• Journal of Food Hygiene and Safety
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• v.28 no.3
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• pp.258-266
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• 2013

This study was conducted to determine the PSL and TL properties of foods irradiated with electron beam and gamma-ray. 5 kinds of food including cereal, pulse, fish powder, dried vegetable and tea were irradiated at 0 to 10 kGy by electron beam accelerator or $^{60}Co$ gamma-ray irradiator. The PSL analysis showed negative results for most of the non-irradiated samples. Non-irradiated shrimp powder showed intermediate result. Irradiated samples gave negative or intermediate or positive value which presented the limitation of PSL technique. In TL analysis, there were TL glow curves at around $300^{\circ}C$ with low intensity on non-irradiated samples. Maximum peak in the range of $150-250^{\circ}C$ was appeared on irradiated samples. TL ratio obtained by re-irradiation with 1 kGy was less than 0.1 on non-irradiated samples and higher than 0.1 on irradiated samples. Therefore, in PSL measurement, electron-beam irradiated samples could obtain more clear results. TL analysis showed obvious difference between non-irradiated and irradiated samples. But the identification was impossible for the sample of rice and lemon tea. Because of it's low contents of mineral.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.8
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• pp.1236-1247
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• 2014

Gamma irradiated-treatment of natural medicinal plants can be used to improve extraction transference number and for qualitative improvement of color when applied to functional material exploration. This study investigated the biological activities of Aralia elata cortex extracts upon gamma irradiation. In addition, different physical techniques [photostimulated luminescence (PSL) and thermoluminescence (TL)] were used for irradiation identification of Aralia elata cortex. In PSL analysis, non-irradiated (0 kGy) sample showed a negative result of 400 photon counts (PCs), whereas irradiated (5, 10, and 30 kGy) samples showed positive results of 90,100.00, 312,614.33, and 321,661.67 PCs, respectively. In the TL method, growth curve showed very unusual behaviors around $200^{\circ}C$ upon natural-irradiation of the non-irradiated (0 kGy) sample and around $150{\sim}250^{\circ}C$ for the irradiated (5, 10, and 30 kGy) samples. The TL ratio was 0.1 in non-irradiated samples at 0.011, whereas the values of irradiated samples (5, 10, and 30 kGy) were 0.1 at 1.105, 1.009, and 2.206, respectively. For phenolics of gamma-irradiated Aralia elata cortex, water and 50% ethanol extracts had the highest amounts, $17.30{\pm}0.40mg/g$ and $18.87{\pm}0.46mg/g$ at 10 kGy irradiation, respectively. The inhibitory activities of angiotensin-converting enzyme and xanthin oxidase were higher in both irradiated water and 50% ethanol extracts than in non-irradiated ones. For pancreatin ${\alpha}$-amylase and ${\alpha}$-glucosidase inhibitory activities, water and 50% ethanol extracts containing $200{\mu}g/mL$ of phenolics showed high inhibitory activities of 60~100% at all irradiation doses (0~30 kGy). This result confirmed that Aralia elata cortex extracts have greater anti-diabetic effects than acabose as a diabetic remedy. Gamma-irradiated Aralia elata cortex extracts are useful as a functional material with anti-diabetic effects. Thus, Aralia elata cortex extracts can be used as a functional material with various biological activities, and gamma-irradiation can be used to amplify biological activities in plants.

• Journal of the Korean Society of Radiology
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• v.12 no.2
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• pp.179-184
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• 2018

In this study, we compared the measured values of the effective beam size of standard gamma irradiator with the simulation results to provide a useful means to the effective beam area determination. Results of the simulation and measured using ion chamber was distributed in a relative error of 4.5 ~ 7.3% of the case of air kerma rate. The size of the effective beam area is when the simulation was implemented in the horizontal direction 27cm, 21.6cm vertical direction, the measured result using a film was obtained similar results with the horizontal direction 26.5cm, 21.9cm vertical direction. The relative error in the horizontal direction is 1.85% and 1.38% vertical effective beam area was also similarly distributed around the field gamma rays. As a result of the study, it was confirmed that the effectiveness of the simulation was sufficient for the gamma irradiation system. In particular, it is small relative errors in the effective beam size than the air kerma rate is considered to be due to the size of the beam is determined by geometric factors rather than the capacity of the standard source. A further study is needed to improve the reliability of the photon energy distribution diagram using simulation.

