• Progress in Medical Physics
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• v.32 no.4
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• pp.99-106
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• 2021

Purpose: In this study, we aimed to manufacture a patient-specific gel phantom combining three-dimensional (3D) printing and polymer gel and evaluate the radiation dose and dose profile using gel dosimetry. Methods: The patient-specific head phantom was manufactured based on the patient's computed tomography (CT) scan data to create an anatomically replicated phantom; this was then produced using a ColorJet 3D printer. A 3D polymer gel dosimeter called RTgel-100 is contained inside the 3D printing head phantom, and irradiation was performed using a 6 MV LINAC (Varian Clinac) X-ray beam, a linear accelerator for treatment. The irradiated phantom was scanned using magnetic resonance imaging (Siemens) with a magnetic field of 3 Tesla (3T) of the Korea Institute of Nuclear Medicine, and then compared the irradiated head phantom with the dose calculated by the patient's treatment planning system (TPS). Results: The comparison between the Hounsfield unit (HU) values of the CT image of the patient and those of the phantom revealed that they were almost similar. The electron density value of the patient's bone and brain was 996±167 HU and 58±15 HU, respectively, and that of the head phantom bone and brain material was 986±25 HU and 45±17 HU, respectively. The comparison of the data of TPS and 3D gel revealed that the difference in gamma index was 2%/2 mm and the passing rate was within 95%. Conclusions: 3D printing allows us to manufacture variable density phantoms for patient-specific dosimetric quality assurance (DQA), develop a customized body phantom of the patient in the future, and perform a patient-specific dosimetry with film, ion chamber, gel, and so on.

• Journal of Mushroom
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• v.20 no.2
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• pp.69-77
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• 2022

Eco-friendly materials, such as alternative vegan materials using various fungal resources, are being actively researched to reduce environmental pollution and facilitate a healthy lifestyle. The fungal mycelium-based mushroom mycelium mat is one such emerging material. In this study, the commonly used mushroom mycelium culture method was modified to reduce the time required to produce the mycelium mat, lower the possibility of contamination, and improve the properties and quality of the mat. Shortening the period required for the previously used primary bag culture and secondary mat production culture. A culture method in which the bag culture was omitted was attempted using a mycelium mutated by gamma irradiation to the mycelium of Trametes orientalis. In addition, various nutrients were added to the fungal solution to observe the change in physical properties of the fungal mat. High-quality mycelium mats were produced in the experimental group containing 1.5% CaCO₃ in sawdust medium, and the period was also reduced by more than 10 days compared to the existing production method. In the future, for mass producing mycelium mats, additional selection of medium components and optimization of culture conditions are essential.

• Nuclear Engineering and Technology
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• v.54 no.12
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• pp.4660-4670
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• 2022

Hydroxyurea (HU) is a novel salt-free reductant used potentially for the separation of U/Pu in the advanced PUREX process. In this work, the radiation stability of HU were systematically investigated in solution by examining the effects of the type of rays (α, β, and γ irradiations), the absorbed dose (10-50 kGy), and the HNO₃ concentration (0-3 mol L^-1). The influence degree on HU radiolysis rates followed the order of the absorbed dose > the ray type > the HNO₃ concentration, but the latter two had moderate effects on HU radiolysis products where NH₄⁺ and NO₂^- were found to be the most abundant ones, suggesting that the differences of α, β, and γ rays should be considered in the study of irradiation effects. The radiolysis mechanism was explored using density functional theory (DFT) calculations, and it proposed the dominant radiolysis paths of HU, indicating that the radiolysis of HU was mainly a free radical reaction among ·H, e_aq^-, H₂O, intermediates, and the radiolytic free radical fragments of HU. The results reported here provide valuable insights into the mechanistic understanding of HU radiolysis under α, β, and γ irradiations and reliable data support for the application of HU in the reprocessing of spent fuel.

• Journal of the Korean Society of Food Science and Nutrition
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• v.40 no.12
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• pp.1781-1786
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• 2011

This study was conducted to investigate the cause of microbiological contamination in yogurt and evaluate the effect of physicochemical treatment on the growth inhibition of Hanseniaspora uvarum isolated from yogurt. The yeast strain Hanseniaspora uvarum Y1 was subjected to heat and pH treatments. H. uvarum Y1 was killed at $70^{\circ}C$ and $80^{\circ}C$ after 15 min and survived in a wide pH range from pH 2 to 9. However, it did not survive under pH 1 and over pH 10. In a disk diffusion susceptibility test on H. uvarum Y1, a clear zone (5 mm) of growth inhibition was observed upon treatment with electrolyzed water. The effect of ozone gas on the growth of H. uvarum Y1 was evaluated by viable cell count. Initial cell numbers of $10^2$ and $10^3$ CFU/mL of H. uvarum Y1 were completely killed by treatment for 10 and 30 min, respectively. H. uvarum Y1 was also sterilized by microwave treatment for 1 min. When treated with gamma-irradiation, the rate of killing of H. uvarum Y1 was proportional to the irradiation dose. and complete killing occurred at a dose of 50 kGy.

