• Journal of radiological science and technology
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• v.34 no.4
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• pp.351-357
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• 2011

The $^{18}F$-FDG is one of the widely used isotopes for PET/CT scans. Dose amount injected to the patient depends on the characteristics of PET/CT systems. Obviously, the technologists who contact with patients would be exposed as well. In this study, we evaluated the exposed dose of the technologist who works on the PET/CT scanner. The exposed dose were measured every month with the TLDs from 6 technologists. Each technologist is shift-worker who manages 3 different PET/CT systems(Scanner 1(S1): 0.15 mCi/kg, Scanner 2(S2): 0.17 mCi/kg, Scanner 3(S3): 0.12 mCi/kg). The average exposed doses of technologists for each PET/CT system were measured as 0.76 mSv for S1, 0.93 mSv for S2 and 0.47 mSv for S3. The maximum dose was 1.12 mSv and minimum was 0.42 mSv. The results showed that there was a correlation between exposed dose and PET/CT system(p<0.005). Less injected dose for patient occurs less exposed dose for technologist. Various studies for the low dose PET/CT system are required for not only the patient but also the technologist.

• Journal of Radiation Protection and Research
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• v.20 no.2
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• pp.97-102
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• 1995

Adaptive response induced by low dose ${\gamma}-ray$ irradiation in human peripheral lymphocytes was examimed. Human lymphocytes were exposured to low dose of ${\gamma}-ray$ (priming dose, 0.01Gy) followed by high dose (challenging dose, 1.5Gy) after various time intervals (4, 7, 20 hours). Frequencies of micronuclei were enumerated in both primed and unprimed groups. Maximum reduction in frequency of micronuclei was observed when challenging dose irradiation was followed by priming dose after 4hr incubation period. When challenging doses were irradiated 7 or 20hr after priming dose, frequencies of micronuclei were reduced slighty. However, these reduction were not statistically significant. In this study, human peripheral lymphocytes were irradiated at Go phase and they showed adaptive response induced by low dose radiation. Since micronucleus assay is relatively simpler and faster than other methods, it may be a good tool for evaluating radiation-induced adaptive responses.

• The Journal of Korean Society for Radiation Therapy
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• v.35
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• pp.33-39
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• 2023

Purpose: The purpose of this study is to find out the dose variation according to thickness of the air gap between the patient's body surface and immobilization device in the treatment plan. Materials and Methods : Four conditions were created by adjusting the air gap thickness using 5 mm bolus, ranging from 0 mm to 3 mm bolus. Immobilization was placed on top in each case. And computed tomography was used to acquire images. The treatment plan that 430 cGy (Relative Biological Effectiveness,RBE) is irradiated 6 times and the dose of 2580 cGy (RBE) is delivered to 95% of Clinical Target Volume (CTV). The dose on CTV was evaluated by Full Width Half Maximum (FWHM) of the lateral dose profile and skin dose was evaluated by Dose Volume Histogram (DVH). Result: Results showed that the FWHM values of the lateral dose profile of CTV were 4.89, 4.86, 5.10, and 5.10 cm. The differences in average values at the on the four conditions were 3.25±1.7 cGy (RBE) among D_95% and 1193.5±10.2 cGy (RBE) among D_95% respectively. The average skin volume at 1% of the prescription dose was 83.22±4.8%, with no significant differences in both CTV and skin. Conclusion: When creating a solid-type immobilization device for carbon particle therapy, a slight air gap is recommended to ensure that it does not extend beyond the dose application range of the CTV.

• Journal of Pharmacopuncture
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• v.13 no.4
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• pp.43-61
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• 2010

Objectives : This study was performed to analyse single dose toxicity of Sweet Bee Venom(Sweet BV) extracted from the bee venom in Beagle dogs. Methods : All experiments were conducted under the regulations of Good Laboratory Practice (GLP) at Biotoxtech Company, a non-clinical study authorized institution. Male and female Beagle dogs of 5-6 months old were chosen for the pilot study of single dose toxicity of Sweet BV which was administered at the level of 9.0 mg/kg body weight which is 1300 times higher than the clinical application dosage as the high dosage, followed by 3.0 and 1.0 mg/kg as midium and low dosage, respectively. Equal amount of excipient(normal saline) to the Sweet BV experiment groups was administered as the control group. Results : 1. No mortality was witnessed in all of the experiment groups. 2. Hyperemia and movement disorder were observed around the area of administration in all the experiment groups, and higher occurrence in the higher dosage treatment. 3. For weight measurement, Neither male nor female groups showed significant changes. 4. To verify abnormalities of organs and tissues, thigh muscle which treated with Sweet BV, brain, liver, lung, kidney, and spinal cords were removed and histologocal observation using H-E staining was conducted. In the histologocal observation of thigh muscle, cell infiltration, inflammation, degeneration, necrosis of muscle fiber, and fibrosis were found in both thigh tissue. And the changes depend on the dose of Sweet BV. But the other organs did not showed in any abnormality. 5. The maximum dose of Sweet BV in Beagle dogs were over 9 mg/kg in this study. Conclusions : The above findings of this study suggest that Sweet BV is a relatively safe treatment medium. Further studies on the toxicity of Sweet BV should be conducted to yield more concrete evidences.

