• Journal of Radiation Industry
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• v.9 no.1
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• pp.47-55
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• 2015

Research and investigation is required for the exposure dose of radiation workers to work in the dental hospital as increasing interest in exposure dose of the dental hospital recently accordingly, study aim to minimize radiation exposure by making a follow-up study of individual exposure doses of radiation workers, analyzing the status on individual radiation exposure management, prediction the radiation disability risk levels by radiation, and alerting the workers to the danger of radiation exposure. Especially given the changes in the dental hospital radiation safety awareness conducted the study in order to minimize radiation exposure. This study performed analyses by a comparison between general and dental hospital, comparing each occupation, with the 116,220 exposure dose data by quarter and year of 5,811 subjects at general and dental hospital across South Korea from January 1, 2008 through December 31, 2012. The following are the results obtained by analyzing average values year and quarter. In term of hospital, average doses were significantly higer in general hospitals than detal ones. In terms of job, average doses were higher in radiological technologists the other workes. Especially, they showed statistically significant differences between radiological technologists than dentists. The above-mentioned results indicate that radiation workers were exposed to radiation for the past 5 years to the extent not exceeding the dose limit (maximum $50mSv\;y^{-1}$). The limitation of this study is that radiation workers before 2008 were excluded from the study. Objective evaluation standards did not apply to the work circumstance or condition of each hospital. Therefore, it is deemed necessary to work out analysis criteria that will be used as objective evaluation standard. It will be necessary to study radiation exposure in more precise ways on the basis of objective analysis standard in the furture. Should try to minimize the radiation individual dose of radiation workers.

• Journal of the Korea Safety Management & Science
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• v.6 no.3
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• pp.87-97
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• 2004

The National Health Insurance Act, the Industrial Health Act and the School Health Act require chest radiography at least once a year. In chest radiographic examination, most group examinations use indirect X-ray primarily aiming at diagnosing diseases and enhancing people's health. This study purposed to minimize radiation exposure dose by comparing it between direct and indirect chest X-ray studies. According to the result of comparing and analyzing radiation exposure dose, the average incident dose and penetrating dose were 0.929μGy and 0.179μGy respectively in direct chest X-ray and 6.807μGy and 1.337μGy in indirect chest X-ray In order to minimize radiation exposure dose at direct and indirect chest X-ray, indirect X-ray should be excluded from group examination if possible. Moreover, it is necessary to control the quality of equipment (Q/A & Q/C) systematically and to avoid using unqualified equipment in order to reduce radiation exposure dose.

• Journal of Radiation Protection and Research
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• v.45 no.2
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• pp.81-87
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• 2020

Background: Kori unit #1 is permanently shut down after a 40-year lifetime. The Nuclear Safety and Security Commission recommends establishing initial decommissioning plans for all nuclear and radwaste treatment facilities. Therefore, the Korea Atomic Energy Research Institute (KAERI) must establish an initial and final decommissioning plan for radwaste-treatment facilities. Radiation safety assessment, which constitutes one chapter of the decommissioning plan, is important for establishing a decommissioning schedule, a strategy, and cost. It is also a critical issue for the government and public to understand. Materials and Methods: This study provides a method for assessing external radiation dose to workers during decommissioning. An external dose is calculated following each exposure scenario, decommissioning strategy, and working schedule. In this study, exposure dose is evaluated using the deterministic method. Physical characterization of the facility is obtained by both direct measurement and analysis of the drawings, and radiological characterization is analyzed using the annual report of KAERI, which measures the ambient dose every month. Results and Discussion: External doses are calculated at each stage of a decommissioning strategy and found to increase with each successive stage. The maximum external dose was evaluated to be 397.06 man-mSv when working in liquid-waste storage. To satisfy the regulations, working period and manpower must be managed. In this study, average and cumulative exposure doses were calculated for three cases, and the average exposure dose was found to be about 17 mSv/yr in all the cases. Conclusion: For the three cases presented, the average exposure dose is well below the annual maximum effective dose restriction imposed by the international and domestic regulations. Working period and manpower greatly affect the cost and entire decommissioning plan; hence, the chosen option must take account of these factors with due consideration of worker safety.

