• Journal of Radiation Protection and Research
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• v.47 no.2
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• pp.86-92
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• 2022

Background: The present study investigated the radiation dose distribution of balloon kyphoplasty (BKP) among surgeons and medical staff, and this is the first research to observe such exposure in Japan. Materials and Methods: The study subjects were an orthopedic surgeon (n = 1) and surgical staff (n = 9) who intervened in BKP surgery performed at the National Hospital Organization Disaster Medical Center (Tokyo, Japan) between March 2019 and October 2019. Only disposable protective gloves (0.022 mmPb equivalent thickness or less) and trunk protectors were used, and no protective glasses or thyroid drapes were used. Results and Discussion: The surgery time per vertebral body was 36.2 minutes, and the fluoroscopic time was 6.8 minutes. The average exposure dose per vertebral body was 1.46 mSv for the finger (70 ㎛ dose equivalent), 0.24 mSv for the lens of the eye (3 mm dose equivalent), 0.11 mSv for the neck (10 mm dose equivalent), and 0.03 mSv for the chest (10 mm dose equivalent) under the protective suit.The estimated cumulative radiation exposure dose of 23 cases of BKP was calculated to be 50.37 mSv for the fingers, 8.27 mSv for the lens, 3.91 mSv for the neck, and 1.15 mSv for the chest. Conclusion: It is important to know the exposure dose of orthopedic surgeons, implement measures for exposure reduction, and verify the safety of daily use of radiation during surgery and examination.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3035-3043
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• 2021

Epidemiological research has revealed that radiation exposure can cause cataracts. The Korean nuclear regulatory body has proposed the reduction of the occupational dose limit for the lens of the eye from 150 mSv/y to 100 mSv/5y, with an additional limitation of not exceeding 50 mSv/y for a specific year, taking into account the recommendations of the International Commission on Radiological Protection, and the International Atomic Energy Agency. This means that radiation workers should receive the same level of radiation safety for the lens of the eye as for whole-body protection. Korean nuclear power plants (NPPs) are conducting research to establish the radiation protection program for the lens of the eye. In terms of the preliminary results of the implementation of the radiation protection program for the lens of the eye dedicated to Korean NPPs, this review article summarizes the current state of understanding of the regulations, technical guidance, eye lens dosimeters, and radiation field conditions resulting in lens dose.

• The Journal of Korean Society for Radiation Therapy
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• v.8 no.1
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• pp.41-54
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• 1996

The secondary electrons developed by interaction between primary beam and a tray mounted for blocks in Megavoltage irradiation result in excess soft radiation dose to the surface layer. To reduce this electron contamination, electron filters have been used to be attached under a tray. Various filters with Cu and Al plates in six different thickness and Cu/Al combined plates in 3 different thickness were tested to measure the reduction rate of secondary electron contamination to the surface layer. The measurement to find optimal filter was performed on 6MV linear accelerator in $10 cm{\times}10 cm$ field size and fixed 78.5cm source to measurement points distance from surface to maximum build up point in 2mm intervals. The result was analyzed as the ratio of measured doses with using filters, to standard doses of measured open beam. The result of this study was fellowing : 1. The contaminated low energy radiation were mainly produced by blocking tray. 2. The surface absorbed dose was slowly increased by increasing irradiation field size but rapidly increased at field size above $15cm{\times}15cm$. 3. Al plate upto 2.5mm thickness used as a filter was found to be inadequate due to the failure of reduction of the surface absorbed dose below doses of the under surface upto the maximal build up. Cu 0.5mm plate and Cu 0.28mm/A1 1.5mm compound plate were found to be optimal filters. 4. By using these 2 filters, the absorbed dose to the surface were effectively reduced $5.5\%$ in field size $4cm{\times}4cm,\;11.3\%$ in field size $10cm{\times}10cm,\;22.3\%$ in field size $25cm{\times}25cm$. 5. In field size $10cm{\times}10cm$, the absorbed dose to the surface of irradiation was reduced by setting TSD 20cm at least,. but effective and enough dose reduction could be achieved by setting TSD 30cm as 2 optimal filters used. 6. More surface dose absorbed at TSD less than 7.4cm with a tray and filters together indicated that soft radiation was also developed by filters. 7. The variation of PDD by the different size of irradiation field was minimal as 2 optimal filters used. There was also not different in variation of PDD according to using any of two different filters. 8. PDD was not effected either by various TSD or by using the different filter among two.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.28 no.1
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• pp.1-6
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• 2020

The purpose of this study is to analyze the radiation dose data of the space crew of the flight crew and to present a plan for the health management of the flight crew on the basis of the analysis. The analysis show that the average exposure dose of the flight attendants continued to rise, and the exposure dose of the flight attendants was five(5) times higher than that of the radiation workers. As a way to reduce the effects of cosmic radiation, this paper suggests appropriate personnel allocation by model, balanced allocation of high and low latitude routes by crew according to the aircraft type, and a low altitude flight plan for high latitude flight. This study will help aviation crew members understand cosmic radiation and trust in the company's policies. In the future, it will be necessary to enhance the flight safety of the crew by deriving meaningful results by analyzing data related to cosmic radiation of various routes.

