• Journal of Radiation Protection and Research
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• v.15 no.1
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• pp.9-13
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• 1990

1959년 한국원자력연구소가 창립됨과 동시에 &Health Physics&, 즉 보건물리라고 하는 명칭과 조직이 탄생되어, 방사선안전관리의 실무와 보건물리의 연구가 시작되었다. 최초 10년간은 선진제국의 보건물리분야의 연구와 기술을 추적하여 우리나라의 방사선안전관리 기술의 기초를 다지는 시기로서 개인방사선모니터링기술, 환경방사선(능) 모니터링기술 및 방사선방어용계측기기의 교정기술 개발에 중점을 두고 연구개발이 추진되었으며, TRIGA Mark-II 연구용원자로의 가동에 따라 원자로 생체차폐체의 건전성 검증에 관한 유익한 방사선량 측정자료도 얻게 되었다. 즉 이 기간은 방사선안전관리의 체제정비 및 기초기술 확립에 노력한 기간이었다. 1970년대는 원자력 연구개발에 대한 기본방향과 정책의 변경등으로 보건물리 연구조직은 방사선안전관리, 환경연구 그리고 방사화학분야로 분산되었으며, 그로인하여 연구개발활동은 거의 정체되어 겨우 방사선안전관리 실무만이 그 명맥을 유지하였다. 그 결과 우리나라 방사선안전관리 및 그와 관련된 연구개발의 기반이 흔들리게 되었으나, 그러한 환경하에서도 방사선량측정평가기술, 방사선차폐설계기술 및 원자로사고시 피폭선량평가기술의 선진화에 필요한 지식을 얻었으며, 방사선 안전관리에 유익한 실무경험도 축적하게 되었다. 1980년대는 통합된 원자력 연구개발체제의 구축으로 방사선작업종사자 및 일반공중의 피폭저감화 기술개발에 필요한 각종 최신기술을 도입하였고, 관리업무에 있어서도 측정의 정확도와 신뢰성향상 및 새로운 관리기술의 개발에 많은 노력을 한 결과, 유익한성과를 얻게된 기간이다. 특히, 이 기간은 방사선안전관리기술의 선진화를 위한 지식이 축적되어 90년대의 방사선안전관리기술자립화를 위한 전환기로서, 이와같이 축적된 기술은 원자력의 평화적 이용에 크게 기여할 것으로 기대된다.서 dithiothreitol를 투여한 군에서는 우라늄단독투여군에 비해 cretinine의 배설이 상당히 증가하였다(P<0.05). 6. 우라늄오염에 의한 신장의 소견에 있어 우라늄단독투여군은 근위곡세뇨관상피의 공포화 및 종창, microvilli와 brush border의 손실, 세뇨관 상피의 괴사가 관찰되었으며, 간장의 충혈, 중심성 괴사 및 모세관 확장증도 관찰되었다. 그리고 sodium bicarbonate와 생리적 식염수를 병행투여한 군과 우라늄을 투여하고 30분이 지나서 dithiothreitol를 투여한 군에서는 우라늄 단독투여군에 비해 높은 방호효과가 관찰되었으나 다른 실험군에서는 큰 효과가 없는 것으로 나타났다. 결론적으로 우라늄의 체내오염시에는 sodium bicarbonate와 생리적 식염수를 가능한 빨리 병행투여하거나 dithiothreitol을 체내오염후 30분이 지나서 투여하는 방법이 우라늄오염에 대한 제염에 매우 유효할 것으로 생각되며, 특히 우라늄에 의한 인체장해를 유의하게 경감시켜줄 것으로 사료되었다.내의 어떤 부위와도 관계가 되는 것으로 간주되는데 이것이 $(^3H)$ QNB가 $(^3H)$ NMS보다 높은 최대 결합능력 $(B_{max})$을 나타낼 이유이다. (b) 두 종류의 다른 제제에서 우리는 같은 양상의 결과를 관찰하었기에 결점이 많은 homogenates 제제보다는 intact cell aggregates 제제를 수용체 연구에 대한 새로운 실험모형(experiment model)으로 사용할 수 있는 가능성을 제시하고자 한다.$가 38.8%로 가장 많고, 그 다음이 ${\ulcorner}$l9세(歲)이후${\lrcorner}$가 25.2%로서 전체

