• Journal of the Korean Society of Radiology
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• v.13 no.4
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• pp.667-674
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• 2019

Because examination with technegas produces images through simple diffusion accumulation, the examination room can become contaminated after scan. Therefore, radiation workers and patients awaiting examination will be affected by internal exposure from technegas inhalation. Before and after gravity ventilation, I am trying to find a way to reduce the exposure dose of waiting patients according to a comparative analysis of horizontal spatial dose rates over time. Spatial dose ratio were measured for 10 minutes from various distances and angles around ventilator's location before and after gravity ventilation. Then, mean values, standard deviation and reduction ratio were calculated. The highest reduction rate of gravity ventilation was 95.31% and the highest reduction ratio was 1 to 3 minutes. Therefore, the gravity ventilation could reduce the exposure dose of radiologic technologists, waiting patients, patient guardians and nurses. In conclusion, the reduction of the exposure dose during the technegas ventilation study through gravity ventilation will play a role in optimiging the protection and it is in accordance with the recommended reduction of the medical exposure by ICRP 103.

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.61-65
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• 2015

Mammography equipment is an essential detector for making an early diagnosis of female's breast lesion. Recently, in most hospitals, a digital mammography detector is used due to the wide and consistent supply of digital mammography equipment. However, the average effective radiation is increasing due to the indiscreet use of CR or DR mammography. The purpose of this study is to recognize the possible indirect radiation damage, which can be occurred due to an excessive effective exposure of radiation, by evaluating spacial radiation rate of the digital mammography detector used for female patient. Consequently, the high mount of spacial radiation showed digital mammography equipment on the horizontal direction. Considering the result, digital mammography equipment should be installed by avoiding along the horizontal direction.

• Journal of radiological science and technology
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• v.32 no.4
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• pp.393-399
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• 2009

In this study, we measured the dose distribution of scattered ray in X-ray radiography room using an ion chamber and examined the dependency of scattered ray content on the scattered ray source and exposure condition. To study the factors of scattered ray occurrence in the acryl phantom, we measured the change in the scatted ray content according to the X-ray tube voltage (40~140 kV) and the field size ($10{\times}10\;cm^2$, $20{\times}20\;cm^2$, $35{\times}35\;cm^2$). For the $35{\times}35\;cm^2$ field size, the side-scattering rate ranged from 3.1% to 14.5%. The scattered ray contributions of the phantom, collimator, X-ray tube and wall were also measured. The scattered ray contribution of the phantom was higher than 95.4% for the entire tube voltage, and those of the collimator, X-ray tube and wall were 2.6%, 1.3% and 0.7%, respectively.

• Journal of the Korean Society of Radiology
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• v.14 no.4
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• pp.367-373
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• 2020

Most of the spatial scattered dose caused by the scattered rays generated by the collision between the object and X-rays is relatively easily absorbed by the human body as electromagnetic waves in the low energy region, thereby increasing the degree of radiation exposure. Such spatial scattering dose is also used as an indicator of the degree of radiation exposure of radiation workers and patients, and there is a need for a method to reduce exposure by reducing the spatial scattered dose that occurs indirectly. Therefore, in this study, a lead-free radiation shielding sheet was proposed as a way to reduce the spatial scattering dose, and a Monte Carlo (MC) simulation was performed based on a chest X-ray examination. The absorbed dose was calculated and the measured value and the shielding rate were compared and evaluated.

• Journal of the Korean Society of Radiology
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• v.15 no.6
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• pp.813-819
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• 2021

In this study, the shielding rate of L-block-type shielding equipment used for radiation protection when radioactive fluorine is injected into the human body and the dose distribution of the space in the injection room were calculated using the Monte Carlo method. The shielding rate of the body and window parts of the L-block-type shielding equipment was 99.99%. The dose distribution calculated at a distance of 1 m was relatively high at 135°, 45°, 225°, 315°, and 180° of the XZ plane, and was calculated to be very low at 0°, 90°, and 270°. In the YZ plane, it was relatively high at 135°, 180°, and 225°, and was calculated very low at the remaining angles. The AZ and BZ planes also showed similar results to the YZ plane. In addition, it was confirmed that the shielding rate was the best in the range of 225° to 315° through the dose distribution in the horizontal direction of the source and the 45° direction above the source. These results can be used as basic data necessary for radiation protection of radiation workers.

