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Photodegradable MEH-PPV in a natural rubber matrix: Toward a biocompatible colorimetric film for real-time light dosimetry
摘要： This paper reports an interesting strategy of incorporating a photodegradable polymeric luminophore, the poly [2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] - OC10C6-PPV (MEH-PPV), in an inert natural rubber (Hevea brasiliensisis) - C5H8 (NR) matrix for monitoring and recording the radiation dose administered to patients under phototherapy, particularly in the treatment for jaundice newborns. A time-trend spectro?uorimetric study has been carried out to characterize the luminescent changes of the MEH-PPV/NR luminophore system upon photodegradation by realistic conditions of phototherapy treatment, and the dependence between color and dose was used to determine the dose-response relationships of this color ?lm dosimeter. Cytotoxicity tests (CHO-K1 cell line) have also been conducted on extracts of the OC10C6-PPV/C5H8 before and after photolysis. The experimental results reported here highlight the potential application of photodegradable polymer/natural rubber as a biocompatible skin-mountable patch to monitor light exposure to improve patient care in phototherapy, photodynamic, lasers and radiation therapies.
关键词： Medical-devices,Dosimeter,Printable device,Photooxidation,Organic device,Semiconducting polymer,Radiation oncology
更新于2025-11-14 15:18:02
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Dose distribution verification in high-dose-rate brachytherapy using a highly sensitive normoxic N-vinylpyrrolidone polymer gel dosimeter
摘要： Rapid technological advances in high-dose-rate brachytherapy have led to a requirement for greater accuracy in treatment planning system calculations and in the verification of dose distributions. In high-dose-rate brachytherapy, it is important to measure the dose distribution in the low-dose region at a position away from the source in addition to the high-dose range in the proximity of the source. The aim of this study was to investigate the accuracy of a treatment plan designed for prostate cancer in the low-dose range using a normoxic N-vinylpyrrolidone-based polymer gel (VIPET gel) dosimeter containing inorganic salt as a sensitizer (iVIPET). The dose response was evaluated on the basis of the transverse relaxation rate (R2) measured by magnetic resonance scanning. In the verification of the treatment plan, gamma analysis showed that the dose distributions obtained from the polymer gel dosimeter were in good agreement with those calculated by the treatment planning system. The gamma passing rate according to the 2%/2 mm criterion was 97.9%. The iVIPET gel dosimeter provided better accuracy for low doses than the normal VIPET gel dosimeter, demonstrating the potential to be a useful tool for quality assurance of the dose distribution delivered by high-dose-rate brachytherapy.
关键词： Iridium-192,MRI,High-dose-rate brachytherapy,Polymer gel dosimeter
更新于2025-09-23 15:23:52
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Radiation induced luminescence properties of Ce-doped Y2O3-Al2O3-SiO2 glass prepared using floating zone furnace
摘要： We synthesized Y2O3-Al2O3-SiO2 glasses doped with various concentrations of Ce (0, 0.03%, 0.10%, 0.30%, and 1.00%). The glasses were obtained by melt-quenching using an IR mirror furnace, and then they were studied in terms of their optical, dosimetric and scintillation properties. The obtained samples indicated photoluminescence (PL) and scintillation due to the 5d-4f transitions of Ce3+ characterized as a broad emission peaking around 350 nm. The PL and scintillation decay times were 35.4-38.1 ns and 47-109 ns, respectively. The 0.10% Ce-doped sample showed the highest PL quantum yield (20%) among the synthesized samples. The quantum yield was well-correlated with the decay time of PL and scintillation. Thermally- and optically-stimulated luminescence were observed after the irradiation of X-rays (10 Gy). The thermally- and optically-stimulated luminescence spectra were confirmed that the luminescence was due to the 5d-4f transitions of Ce3+ in the 0.03% and 0.10% Ce-doped samples. Overall, the samples showed sensitive response of thermally-stimulated luminescence, and it was the highest for the 0.10% and 0.30% Ce-doped samples, having the dynamic range from 0.01 mGy to 1 Gy.