• The Korean Journal of Nuclear Medicine
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• v.35 no.5
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• pp.313-323
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• 2001

Purpose: The purpose of this study was to search activated genes that could be related to radiation adaptive response (RAR) induced by low-level radiation from $^{99m}Tc$ in human cell lines. Methods: We used gene discovery array (GDA) and representational difference analysis (RDA) methods. $^{99m}Tc$-pertechnetate was added to $2{\times}106/mL$ NC-37 cells (human lymphoblastic cells) to make concentrations ranging from 148 MBq/mL to 148 Bq/mL by serial 10 fold dilutions. After 44 hours, 2 Gy gamma irradiation was given to them using a Cs-137 cell irradiator. Results: As compared to the control (Con) group to which no $^{99m}Tc$ was added, those cells to which 148 and 14.8 KBq of $^{99m}Tc$ were added showed significantly lower damage to chromosomes, which was evaluated by metaphase analysis. Cells with 148 KBq $^{99m}Tc$ (T148 group) showed most significant protection. Activated genes in the T148 group as compared to Con group were evaluated by GDA and GDA methods. GDA revealed genes of casein kinase 2 (CK2) beta chain, immunoglobulins (lg), human leukocyte antigen (HLA)-B, and two novel genes. Twenty RAR related clones were selected by RDA method. The size of those genes was from 234 to 603 base pairs. Conclusions: RAR was induced by low dose irradiation from $^{99m}Tc$ in NC-37 cell lines. Genes related to the response included CK2, lg, HLA-B in human lymphoblastic cell lines.

• Korean Journal of Agricultural Science
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• v.2 no.2
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• pp.381-398
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• 1975

Present work was executed to evaluate effects of adjuvants. stabilizers. moisture. pH and heavy metals on the stability of Fenitrothion in the emulsifiable concentrate. In addition, susceptibility ' of Fenitrothion in various formulations, to UV-irradiation has been also examined. The results are summarized as follows; 1. Xylene and benzene were found to be satisfactory solvents for Fenitrothion emulsifiable concentrate. As expected, polar sol vents such as aliphatic alcohols considerably reduced stability of the pesticides. 2. Of the two non-ionic emulsifiers, an alkyl aryl type Sorpol-1200, in contrast to sorbitan type Tweens, substantially reduced decomposition of Fenitrothion in the emulsifiable concentrates. Moisture and pH of emulsifiers. in the ranges studied. affected little if any. on the stabi ity of the Fenitrothion during the experiment periods. 3. Maleic anhydride, p-toluene sulfonic acid, sulfosalicylic acid, maleic anhydride-sulfosalicylic acid reduced decomposition of Fenitrothion in the emulsifiable concentrate. Addition of organic acids, however, increased liability of Fenitrothion in the emulsifiable concentrate. 4. Presence of either zinc or copper metals in the emulsifiable concentrate containing Tween-80 as a emulsifier, reduced stability of the Fenitrothion. 5. UV-irradiation, as expected, brought decomposition of Fenitrothion. The liability of Fenitrothion formulations decreased in the order, wettable powder ${\gg}$ dust > emulsifiable concentrate.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.73-77
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• 2004

Purpose of the radio-therapy is maximize the radiation dose to the tumor while minimizing the dose to the critical organ. Carcinoma of the uterine cervix treatment are external irradiation or an interstitial brachtheraphy make use of isotope. Brachytherapy is a method of radiotherapy in advantage to achieve better local control with minimum radiation toxicity in comparison with external irradiation because radiation dose is distributed according to the inverse square low of gamma-ray emitted from the implanted sources. Authors make use of the patients data which 192Ir gives medical treatment intrcavity. Intracavitary radiation of the uterine cervix cancer, critical organ take $20\%$ below than exposure dose of A point in the ICRU report. None the less of the advice, Radiation proctitis and radiation cystitis are frequent and problematic early complications in patients treated with radiation for the uterine cervix cancer. In brachytherapy of uterine cervical cancer using a high dose rate remote afterloading system, it is of prime importance to deliver a accurate dose in each fractionated treatment by minimizing the difference between the pre-treatment planned and post-treatment calculated doses. Use of packing to reduce late complications intracavitary radiation of the uterine cervix cancer. Bladder and rectum changes exposure dose rate by radiotherphy make use of packing.