• The Journal of Korean Society for Radiation Therapy
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• v.26 no.2
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• pp.265-272
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• 2014

Purpose : To reduce the radiation dose to the thyroid that is affected to scattered radiation, the shield was used. And we evaluated the shielding effect for the thyroid during whole brain radiation therapy. Materials and Methods : To measure the dose of the thyroid, 300cGy were delivered to the phantom using a linear accelerator(Clinac iX VARIAN, USA.)in the way of the 6MV X-ray in bilateral. To measure the entrance surface dose of the thyroid, five glass dosimeters were placed in the 10th slice's surface of the phantom with a 1.5 cm interval. The average values were calculated by measured values in five times each, using bismuth shield, 0.5 mmPb shield, self-made 1.0 mmPb shield and unshield. In the same location, to measure the depth dose of the thyroid, five glass dosimeters were placed in the 10th slice by 2.5 cm depth of the phantom with a 1.5 cm interval. The average values were calculated by measured values in five times each, using bismuth shield, 0.5 mmPb shield, self-made 1.0 mmPb shield and unshield. Results : Entrance surface dose of the thyroid were respectively 44.89 mGy at the unshield, 36.03 mGy at the bismuth shield, 31.03 mGy at the 0.5 mmPb shield and 23.21 mGy at a self-made 1.0 mmPb shield. In addition, the depth dose of the thyroid were respectively 36.10 mGy at the unshield, 34.52 mGy at the bismuth shield, 32.28 mGy at the 0.5 mmPb shield and 25.50 mGy at a self-made 1.0 mmPb shield. Conclusion : The thyroid was affected by the secondary scattering dose and leakage dose outside of the radiation field during whole brain radiation therapy. When using a shield in the thyroid, the depth dose of thyroid showed 11~30% reduction effect and the surface dose of thyroid showed 20~48% reduction effect. Therefore, by using the thyroid shield, it is considered to effectively protect the thyroid and can perform the treatment.

• Radiation Oncology Journal
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• v.37 no.4
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• pp.254-258
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• 2019

Purpose: Deep inspiration breath hold (DIBH) is a well-established technique that enables efficient cardiac sparing in patients with left-sided breast cancer. The aim of the current study was to determine if DIBH is effective for reducing radiation exposure of of liver and other organs at risk in right breast radiotherapy (RT). Materials and Methods: Twenty patients with right-sided breast cancer were enrolled in this study. Three-dimensional conformal RT plans were generated for each patient, with two different computed tomography scans of free breathing (FB) and DIBH. Nodes were contoured according to the Radiation Therapy Oncology Group contouring guidelines. Dose-volume histograms for the target volume coverage and organs at risk were evaluated and analyzed. Results: DIBH plans showed significant reduction in mean liver dose (5.59 ± 2.07 Gy vs. 2.54 ± 1.40 Gy; p = 0.0003), V_20Gy (148.38 ± 73.05 vs. 64.19 ± 51.07 mL; p = 0.0003) and V_10Gy (195.34 ± 93.57 vs. 89.81 ± 57.28 mL; p = 0.0003) volumes compared with FB plans. Right lung doses were also significantly reduced in DIBH plans. Heart and left lung doses showed small but statistically significant improvement with application of the DIBH technique. Conclusion: We report that the use of DIBH for right-sided breast cancer significantly reduces the radiation doses to the liver, lungs, and heart.

• Korean Journal of Environmental Agriculture
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• v.21 no.2
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• pp.83-89
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• 2002

The effect of low dose $\gamma$ radiation on photosynthesis and the reduction of photoinhibition in red pepper plant was investigated. The seedling height leaf width and leaf length of pepper were stimulated in plants grown from seeds irradiated with the low dose of 4 Gy. The $O_2$ evolution in the 4 Gy irradiation group was 1.5 times greater than in the control. To investigate the effect of low dose $\gamma$ radiation on response to high light stress, photoinhibition was induced in leaves of pepper by illumination of high light (900 $\mu mol/m^2/s$). Pmax was decreased with increasing illumination time by 20% in the control, while hardly decreased in the 4 Gy irradiation group. The photochemical yield of PSII, estimated as Fv/Fm, was decreased with increasing illumination time by 50% after 4 hours while Fo did not change. However, Fv/Fm in the 4 Gy irradiation group was decreased by 37% of inhibition, indicating that the photoinhibition was decreased by the low dose $\gamma$ radiation. Changes in the effective quantum yield of PSII, $\Phi_{PSII}$, and 1/Fo-1/Fm, a measure of the rate constant of excitation trapping by the PSII reaction center, showed similar pattern to Fv/Fm. And NPQ was decreased after photoinhibitory treatment showing no difference between the control and the 4 Gy irradiation group. These results showed the positive effect of low dose $\gamma$ radiation on the seedling growth and the reduction of photoinhibition.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2003.09a
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• pp.63-63
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• 2003

