• Journal of Radiation Protection and Research
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• v.40 no.3
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• pp.124-131
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• 2015

Radiation exposure to humans can be caused by the gamma rays emitted from natural radioactive elements(such as uranium, thorium and potassium and any of their decay products) of Naturally Occurring Radioactive Materials(NORM) or Technologically Enhanced Naturally Occurring Radioactive Materials(TENORM) added consumer products. In this study, assume that activity of radioactive elements is $^{238}U$, $^{235}U$, $^{232}Th$ $1Bq{\cdot}g^{-1}$, $^{40}K$ $10Bq{\cdot}g^{-1}$ and the gamma rays emitted from these natural radioactive elements radioactive equilibrium state. In this study, reflected End-User circumstances and evaluated annual exposure dose for products based on ICRP reference voxel phantoms and ICRP Recommendation 103 using the Monte Carlo Method. The consumer products classified according to the adhere to the skin(bracelet, necklace, belt-wrist, belt-ankle, belt-knee, moxa stone) or not(gypsum board, anion wallpaper, anion paint), and Geometric Modeling was reflected in Republic of Korea "Residential Living Trend-distributions and Design Guidelines For Common Types of Household.", was designed the Room model($3m{\times}4m{\times}2.8m$, a closed room, conservatively) and the ICRP reference phantom's 3D segmentation and modeling. The end-user's usage time assume that "Development and Application of Korean Exposure Factors." or conservatively 24 hours; in case of unknown. In this study, the results of the effective dose were 0.00003 ~ 0.47636 mSv per year and were confirmed the meaning of necessary for geometric modeling to ICRP reference phantoms through the equivalent dose rate of belt products.

• Journal of radiological science and technology
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• v.38 no.1
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• pp.23-30
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• 2015

Positron emission tomography scan has been growing diagnostic equipment in the development of medical imaging system. Compare to 99mTc emitting 140 keV, Positron emission radionuclide emits 511 keV gamma rays. Because of this high energy, it needs to reduce radioactive emitting from patients for radio technologist. We searched the external dose rates by changing distance from patients and measure the external dose rates when we used shielder investigate change external dose rates. In this study, the external dose distribution were analyzed in order to help managing radiation protection of radio technologists. Ten patients were searched (mean age: $47.7{\pm}6.6$, mean height: $165.5{\pm}3.8cm$, mean weight: $65.9{\pm}1.4kg$). Radiation was measured on the location of head, chest, abdomen, knees and toes at the distance of 10, 50, 100, 150, and 200 cm, respectively. Then, all the procedure was given with a portable radiation shielding on the location of head, chest, and abdomen at the distance of 100, 150, and 200 cm and transmittance was calculated. In 10 cm, head ($105.40{\mu}Sv/h$) was the highest and foot($15.85{\mu}Sv/h$) was the lowest. In 200 cm, head, chest, and abdomen showed similar. On head, the measured dose rates were $9.56{\mu}Sv/h$, $5.23{\mu}Sv/h$, and $3.40{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.24{\mu}Sv/h$, $1.67{\mu}Sv/h$, and $1.27{\mu}Sv/h$ in 100, 150, and 200 cm on head. On chest, the measured dose rates were $8.54{\mu}Sv/h$, $4.90{\mu}Sv/h$, $3.44{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.27{\mu}Sv/h$, $1.34{\mu}Sv/h$, and $1.13{\mu}Sv/h$ in 100, 150, and 200 cm on chest. On abdomen, the measured dose rates were $9.83{\mu}Sv/h$, $5.15{\mu}Sv/h$, and $3.18{\mu}Sv/h$ in 100, 150, and 200 cm, respectively. When using shielder, it shows $2.60{\mu}Sv/h$, $1.75{\mu}Sv/h$, and $1.23{\mu}Sv/h$ in 100, 150, and 200 cm on abdomen. Transmittance was increased as the distance was expanded. As the distance was further, the radiation dose were reduced. When using shielder, the dose were reduced as one-forth of without shielder. The Radio technologists are exposed of radioactivity and there were limitations on reducing the distance with Therefore, the proper shielding will be able to decrease radiation dose to the technologists.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.94-98
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• 2011