• The Journal of the Korean dental association
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• v.53 no.8
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• pp.558-568
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• 2015

Objective: The objectives of this study were to measure pediatric organ and effective doses of cone-beam computed tomography (CBCT) for orthodontic analysis and to compare them to those of panoramic and lateral cephalometric radiography, the conventional radiography for orthodontic analysis. Materials and Methods: Alphard VEGA for CBCT, Planmeca Proline XC for panoramic radiography and Orthophos CD for cephalometric radiography were used for this study. Thermoluminescent dosimeter (TLD) chips were located at 24 anatomic sites of 10-year-old anthropomorphic phantom and exposed during CBCT (C-mode; $200{\times}179mm$ FOV), panoramic and lateral cephalometric radiographic procedures at the clinical exposure settings for 10-year-old patient. Pediatric organ and effective doses were measured and calculated using ICRP 2007 tissue weighting factors. Results: Effective doses of CBCT, panoramic radiography and lateral cephlometric radiography in pediatric clinical exposure settings were $292.5{\mu}Sv$, $19.3{\mu}Sv$, and $4.4{\mu}Sv$ respectively. The thyroid gland contributed most significantly to the effective dose in all the radiographic procedures. Conclusion: Effective dose of CBCT was about 12 times to conventional radiographic procedures for orthodontic analysis in pediatric patient. The use of CBCT for orthodontic analysis should be fully justified over conventional radiography and dose optimization to decrease thyroid dose is needed in pediatric patients.

• Radiation Oncology Journal
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• v.7 no.2
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• pp.299-303
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• 1989

Authors have developed highly reproducible calibration method for the Micro-Selectron HDR Ir-192 system (Nucletron, Motherland). The new jig has a 10cm radius circular hole in the $30cm{\times}30cm{\times}0.2cm$ acrylic plate, and 5F flexible bronchial tubes are attached around the hole. The source moves along the circle in the tubes and the ionization chamber is placed verticaly at the center of the circular hole (center of the jig). Dose distribution near the center was derived theoretically, and measured with the film dosimetry system. Theoretical calculation and measurement show the error margin below $0.1\%$ for 1mm or 2mm position deviation. We have measured at 12 and 24 points of circle with 1, 6, 11 and 21 second dwell time of source in order to calculate the activity of the source. Measurements have been repeated daily for 50 days. The accuracy and the reproducibility are below $1\%$ error margin. The half life of the source from our measurement is estimated $73.4\pm0.4$ days.

• Progress in Medical Physics
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• v.21 no.4
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• pp.360-366
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• 2010

To generate on-board digital tomosynthesis (DTS) for three-dimensionalimage-guided radiation therapy (IGRT) as an alternative to conventional portal imaging or on-board cone-beam computed tomography (CBCT), two clinical cases (liver and bladder) were selected to illustrate the capabilities of on-board DTS for IGRT. DTS images were generated from subsets of CBCT projection data (45, 162 projections) using half-fan mode scanning with a Feldkamp-type reconstruction algorithm. Digital tomosynthesis slices appeared similar to coincident CBCT planes and yielded substantially more anatomic information. Improved bony and soft-tissue visibility in DTS images is likely to improve target localization compared with radiographic verification techniques and might allow for daily localization of a soft-tissue target. Digital tomosynthesis might allow targeting of the treatment volume on the basis of daily localization.