• Progress in Medical Physics
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• v.27 no.2
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• pp.98-104
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• 2016

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.

• Progress in Medical Physics
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• v.25 no.3
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• pp.151-156
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• 2014

The purpose of this study was to confirm the feasibility of imaging of therapy region from the boron neutron capture therapy (BNCT) using the measurement of the prompt gamma ray depending on the neutron flux. Through the Monte Carlo simulation, we performed the verification of physical phenomena from the BNCT; (1) the effects of neutron according to the existence of boron uptake region (BUR), (2) the internal and external measurement of prompt gamma ray dose, (3) the energy spectrum by the prompt gamma ray. All simulation results were deducted using the Monte Carlo n-particle extended (MCNPX, Ver.2.6.0, Los Alamos National Laboratory, Los Alamos, NM, USA) simulation tool. The virtual water phantom, thermal neutron source, and BURs were simulated using the MCNPX. The energy of the thermal neutron source was defined as below 1 eV with 2,000,000 n/sec flux. The prompt gamma ray was measured with the direction of beam path in the water phantom. The detector material was defined as the lutetium-yttrium oxyorthosilicate (Lu0,6Y1,4Si0,5:Ce; LYSO) scintillator with lead shielding for the collimation. The BUR's height was 5 cm with the 28 frames (bin: 0.18 cm) for the dose calculation. The neutron flux was decreased dramatically at the shallow region of BUR. In addition, the dose of prompt gamma ray was confirmed at the 9 cm depth from water surface, which is the start point of the BUR. In the energy spectrum, the prompt gamma ray peak of the 478 keV was appeared clearly with full width at half maximum (FWHM) of the 41 keV (energy resolution: 8.5%). In conclusion, the therapy region can be monitored by the gamma camera and single photon emission computed tomography (SPECT) using the measurement of the prompt gamma ray during the BNCT.

• Korean Journal of Food Science and Technology
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• v.46 no.2
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• pp.256-261
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• 2014

This study was conducted to determine the effect of gamma-ray and electron-beam irradiation on dried spices (black pepper, red pepper, parsley, and basil) using the photostimulated luminescence (PSL), thermoluminescence (TL) and electron spin resonance (ESR) methods. The spices were irradiated at 0, 1, 5, and 10 kGy. All non-irradiated spices had photon counts (PCs) less than 700 PCs. The PCs of three irradiated spices (red pepper, parsley, and basil) were clearly distinguishable from those of non-irradiated ones, exhibiting PSL signals higher than 5000 PCs. However, negative PSL counts (<700 PCs) were obtained for most irradiated black pepper, except those irradiated with 5 kGy gamma rays and 10 kGy electron-beams. TL glow curves of the irradiated spices showed a higher peak at $150-250^{\circ}C$. TL ratios were found to be less than 0.1 for non-irradiated spices and higher than 0.1 for irradiated ones. No ESR signal was observed for any irradiated spice except red pepper, which displayed cellulose-based ESR spectra. Therefore, the results suggest that the PSL, TL, and ESR methods are effective detection techniques for dried spices irradiated with electron beams as well as gamma rays.

• Journal of the Korean Society of Radiology
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• v.16 no.7
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• pp.863-870
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• 2022

DLG (Dosimetric Leaf Gap) and transmission factor are important parameters of MLC modeling in treatment planning system. In this study, DLG and transmission factor of HD-MLC were measured using detector with different measuring volumes, and the accuracy of the treatment plans was evaluated according to the DLG values. DLG was measured using the dynamic sweeping gap method with Semiflux3D and MicroDiamond detectors. Then, 10 radiation treatment plans were generated to optimize the DLG value and compared with the measurement results. Photon energies 6, 8, 10 MV, the DLG measured by Semiflux3D were 0.76, 0.83, and 0.85 mm, and DLG measured by MicroDiamond were 0.78, 0.86, and 0.9 mm. All plans were measured by portal dosimetry and analyzed using Gamma Evaluation. In the 6 MV photon beams, the average gamma passing rate were 94.3% and 98.4% for DLG 0.78 mm and 1.15 mm. In the 10 MV photon beam, the average gamma passing rate were 91.2% and 97.6% for DLG 0.9 mm and 1.25 mm. HD-MLC needs accurate modeling in the treatment planning system. DLG could be used measured data using small volume detector. However, for better radiation therapy, DLG should be optimized at the commissioning stage of LINAC.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.564-567
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• 2012