• Journal of Radiation Protection and Research
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• v.19 no.2
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• pp.121-132
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• 1994

This study concerns about the measurement and the investigation of environmental radiation characteristics which the components and the distribution of exposure rates by terrestrial y-rays in Taegu area. $4^{'}{\phi}{\times}4^{'}$ NaI(T1) scintillation detector with a multichannel analyzer was used in the measurement of y-rays as a part of in-situ spectrometry at twenty eight different locations in this area. The conversion into the exposure rate from the measured ${\gamma}-ray$ spectrum has been carried out leading to a net exposure rate and component ones by $^{40}K,\;^{238}U$ series and $^{232}Th$ series products which are known by the major parts in the terrestrial ${\gamma}-rays$ generally. As a result, the average exposure rate by the terrestrial ${\gamma}-rays$ in Taegu area is $9.4{\mu}R/h$ and the distribution of individual exposure rates shows more or less differences between these locations even after the consideration of diurnal and yearly variations which are always involved in these measurements. The component parts of exposure rates are distributed $^{40}K\;2.9{\sim}4.6{\mu}R/h,\;^{238}U$ series $1.2{\sim}3,\;1{\mu}R/h,\;^{232}Th$ series $2.5{\sim}5.0{\mu}R/h$ over the measured locations.

• Journal of Radiation Protection and Research
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• v.13 no.2
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• pp.29-40
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• 1988

A spectrum-exposure rate conversion operator G(E) for a portable HPGe detector used for field environmental radiation survey was theoretically developed on the basis of a space distribution function of gamma flux emitted from a disk source and an areal efficiency of the detector. The radiation exposure rates measured using this G(E) and the portable HPGe. detector connected to a portable multichannel analyzer were compared with those measured by a 3' ${\phi}\;{\times}$3' NaI(Tl) scintillation detector with the reported G(E) and a pressurized ionization chamber. A comparison of the three results showed that the result obtained using the HPGe detector was lower than those determined using the NaI(Tl) detector and ionization chamber by 17% to 29%, The difference obtained is close to that reported in literature. The method developed here can be easily applicable to obtain a G(E) factor suitable to any detector for detecting the exposure rate of environmental gamma radiation, since the spectrum-exposure rate conversion operator can be calculated by a hand calculator.

• Journal of Digital Convergence
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• v.12 no.4
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• pp.427-435
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• 2014

This study is performed in the intervention unit, during interventional procedures and in accordance with the direction and distance during the exposure indoor space is to measure the dose. I was classified at an angle of $45^{\circ}$ counterclockwise from the phantom. Seven(A, B, C, D, E, F, G) were classified as direction. Length was measured from the center of the phantom. Each direction 50cm, 100cm, 150cm, 200cm were classified. I was analyzed by measuring of frontal, lateral, Bi-plan fluoroscopic Spatial dose rate in all 28 points. Measured dose was the highest at 50cm and over 200cm, dose was rapidly decreasing as increased distance. Dose was different more than nine times depending on the distance and direction, Installation of shielding wall can reduce exposure about 84.52% to 93.54%.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.825-830
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• 2007

