• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.11-20
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• 2024

As the importance of intervention has recently increased, interest in the health of medical staff performing the procedure is increasing. Existing radiation shielding devices have limited the operator's movement and have not been properly used due to the risk of infection, and adequate radiation shielding of the operator's gonads and furthermore, the entire area of the procedure room has not been achieved. An auxiliary shielding device was manufactured by attaching a Bismuth to the elbow support used in the procedure, and the radiation shielding effect was measured. As a result of the measurement, the average spatial dose rate decreased by about 64.8%, and the independent sample t-test analysis showed statistically significant below the significance probability (p<0.05). The use of an auxiliary shielding device is considered to be an effective shielding method that can shield the operator's gonads and reduce the radiation spatial dose rate of the entire area of the procedure room.

• The Journal of Korean Society for Radiation Therapy
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• v.34
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• pp.43-50
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• 2022

Objective: The purpose of this study is to choose a treatment plan and equipment to maximize tangential irradiation to protect the normal brain tissues as much as possible during total scalp irradiation. Subjects and Methods: After zoning the total scalp of a phantom and selecting a target area for treatment, the study made a Helical TomoTherapy(HT) plan, a Helical TomoTherapy with a Complete Block(HTCB) plan, and a Volumetric Modulated Arc Therapy(VMAT) plan. All of these plans made sure that the volume of a treatment plan with 95% of a prescription dose(40 Gy) would not exceed 95% of the entire volume and that Dmax would not be more than 110% of the prescription dose. The therapy plans compared doses among organs at risk of damage including the brain. Doses in the brain tissues were assessed based on the volumetric criteria for normal tissues in Emami et al. Results: HT, HTCB, and VMAT had a dose of 21.68 Gy, 13.75 Gy, and 20.89 Gy, respectively, in brain tissues at D_33%, a dose of 7.06 Gy, 3.21 Gy, and 7.84 Gy, respectively, at D_67%, and a dose of 3.14 Gy, 1.75 Gy, and 3.84 Gy, respectively, at D_100%. They recorded a Dmean of 16.64 Gy, 11.78 Gy, and 16.64 Gy, respectively. These results show that the overall dose was low in the HTCB plan. When the volume of a low dose was calculated based on 5 Gy, they recorded 87%, 49%, and 96%, respectively, in V_5Gy. In addition, the maximum dose in the remaining organ(brain stem, hippocampus, and both lenses) except for the optic pathway was the lowest in HTCB Conclusion: The findings demonstrate that TomoTherapy with a complete block minimized a dose in organs at risk of damage including the brain and hippocampus on both sides and accordingly reduced the probability of side effects such as radiation-induced brain injuries and a resulting decrease in neurocognitive functions. In addition to total scalp irradiation, if additional studies on ring targets treated in various areas are conducted to establish the benefits of tangential irradiation, it is believed that TomoTherapy using Complete Block can be used to maximize tangential irradiation in treatment planning.

• Journal of Radiation Protection and Research
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• v.40 no.4
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• pp.252-260
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• 2015

This paper describes the technical background for the Korean wildlife radiation dose assessment code, K-BIOTA, and the summary of its application. The K-BIOTA applies the graded approaches of 3 levels including the screening assessment (Level 1 & 2), and the detailed assessment based on the site specific data (Level 3). The screening level assessment is a preliminary step to determine whether the detailed assessment is needed, and calculates the dose rate for the grouped organisms, rather than an individual biota. In the Level 1 assessment, the risk quotient (RQ) is calculated by comparing the actual media concentration with the environmental media concentration limit (EMCL) derived from a bench-mark screening reference dose rate. If RQ for the Level 1 assessment is less than 1, it can be determined that the ecosystem would maintain its integrity, and the assessment is terminated. If the RQ is greater than 1, the Level 2 assessment, which calculates RQ using the average value of the concentration ratio (CR) and equilibrium distribution coefficient (Kd) for the grouped organisms, is carried out for the more realistic assessment. Thus, the Level 2 assessment is less conservative than the Level 1 assessment. If RQ for the Level 2 assessment is less than 1, it can be determined that the ecosystem would maintain its integrity, and the assessment is terminated. If the RQ is greater than 1, the Level 3 assessment is performed for the detailed assessment. In the Level 3 assessment, the radiation dose for the representative organism of a site is calculated by using the site specific data of occupancy factor, CR and Kd. In addition, the K-BIOTA allows the uncertainty analysis of the dose rate on CR, Kd and environmental medium concentration among input parameters optionally in the Level 3 assessment. The four probability density functions of normal, lognormal, uniform and exponential distribution can be applied.The applicability of the code was tested through the participation of IAEA EMRAS II (Environmental Modeling for Radiation Safety) for the comparison study of environmental models comparison, and as the result, it was proved that the K-BIOTA would be very useful to assess the radiation risk of the wildlife living in the various contaminated environment.