• Radiation Oncology Journal
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• v.13 no.4
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• pp.403-409
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• 1995

Purpose : Authors tried to enhance the safety and accuracy of radiosurgery by verifying stereotacitc target point in actual treatment position prior to irradiation. Materials and Methods : Before the actual treatment, several sections of anthropomorphic head phantom were used to create a condition of unknown coordinates of the target point. A film was sandwitched between the phantom sections and punctured by sharp needle tip. The tip of the needle represented the target point. The head phantom was fixed to the stereotactic ring and CT scan was done with CT localizer attached to the ring. After the CT scanning, the stereotactic coordinates of the target point were determined. The head phantom was secured to accelerator's treatment couch and the movement of laser isocenter to the stereotactic coordinates determined by CT scanning was performed using target positioner. Accelerator's anteroposterior and lateral portal films were taken using angiographic localizers. The stereotactic coordinates determined by analysis of portal films were compared with the stereotactic coordinates previously determined by CT scanning. Following the correction of discrepancy the head phantom was irradiated using a stereotactic technique of several arcs. After the irradiation, the film which was sandwitched between the phantom sections was developed and the degree of coincidence between the center of the radiation distribution with the target point represented by the hole in the film was measured. In the treatment of the actual patients, the way of determining the stereotactic coordinates with CT localizers and angiograuhic localizers was the same as the phantom study. After the correction of the discrepancy between two sets of coordinates, we proceeded to the irradiation of the actual patient. Results : In the phantom study, the agreement between the center of the radiation distribution and the localized target point was very good. By measuring optical density profiles of the sandwitched film along axes that intersected the target point, authors could confirm the discrepancy was 0.3 mm. In the treatment of an actual patient, the discrepancy between the stereotactic coordinates with CT localizers and angiographic localizers was 0.6 mm. Conclusion : By verifying stereotactic target point in actual treatment position prior to irradiation, the accuracy and safety of streotactic radiosurgery procedure were established.

• The Korean Journal of Nuclear Medicine Technology
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• v.20 no.2
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• pp.32-35
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• 2016

Purpose The goal for this study is to figure out that medical staff except Nuclear Medicine Department could be exposed to radiation from the patients who take Nuclear Medicine examination. Materials and Methods Total 250 patients (Bone scan 100, Myocardial SPECT 100, PET/CT 50) were involved from July to October in 2015, and we measured patient dose rate two times for every patients. First, we checked radiation dose rate right after injecting an isotope (radiopharmaceutical). Secondly, we measured radiation dose rate after each examination. Results In the case of Bone scan, dose rate were $0.0278{\pm}0.0036mSv/h$ after injection and $0.0060{\pm}0.0018mSv/h$ after examination (3 hrs 52 minutes after injection on average). For Myocardial SPECT, dose rate were $0.0245{\pm}0.0027mSv/h$ after injection and $0.0123{\pm}0.0041mSv/h$ after examination (2 hrs 09 minutes after injection on average). Lastly, for PET/CT, dose rate were $0.0439{\pm}0.0087mSv/h$ after examination (68 minutes after injection on average). Conclusion Compared to Nuclear Safety Commission Act, there was no significant harmful effect of the exposure from patients who have been administered radiopharmaceuticals. However, we should strive to keep ALARA(as low as reasonably achievable) principle for radiation protection.

• Journal of Radiation Protection and Research
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• v.23 no.4
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• pp.229-236
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• 1998

In order to establish a testing system for personnel dosimetry performance, the radiation fields from photons, beta particles and neutrons are required, in recent, Korea Institute of Nuclear Safety(KINS) established the reference radation fields except neutrons and tested a variety of their properties. As a result of the test, the reference beams were shown to meet satisfactorily not only the standards of the International Organization for Standardization(ISO), but also the standard levels of the developed countries which are intercomparable with the international traceability. This paper describes the reference beam of gamma radiation. The self-designed and established reference radiation fields were investigated and analyzed by ISO and other international standards. The secondary photon contribution and the beam uniformity of the gamma radiation field were measured and evaluated to fulfill those requirements suggested by the ISO-4037. The measured air kerma rate for the $^{137}$Cs and $^{60}$Co gamma fields was 0.1891 $\sim$ 23.4967 $\mu$Gy/s sand 0.5844 $\sim$ 15.9954 $\mu$Gy/s respectively. The uncertainty with 95 % confidence level of the measured air kerma rate was determined to be less than 2.5 % which is comparable to the international reference gamma radiation fields. It was found that the evaluated air kerma calibration factors of Exradin ionization chamber were in good agreement within 0.9 % and 0.03 % with those given by PTB and NIST, respectively. The gamma radiation fields installed at KINS can maintain traceability systems in Korea, Germany and United State.

