• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.351-356
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• 2022

The purpose of this study was to evaluate the cancer incidence rate and provide basic data by measuring the photoneutron dose generated during intensity-modulated radiation therapy and volumetric modulated arc therapy used in radiation therapy for prostate cancer. The optically stimulated luminescence albedo neutron dosimeter for neutron measurement was placed on the Rando phantom in the abdomen and thyroid and photoneutron dose generated was measured. As a result of the study, intensity-modulated radiation therapy (7 portal) was measured to be higher than volumetric rotational radiation therapy in both abdominal and thyroid locations. When the cancer incidence rate was evaluated using the nominal risk coefficient of ICRP 103, the cancer incidence rate due to exposure to the colon and thyroid during intensity-modulated radiation therapy was 9.9 per 1,000 people, and volumetric rotational radiation therapy for 1,000 people. It was 3.5 per person. Based on the principle of ALARA (As low as reasonably archievable), it is considered to be a guideline for minimizing the exposure dose to normal organs in the establishment of a radiation treatment plan.

• Journal of the Korean Society of Radiology
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• v.17 no.2
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• pp.249-255
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• 2023

In this study, radiation exposure doses were measured in the course of clinical practice of radiation workers, radiological technologists in the radiation-related worker group, and preliminary-radiological technologists who were classified as frequent visitors. Radiological technologists who worked in the radiation area of C University Hospital in Incheon for a year from January 2021 and 121 students who completed clinical practice at the same medical institution from July 1 to August 31 were the subjects of the study. The nominal risk factor based on ICRP 103 was used to evaluate the probability of side effects due to the exposure dose to the lungs, which are organs at risk of damage due to radiation exposure dose. During the clinical practice period, radiology students, who were classified as frequent visitors, had a surface dose of 0.98 ± 0.14 mSv and a deep dose of 0.93 ± 0.14 mSv. In other words, 6.7 per 1,000,000 for shallow dose and 6.4 per 1,000,000 for deep dose were found to have side effects due to exposure to the lungs. This is a value in terms of exposure dose in one year. Considering that the radiation (science) education course is 3 or 4 years, systematic management and attention to prospective radiation workers who are going to clinical practice are required, and the stochastic effect of radiation In relation to this, it is considered that it will be used as basic data for radiation safety management.

• Journal of the Korean Society of Radiology
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• v.18 no.4
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• pp.383-389
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• 2024

In this study, we aimed to analyze the probability of secondary cancer occurring in the abdomen, a normal organ, due to photoneutron exposure during intensity-modulated radiotherapy for prostate cancer. The design of the radiation treatment plan for prostate cancer was established as a daily prescription dose of 220 cGy, a total of 35 treatments, and 7700 cGy. The experimental equipment was a True Beam STx (Varian, USA) linear accelerator from Varian. The energy used in the experiment was 15 MV, and the treatment plan was designed so that the photoneutron dose would be generated within the planning target volume (PTV). The radiation treatment plan was an Eclipse System (Varian Ver. 10.0, USA), and the number of irradiation portals was set to 5 to 9. The irradiation angle was designed so that 95% of the prescription dose area was set to 0 to 320°, and the number of beamlets per irradiation portal was set to 100. The optically stimulated luminescence dosimeter used in this study to measure the dose of photoneutrons was designed to measure photoneutron doses by coating ⁶LiCO₃ on a device containing aluminum oxide components. It was studied that there is a minimum of 7.07 to 11 cases per 1,000 people with secondary cancer due to the photoneutron dose to the abdomen during intensity-modulated radiotherapy. In this study, we studied the risk of secondary radiation dose that may occur during intensity-modulated radiotherapy, and we expect that this will be used as meaningful data related to the probabilistic effects of radiation in the future.