Purpose: Planning target volume (PTV) for tumors in abdomen or thorax includes enough margin for breathing-related movement of tumor volumes during treatment. We developed a simple and handy method, which can reduce PTV margins in patients with moving tumors, respiratory motion reduction device system (RMRDs). Materials and Methods: The patients clinical database was structured for moving tumor patients and patient setup error measurement and immobilization device effects were investigated. The system is composed of the respiratory motion reduction device utilized in prone position and abdominal presser (strip device) utilized in the supine position, moving phantom and the analysis program, which enables the analysis on patients setup reproducibility. It was tested for analyzing the diaphragm movement and CT volume differences from patients with RMRDs, the magnitude of PTV margin was determined and dose volume histogram (DVH) was computed using a treatment planning software. Dose to normal tissue between patients with RMRDs and without RMRDs was analyzed by comparing the fraction of the normal liver receiving to 50% of the isocenter dose(TD50). Results: In case of utilizing RMRDs, which was personally developed in our hospital, the value was reduced to $5pm1.4 mm$, and in case of which the belt immobilization device was utilized, the value was reduced to 3$pm$0.9 mm. Also in case of which the strip device was utilized, the value was proven to reduce to $4pm.3 mm$0. As a result of analyzing the TD50 is irradiated in DVH according to the radiation treatment planning, the usage of the respiratory motion reduction device can create the reduce of 30% to the maximum. Also by obtaining the digital image, the function of comparison between the standard image, automated external contour subtraction, and etc were utilized to develop patients setup reproducibility analysis program that can evaluate the change in the patients setup. Conclusion: Internal organ motion due to breathing can be reduced using RMRDs, which is simple and easy to use in clinical setting. It can reduce the organ motion-related PTV margin, thereby decrease volume of the irradiated normal tissue.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.819-825
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• 2024

The reason for recording dose data when using a diagnostic radiation source is to record and manage the dose to healthcare personnel and patients. The purpose of this study was to verify the difference in radiation dose when using diagnostic radiation generating devices and to inform users' awareness of dose reduction through measurement and analysis of dose in situations with and without shielding. The dose analysis of each equipment for two Korean C-arms and two German C-arms showed that the Korean FPD type C-arm had the highest dose value, followed by the German I.I type C-arm, German FPD type C-arm, Korean, and I.I type C-arm. The results of the dose analysis with and without shielding showed that the dose to the human phantom in a normal atmosphere increased by about 2 times due to scattered radiation, but the dose to the human phantom was reduced by about 5 times by wearing a shield (0.5mm/lead apron). More important than the management of radiation dose is the study of how to reduce exposure when using radiation, and since the radiation dose output from different equipment is different, it is necessary to provide dose information with and without shielding.

• Progress in Medical Physics
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• v.30 no.4
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• pp.75-88
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• 2019

Diagnostic reference level (DRL) is employed to optimize the radiation doses of patients. The objective of this study is to review the DRLs for interventional procedures in Korea and abroad. Literature review was performed to investigate radiation dose index and measurement methodology commonly used in DRL determination. Dose area product (DAP) and fluoroscopy time within each major procedure category were systematically abstracted and analyzed. A wide variation was found in the radiation dose. The DAP values and fluoroscopy times ranged 0.01-3,081 Gy·㎠ and 2-16,878 seconds for all the interventional procedures, 8.5-1,679 Gy·㎠ and 32-5,775 seconds for the transcatheter arterial chemoembolization (TACE), and 0.1-686 Gy·㎠ and 16-6,636 seconds for the transfemoral cerebral angiography (TFCA), respectively. The DRL values of the DAP and fluoroscopy time were 238 Gy·㎠ and 1,224 seconds for the TACE and 189 Gy·㎠ and 686 seconds for the TFCA, respectively. Generally, the DRLs of Korea were lower than those of other developed countries, except for the percutaneous transluminal angioplasty with stent in arteries of the lower extremity (LE PTA and stent), aneurysm coil embolization, and Hickman insertion procedures. The wide variation in the radiation doses of the different procedures suggests that more attention must be paid to reduce unnecessary radiation exposure from medical imaging. Furthermore, periodic nationwide survey of medical radiation exposures is necessary to optimize the patient dose for radiation protection, which will ultimately contribute to patient dose reduction and radiological safety.