• Journal of radiological science and technology
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• v.47 no.4
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• pp.249-254
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• 2024

This study compared the X-ray shielding abilities of the shields using Computed Radiography(CR) System after manufacturing a lead-free boards using gypsum and BaSO₄, an eco-friendly X-ray shielding material. Total six lead-free boards were manufactured with BaSO₄ concentrations of 25 %, 50 % and thickness of 10 mm, 15 mm, 20 mm respectively, and additional thickness of 1.0 mm, 1.5 mm, 2.0 mm leads were prepared. In the experiment, Nine shields were placed on the Image Plate and placed in a Computed Tomography(CT) Room where CT scans were performed for 2 weeks. After that, the X-ray image of the shields were obtained through CR Reader, and Pixel Value(PV) were measured to evaluated the X-ray shielding abilities of the lead-free shields. The criterion for evaluating the shields was determined by comparing PV of lead-free board to that of the 1.5 mm thickness lead used in the CT rooms. As a result of the experiment, the PV of the lead-free boards within 25 % of the BaSO₄ concentration and within 10 mm of the thickness were not enough to be used as X-ray shields in the CT Room because they did not reach the PV of the 1.5 mm thickness lead. BaSO₄ concentration of 50 % at 20 mm thickness showed PV of 1.5 mm lead thickness or more indicating that it has an X-ray shielding ability to replace lead in the CT room

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.324-326
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• 2006

CCD형 영상소자는 방사선 피폭 시 표면과 격자내부에 모두 손상을 받게 되며, 감마방사선이나 X선과 같은 고에너지의 이온화 방사선에 노출될 경우 격자 실리콘 내부에 전자-전공쌍(Electron-hole pair, EHP)이 발생된다. 이러한 EHP는 CCD의 순간 출력 광전류로 변환되어 백색 화소 형태의 영상잡음으로 가시화되며, 이 화소 수는 피폭 방사선량에 비례하여 증가하는 특성을 지니고 있다. 따라서 출력 영상정보를 분석하면 조사된 방사선의 양과 특성을 측정할 수 있다. 본 연구에서는 CCD를 이용하여 가상의 방사능 물질 누출 공간에서 방사선원의 방향과 거리정보를 고속으로 탐지하기 위한 장치와 고속 측정 알고리즘을 구현하고 실제 방사선장에서 실증시험을 수행하였다. 방사선 탐지기는 콘형 납 콜리메이터(Collimator)와 가시광 변환용 신틸레이터(CsITl) 및 차폐체로 구성된 센서부와 제어 및 방사광 신호처리를 수행하는 PC부로 구성된다. 감마방사선($^{60}Co$) 방사선장 실증시험에서 방사선원간 거리 83cm에서 측정된 거리 탐지는 5.3%의 오차로 확인되었다. 이 방사선 탐지기는 임의의 고방사선 누출사고에 대한 초기대응 작업을 수행하기 위한 무인 이동로봇용 방사선 탐지기로 활용이 가능하다.

• The Journal of Korean Society for Radiation Therapy
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• v.7 no.1
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• pp.156-166
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• 1995

Total body irradiation (TBI) requires large radiation field and extended source to axis distance (SAD), therefore in needs large size treatment room and it needs compensators which components. Appropriate thickness beam spoiler should be used to raise skin dose. Treatment machine, photon energy, total dose, dose rate, dose fractionation, patient position, shield of normal tissues and organs were known to important parameters for TBI. TBI disturbes regular daily treatment schedule and significantly overloads Radiation on oncology departments and during the treatment session it requires accurate reproduction of radiation field and patient position. We were enable to TBI in small size treatment room and short SAD with parallel opposing lateral fields technique and achieved homogenious whole body dose distribution using pb compensators and controled lung dose by lung shield blocks. Drawing a patient shadow on the wall, we could shortened set up time and possible to accurate reproduction of radiation field and patient position.