Purpose: The radiation exposure from radioisotope at the hands and foots of radiation workers who works in PET/CT part at the department of nuclear medicine was investigated in this study. Materials and Methods: From 4th August 2010 to 14th January 2011, 6 radio-technologists' radiation on hands and feet were measured. All radio-technologist have been examined around 8; morning, 12; afternoon, and 16 o'clock; evening, respectively. SPSS version 17 was used for statistical analysis. Results: The statistical significances were calculated in several ways. The radiation from both hands and feet in the Morning was lower than Afternoon and Evening. In some cases, the detected radiation showed extremely high values in data. In order to find the effect of the ${\gamma}$-ray on the hand, the estimated doses were presumably calculated, however, the exposure dose on feet were unmeasured. Conclusion: Even if the radiation exposure from the radioisotope at the hands and feet were under the limitations, it is definitely needs to prevent the radiation-contamination. Therefore, the radio-technologists need to have a proper radiation-dealing-procedure of their own, and must try to prevent a radiation exposure by themselves.

• Journal of Radiation Protection and Research
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• v.26 no.4
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• pp.385-392
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• 2001

Environmental risk factors such as ionizing radiations, heavy metals, and pesticides can cause environmental disasters when they exist in excess. The increases in use of ionizing radiation and agricultural pesticide are somewhat related to the possibility of the disaster. The risk of radiation and pesticide was evaluated by means of the single cell gel electrophoresis (SCGE) assay on the human blood lymphocytes. The lymphocytes were irradiated with $0{\sim}2.0Gy$ of $^{60}Co$ gamma ray. Another groups of lymphocytes were exposed to various concentrations of parathion. Significantly increased tail moment, which was a marker of DNA strand breaks in SCGE assay, showed a clear dose- or concentration-response relationship. Parathion of a recommended concentration for agricultural use ($1mg {\ell}^{-1}$ ) has a strong cytotoxic effect on lymphocytes, which is equivalent to damage induced by 0.1 Gy of ${\gamma}$-ray. Furthermore, $2mg{\ell}^{-1}$ of parathion can give rise to DNA damage equivalent to that induced by 0.25 Gy at which the radiation-induced damage can start to develop into clinical symptoms. The comparative results of this study can provide an experimental basis and biological information for the prevention of environmental disaster.

• The Korean Journal of Nuclear Medicine Technology
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• v.17 no.1
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• pp.62-66
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• 2013

Purpose: I-131 is a radioisotope widely used for thyroid gland treatments. The physical half life is 8.01 and characterized by emitting beta and gamma rays which is used in clinical practice for the purpose of acquiring treatment and images. In order to reduce the recurrence rate after surgery in high-risk thyroid cancer patients, the remaining thyroid tissue is either removed or the I-131 is used for treatment during relapse. In cases of using a high dosage of radioactive iodine requiring hospitalization, the patient is administered dosage in the hospital isolation ward over a certain period of time preventing I-131 exposure to others. By checking the radiation amount emitted from patients before discharge, the patients are discharged after checking whether they meet the legal standards (50 uSv/h). After patients are discharged from the hospital, the contamination level is checked in many parts of the ward before the next patients are hospitalized and when necessary, decontamination operations are performed. It is expected that there is exposure to radiation when measuring the ward contamination level and dose check emitted from patients at the time of discharge whereby the radiation exposure by health workers that come from the patients in this process is the main factor. This study analyzed the correlation between discharge dose of patients and ward contamination level through a variety of factors such as renal functions, gender, age, dosage, etc.). Materials and Method: The study was conducted on 151 patients who received high-dosage radioactive iodine treatment at Soon Chun Hyang University Hospital during the period between 8/1/2011~5/31/2012 (Male: Female: 31:120, $47.5{\pm}11.9$, average dosage of $138{\pm}22.4$ mCi). As various factors expected to influence the patient discharge dose & ward contamination such as the beds, floors, bathroom floors, and washbasins, the patient renal function (GFR), age, gender, dosage, and the correlation between the expected Tg & Tg-Tb expected to reflect the remaining tissue in patients were analyzed. Results: In terms of the discharge dose and GFR, a low correlation was shown in the patient discharge dose as the GFR was higher (p < 0.0001). When comparing the group with a dosage of over 150mCi and the group with a lower dosage, the lower dosage group showed a significantly lower discharge dose ($24{\pm}10.4uSv/h$ vs $28.7{\pm}11.8uSv/h$, p<0.05). Age, gender, Tg, Tg-Tb did not show a significant relationship with discharge dose (p> 0.05). The contamination level in each spot of the treatment ward showed no significant relationship with GFR, Tg, Tg-Tb, age, gender, and dosage (p>0.05 ). Conclusion: This study says that discharge of the dose in the patient's body is low in GFR higher and Dosage 150mCi under lower. There was no case of contamination of the treatment ward, depending on the dose and renal association. This suggests that patients' lifestyles or be affected by a variety of other factors.