• Progress in Medical Physics
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• v.28 no.4
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• pp.218-225
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• 2017

Effects on skin caused by the dose from linear accelerator (LINAC) opposing portal irradiation and TomoDirect 3-D modeling treatment according to the radiation devices and treatment methods were measured, and a comparative analysis was performed. Two groups of 10 patients each were created and measurements were carried out using an optically stimulated luminescence dosimeter. These patients were already receiving radiation treatment in the hospital. Using the SPSS statistical program, the minimum and maximum average standard deviations of the measured skin dose data were obtained. Two types of treatment method were selected as independent variables; the measured points and total average were the dependent variables. An independent sample T-test was used, and it was checked whether there was a significance probability between the two groups. The average of the measured results for the LINAC opposing portal radiation was 117.7 cGy and PDD 65.39% for the inner breast, 144.7 cGy and PDD 80.39% for the outer breast, 143.2 cGy and PDD 79.56% for the upper breast, 151.4 cGy and PDD 84.11% for the lower breast, 149.6 cGy and PDD 83.11% for the axilla, and 141.32 cGy and PDD 78.51% for the total average. In contrast, for TomoDirect 3-D conformal radiotherapy, the corresponding measurement values were 137.6 cGy and PDD 76.44%, 152.3 cGy and PDD 84.61%, 148.6 cGy and PDD 82.56%, 159.7 cGy and PDD 88.72%, and 148.6 cGy PDD 82.56%, respectively, and the total average was 149.36 cGy and PDD 82.98%. To determine if the difference between the total averages was statistically significant, the independent sample T-test of the SPSS statistical program was used, which indicated that the P-value was P=0.024, which was 0.05 lower than the significance level. Thus, it can be understood that the null hypothesis can be dismissed, and that there was a difference in the averages. In conclusion, even though the treatment dose was similar, there could be a difference in the dose entering the body surface from the radiation treatment plan; however, depending on the properties of the treatment devices, there is a difference in the dose affecting the body surface. Thus, the absorbed dose entering the body surface can be high. During breast cancer radiotherapy, radiation dermatitis occurs in almost all patients. Most patients have a difficult time while undergoing treatment, and therefore, when choosing a radiotherapy treatment method, minimizing radiation dermatitis is an important consideration.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.27 no.3
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• pp.170-179
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• 2017

Objectives: This study aims to investigate the occupational radiation exposures of emergency medical technicians(EMTs) in emergency medical centers in Korea. The results will provide a basis for developing prevention programs to minimize adverse health effects relating to radiation exposure among emergency medical technicians working in this area. Methods: Radiation exposure doses were measured for twenty-two EMTs working in six emergency medical centers. Thermo Luminescent Dosimeters(TLD) were placed on three representative body parts, including chest, neck, and a finger. Measurements were conducted over the entire working hours of the participants for foor weeks. Dosimeters were analyzed according to a standard method by a KFDA-designated lab. Detection rate, annual radiation exposure dose, and relative levels to dose limit were derived based on the measured doses from the dosimeters. SPSS/Win 18.0 software(IBM, US) was used for statistical analysis. Results: Detection rates were 45.5%, 36.4%, and 45.5% for the dosimeters sampled from chest, neck, and a finger, respectively. The average annual doses were $2.39{\pm}3.44mSv/year$(range 0.38-10.0 mSv/year) for the chest, $2.72{\pm}3.05mSv/year$(2.00-11.34) for the neck, and $20.98{\pm}17.57mSv/year$(1.25-53.50) for the hand dose. The average annual eye dose was estimated to $3.61{\pm}2.37mSv/year$(1.50-8.34). The exposure dose levels of EMTs were comparable to those of radiologists, who showed relatively higher radiation dose among health care workers, as reported in another study. Conclusions: EMTs working in emergency medical centers are considered to be at risk of radiation exposure. Although the radiation exposure dose of EMTs does not exceed the dose limit, it is not negligible comparing to other professionals in health care sectors.