Optical fibers are going to be used for telecommunication, image fibers, sensors under irradiation in nuclear power plants and various irradiation facilities. Especially, Temperature detection sensors using Raman light scattering, temperature or strain sensors using fiber gratings, magnet-optical sensors using photo-magnetic effect, are already commercialized. However, When fibers are exposed to ionizing radiation, color centers are formed in fibers which reduces their light transmission, and it is limited in applying under radiation environments. In this study, $Co^{60}$ gamma-ray induced optical attenuation on Ge-doped single mode(SM) fiber has been measured. Gamma-ray is irradiated for 4hours at the dose rate of 0.5kGy/hr, 2kGy/hr, 8kGy/hr. Consequently, gamma-ray induced loss based on radiation effects in Ge-doped SM fiber occur precisely. Furthermore, dose rate effect that the higher dose rate in the same total dose, the more increase loss of optical fiber and annealing effect that the higher the loss after irradiation, the more increase the recovery rate of the loss are observed in the fiber. This results plan to make use of bases in the study of the radiation-hardened optical fiber.

• Korean Journal of Food Science and Technology
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• v.49 no.3
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• pp.252-257
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• 2017

In this study, the physicochemical properties of irradiated (gamma-ray and electron-beam) soybeans with different processing (dry and powder) and origins (Korea, China, and USA) were investigated and compared. The results of photostimulated luminescence (PSL) screening indicated that all non-irradiated soybeans showed photon counts (PCs) ${\leq}700$, while all irradiated soybeans showed positive values-gamma-ray 5,815-39,591 count/min; electron beam 5,791-60,055 count/min. The results of thermoluminescence (TL) analysis of all irradiated soybeans indicated that the $TL_1$ glow curves exhibited maximum peaks at 150-250. TL ratio of irradiated samples was ${\geq}0.1$; therefore, the clear identification of irradiated samples was guaranteed by analysis of the $TL_1$ curve shape and TL ratios. The results of electron spin resonance (ESR) signal of 3 irradiated and dried soybeans showed two side peaks mutually spaced at 6.0 mT (cellulose radical). Non-specific signal was detected for all irradiated soybean powders; hence, ESR analysis could not be performed.

• Journal of Radiation Protection and Research
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• v.29 no.4
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• pp.263-268
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• 2004

Using the Monte Carlo simulation, a study on the lion-proportionality of the prototype phoswich detector with $2'{\times}2'$ CSI(Tl) and plastic scintillator, which was made by KAERI, has been carried. The defector response functions (DRFs) calculated by simulations were compared with the experimental measurement on the $^{137}Cs\;and\;^{60}Co$. To precisely simulate the DRF for the phoswich, the CSI(Tl) non-proportionality was calculated using the electron response and the simplified electron cascade sequence for treating the photoelectric absorption event. The resulting DRFs of $^{137}Cs\;and\;^{60}Co$ sources obtained by simulations were compared with experiments for verification. For $^{137}Cs$, gamma-ray responses simulated by MCNP5 are generally good agreement with the measured ones. But the DRF of $^{60}Co$ does not match well with the results of experiment in the energy region below second peak due to the coincidence effect of two gamma-rays (1.17 MeV and 1.33 MeV). Through the analysis of the non-proportionality of CsI(Tl) in the prototype phoswich, the improved DRFs considering non-proportionality were produced and the simulation results were verified using the experimental measurements. However, to more precisely reproduce the DRF for the phoswich, further studies in relation to the electron channeling effect and the Doppler broadening effect of a scintillator are still needed as well as considering that effect of the transfer contribution.