• Journal of Radiation Industry
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• v.7 no.1
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• pp.7-14
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• 2013

In this study, we investigated the applicability of the photostimulated luminescence (PSL), thermoluminescence (TL) and electron spin resonance (ESR) methods for various foods. The analysed samples consist of 11 items including dried fruits (6 items) and mushrooms (5 items). To compare between non-irradiated and irradiated food, all samples were irradiated with $^{60}Co$ gamma-ray source. In PSL study, the photon counts of all the unirradiated sample were identified negative (lower than 700). The photon counts irradiated (1, 5, 10 kGy) dried date-palm, dried jujube and mushrooms (Auricularia auricula, Phellinus linteus and Sarcodon aspratus) showed positive (higher than 5,000) and the results for the other samples were negative or intermediate (>700 and >5,000). In TL analysis most of items can be applicable to detect irradiated foods because of showing TL ratio above 0.1. The glow curves by TL method were estimated in the range of $150{\sim}250^{\circ}C$ in irradiated samples. In ESR measurements, the intensity of ESR signal (single-line) increased as the dose of irradiation increased. In particular, the specific ESR signals of irradiation-induced radical were detected in dried papaya, dried date-palm, dried banana, dried pineapple and S. aspratus. According to the results, PSL, TL and ESR methods were successfully applied to detect the irradiated foods. It is concluded that PSL, TL and ESR methods are suitable for detection of irradiated samples and a combined method is recommendable for enhancing the reliability of detection results.

• Journal of the Korean Society of Radiology
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• v.18 no.2
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• pp.161-169
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• 2024

This study confirmed the radioprotective effects of a mixed extracts of Hottuynia, Perilla Frutescens, and Camellia Sinnensis as natural radioprotectors on the prostate, small intestine, and liver of SD rats. It is known that Hottuynia, Perilla Frutescens, and Camellia Sinnensis have antioxidant effects on the prostate, small intestine, and liver, respectively.In this study, SD rats were irradiated with 8 Gy of gamma rays to confirm the radioprotective effects of a mixed extracts of Hottuynia, Perilla Frutescens, and Camellia Sinnensis. After radiation irradiation, histological analysis of the prostate, small intestine, and liver was performed. After radiation irradiation, histological analysis of the prostate, small intestine, and liver was performed. In the case of the prostate, the HPC+IR Group had less prostate damage and better recovery due to radiation compared to the IR Group. It was confirmed that the prostate size of the HPC+IR Group was 11.48%p and 24.54%p higher than the IR Group on 1st and 7th days. In the case of the small intestine, the HPC+IR Group had less radiation-induced small intestinal damage and recovery was better than the IR Group. The length of small intestine villus in the HPC+IR Group was confirmed to be 23.73%p and 24.27%p higher than the IR Group on the 1st and 7th days. In the case of the liver, the HPC+IR Group had less liver damage due to radiation and had better recovery than the IR Group. This was confirmed through the hepatic portal vein and surrounding cells. The results of this study are considered to be used as basic data for research on natural radiation protection using mixed extracts.

• Journal of Plant Biotechnology
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• v.34 no.1
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• pp.61-68
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• 2007

To develop rice (Oryza sativa L.) cultivars to be planted on salt-affected sites, cell lines with enhanced proline content and resistance to growth inhibition by Azetidine-2-carboxylic acid (AZCA), a proline analogue, were screened out among calli irradiated with gamma ray of 50, 70, 90, and 120 Gy. The calli had been derived from embryo culture of the cultivar Donganbyeo. Selected AZCA resistant lines that had high proline accumulation were used as sources for selection of NaCl resistant lines. To determine an optimum concentration for selection of NaCl resistant lines, Donganbyeo seeds were initially cultured on the media containing various NaCl concentrations (0 to 2.5%) for 40 days, and 1.5% NaCl concentration was determined as the optimum concentration. One hundred sixteen salt-tolerant (ST) lines were selected from bulked 20,000 seeds of the AZCA resistant $M_{3}$ seeds in the medium containing 1.5% NaCl. The putative 33 lines ($M_{4}$ generation) considered with salt-tolerance were further analyzed for salt tolerance, amino acid and ion contents, and expression patterns of the salt tolerance-related genes. Out of the 33 lines, 7 lines were confirmed to have superior salt tolerance. Based on growth comparison of the entries, the selected mutant lines exhibited greater shoot length with average 1.5 times, root length with 1.3 times, root numbers with 1.1 times, and fresh weight with 1.5 times than control. Proline contents were increased maximum 20%, 100% and 20% in the leaf, seed and callus, respectively, of the selected lines. Compared to control, amino acid contents of the mutants were 24 to 29%, 49 to 143%, 32 to 60% higher in the leaf, seed and callus, respectively. The ratio of $Na^{+}/K^{+}$ for most of the ST-lines were lower than that of control, ranging from 1.0 to 3.8 for the leaf and 11.5 to 28.5 for the root, while the control had 3.5 and 32.9 in the leaf and root, respectively. The transcription patterns for the P5CS and NHXI genes observed by RT-PCR analysis indicated that these genes were actively expressed under salt stress. The selected mutants will be useful for the development of rice cultivar resistant to salt stress.