• Radiation Oncology Journal
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• 제6권1호
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• pp.109-116
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• 1988

The Alcyon Co-60 gamma rays was studied for electron contamination. The surface dose, attributable almost entirely to contamination electrons, has a linear dependence on field width for square fields and an inverse square dependence on distance from the bottom of the fixed head assembly Build-up and surface dose measurements were taken with and without an acrylic blocking tray in place. Further measurements were made with a copper filter designed to reduce secondary electrons emitted by photon interactions with the acrylic tray. The results are discussed in relation to skin sparing effect for radiation therapy Patients. And to achieve the maximum skin sparing effect, the selection of the optimum SSD and TSD is needed.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2001년도 추계학술발표회요약집
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• pp.269.2-269
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• 2001

• Journal of Radiation Protection and Research
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• 제11권2호
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• pp.123-129
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• 1986

Cs-137 및 Co-60감마선 조사장치를 사용하여 비임의 입체각이 $2.4{\pi}{\times}10^{-3}sr$에서 $17.3{\pi}{\times}10^{-3}sr$로 변함에 따른 공기의 산란인자와 두께 2.9cm 납 흡수체 사용에 따른 축적인자를 결정하였다. 그 결과 산란인자는 $1{\sim}1.064$, 축적인자는 $1.054{\sim}1.194$범위의 값을 갖는 것으로 각각 나타났다. 결정된 인자들의 검증을 위하여 계산값과 측정값을 비교한 결과 그 차이는 3.3%이하인 것으로 나타났다.

• 한국의학물리학회지:의학물리
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• 제13권1호
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• pp.44-50
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• 2002

실험실에서 성장시킨 CsI(T1)섬광체를 이용하여 검출기를 설계 제작하고 분광 및 출력특성을 조사하여 핵분광과 진단방사선센서로서의 응용가능성을 타진해 보았다. CsI(T1)단결정은 수직 Bridgman성장장치를 이용하여 지름 11mm, 몰농도 0.001mo1%로 성장시키었다. 이 단결정을 광다이오드를 이용하여 방사선 센서로 제작한 후, $^{22}$ Na, /up 137/Cs, $^{30}$ Co 표준감마선원에 대한 에너지 분해능을 각각 측정하였으며 진단 X선 영역에 대한 출력특성도 측정하였다. $^{22}$ Na의 0.511 MeV 의 경우13.2%, $^{137}$Cs의 0.662 MeV의 경우 8.3%, 그리고 $^{60}$Co의 1.17 MeV와 1.332 MeV에 대해서는 각각 6.7%와 5.1%의 에너지 분해능을 얻었다. 또한 관전압 60kVp, 80kVp, 100kVp, 120kVp 에 대하여 5mAs부터 80mAs 까지 진단 X선영역에 대한 출력 선형성을 확인하였다.

• Fibers and Polymers
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• 제5권3호
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• pp.225-229
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• 2004

The effect of UV and $^60{Co}$ gamma radiations on the physical and mechanical properties of nylon 6 mono-filaments with different draw ratios has been studied. Specimens were exposed to either up to 25 Mrad of gamma or up to 168 hrs of intense UV irradiation. The results show that nylon mono-filaments exposed to gamma rays, with much higher quantum energy than UV, undergo a larger extent of molecular chain scission. Higher irradiation dose also results in the production of insoluble, macroscopic three-dimensional cross-linked network structure. The amorphous regions with a lower density of cohesive energy (lower molecular orientation) show a higher extent of cross linking reaction whereas amorphous regions with a higher density of cohesive energy (higher orientation) show higher extent of chain scission reaction, irrespective of UV ray or gamma ray irradiation.

• Radiation Oncology Journal
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• 제2권1호
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• pp.149-153
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• 1984

Postoperative radiotherapy of breast cancer makes it possible to reduce loco-regional recurrence of breast cancer. The treatment technique, which can reduce the low-dose region at the junction and lung, is required. To produce proper dose distribution of internal mammary chain and chest wall, authors tried to find the method to expose $^{60}Co\;\gamma-ray$ on internal mammary region and 7MeV electron on chest wall. Exposure time of $^{60}Co\;\gamma$ and monitor unit of 9MeV were selected so that dose of $^{60}Co$ at 4cm depth was the same as that of 7Mev electron at $80\%$ dose depth. The position and direction of electron beam were changed for $^{60}Co$ beam: $0^{\circ},\;5^{\circ}$ for 0cm seperation; $0^{\circ},\;5^{\circ},\;10^{\circ}$ for 0.5cm seperation; $5^{\circ},\;10^{\circ},\;15^{\circ}$ for 1cm seperation. The results are as followings. 1. When the seperation of two fields was increased, dose on the axis of $^{60}Co$ beam was increased and dose at the junction region decreased while the volume of lung to be exposed to high dose and hot spot size were irregularly changed. 2. The dose distribution in the target volume of internal mammary and chest wall was most ideal when the seperation of two fields was $0\~0.5cm$ and the direction of electron beam was parallel to $^{60}Co$ beam.

• 대한방사선치료학회지
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• 제4권1호
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• pp.83-86
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• 1990

• 대한방사선치료학회지
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• 제3권1호
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• pp.27-36
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• 1989

In order to calculate the dose on each interest point in five types of irregularly shaped fields used commonly in radiotherapy, the tissue-air ratios (TAR) in these fields for Go-60 gamma radiation were calculated using the newly devised SAR-chart. The TARs calculated from newly method of using the SAR-chart, computer method and approximation method at the interest point were compared to the TARs obtained from measurement. The result are as follows; In case of the interest points on central axis the calculated TARs in irregularly shaped fields by the above mentioned methods were well agreed within the error of $1\%$, whereas for the interest points on off-axis the calculated TARs were resulted in the maximum errors of $2.4\%,\;2.3\%$ and $8.8\%$ respectively. From these results, the accuracy of calculation method of using the SAR-chart was comfirmed.

• Journal of Radiation Protection and Research
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• 제16권2호
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• pp.7-16
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• 1991

감마선 조사선량의 국가표준을 확립하기 위하여 Co-60 감마선에 대한 조사선량률 절대 측정을 수행하였고 그 값이 갖는 오차한계를 분석 평가하였다. 측정기로는 고순도 흑연으로 제작된 원통형 이온전리함을 사용하였고 이온화 전류 측정은 vibrating reed 증폭기를 사용한 전하모드법에 의해 수행되었으며 관련 물리상수 및 각종 관련 보정인자를 평가하여 이온화 전류 측정값으로부터 조사선량률을 결정하였다.

• Journal of Microbiology and Biotechnology
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• 제28권4호
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• pp.527-533
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• 2018

This study compared the radioprotective effects of high-molecular-weight poly-gamma-glutamate (${\gamma}-PGA$, average molecular mass 3,000 kDa) and a reduced form of glutathione (GSH, a known radioprotector) on calf thymus DNA damage. The radiation-induced DNA damage was measured on the basis of the decreased fluorescence intensity after binding the DNA with ethidium bromide. All the experiments used $^{60}Co$ gamma radiation at 1,252 Gy, representing 50% DNA damage. When increasing the concentration of ${\gamma}-PGA$ from 0.33 to $1.65{\mu}M$, the DNA protection from radiation-induced damage also increased, with a maximum of 87% protection. Meanwhile, the maximal DNA protection when increasing the concentration of GSH was only 70%. Therefore, ${\gamma}-PGA$ exhibited significant radioprotective effects against gamma irradiation.