사면에서 발생되는 강우유출과정에 기여하는 대공극의 영향은 그 중요성에도 불구하고 잘 알려져 있지 않다. 특히 대공극의 공간적분포특상에 대한 현장측정은 이뤄지지 않았다. 본 연구의 실험지역은 경기도 포천시 광릉수목원에 있는 작은 소유역이다. 이 지역의 정밀한 측량을 하여 수치고도모형(DEM)을 얻었다. 이 수치고도모형을 바탕으로 수치지형분석을 통해 흐름선을 파악하여 총 20지점을 선정하였다. 각 지점에서의 대공극을 통한 수직적인 유동들은 장력침투계를 사용하여 지표면아래 깊이 10cm에서 측정하였다. 공간적 토양의 특성분포를 파악하기 위해 각 지점에서의 체적밀도와 점토함량을 조사하였다. 토양수분의 공간적 분포 특성은 TDR(Time Domain Reflectometry)방식인 TRASE를 이용하여 토양수분 값을 얻었다. 이러한 다양한 공간적 특성들은 대공극발달의 공간적 분포특성을 파악하는 중요자료가 된다. 소유역을 크게 기여사면 면적을 기준으로 상부, 중부, 하부로 나누어 대공극의 유효 공극율과 대공극흐름율을 계산하였다. 상부에서의 유효 대공극율의 평균값과 변동계수는 각각 4.3%, 42.1%이고, 대공극흐름율의 평균값과 변동계수는 각각 45.0%, 26.6%이다. 중부에서는 유효 대공극율의 평균값과 변동계수는 6.8%, 37.3%이고, 대공극흐름율의 평균값과 변동계수는 56.2%, 14.4% 이다. 그리고 하부에서의 유효공극율의 평균값과 변동계수는 12.5%, 58.3% 이고 대공극흐름율의 평균값과 변동계수는 64.5%, 24%이다. 이는 유효 대공극율과 대공극흐름율의 비율은 기여사면 면적이 증가할수록 증가하였다. 이는 대공극을 통한 물 이송 능력이 원두부로 갈수록 증가한다는 것을 보여주고 있다.e, taurine, methionine, phenylalanine은 함량(含量)이 적었다. 5. 일건(日乾)중 총유리아미노산의 변화(變化)는 생시료(生試料)의 경우 2,041.2 mg%였으나 1일(日) 건조(乾燥) 후는 1,784.0 mg%로 감소(減少)하다가 그 이후 계속 증가(增加)하여 20일(日) 건조(乾燥) 후는 5,277.0 mg%였다. 6. 일건(日乾)중 leucine, isoleucine, valine은 대체로 증가(增加)하는 경향(傾向)을 나타내었으나 aspartic acid, proline, taurine은 대체로 감소(減少)하는 경향(傾向)을 나타내었다. 436.59mg%로 가장 많았고 군유산(軍有山) 차엽(茶葉)이 146.94mg%로 가장 적었으며 일반차엽(一般茶葉)의 평균치(平均値)는 264.59mg%, 용장(龍欌) 차엽(茶葉)이 223.10mg%, Yabukita 차엽(茶葉)이 256.49mg%였다. 7) 이상(以上)의 결과(結果)를 종합(綜合)할 때 용장(龍欌) 차엽(茶葉)은 일반차엽(一般茶葉)과 형질(形質) 뿐만 아니라, 성분(成分)도 다르므로 품종(品種)이 다른 수종(樹種)으로 추정(推定)되며 와운(臥雲) 차엽(茶葉)은 일반차엽(一般茶葉)과 형질(形質)은 다르나 성분상(成分上)의 비슷한 점으로 보아 동일계통(同一系統)의 변이(變異)된 대엽종(大葉種)으로 추정(推定)된다.5(${\pm}0.77$0.77) % 의 오차로 크게 감소하였다. 결론: 방사선이 통과하는 경로에 불균질조직인 폐가 존재할 경우에도 불균질조직에 대하여 조직의 밀도를 이용하여 보정하는 방법을 사용하여 투과선량으로부터 종양선량을 계산할 수 있음을 알 수 있었다.X>로 평균$43.26{\m

• Journal of radiological science and technology
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• v.38 no.3
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• pp.237-244
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• 2015

Health professionals in nuclear medicine were known that they get high radiation exposure. To reduce radiation exposure, using shielding materials is needed. In this study, we analyzed the shielding effect about apron during 18F-FDG treatment by using simulation based on Monte Carlo techniques and actual measurement. As a result, absorbed dose distribution of organ varies with handling position of the source. Dose reduction ratio by lead thickness of apron tended to decease, when handling position of the source come close to organ and away from radiation source for simulation. In the case of actual measurement with the dosimetry device, It showed that mean spatial dose distribution was different due to characteristics of dosimetry device. However, spatial dose rate was exponentially reduced according to distance with increasing lead content.