• Radiation Oncology Journal
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• v.14 no.3
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• pp.237-244
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• 1996

Purpose : The accurate dosimetry of independent collimator equipped for 6MV and 15MV X-ray beam was investigated to search for the optimal correction factor. Materials and Methods : The field size factors, beam quality and dose distribution were measured by using 6MV, 15MV X-ray Field size factors were measured from $3{\times}3cm^2$ to $35{\times}35cm^2$ by using 0.6cc ion chamber (NE 2571) at Dmax. Beam qualities were measured at different field sizes, off-axis distances and depths. Isodose distributions at different off-axis distance using $10\times10cm^2$ field were also investigated and compared with symmetric field. Result: 1) Relative field size factors was different along lateral distance with maximum changes in $3.1\%$ for 6MV and $5\%$ for 15MV. But the field size factors of asymmetric fields were identical to the modified central-axis values in symmetric field, which corrected by off-axis ratio at Dmax. 2) The HVL and PDD was decreased by increasing off-axis distance. PDD was also decreased by increasing depth For field size more than $5{\times}cm^2$ and depth less than 15cm, PDD of asymmetric field differs from that of symmetric one ($0.5\~2\%$ for 6MV and $0.4\~1.4\%$ for 15MV). 3) The measured isodose curves demonstrate divergence effects and reduced doses adjacent to the edge close to the flattening filter center was also observed. Conclusion . When asymmetric collimator is used, calculation of MU must be corrected with off-axis and PDD with a caution of underdose in central axis.

• Progress in Medical Physics
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• v.14 no.3
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• pp.196-202
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• 2003

In 3-dimensional conformal radiation therapy (3D-CRT) and intensity-modulated radiation therapy (IMRT), many studies on reducing setup error have been conducted in order to focus the irradiation on the tumors while sparing normal tissues as much as possible. As one of these efforts, we developed an image enhancement and registration tool for simulators and portal images that analyze setup errors in a quantitative manner. For setup verification, we used simulator (films and EC-L films (Kodak, USA) as portal images. In addition, digital-captured images during simulation, and digitally-reconstructed radiographs (DRR) can be used as reference images in the software, which is coded using IDL5.4 (Research Systems Inc., USA). To improve the poor contrast of portal images, histogram-equalization, and adaptive histogram equalization, CLAHE (contrast limited adaptive histogram equalization) was implemented in the software. For image registration between simulator and portal images, contours drawn on the simulator image were transferred into the portal image, and then aligned onto the same anatomical structures on the portal image. In conclusion, applying CLAHE considerably improved the contrast of portal images and also enabled the analysis of setup errors in a quantitative manner.

• Progress in Medical Physics
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• v.25 no.1
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• pp.8-14
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• 2014

The amounts of radioactive wastes to be disposed in the medical institute have been increased due to development of radiation diagnosis and therapy rapidly. They are produced mostly by the very short lived radioisotopes such as $^{18}F$ used in PET/CT, $^{99m}Tc$, $^{123}I$, $^{125}I$ and $^{201}Tl$, etc. IAEA proposed a criteria for the clearance level of waste which depends on the individual ($10{\mu}Sv/y$) and collective dose (1 man-Sv/y), and concentration of each nuclide (IAEA Safety Series No 111-P-1.1, 1992 and IAEA RS-G-1.7, 2004). Radioactive wastes of $^{18}F$, $^{99m}Tc$, $^{123}I$, $^{125}I$ and $^{201}TI$ in the several types of container like Marinelli beaker, vial and plastic, were collected to measure the concentration of the waste of each nuclide in accordance with IAEA criteria. The measurement method and procedure of determining specific activity of the wastes using gamma emitters like MCA, gamma counter and beta emitters were developed. For the efficiency calibration of the detectors, CRM (certified reference material) which has the same dimension and shape was provided by Korea Research Institute of Standards and Science (KRISS). Correction factor of the radioactivity decay was calculated based on the measurement results, and the consideration of mutual relation with theoretical equation. The result of this study will be proposed as ISO standard.