• Korean Journal of Environmental Agriculture
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• v.23 no.1
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• pp.52-58
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• 2004

This work was conducted to provide the reference data of radioactivity in the foodstuffs at a radiological emergency situation in Jeju Island The sampled foodstuffs were agricultural (31), livestock (6), marine (12) and forest products (4), and processed foods (3) consumed by Jeju Islanders. $^{137}Cs$ and $^{40}K$ activities were determined by HPGe r-ray spectromety. The activity ranges of $^{137}Cs$ was ${\sim}650\;mBq/kg$ fresh in the agricultural products, ${\sim}131\;mBq/kg$. fresh in the livestock, ${\sim}834\;mBq/kg$ fresh in the forest, ${\sim}253\;mBq/kg$ fresh in the marine and $32.0{\sim}483\;mBq/kg$. fresh in the processed foods (tea). In case of $^{40}K$ the activity was $16.6{\sim}542\;Bq/kg$. fresh in the agricultural products, $39.1{\sim}294\;Bq/kg$ fresh in the livestock, $85.5{\sim}116\;Bq/kg$ fresh in the forest, $50.1{\sim}657\;Bq/kg$ fresh in the marine, and $33.6{\sim}1,065\;Bq/kg$ fresh in the processed foods (tea). The highest activity of $^{137}Cs$, 834mBq/kg fresh was observed in oak mushroom and $^{40}K$ 1,065 Bq/kg fresh in coffee. Annual effective doses of $^{137}Cs$ and $^{40}K$ by intake of foodstuffs per capita were the following order; agricultural products (66,543 nSv) > livestock products (19,311 nSv) > processed foods (6,648 nSv) > marine products (6,579 nSv) > forest products (860 nSv). Therefore, total annual effective dose was summed 99,941 nSv which is quite low level comparing to the annual effective dose by external exposure, 2,400,000 nSv. The data obtained in this study can be useful for monitoring whether the foodstuffs are contaminated or not at an emergency radiation accident, and showed that the foodstuffs consumed in Jeju are safe in terms of annual effective dose of $^{137}Cs$ and $^{40}K$

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.194-201
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• 2015

We have investigated the EPR signal properties in 12 components of two mobile phones (LCD, OLED) using electron paramagnetic resonance (EPR) spectrometer in this study.EPR measurements were performed at normal atmospheric conditions using Bruker EXEXSYS-II E500 spectrometer with X-band bridge, and samples were irradiated by $^{137}Cs$ gamma-ray source. To identify the presence of radiation-induced signal (RIS), the EPR spectra of each sample were measured unirradiated and irradiated at 50 Gy. Then, dose-response curve and signal intensity variating by time after irradiation were measured. As a result, the signal intensity increased after irradiation in all samples except the USIM plastic and IC chip. Among the samples, cover glass(CG), lens, light guide plate(LGP) and diffusion sheet have shown fine linearity ($R^2$ > 0.99). Especially, the LGP had ideal characteristics for dosimetry because there were no signal in 0 Gy and high rate of increase in RIS. However, this sample showed weakness in fading. Signal intensity of LGP and Diffusion Sheet decreased by 50% within 72 hours after irradiation, while signals of Cover Glass and Lens were stably preserved during the short period of time. In order to apply rapidly EPR dosimetry using mobile phone components in large-scale radiation accidents, further studies on signal differences for same components of the different mobile phone, fading, pretreatment of samples and processing of background signal are needed. However, it will be possible to do dosimetry by dose-additive method or comparative method using unirradiated same product in small-scale accident.