• Journal of radiological science and technology
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• v.39 no.4
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• pp.549-555
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• 2016

This study was an evaluation of the significance of each parameter through aimed at pregnant women subjected to screening test(integrated test) in predicting risk of Down syndrome. We retrospectively analysed the correlation of risk of Down's syndrome with Nuchal Translucency(NT) images measured by ultrasound, Pregnancy Associated Plasma Protein A(PAPP-A), alpha-fetoprotein(AFP), unconjugated estriol(uE3), human chorionic gonadotrophin(hCG) and Inhibin A by maternal serum. As a result, a significant correlation with NT, uE3, hCG, Inhibin A is revealed with Down's syndrome risk(P<.001). In ROC analysis, AUC of Inhibin A is analysed as the biggest predictor of Down's syndrome(0.859). And the criterion for cut-off was inhibin A 1.4 MoM(sensitivity 81.8%, specificity 75.9%). In conclusion, Inhibin A was the most useful in parameters to predict Down's syndrome in the integrated test. If we make up for the weakness based on the cut-off value of parameters they will be able to be used as an independent indicator in the risk of Down's syndrome screening.

• The Journal of Korean Society for Radiation Therapy
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• v.30 no.1_2
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• pp.177-183
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• 2018

Purpose : Volumetric Modulated Arc Therapy(VMAT) has the advantage of uniformly and precisely irradiating the tumor to the shape of the tumor while reducing the risk of radiation damage to normal tissues. such as brain cancer, head and neck cancer and prostate cancer, It is being used for treatment. The purpose of this study is to evaluate the usefulness of the Jaw-Tracking technique(JTT) in VMAT for brain and head and neck cancer. Materials and Methods : We selected eight patients with brain and head and neck cancer(4 Brain, 4 head and neck) who were treated with the VMAT treatment technique. Contouring information of the patient's tumor and normal organ was fused to the Rando phantom using the deformable registration of Velocity(Varian, USA). A treatment plan was developed using the Varian Eclipse(ver 15.5, Varian, USA) with the same patient actual beam parameters except for the use of jaw-tracking. As the evaluation index, the maximum dose and mean dose of target and OAR were compared and a portal dosimetry was performed for the treatment plan verification. Results : When using JTT, the relative dose of OAR decreased by 5.24 % and the maximum dose by 7.05 %, respectively, compared with the Static-Jaw technique(SJT). In the various OARs, the mean dose and maximum dose reduction ranges ranged from 0.01 to 3.16 Gy and from 0.12 to 6.27 Gy, respectively. In the case of the target, the maximum dose of GTV, CTV, PTV decreased by 0.17 %, 0.43 %, and 0.37 % in JTT, and the mean dose decreased by 0.24 %, 0.47 % and 0.47 %, respectively. Gamma analysis The JTT and SJT passing rates were $98{\pm}1.73%$ and $97{\pm}1.83%$ on the basis of 3 % / 3 mm, respectively. Comparing the doses of all OARs applied to the experiment, it was found that the use of JTT resulted in a significant decrease in dose due to additional jaw shielding besides MLC than SJT. Conclusion : In radiation therapy using VMAT treatment plan, we can apply JTT in the case of adjacent tumor and normal organs such as brain cancer and head and neck cancer, and in radiotherapy required large field and high energy caused increase leakage dose through MLC. It is considered that the target dose of PTV can be increased by lowering the dose of normal tissue surrounding the tumor.

