• Journal of Radiation Industry
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• v.11 no.1
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• pp.39-45
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• 2017

A cyclotron is a kind of particle accelerator that produces a beam of charged particles for the production of medical, industrial, and research radioisotopes. More than 30 cyclotrons are operated in Korea to produce $^{18}F$, an FDG synthesis at hospitals. A 30-MeV cyclotron was installed at ARTI (Advanced Radiation Technology Institute, KAERI) mainly for research regarding isotope production. In this study, we analyze and estimate the items of risk such as the problems in the main components of the cyclotron, the loss of radioactive materials, the leakage of coolant, and the malfunction of utilities, fires and earthquakes. To estimate the occurrence frequency in an accident risk assessment, five levels, i.e., Almost certain, Likely, Possible, Unlikely, and Rare, are applied. The accident consequence level is classified under four grades based on the annual permissible dose for radiation workers and the public in the nuclear safety law. The analysis of the accident effect is focused on the radioactive contamination caused by radioisotope leakage and radioactive material leakage of a ventilation filter due to a fire. To analyze the risks, Occupation Safety and Health Acts is applied. In addition, action plans against an accident were prepared after a deep discussion among relevant researchers. In this acts, we will search for hazard and introduce the risk assessment for the research 30-MeV cyclotron facilities of ARTI.

• Journal of Radiation Protection and Research
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• v.35 no.1
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• pp.6-11
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• 2010

Embodying the safety of radioactive waste disposal requires the relevant safety criteria and the corresponding stylized methods to demonstrate its compliance with the criteria. This paper proposes a conceptual model of risk-based safety evaluation for integrating complex potential radiation exposure situations in radioactive waste disposal. For demonstrating compliance with a risk constraint, the approach deals with important exposure scenarios from the viewpoint of the receptor to estimate the resulting risk. For respective exposure situations, it considers the occurrence probabilities of the relevant exposure scenarios as their probability of giving rise to doses to estimate the total risk to a representative person by aggregating the respective risks. In this model, an exposure scenario is simply constructed with three components:radionuclide release, radionuclide migration and environment contamination, and interaction between the contaminated media and the receptor. A set of exposure scenarios and the representative person are established from reasonable combinations of the components, based on a balance of their occurrence probabilities and the consequences. In addition, the probability of an exposure scenario is estimated on the assumption that the initiating external factors influence release mechanisms and transport pathways, and its effect on the interaction between the environment and the receptor may be covered in terms of the representative person. This integrated approach enables a systematic risk assessment for complex exposure situations of radioactive waste disposal and facilitates the evaluation of compliance with risk constraints.

• Environmental Analysis Health and Toxicology
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• v.31
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• pp.1.1-1.13
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• 2016

Objectives To investigate the accuracy and scientific validity of the current very low risk factor for hereditary diseases in humans following exposures to ionizing radiation adopted by the United Nations Scientific Committee on the Effects of Atomic Radiation and the International Commission on Radiological Protection. The value is based on experiments on mice due to reportedly absent effects in the Japanese atomic bomb (A-bomb) survivors. Methods To review the published evidence for heritable effects after ionising radiation exposures particularly, but not restricted to, populations exposed to contamination from the Chernobyl accident and from atmospheric nuclear test fallout. To make a compilation of findings about early deaths, congenital malformations, Down's syndrome, cancer and other genetic effects observed in humans after the exposure of the parents. To also examine more closely the evidence from the Japanese A-bomb epidemiology and discuss its scientific validity. Results Nearly all types of hereditary defects were found at doses as low as one to 10 mSv. We discuss the clash between the current risk model and these observations on the basis of biological mechanism and assumptions about linear relationships between dose and effect in neonatal and foetal epidemiology. The evidence supports a dose response relationship which is non-linear and is either biphasic or supralinear (hogs-back) and largely either saturates or falls above 10 mSv. Conclusions We conclude that the current risk model for heritable effects of radiation is unsafe. The dose response relationship is non-linear with the greatest effects at the lowest doses. Using Chernobyl data we derive an excess relative risk for all malformations of 1.0 per 10 mSv cumulative dose. The safety of the Japanese A-bomb epidemiology is argued to be both scientifically and philosophically questionable owing to errors in the choice of control groups, omission of internal exposure effects and assumptions about linear dose response.

