthetized TL samples showed their suitability for use as dosimeters in diagnostic radiology radiation dosimetry.
Subject(s)
Radiology , Silicon , Radiation Dosimeters , Aluminum , Calcium , Hot Temperature , Silicon Dioxide , Reproducibility of Results , Borates , Thermoluminescent Dosimetry , RadiometryABSTRACT
Ternary nanocomposites, including graphene oxide (GO), hydroxyapatite (HAP), and cadmium selenite (CdSe) have been encapsulated into nanofibrous scaffolds of polylactic acid. These compositions were indexed as HAP@PLA (C1), CdSe@PLA (C2), HAP/CdSe@PLA (C3), HAP/GO@PLA (C4), and HAP/CdSe/GO@PLA (C5). Structural confirmation is executed by XRD and XPS techniques, while FESEM performs morphological characteristics. CdSe and GO dopants cause a significant increase in nanofiber diameter, HAP/GO@PLA (C4), showing thin surface fibers with fiber diameter up to 3.1 µm, followed by HAP/CdSe/GO@PLA (C4) composite that belongs to filament size up to 2.1 µm. On the other hand, the mechanical properties reveal that the dual dopant composites HAP/CdSe@PLA (C3) and HAP/GO@PLA (C4) hit the maximum tensile fracture values with 1.49 ± 0.3 and 0.99 ± 0.2 MPa. Further, the ternary C5 composite represents the lowest contact angle of 86.1 ± 3.7°. The antibacterial activity increased from 32.4 ± 9.7 and 28.4 ± 6.5% to be 85.3 ± 4.6 and 88.1 ± 5.6% for C1 and C5, respectively, against both E. coli and S. aureus in dark conditions. Moreover, the antibacterial potency enhanced from 75.4 ± 7.6 to be 83.5 ± 6.5 from dark to light conditions against E. coli for the composition of PLA containing the binary composition of HAP/CdSe.
Subject(s)
Anti-Bacterial Agents/chemistry , Cadmium Compounds/chemistry , Durapatite/chemistry , Graphite/chemistry , Nanocomposites , Nanofibers , Polyesters/chemistry , Selenium Compounds/chemistry , Tissue Scaffolds , Wound Healing , Anti-Bacterial Agents/pharmacology , Cadmium Compounds/pharmacology , Cell Adhesion , Cell Line , Cell Proliferation , Drug Compounding , Escherichia/drug effects , Escherichia/growth & development , Fibroblasts/physiology , Humans , Nanotechnology , Selenium Compounds/pharmacology , Staphylococcus aureus/drug effects , Staphylococcus aureus/growth & development , Surface Properties , Tensile StrengthABSTRACT
BACKGROUND: The accurate calculation of doses during external radiotherapy sessions is necessary. Recently, the models used for this purpose have been the point kernel, pencil-beam, and collapsed cone superposition/convolution combination models. METHODS: In this study, it is aimed to determine point/pencil-beam kernels to be used in dose calculations. For this purpose, tallying pencil-beam fluence based on Monte Carlo (MC) simulations is investigated by scoring a volume of interest centered in a cubic water phantom at a depth of 10 cm and the irradiated field of 10 cm × 10 cm. The fluence is calculated for each mono-energetic photon ranging from 0.25-6 MV at increments of 250 keV. RESULTS: The output of the four fluence kernels along the depth Z around the central axis is categorized for both the primary and secondary photons and electrons. Here, a database for pencil-beam kernels is established for each category. For validation purposes, other MC simulations are carried out for fluence calculations as produced by the predetermined poly-energetic spectra for a Varian 6 MV linear accelerator. CONCLUSIONS: The net results show a good fit of the two convoluted fluence spectra quantities for both mono-energetic and poly-energetics-based simulations except little singular peaks.