• Journal of Radiation Protection and Research
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• v.38 no.4
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• pp.214-227
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• 2013

Computed tomographic scan as a screening procedures in asymptomatic individuals has seen a steady increase with the introduction of multiple-raw detector CT scanners. This report provides a brief review of the current controversy surrounding CT cancer screening, with a focus on the radiation induced cancer risks and clinical efficacy. 1. A large study of patients at high risk of lung cancer(the National Lung Screening Trial[NLST]) showed that CT screening reduced cancer deaths by 20%(1.33% in those screened compared with 1.67% in those not screened). The rate of positive screening tests was 24.2% and 96.4% of the positive screening results in the low-dose CT group were false-positive. Radiation induced lung cancer risk was estimated the most important in screening population because ERR of radiation induced lung cancer does not show the decrease with increasing age and synergistic connection between smoking and radiation risk. Therefore, the radiation risk may be on the same order of magnitude as the benefit observed in the NLST. Optimal screening strategy remain uncertain, CT lung cancer screening is not yet ready for implementation. 2. Computed tomographic colonography is as good as colonoscopy for detecting colon cancer and is almost as good as colonoscopy for detecting advanced adenomas, but significantly less sensitive and specific for smaller lesions and disadvantageous for subsequent therapeutic optical colonoscopy if polyps are detected. The average effective dose from CT colonography was estimated 8-10 $mS{\nu}$, which could be a significant dose if administered routinely within the population over many years. CT colonography should a) achieve at least 90% sensitivity and specificity in the size category from 6 and 10 mm, b) offer non-cathartic bowl preparation and c) be optimized and standardized CT parameters if it is to be used for mass screening. 3. There is little evidence that demonstrates, for whole-body scanning, the benefit outweighs the detriment. This test found large portion of patient(86~90.8%) had at least one abnormal finding, whereas only 2% were estimated to have clinically significant disease. Annual scans from ages 45 to 75 years would accrue an estimated lifetime cancer mortality risk of 1.9%. There is no group within the medical community that recommends whole-body CT. No good studies indicate the accuracy of screening CT, at this time. The benefit/risk balance for any of the commonly suggested CT screening techniques has yet to be established. These areas need further research. Therefore wild screening should be avoided.

• Journal of the Korean Society of Radiology
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• v.9 no.1
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• pp.1-7
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• 2015

Acute phase patients who are unconscious and are suffering from cerebral infarction, cranial nerve disorders, or cerebral apoplexy are susceptible to aspiration pneumonia due to dysphagia. In these cases, a nasogastric tube is inserted to supply nutrients. Although bedside screening tests are administered during recovery after rehabilitation, clinical examinations may not be able to ascertain asymptomatic aspiration. Therefore, a video fluoroscopy swallowing study (VFSS) was performed in 10 patients with dysphagia after rehabilitation therapy; these patients had nasogastric tubes inserted, and a rehabilitation specialist assessed the degree of swallowing based on the patients' diet and posture. If aspiration or swallowing difficulties were observed, dysphagia rehabilitation therapy was administered. The patients were reassessed approximately 30-50 days after administration of therapy, based on the patients' condition. If aspiration is not observed, the nasogastric tube was removed. A functional dysphagia scale was used to analyze the VFSS images, and the scores were statistically calculated. The mean score of patients with nasogastric tubes was $49.79{\pm}9.431$, thereby indicating aspiration risk, whereas the group without nasogastric tubes showed a mean score of $11.20{\pm}1.932$, which indicated low risk of aspiration. These results demonstrated that a significantly low score was associated with nasogastric tube removal. Mann-Whitney's test was performed to assess the significance of both the groups, and the results were statistically significant with a P value <0.001. In conclusion, VFSS can effectively assess the movements and structural abnormalities in the oral cavity, pharynx, and esophagus. It can also be used to determine the aspiration status and ascertain the appropriate diet or swallowing posture for the patient. Therefore, VFSS can potentially be used as a reliable standard test to assess swallowing in order to determine nasogastric tube removal.