• The Korean Journal of Financial Management
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• v.8 no.1
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• pp.155-177
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• 1991

기업의 재무구조와 인플레이션과의 관계는 세율에 대한 다양한 형태의 가정을 통하여 연구, 분석되어 왔으나, 이 문제를 확실히 해결하지는 못하였다. 근자에 A. Marcus(1983)가 미국의 은행의 재무구조를 대상으로 한 시계열분석 결과에 의하면 명목이자율의 상승이 미국은행의 부채 대비 자본금 비율을 하락시키는 절대적 요인이 되었다고 한다. 본 연구의 목적은 인플레이션과 은행의 부채 대비 자본금 비율의 상관관계, 더욱 나아가서 은행자산의 위험도가 이 상관관계에 미치는 영향을 분석코자 한다. 본고는 은행규제기관(FDIC 등)의 부채비율과 은행자산(포트폴리오)의 위험도에 대한 규제하에서 은행이 부채(예금)와 자본금의 가치를 극대화하고자 하는 모델을 설정하여 기대 인플레이션 수준이 은행의 적정 자본비율과 자산의 위험도와 어떤 관계가 있는가를 밀러의 균형모델(Miller Equilibrium Model)을 원용하여 분석하였다. 밀러의 균형모델하에서는 기업의 재무구조는 기업가치와 무관한 것으로 나타나고 있다. 즉, 부채를 통한 자금조달에 의해 발생되는 한계세금혜택은 균형하에서는 사라진다는 이론이다. 따라서 인플레이션은 적정 재무구조에는 영향을 미치지 못하게 된다. 왜냐하면 인플레이션은 기업의 세후 부채조달비용과 회사채 투자자 수익에 동일한 영향을 미치기 때문이다. 그러나 은행의 경우 일반 기업과는 달리 은행규제기관의 부채비율 및 자산위험도에 대한 규제압력이 소위 암묵적 규제비용으로 작용하여 은행의 적정자본금비율은 부채(예금)를 통한 자금조달의 한계세금혜택과 이에 따른 한계규제바용이 동일하게 되는 경우에 결정된다. 밀러의 단순균형 모델하에서 한계세금혜택이 없는 것과는 달리 은행의 부채조달에 따른 한계규제비용이 존재하는 이유로 균형조건으로 한계세금이익이 존재하게 된다. 이 경우 인플레이션은 예금자의 실질 세후 예금이자를 상승시키는 것 이상으로 은행의 실질 세후 예금이자 지급비용을 하락시키게 되어 은행의 부채비율을 더욱 높이게 되는 원인이 된다. 또한 은행의 부채비율이 인플레이션과 정(正)의 관계에 있다면 은행규제의 강도에 따라 이 상관계수는 은행자산의 위험도와도 역시 정(正)의 관계에 있게 된다. 미국은행을 대상으로 한 회귀분석에서도 그들의 부채(예금)비율이 기대 인플레이션과 정(正)의 상관관계가 있음이 나타났고 그 상관계수는 은행자산의 위험도와 동일 방향으로 움직임이 판명되었다.

• Journal of the Korean Society of Radiology
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• v.16 no.3
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• pp.357-363
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• 2022

This study aims to improve the safety inspection awareness of occupational exposure and help radiation safety management by analyzing radiation exposure doses by occupational type of radiation related-workers and radiation workers. Radiation-related workers and radiation workers were classified into three occupations (radiological technologist, doctors, and nurses). A nominal risk coefficient based on ICRP 103 was used to calculate the probability of causing side effects of the lungs due to exposure doses. As a result of analyzing the exposure dose of all workers for one year, the exposure dose of radiological technologist among radiation-related workers was 1.63 ± 2.84 mSv, doctors 0.12 ± 0.22 mSv, and nurses 0.59 ± 1.08 mSv. The one-year deep dose for radiation workers was 2.44 ± 3.30 mSv for radiological technologists, 0.19 ± 0.26 mSv for doctors, and 0.12 ± 0.00 mSv for nurses. Due to this dose, the probability of causing side effects in the lungs was 1.2 per 100,000 radiological technologist, 0.096 doctors, and 0.06 nurses. In this study, it is believed that the probability of side effects on lungs by occupation of radiation exposure dose will be studied and used as useful data for radiation safety management in relation to probabilistic effects in the future.