• Journal of Biomedical Engineering Research
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• v.39 no.3
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• pp.116-123
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• 2018

This study is a model experimental study using a phantom to propose an optimized brain CT scan protocol that can reduce the radiation dose of a patient and remain quality of image. We investigate the CT scan parameters of brain CT in clinical medical institutions and to measure the important parameters that determine the quality of CT images. We used 52 multislice spiral CT (SOMATOM Definition AS+, Siemens Healthcare, Germany). The scan parameters were tube voltage (kVp), tube current (mAs), scan time, slice thickness, pitch, and scan field of view (SFOV) directly related to the patient's exposure dose. The CT dose indicators were CTDIvol and DLP. The CT images were obtained while increasing the imaging conditions constantly from the phantom limit value (Q1) to the maximum value (Q4) for AAPM CT performance evaluation. And statistics analyzed with Pearson's correlation coefficients. The result of tube voltage that the increase in tube voltage proportionally increases the variation range of the CT number. And similar results were obtained in the qualitative evaluation of the CT image compared to the tube voltage of 120 kVp, which was applied clinically at 100 kVp. Also, the scan conditions were appropriate in the tube current range of 250 mAs to 350 mAs when the tube voltage was 100 kVp. Therefore, by applying the proposed brain CT scanning parameters can be reduced the radiation dose of the patient while maintaining quality of image.

• Journal of Physiology & Pathology in Korean Medicine
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• v.23 no.5
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• pp.1145-1153
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• 2009

The object of this study was to obtain acute information single oral dose toxicity of Mahwangbujaseshin-tang extracts, with mouse bone marrow cell micronucleus test for detecting possible genotoxicity. In order to observe the 50% lethal dose, approximate lethal dosage, maximum tolerance dosage and target organs, test articles were once orally administered to ICR mice at dose levels of 2000, 1000, 50 mg/kg according to the recommendation of KFDA Guidelines. The mortality and changes on body weight, clinical signs and gross observation were monitored during 14 days after dosing according to KFDA Guidelines with organ weights of 12 types of principle organs. In addition, after twice oral treatment of Mahwangbujaseshin-tang extracts 2000, 1000 and 500 mg/kg, we checked the changes on the number of MNPCE. We could not find any mortality, clinical signs, changes in the body weight and gross findings upto 2000 mg/kg treated group. The limited dosages in rodents except for increases of lymphoid organ weights and hypertrophy encounted as results from pharmacological effects of Mahwangbujaseshin-tang extracts, immune modulator effects with some sporadic accidental findings not toxicological signs. No evidence of increases of MNPCE numbers were also detected in all three different dosages of Mahwangbujaseshin-tang extracts treated mice. The results obtained in this study suggest that the LD50 and ALD of Mahwangbujaseshin-tang extracts in mice were considered as over 2000 mg/kg because no mortalities were detected upto 2000 mg/kg that was the highest dose recommended by KFDA and OECD. And the results of mouse bone marrow micronucleus test of Mahwangbujaseshin-tang extracts is negative results.

• Progress in Medical Physics
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• v.13 no.2
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• pp.62-68
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• 2002

A muiltileaf collimator (MLC) is used as a replacement for conventional blocks. The MLC, however may not be appropriate for a fine field shaping. For the fine field shaping, conventional block can be added under the MLC. But it may significantly affect on the dosimetric characteristics such as surface dose of skin, buildup region and percent depth doses. We performed the study to evaluate the surface dose and the maximum depth dose using MLC conjunction with conventional blocks for various field sizes and energies. We confirmed the surface dose was increased by using the additional conventional block under the MLC ranging from 10 to 35.6％ according to various field sizes and radiation beam energies. The surface dose was effectively reduced by application of 2 or 3 m thickness of lead plate as electron filter.