• Journal of the Korean Society of Radiology
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• v.17 no.6
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• pp.947-955
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• 2023

This study was conducted to investigate the awareness of spent nuclear fuel among residents in nuclear power plant areas and use it as basic data for establishing a disposal facility for high-level radioactive waste. 204 questionnaires collected online were analyzed using SPSS Window Ver 28.0. To verify differences between groups, t-test and one-way ANOVA were performed. And correlation analysis was conducted to confirm the relationship between variables. As a result, first, risk perception regarding nuclear-related accidents showed statistically significant differences depending on gender and educational level. The position on the construction of a permanent disposal facility for spent nuclear fuel showed a statistically significant difference depending on gender, education, and age, and the perception of the importance of each evaluation standard for establishing a spent nuclear fuel management plan showed a statistically significant difference depending on education and age. In terms of trust in information-providing institutions, trust in the National Assembly was found to be the lowest. Second, the results of the correlation analysis between variables showed that local residents are aware that an alternative to the current disposal of spent nuclear fuel is needed, and that financial support for the construction of a permanent disposal facility is needed. Therefore, in order to build a high-level radioactive waste disposal site, it is believed that it is necessary to increase trust in the government, collect opinions from local residents, and provide economic support.

• Radiation Oncology Journal
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• v.26 no.1
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• pp.1-9
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• 2008

Purpose: To evaluate the impact of postoperative radiotherapy on loco-regional failure in patients with vulvar carcinoma and to determine the treatment strategy for inguinal lymph nodes. Materials and Methods: Sixty-six patients who received treatment for primary vulvar carcinoma at Seoul National University Hospital, from October 1979 through June 2004, were retrospectively analyzed. Sixteen patients were excluded from the analysis due to the following reasons: distant metastases in two patients; palliative intent for six patients; previous radiotherapy given to the pelvis in three patients; follow-up loss after surgery for four patient; insufficient medical records for one patient. Of 50 eligible patients, 35 were treated with surgery alone(S), ten were treated with surgery followed by radiotherapy(S+RT), and five were treated with radiotherapy alone. Results: The 5-year overall survival(OS) and disease-free survival(DFS) rates of all patients were 91% and 78%, respectively. Twelve patients(26%) experienced treatment failures and the sites of initial failure were as follows: a primary site in eight patients; regional lymph nodes in three patients; the lung in one patient. Although risk factors for failure were more common in the S+RT group than the S group of patients(p<0.05), the DFS rates were similar for the two groups(5-year DFS rates, 78% vs. 83%, p=0.66). The incidences of occult lymph node metastases was 10%. Ten of 31 patients with clinically negative lymph nodes did not received inguinal lymph node dissection, but no patient experienced regional failure. Conclusion: Postoperative radiotherapy may have a potential benefit for patients with risk factors for failure. The omission of inguinal dissection or elective radiotherapy to the inguinal lymph nodes may be considered in low-risk patients with clinically negative lymph nodes.

• Journal of Radiation Protection and Research
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• v.37 no.2
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• pp.96-102
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• 2012

International Commission on Radiological Protection (ICRP) has revised its recommendations concerning the tissue reaction to ionizing radiation in accordance with consideration of the detriment arising from non-cancer effects of radiation on health based on recent epidemiological basis. Particularly, for the lens of the eye, the threshold in absorbed dose revised to be 0.5 Gy, for occupational exposure in planned exposure situation the commission recommended "An equivalent dose limit for the lens of the eye of 20 mSv in a year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv." To monitor the radiation exposure of radiation worker, TLD is typically provided and the lens of eye dose can be assessed by run of dose calculation algorithm with TL element response data. This study is to assess equivalent dose of the lens of eye using the Harshaw TLD system and its two different dose calculation algorithms. The result provides the Harshaw TLD system showed the assessment of the lens of eye dose with 48.84% error range.