Purpose. This study aimed to identify proper exposure techniques to maintain optimal diagnostic image quality with minimum radiation dose for anteroposterior chest X-ray projection in pediatric patients. Methods. Briefly, an in-house developed pediatric chest phantom was constructed. Next, nanodot OSLDs were used for organ absorbed dose measurement and placed in the lung area, and the phantom was exposed to various exposure techniques (ranging from 50 to 70 kVp with 1.6, 2, and 2.5 mAs). After that, the phantom was used to assess image quality parameters, including SNR and CNR. Two radiologists assessed the subjective image quality using a visual grading analysis (VGA) technique. Finally, the figure of merit (FOM) was analyzed. Results. The developed phantom was constructed successfully and could be useful for dose measurement and image quality assessment. The absorbed dose varied from 0.009 to 0.031 mGy for the range of exposure techniques used. SNR and CNR showed a gradually increasing trend, while kVp and mAs values were increased. The highest kVp (70 kVp) produced the highest SNR and CNR, exhibiting a significant difference compared with 50 and 60 kVp ( P < 0.05 ). The overall VGA score was 3.2 ± 0.3, and the low kVp technique demonstrated better image quality compared with the reference image. Conclusion. The optimized exposure technique was identified as 60 kV and 2.5 mAs, indicating the highest FOM score. This work revealed practicable techniques that could be implemented into clinical practice for performing pediatric chest radiography.
Growth in radiation diagnosis and therapy drives personal radiation dosimeters for physical and radiological protection control. Nevertheless, OSL (optically stimulated luminescence) personal dosimeters in Thailand are all imported. In this work, the particulate and flower-like structure of carbon-doped alpha aluminum oxide polycrystal (α-Al2O3:C) with the various carbon dopants (0.1% and 1 %) were studied as a detector in the OSL personal dosimeter. The particulate powder was prepared by alumina powder (295 nm). The flower-like structure α-Al2O3:C was prepared by boehmite precursors, synthesizing from aluminum sulfate via the low-cost and low-temperature hydrothermal method and sucrose as carbon sources. The crystalline structure was identified by x-ray diffraction (XRD). The chemical properties and oxygen vacancies were investigated by Fourier-transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The size of as-prepared flower-like structure α-Al2O3: C was 2–3 μm confirmed by scanning electron microscopy (SEM). The alumina precursors and carbon dopants affected electron trapping states, morphologies, and OSL outputs. This finding successfully proved that the flower-like α-Al2O3 derived from boehmite precursor exhibits excellent OSL sensitivities to beta irradiation (better than that of the particulate power of α-Al2O3: C) and responded linearly in the range of 0–80 kGy.
Background: High-energy photons produced from a medical linear accelerator (LINAC) have long been used as one of the most effective ways for treating cancers. During the treatment process, some photo neutrons are unavoidably created by [γ,n] reactions, imposing additional and undesirable dose on a patient. This amount of unplanned dose from photo neutrons can potentially harm the patient as well as medical personnel during the treatment. This study is aimed to develop a methodology for measuring fast neutron dose generated from 10 MV LINAC by employing polycarbonate from base material of compact disk (CDs) and a fast neutron converter. Materials and methods: The polycarbonate base layer of CDs has been applied to fast neutron dosimetry with nuclear track method by combining with polymethyl methacrylate (PMMA) converter for fast neutrons. A number of CDs badges were irradiated with high energy photon from 10 MV Elekta Synergy LINAC in the solid water phantom at depth of 0, 2.5, 5, 10, 15 and 20 cm then etched with potassium hydroxide ethanol water (PEW) solution that containing with potassium hydroxide, ethanol and water with ratio of 15:45:40. The optimal condition for the chemical etching were found at 60±2 °C, for 14 hr. Results: Comparison of neutron equivalent doses from measurement of CD track detector and CR-39 track detector has shown that the maximum fast neutron dose equivalent was at depth of 5 cm of phantom. This agreement has confirmed that the CD track detector can be employed to measure fast neutron doses produced from LINAC in an accurate and affordable fashion. Conclusion: It is confirmed that the CD track detector can be employed to measure fast neutron doses produced from LINAC in an accurate and affordable fashion.
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