• Journal of Gynecologic Oncology
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• v.29 no.6
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• pp.97.1-97.12
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• 2018

Objective: Women with cervical cancer (CC) found to have positive surgical margins, positive lymph nodes, and/or parametrial invasion receive a survival benefit from postoperative chemoradiotherapy (CRT) vs. radiation therapy (RT) alone. However, older women may not benefit to the same extent, as they are at increased risk of death from non-oncologic causes as well as toxicities from oncologic treatments. This study sought to evaluate whether there was a survival benefit of CRT over RT in elderly patients with cervical cancer. Methods: The National Cancer Database was queried for patients ${\geq}70$ years old with newly diagnosed IA2, IB, or IIA CC and positive margins, parametrial invasion, and/or positive nodes on surgical resection. Statistics included logistic regression, Kaplan-Meier overall survival (OS), and Cox proportional hazards modeling analyses. Results: Altogether, 166 patients met inclusion criteria; 62 (37%) underwent postoperative RT and 104 (63%) underwent postoperative CRT. Younger patients and those living in areas of higher income were less likely to receive CRT, while parametrial invasion and nodal involvement were associated with an increased likelihood (p<0.05 for all). There were no OS differences by treatment type. Subgroup analysis by number of risk factors, as well as each of the 3 risk factors separately, also did not reveal any OS differences between cohorts. Conclusion: In the largest such study to date, older women with postoperative risk factor(s) receiving RT alone experienced similar survival as those undergoing CRT. Although causation is not implied, careful patient selection is paramount to balance treatment-related toxicity risks with theoretical outcome benefits.

• Journal of Trauma and Injury
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• v.26 no.3
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• pp.198-206
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• 2013

Purpose: This study was performed to calculate and analyze the effective radiation doses from computed tomography (CT) and radiologic intervention in patients in the emergency department (ED) with trauma critical pathway (CP) activation and further to estimate the lifetime attributable risks (LARs) for the incidence of and mortality from cancers induced by the radiation dose. Methods: Through a retrospective electrical chart review of 104 injured patients who trauma critical pathway were activated from November 2012 to March 2013, we calculated effective radiologic doses by taking the product of the dose-linear product of the scan and the conversion coefficient. After a determination of the image results, we divided the patients into two groups, negative or positive, and calculated the effective dose for each group. With these results, we estimated the LARs for the incidence of and the mortality from cancers by using the table in the Biologic Effects of Ionizing Radiation (BEIR)-VII report. Results: A total of 76 patients were enrolled. The mean age was $49.0{\pm}8.5$ years. The mean injury severity score (ISS) was $12.7{\pm}8.4$. The cumulative effective dose (CED) for individual patients varied from 2.8 mSv to 238.8 mSv, and the mean was $47.6{\pm}39.9$ mSv. The CED in patients with an $ISS{\geq}16$($63.2{\pm}26.6$ mSv) was higher than that of patients whose ISS<16($33.5{\pm}23.1$ mSv) (p<0.001). The CED in patients who were treated with surgery or intervention($69.0{\pm}45.2$ mSv) was higher than that of patients who were treated conservatively($33.6{\pm}22.4$ mSv) (p<0.001). The LARs for cancer incidence and mortality were $328.5{\pm}308.6$ and $189.0{\pm}159.3$ per 100,000 people, respectively. Conclusion: The CED and the LAR for trauma CP-activated patients in the ED were significant, so efforts should be made to decrease the effective dose received by severely injured patients.

• Journal of Radiation Protection and Research
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• v.43 no.3
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• pp.107-113
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• 2018

Background: The purpose of our study was to compare the dosimetric advantages of Flattening filter free (FFF) beams for trigeminal neuralgia patients using 4 mm conical collimators over previously treated patients with 6 MV SRS beam. Materials and Methods: A retrospective study was conducted for 5 TN patients who had been previously treated at our institution using frame-based, LINAC-based stereotactic radiosurgery (SRS) on Novalis Tx using 6 MV SRS beam were replanned on 6X FFF beams on Edge Linear accelerator with same beam angles and dose constraints using 4 mm conical collimator. The total number of monitor units along with the beam on time was compared for both Edge and Novalis Tx by redelivering the plans in QA mode of LINAC to compare the delivery efficiency. Plan quality was evaluated by homogeneity index (HI) and Paddick gradient index (GI) for each plan. We also analyzed the doses to brainstem and organ at risks (OARs). Results and Discussion: A 28% beam-on time reduction was achieved using 6X FFF when compared with 6X SRS beam of Novalis Tx. A sharp dose fall off with gradient index value of $3.4{\pm}0.27$ for 4 mm Varian conical collimator while $4.17{\pm}0.20$ with BrainLab cone. Among the 5 patients treated with a 4 mm cone, average maximum brainstem dose was 10.24 Gy for Edge using 6X FFF and 14.28 Gy for Novalis Tx using 6X SRS beam. Conclusion: The use of FFF beams improves delivery efficiency and conical collimator reduces dose to OAR's for TN radiosurgery. Further investigation is warranted with larger sample patient data.