• Nuclear Engineering and Technology
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• v.15 no.4
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• pp.248-255
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• 1983

The thermal analysis on the spent fuel shipping cask for a PWR fuel assembly is performed. Under the normal and fire-accident conditions the temperature distribution through a multilayer cask calculated in compliance with 10 CFR Part 71. A KNU 5&6 spent fuel assembly is assumed to be the decay heat source, which has the maximum discharge turnup of 45, 000MWD/MTU and has been stored in the spent fuel storage pool for 300 days. As a result of thermal analysis, the maximum cladding temperature in case of dry cavity under fire-accident conditions is calculated to be 455$^{\circ}C$. This value is much less than the limiting value specified in 10 CFR Part 50.46. It indicates that no fuel rod cladding rupture could occur under fire-accident conditions. It was also found that no melting of lead would take place in the major shield region.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.9-20
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• 1988

In order to quantify the contribution of cosmic-ray ionizing component to the dose given by natural background radiation, a series of measurement has been carried out using LiF TLDs for about one and a half years on quarterly basis. Three different types of LiF TLDs namely, chips and PTFE based disks of $^{7}LiF$, and the same disks of $^{6}LiF$ for identifying possible contribution of neutron component were used. Measurements were made by placing badge-incased TLDs in a lead castle of 10 to 15cm thick installed in a room on the third floor of a four-story building in CNU Daedeok campus for 5 cycles of 90 days. For comparison a series of spectrometric study was also performed for the energy region over 3MeV using a 3'${\phi}\;{\times}\;3$'NaI(Tl) scintillation detector in association with an MCA of 1024 channels, and it was found that the data obtained by the TLDs placed in the lead castle indicate 75% of the dose given by outdoor cosmic-ray component. The results obtained by the TLDs through correction for shielding loss show that the outdoor dose contribution of ionizing component of cosmic rays at this campus is $34.3{\pm}1.1nGy/h$ which satisfactorily agrees with that expected for our particular location of measurement.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.2
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• pp.87-94
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• 2005

Purpose : Heavy metal use when producing the block from the workshop. At this time, production of heavy metal dust and fume gives risk in human. This like heavy metal to improve seriousness through measurement and analysis. And by the quest in solution is purpose of this thesis. Materials and Methods : Organization is Inductively Coupled Plasma Atomic Emission Spectrometer, and the object is Deajeon city 4 workshops in university hospital radiation oncology (Bismuth, Lead, Tin and cadmium). Method is the ppb the pumping it does at unit, comparison analysis. And the Calculation heavy metal standard level in air through heavy metal standard level in body and blood, so Heavy metal temporary standard set. Results : Subterranean existence room air quality the administration laws appointed Lead and Cadmium's exposure recommend that it is $3{\mu}g/m^3\;and\;2{\mu}g/m^3$. And Bismuth and Tin decides $7{\mu}g/m^3\;and\;6{\mu}g/m^3$ through standard level in air heavy metal and standard level in body and blood. Heavy metal measurement level of workshops in 4 university hospital Daejeon city compares with work existence and nonexistence. On work nonexistence almost measurement level is below the recommend level. But work existence case express high level. Also consequently in composition ratio of the block is continuous with the detection ratio. Conclusion : Worker's heavy metal contamination imbrued serious for solution founds basic part. In hospital may operation on local air exhauster and periodical efficiency check, protector offer, et al. And worker have a correct understanding part of heavy metal contamination, and have continuous interest, health control. Finally, learned society sphere administer to establishment standard level and periodical measurement. And it founds basic solution plan of periodical special health checkup.

• The Korean Journal of Nuclear Medicine Technology
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• v.16 no.2
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• pp.115-119
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• 2012

Purpose : The initial Breast-Specific Gamma Imaging (BSGI) protocol included bilateral breast imaging with 2 views of each breast-craniocaudal (CC) and mediolateral oblique (MLO). Furthermore, Axillary lymph nodes view can be acquired easily. The most meaningful prognosis factor for prediction of breast cancer is whether or not the breast cancer has metastasized to the lymph nodes. However, axillary view doesn't conduct in clinical. This article collates a diverse data of BSGI and describes technical details to acquire optimal imaging. Materials and Methods : A retrospective review was performed on 343 patients who had undergone BSGI between May 2011 and March 2012. Patients who had undergone BSGI received intravenous injection of 740 MBq (20 mCi) $^{99m}Tc$-sestamibi. Results : The following contents are the technical details for optimal axillary imaging. $^{99m}Tc$-sestamibi should be administered using an indwelling venous catheter or scalp needle followed by 10 cc of saline to flush to reduce extravasation and vascular trapping. After administration, patients raise their arm over their head and exercise with stress ball for 1 full minute. A lead shield attached to the gamma camera is removed and patients axilla is placed as close as possible to the camera at a $90^{\circ}$ angle. A lead apron is placed across the shoulder to reduce background from other organs. Acquisition time is enough for 120 sec~180 sec. Conclusion : If patients undergo bilateral axillary imaging as a standard with CC, MLO views, it could improve cancer treatment. Result of this study could maximize efficiency axillary imaging of breast cancer patients.