• Progress in Medical Physics
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• v.28 no.1
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• pp.33-38
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• 2017

Creating individualized build-up material for superficial photon beam radiation therapy at irregular surface is complex with rice or commonly used flat shape bolus. In this study, we implemented a workflow using 3D printed patient specific bolus and describe our clinical experience. To provide better fitted build-up to irregular surface, the 3D printing technique was used. The PolyLactic Acid (PLA) which processed with nontoxic plant component was used for 3D printer filament material for clinical usage. The 3D printed bolus was designed using virtual bolus structure delineated on patient CT images. Dose distributions were generated from treatment plan for bolus assigned uniform relative electron density and bolus using relative electron density from CT image and compared to evaluate the inhomogeneity effect of bolus material. Pretreatment QA is performed to verify the relative electron density applied to bolus structure by gamma analysis. As an in-vivo dosimetry, Optically Stimulated Luminescent Dosimeters (OSLD) are used to measure the skin dose. The plan comparison result shows that discrepancies between the virtual bolus plan and printed bolus plan are negligible. (0.3% maximum dose difference and 0.2% mean dose difference). The dose distribution is evaluated with gamma method (2%, 2 mm) at the center of GTV and the passing rate was 99.6%. The OSLD measurement shows 0.3% to 2.1% higher than expected dose at patient treatment lesion. In this study, we treated Mycosis fungoides patient with patient specific bolus using 3D printing technique. The accuracy of treatment plan was verified by pretreatment QA and in-vivo dosimetry. The QA results and 4 month follow up result shows the radiation treatment using 3D printing bolus is feasible to treat irregular patient skin.

• Journal of Physiology & Pathology in Korean Medicine
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• v.24 no.1
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• pp.124-133
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• 2010

The object of this study was to obtain acute information single oral dose toxicity of Mahwangbujaseshin-tang extracts, with mouse bone marrow cell micronucleus test for detecting possible genotoxicity. In order to observe the 50% lethal dose, approximate lethal dosage, maximum tolerance dosage and target organs, test articles were once orally administered to ICR mice at dose levels of 2000, 1000, 50 mg/kg according to the recommendation of KFDA Guidelines. The mortality and changes on body weight, clinical signs and gross observation were monitored during 14 days after dosing according to KFDA Guidelines with organ weights of 12 types of principle organs. In addition, after twice oral treatment of Mahwangbujaseshin-tang extracts 2000, 1000 and 500 mg/kg, we checked the changes on the number of MNPCE. We could not find any mortality, clinical signs, changes in the body weight and gross findings upto 2000 mg/kg treated group. The limited dosages in rodents except for increases of lymphoid organ weights and hypertrophy encounted as results from pharmacological effects of Mahwangbujaseshin-tang extracts, immune modulator effects with some sporadic accidental findings not toxicological signs. No evidence of increases of MNPCE numbers were also detected in all three different dosages of Mahwangbujaseshin-tang extracts treated mice. The results obtained in this study suggest that the LD50 and ALD of Mahwangbujaseshin-tang extracts in mice were considered as over 2000 mg/kg because no mortalities were detected upto 2000 mg/kg that was the highest dose recommended by KFDA and OECD. And the results of mouse bone marrow micronucleus test of Mahwangbujaseshin-tang extracts is negative results.

• Nuclear Engineering and Technology
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• v.12 no.3
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• pp.171-179
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• 1980

This paper presentss flux-to-dose conversion factors for neutrons and gamma-rays based on the concept of the maximum absorbed dose. Neutron flux-to-does-rate conversion factors for energies from 2.5$\times$10$^{-8}$ to 20 MeV are presented while the conversion factors for gamma-rays are given in the energy range of 0.01 to 15MeV. Flux-to-does-rate conversion factors, which were calculated under the assumption that the radiation energy distribution has nonlinearity in phantom, are different from those values obtained by monoenergetic radiation. Especially, these values obtained here were determined for the cross section libray such as DLC-23, DLC-27, and DLC-31. The flux-to-dose-rate conversion factors obtained in this work are in a good agreement with the values presented by American National Standard Institute (ANSI) N666. These results are used to calculate the dose rate distribution of neutron and gamma-ray in any radiation fields, and will be useful for the radiation shielding analysis, radiation protection and radiation dosimetry concerned with problems of continuous energy distribution.