• Journal of Radiation Protection and Research
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• v.39 no.4
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• pp.182-186
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• 2014

Recently, the use of panoramic radiography has shown a constant increase, and significant research is underway. However, radiation exposure attracts less attention in dental radiography than in other types of radiography. We used an OSLD for measurement of the entrance skin dose in eyeballs and the thyroid region, both of which are not covered by examinations but are included in radiographical regions and are sensitive to radiation, as well as orally in Incheon and reported the results. The entrance skin dose was 0.0282 mSv on average for the oral region, and 0.0259 mSv on average for the eyeball, and 0.0261mSv on average, for thyroid gland. While there is no proper shielding method for the eyeball, a thyroid protector is not used by most hospitals and most hospitals are equipped with an apron and a thyroid protector separately; thus, it is necessary to use an integration of an apron and a thyroid protector and medical device manufacturers need to develop a method for controlling the length of the slit in the slit-type area of radiation occurrence in order to reduce unnecessary exposure.

• Journal of Radiation Protection and Research
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• v.36 no.4
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• pp.183-189
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• 2011

To quantitatively evaluate how setup errors in conjunction with dose gradients contribute to the error in IMRT dose quality assurance (DQA) measurements. The control group consisted of 5 DQA plans of which all individual field dose differences were less than ${\pm}5%$. On the contrary, the examination group was composed of 16 DQA plans where any individual field dose difference was larger than ${\pm}10%$ even though their total dose differences were less than ${\pm}5%$. The difference in 3D dose gradients between the two groups was estimated in a cube of $6{\times}6{\times}6\;mm^3$ centered at the verification point. Under the assumption that setup errors existed during the DQA measurements of the examination group, a three dimensional offset point inside the cube was sought out, where the individual field dose difference was minimized. The average dose gradients of the control group along the x, y, and z axes were 0.21, 0.20, and 0.15 $cGy{\cdot}mm^{-1}$, respectively, while those of the examination group were 0.64, 0.48, and 0.28 $cGy{\cdot}mm^{-1}$, respectively. All 16 plans of the examination group had their own 3D offset points in the cube. The individual field dose differences recalculated at the offset points were mostly diminished and thus the average values of total and individual field dose differences were reduced from 3.1% to 2.2% and 15.4% to 2.2%, respectively. The offset distribution turned out to be random in the 3D coordinate. This study provided the quantitative data that support the large individual field dose difference mainly stems from possible geometric errors (e.g., random setup errors) under the influence of steep dose gradients of IMRT field.

• Journal of Radiation Protection and Research
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• v.43 no.1
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• pp.10-19
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• 2018

Background: Monte Carlo (MC) simulation is the most accurate for calculating radiation dose distribution and determining patient dose. In MC simulations of the therapeutic accelerator, the characteristics of the initial electron must be precisely determined in order to achieve accurate simulations. However, It has been computation-, labor-, and time-intensive to predict the beam characteristics through predominantly empirical approach. The aim of this study was to analyze the relationships between electron beam parameters and dose distribution, with the goal of simplifying the MC commissioning process. Materials and Methods: The Varian Clinac 2300 IX machine was modeled with the Geant4 MC-toolkit. The percent depth dose (PDD) and lateral beam profiles were assessed according to initial electron beam parameters of mean energy, radial intensity distribution, and energy distribution. Results and Discussion: The PDD values increased on average by 4.36% when the mean energy increased from 5.6 MeV to 6.4 MeV. The PDD was also increased by 2.77% when the energy spread increased from 0 MeV to 1.019 MeV. In the lateral dose profile, increasing the beam radial width from 0 mm to 4 mm at the full width at half maximum resulted in a dose decrease of 8.42% on the average. The profile also decreased by 4.81% when the mean energy was increased from 5.6 MeV to 6.4 MeV. Of all tested parameters, electron mean energy had the greatest influence on dose distribution. The PDD and profile were calculated using parameters optimized and compared with the golden beam data. The maximum dose difference was assessed as less than 2%. Conclusion: The relationship between the initial electron and treatment beam quality investigated in this study can be used in Monte Carlo commissioning of medical linear accelerator model.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.2
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• pp.3-12
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• 2011