关键词： Cerium,Scintillator,Dosimeter,Glass
更新于2025-09-23 15:23:52
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Photoluminescence, scintillation and TSL properties of Eu-doped Al2O3 transparent ceramics synthesized by spark plasma sintering method
摘要： We synthesized Al2O3 transparent ceramics doped with different concentrations of Eu (0.001, 0.01, 0.1 and 1.0%) by the spark plasma sintering (SPS) method, and then we investigated their photoluminescence (PL), scintillation and thermally-stimulated luminescence (TSL) properties. In the PL, the samples showed a broad emission peak at 400 nm due to the 5d-4f transitions of Eu2+ and several sharp emission peaks across 550–750 nm due to the 4f-4f transitions of Eu3+ and the 3d-3d transitions of Cr3+ impurity ion. In addition to these peaks over 550–750 nm, in scintillation, the samples exhibited two broad peaks over 300–400 nm possibly due to not the 5d-4f transitions of Eu2+ but F and F+ centers. In TSL, the glow curve consisted of peaks at approximately 100, 160, 210 and 320 °C. The TSL intensity of the 0.001% Eu-doped sample was the highest, and the TSL response was confirmed to be linear to irradiated X-ray dose in the range from 0.1 to 1000 mGy.
关键词： Transparent ceramic,Scintillator,Eu,Dosimeter,Al2O3
更新于2025-09-23 15:23:52
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Image-based Absorbed Dosimetry of Radioisotope
摘要： An absorbed dose calculation method using a digital phantom is implemented in normal organs. This method cannot be employed for calculating the absorbed dose of tumor. In this study, we measure the S-value for calculating the absorbed dose of each organ and tumor. We inject a radioisotope into a torso phantom and perform Monte Carlo simulation based on the CT data. The torso phantom has lung, liver, spinal, cylinder, and tumor simulated using a spherical phantom. The radioactivity of the actual absorbed dose is measured using the injected dose of the radioisotope, which is Cu-64 73.85 MBq, and detected using a glass dosimeter in the torso phantom. To perform the Monte Carlo simulation, the information on each organ and tumor acquired using the PET/CT and CT data provides anatomical information. The anatomical information is offered above mean value and manually segmented for each organ and tumor. The residence time of the radioisotope in each organ and tumor is calculated using the time activity curve of Cu-64 radioactivity. The S-values of each organ and tumor are calculated based on the Monte Carlo simulation data using the spatial coordinate, voxel size, and density information. The absorbed dose is evaluated using that obtained through the Monte Carlo simulation and the S-value and the residence time in each organ and tumor. The absorbed dose in liver, tumor1, and tumor2 is 4.52E-02, 4.61E-02, and 5.98E-02 mGy/MBq, respectively. The difference in the absorbed dose measured using the glass dosimeter and that obtained through the Monte Carlo simulation data is within 12.3%. The result of this study is that the absorbed dose obtained using an image can evaluate each difference region and size of a region of interest.
关键词： Absorbed dosimetry,Torso phantom,Cu-64,PET/CT,Glass dosimeter
更新于2025-09-23 15:23:52
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Changes of Optically Stimulated Luminescence Dosimeter Sensitivity with High Dose
摘要： We investigated the effect of high dose on the sensitivity of optically stimulated luminance dosimeters (OSLDs) on Co-60 gamma rays and used a commercial OLSD (Landauer, Inc., Glenwood, IL). New OSLDs were chosen arbitrarily and were irradiated with 1 Gy repeatedly. We confirmed the change in the radiation sensitivity after repeated irradiation. The OSLD sensitivity increased up to 3% after irradiating for seven times and decreased continuously after the eighth time. It dropped by approximately 0.35 Gy per irradiation. Finally, after irradiating for 30 times, the OSLD sensitivity decreased by approximately 7%. When the OSLDs were irradiated 10 times with 1 Gy after their irradiation using a high dose of 15 Gy and 30 Gy, their sensitivity decreased by 6% and 12%, respectively, compared to that before high-dose irradiation. The change in the OSLD sensitivity with a high dose could be modeled by an exponential equation. We confirmed the radiation sensitivity variation caused by a high dose, and the irradiation history of dosimeters was considered to reuse OSLDs irradiated with a high dose.
关键词： High dose,Co-60,Optically stimulated luminescence dosimeter sensitivity
更新于2025-09-23 15:22:29
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On the role of magnesium in LiF:Mg,Ti thermoluminescent dosimeter
摘要： LiF doped with Mg and Ti is the most widely used thermoluminescent (TL) dosimeter for a large variety of applications. It has been argued that the Mg dopant is the most important defect in the TL process. Besides the common F-centre defects in LiF, optical absorption measurements have suggested the presence of Mg-related absorption bands at 380 nm (3.26 eV), and 310 nm (4.0 eV) when LiF:Mg is exposed to ionizing radiation, whose origin is not yet well understood. This work presents an investigation of the role of defects induced by Mg in LiF through electronic structure calculations. The calculations show that Mg interstitials induce a local lattice distortion characterized by the displacement of two opposite fluorine atoms, adjacent to the magnesium, away from their original sites by an average distance of 0.6 ? each, while the closest Li atoms are displaced by 0.1 ?. This defect introduces electronic states in the band-gap that can trap excess electrons produced during irradiation, thus enhancing the efficiency of the detector. Holes, on the other hand, are created and trapped in orbitals of mainly Mg-3s character. Additionally, the results suggest that irradiation can simultaneously remove a Li atom nearby a Mg interstitial; substitute a Li by a Mg atom or create a Li vacancy plus a Mg substitutional, giving rise to defects within the LiF gap that are more stable thermodynamically than the Mg interstitial itself.