• Journal of the Korean Society of Radiology
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• v.15 no.7
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• pp.943-948
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• 2021

The purpose of this study was to investigate changes in surface dose due to increased scattering of gamma rays from patients injected with ^99mTc and ¹⁸F, which are radioactive isotopes, in close contact with materials with high atomic number such as the walls of the stable room. Prepare ^99mTc and ¹⁸F by injecting 20 and 10 mCi respectively into the NEMA phantom, and then measuring the surface dose for 60 minutes by positioning the phantom at a height of 1 m above the surface, at a distance of 0, 5 and 10 cm from the wall, and at the same location as the phantom facing the wall. Each experiment was repeated five times for reproducibility of the experiment and one way analysis of variability (ANOVA) was performed for significance testing and Tukey was used as a post-test. The study found that surface doses of 220.268, 287.121, 243.957, and 226.272 mGy were measured at ^99mTc, respectively, in the case of empty space and in the case of 0, 5 and 10 cm, while those of ¹⁸F were measured at 637.111, 724.469, 657.107, and 640.365 mGy, respectively. In order to reduce changes in surface dose depending on the patient's location while waiting, it is necessary to keep the distance from the ground or the wall where the patient is closely adhered to, or install an air mattress, etc., to prevent the scattered lines as much as possible, considering the scattered lines due to the wall etc. in future setup of the patient waiting room and safety room, and in addition to the examination, the external skin width may be reduced.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.4
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• pp.343-356
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• 2016

The Korea Radioactive Waste Agency (KORAD) has developed a dual-purpose metal cask for the dry storage of spent nuclear fuel that has been generated by domestic light-water reactors. The metal cask was designed in compliance with international and domestic technology standards, and safety was the most important consideration in developing the design. It was designed to maintain its integrity for 50 years in terms of major safety factors. The metal cask ensures the minimization of waste generated by maintenance activities during the storage period as well as the safe management of the waste. An activation evaluation of the main body, which includes internal and external components of metal casks whose design lifetime has expired, provides quantitative data on their radioactive inventory. The radioactive inventory of the main body and the components of the metal cask were calculated by applying the MCNP5 ORIGEN-2 evaluation system and by considering each component's chemical composition, neutron flux distribution, and reaction rate, as well as the duration of neutron irradiation during the storage period. The evaluation results revealed that 10 years after the end of the cask's design life, $^{60}Co$ had greater radioactivity than other nuclides among the metal materials. In the case of the neutron shield, nuclides that emit high-energy gamma rays such as $^{28}Al$ and $^{24}Na$ had greater radioactivity immediately after the design lifetime. However, their radioactivity level became negligible after six months due to their short half-life. The surface exposure dose rates of the canister and the main body of the metal cask from which the spent nuclear fuel had been removed with expiration of the design lifetime were determined to be at very low levels, and the radiation exposure doses to which radiation workers were subjected during the decommissioning process appeared to be at insignificant levels. The evaluations of this study strongly suggest that the nuclide inventory of a spent nuclear fuel metal cask can be utilized as basic data when decommissioning of a metal cask is planned, for example, for the development of a decommissioning plan, the determination of a decommissioning method, the estimation of radiation exposure to workers engaged in decommissioning operations, the management/reuse of radioactive wastes, etc.

• Journal of radiological science and technology
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• v.39 no.2
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• pp.237-246
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• 2016

This study is therefore aimed at measuring the surface dose rate and the spatial dose rate in and outside the radionuclide facility in order to ensure safety of the patients, radiation workers and family care-givers in their use of such equipment and to provide a basic framework for further research on radiation protection. The study was conducted at 4 restrooms in and outside the radionuclide facility of a general hospital in Incheon between May 1 and July 31, 2014. During the study period, the spatial contamination dose rate and the surface contamination dose rate before and after radiation use were measured at the 4 places-thyroid therapy room, PET center, gamma camera room, and outpatient department. According to the restroom use survey by hospitals, restrooms in the radionuclide facility were used not only by patients but also by family care-givers and some of radiation workers. The highest cumulative spatial radiation dose rate was 8.86 mSv/hr at camera room restroom, followed by 7.31 mSv/hr at radioactive iodine therapy room restroom, 2.29 mSv/hr at PET center restroom, and 0.26 mSv/hr at outpatient department restroom, respectively. The surface radiation dose rate measured before and after radiation use was the highest at toilets, which are in direct contact with patient's excretion, followed by the center and the entrance of restrooms. Unsealed radioactive sources used in nuclear medicine are relatively safe due to short half lives and low energy. A patient who received those radioactive sources, however, may become a mobile radioactive source and contaminate areas the patient contacts-camera room, sedation room, and restroom-through secretion and excretion. Therefore, patients administered radionuclides should be advised to drink sufficient amounts of water to efficiently minimize radiation exposure to others by reducing the biological half-life, and members of the public-family care-givers, pregnant women, and children-be as far away from the patients until the dose remains below the permitted dose limit.