Purpose: With increasing medical use of radiation and radioactive isotopes, there is a need to better manage the risk of radiation exposure. This study aims to grasp and analyze the individual radiation exposure situations of radiation-related workers in a medical facility by specific job, in order to instill awareness of radiation danger and to assist in safety and radiation exposure management for such workers. Materials and Methods: From January 1, 2010 December 31, 2010, medical practitioners working in the radiation is classified as a regular personal radiation dosimetry, and subsequently one year 540 people managed investigation department to target workers, dose sectional area, working period, identify the job function-related tasks for a deep dose, respectively, the annual average radiation dose were analyzed. Frequency analysis methods include ANOVA was performed. Results: Medical radiation workers in the department an annual radiation dose of Nuclear and 4.57 mSv a was highest, dose zone-specific distribution of nuclear medicine and in the 5.01~19.05 mSv in the high dose area distribution showed departmental radiation four of the annual radiation dose of Nuclear and 7.14 mSv showed the highest radiation dose. More work an average annual radiation dose according to the job function related to the synthesis of Cyclotron to 17.47 mSv work showed the highest radiation dose, Gamma camera Cinema Room 7.24 mSv, PET/CT Cinema Room service is 7.60 mSv, 2.04 mSv in order of intervention high, were analyzed. Working period, according to domain-specific average annual dose of radiation dose from 10 to 14 in oral and maxillofacial radiology practitioners as high as 1.01~3.00 mSv average dose showed the Department of Radiology, 1-4 years, 5-9 years, respectively, 1.01 workers~8.00 mSv in the range of the most high-dose region showed the distribution, nuclear medicine, and the 1-4 years, 5-9 years 3.01~19.05 mSv, respectively, workers of the highest dose showed the distribution of the area in the range of 10 to 14 years, Workers at 15-19 3.01~15.00 mSv, respectively in the range of the high-dose region were distributed. Conclusion: These results suggest that medical radiation workers working in Nuclear Medicine radiation safety management of the majority of the current were carried out in the effectiveness, depending on job characteristics has been found that many differences. However, this requires efforts to minimize radiation exposure, and systematic training for them and for reasonable radiation exposure management system is needed.

• Journal of Korean Neurosurgical Society
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• v.64 no.6
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• pp.933-943
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• 2021

Objective : Percutaneous pedicle screw (PPS) fixation is a needle based procedure that requires fluoroscopic image guidance. Consequently, radiation exposure is inevitable for patients, surgeons, and operation room staff. We hypothesize that reducing the production of radiation emission will result in reduced radiation exposure for everyone in the operation room. Research was performed to evaluate reduction of radiation exposure by modifying imaging manner and mode of radiation source. Methods : A total of 170 patients (680 screws) who underwent fusion surgery with PPS fixation from September 2019 to March 2020 were analyzed in this study. Personal dosimeters (Polimaster Ltd.) were worn at the collar outside a lead apron to measure radiation exposure. Patients were assigned to four groups based on imaging manner of fluoroscopy and radiation modification (pulse mode with reduced dose) : continuous use without radiation modification (group 1, n=34), intermittent use without radiation modification (group 2, n=54), continuous use with radiation modification (group 3, n=26), and intermittent use with radiation modification (group 4, n=56). Post hoc Tukey Honest significant difference test was used for individual comparisons of radiation exposure/screw and fluoroscopic time/screw. Results : The average radiation exposure/screw was 71.45±45.75 µSv/screw for group 1, 18.77±11.51 µSv/screw for group 2, 19.58±7.00 µSv/screw for group 3, and 4.26±2.89 µSv/screw for group 4. By changing imaging manner from continuous multiple shot to intermittent single shot, 73.7% radiation reduction was achieved in the no radiation modification groups (groups 1, 2), and 78.2% radiation reduction was achieved in the radiation modification groups (groups 3, 4). Radiation source modification from continuous mode with standard dose to pulse mode with reduced dose resulted in 72.6% radiation reduction in continuous imaging groups (groups 1, 3) and 77.3% radiation reduction in intermittent imaging groups (groups 2, 4). The average radiation exposure/screw was reduced 94.1% by changing imaging manner and modifying radiation source from continuous imaging with standard fluoroscopy setting (group 1) to intermittent imaging with modified fluoroscopy setting (group 4). A total of 680 screws were reviewed postoperatively, and 99.3% (675) were evaluated as pedicle breach grade 0 (<2 mm). Conclusion : The average radiation exposure/screw for a spinal surgeon can be reduced 94.1% by changing imaging manner and modifying radiation source from real-time imaging with standard dose to intermittent imaging with modified dose. These modifications can be instantly applied to any procedure using fluoroscopic guidance and may reduce the overall radiation exposure of spine surgeons.