关键词： magnesium dopant,LiF:Mg,Ti,thermoluminescent dosimeter,electronic structure calculations,defect states
更新于2025-09-23 15:21:01
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Photon energy response optimization using few-channel spectroscopy dose method for Si-PIN photodetector applied in personal dose equivalent measurements
摘要： Si-PIN photodetectors having features such as low cost, small size, low weight, low voltage, and low power consumption are widely used as radiation detectors in electronic personal dosimeters (EPDs). The technical parameters of EPDs based on the Si-PIN photodetectors include photon energy response (PER), angular response, inherent error, and dose rate linearity. Among them, PER is a key parameter for evaluation of EPD measurement accuracy. At present, owing to the limitations of volume, power consumption, and EPD cost, the PER is usually corrected by a combination of single-channel counting techniques and filtering material methods. However, the above-mentioned methods have problems such as poor PER and low measurement accuracy. To solve such problems, in this study, a 1024-channel spectrometry system using a Si-PIN photodetector was developed and full-spectrum measurement in the reference radiation fields was conducted for radiation protection. The measurement results using the few-channel spectroscopy dose method showed that the PER could be controlled within ± 14% and ± 2% under the conditions of two and three energy intervals, respectively, with different channel numbers. The PER measured at 0° angle of radiation incidence meets the IEC 61526:2010 - 29% to +67% requirements of. Meanwhile, the channel number and counts-to-dose conversion factors formed in the experiment can be integrated into an EPD.
关键词： Si-PIN photodetector,Personal dose equivalent,Photon energy response,Electronic personal dosimeter,Few-channel spectroscopy dose method
更新于2025-09-23 15:19:57
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Effectiveness of a novel real-time dosimeter in interventional radiology: a comparison of new and old radiation sensors
摘要： Radiation dose management is important in interventional radiology (IR) procedures, such as percutaneous coronary intervention, to prevent radiation-induced injuries. Therefore, radiation dose should be monitored in real time during IR. This study evaluated the fundamental characteristics of a novel real-time skin dosimeter (RTSD) developed at our institution. In addition, we compared the performance of our new and old radiation sensors and that of a skin dose monitor (SDM), with ion chamber reference values. We evaluated the fundamental characteristics (e.g., energy dependence, dose dependence, and angular dependence) of the RTSD developed by us in the diagnostic X-ray energy range. The performance of our RTSD was similar to that of the SDM. In particular, the new radiation sensor of our RTSD demonstrated better dose rate dependence compared to the old sensor. In addition, the new sensor had the advantage of being small in size and thus minimally affecting the X-ray images compared to the old sensor. Therefore, the developed skin dosimeter and radiation sensor may be useful in real-time measurement of patients’ exposure to and multi-channel monitoring of radiation in IR procedures. The new dosimeter system can be recommended for visualization and management of the radiation dose to which the patients’ skin is exposed.
关键词： Radiation dose,Real-time skin dosimeter,Interventional radiology,Radiation skin injuries
更新于2025-09-23 15:19:57
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Effect of co-doping of lithium on the dosimetric properties of dysprosium-doped sodium borate glass system
摘要： The effect of lithium (Li) as a co-dopant on the Thermoluminescence (TL) properties of dysprosium-doped sodium borate (NB: Dy) exposed to two radiation sources (linear accelerator and Gamma-ray from Co-60) is reported in this study. The results showed an enhancement in the TL intensity with the increment of lithium to NB: Dy. Promising dosimetric properties were recorded; glow curve with simple and prominent peak, high signal stability and simple annealing process. Furthermore, the phosphor is reusable and high dose linearity range (up to 103 Gy). The current results propose the using of the new dosimeter in different dosimetric applications.
关键词： Borate glass,Dysprosium oxide,Dosimeter
更新于2025-09-19 17:15:36