• The Journal of the Korea Contents Association
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• v.13 no.9
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• pp.281-287
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• 2013

Based on surveys of Busan residents, this study aimed to analyze general perception: radiation knowledge, recognition of the standard of knowledge, radiation benefits, recognition of the risks of nuclear power, collection of information on the Fukushima nuclear accident, recognition of changes before and after the Fukushima nuclear accident, and the path of collecting information about nuclear power and radiation. This analysis was based on 414 people who reside in Busan metropolitan city. It has been found that the Busan metropolitan city residents acknowledged the necessity of radiation in principle, however, most have negative awareness relating to safety. It is assumed that this negative awareness is a result from past nuclear power plant accidents, rather than being based on their own knowledge of radiation. Therefore, it is considered that efforts to change people's awareness necessitate education of the public. This can be done via media, widening the range of people's knowledge, and furthermore, promoting changes within people's awareness and perspectives.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1998.05a
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• pp.235-242
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• 1998

Aiming at one of decisive alternatives for long term aspect of nuclear power concerns, an integral and closed nuclear system, AMBIDEXTER (Advanced Molten-salt Break-even Inherently-safe Dual-mission Experimental and TEst Reactor) concept is under development. The AMBIDEXTER complex essentially comprises two mutually independent loops of the radiation/material transport and the heat/energy conversion, centered at the integrated reactor assembly, which enables one to utilize maximum benefits of nuclear energy under minimum risks of nuclear radiation. And it provides precious radioisotopes and radiation sources from its waste stream. Also the reactor operates at very low level of fission products inventory throughout its lifetime. The nuclear and thermalhydraulic characteristics of the molten TH/$^{233}$ U fuel salt extend the capability of the self-sustaining AMBIDEXTER fuel cycle to enhance resource security and safeguard transparency. The reactor system is consisted of a single component module of the core, heat exchangers and recirculation pumps with neither pipe connections nor active valves in between, which will significantly improve inherent features of nuclear safety. States of the core technologies associated with designing and developing the AMBIDEXTER concept are mostly available in commercialized form and thus demonstration of integral aspects of the concept should be the prime area in future R＆D programs.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.1136-1140
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• 2009

The current population of elderly is increasing and the with an extended average lifespan, the frequency of cancerous occurrences have also increased, with these increases and the increase in radiotherapy for cancer patients, recognitions of harm and importance have become known. This article was known tumor treatment of patients with hematopoietic disorder by doing a comparative study on the changes in blood cells caused by the acute effects of trace dose to high dose of radiation exposed to mice. According to the sensitizer injection may give rise to harm to the components of peripheral blood. This material needs to be considered when for treating tumor patients and the risks of hematopoietic harm and believe that radiation therapy will be reasonable.

• The Journal of the Korean dental association
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• v.52 no.3
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• pp.132-138
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• 2014

The emergence of Cone Beam Computed Tomography(CBCT) in the late 1990s represented an innovative advancement in the field of dental and maxillofacial radiology because it greatly reduced the radiation exposure to patients and offered 3D images easily. The 3D information generated by this technique brings the potential of improved diagnosis and treatment planning for a wide range of clinical applications in dentistry. The use of CBCT includes diagnosis and surgical assessment of the orofacial hard tissue lesions, dental implant treatment planning and postoperative evaluation, TMJ assessment, diagnosis of craniofacial fracture, orthodontics, endodontics, and so on. All CBCT examinations should be justified on an individualized needs. The clinical benefits to the patient for each CBCT scan must outweigh the potential risks associated with exposure to ionizing radiation. CBCT scans should be taken with initially obtained medical and dental histories of patients and a close clinical examination. CBCT should be considered as an imaging alternative of other conventional radiography in cases where the anatomical structures of interest may not be seen. The smallest possible field of view(FOV) and the lowest setting of tube current and scan time should be chosen, and the entire images scanned should be interpreted by a qualified expert.