• Radiation Oncology Journal
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• v.34 no.2
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• pp.145-155
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• 2016

Purpose: Radiation therapy targeting axilla and groin lymph nodes improves regional disease control in locally advanced and high-risk skin cancers. However, trials generally used conventional two-dimensional radiotherapy (2D-RT), contributing towards relatively high rates of side effects from treatment. The goal of this study is to determine if three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), or volumetric-modulated arc therapy (VMAT) may improve radiation delivery to the target while avoiding organs at risk in the clinical context of skin cancer regional nodal irradiation. Materials and Methods: Twenty patients with locally advanced/high-risk skin cancers underwent computed tomography simulation. The relevant axilla or groin planning target volumes and organs at risk were delineated using standard definitions. Paired t-tests were used to compare the mean values of several dose-volumetric parameters for each of the 4 techniques. Results: In the axilla, the largest improvement for 3D-CRT compared to 2D-RT was for homogeneity index (13.9 vs. 54.3), at the expense of higher lung $V_{20}$ (28.0% vs. 12.6%). In the groin, the largest improvements for 3D-CRT compared to 2D-RT were for anorectum $D_{max}$ (13.6 vs. 38.9 Gy), bowel $D_{200cc}$ (7.3 vs. 23.1 Gy), femur $D_{50}$ (34.6 vs. 57.2 Gy), and genitalia $D_{max}$ (37.6 vs. 51.1 Gy). IMRT had further improvements compared to 3D-CRT for humerus $D_{mean}$ (16.9 vs. 22.4 Gy), brachial plexus $D_5$ (57.4 vs. 61.3 Gy), bladder $D_5$ (26.8 vs. 36.5 Gy), and femur $D_{50}$ (18.7 vs. 34.6 Gy). Fewer differences were observed between IMRT and VMAT. Conclusion: Compared to 2D-RT and 3D-CRT, IMRT and VMAT had dosimetric advantages in the treatment of nodal regions of skin cancer patients.

• Journal of Environmental Health Sciences
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• v.50 no.4
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• pp.229-236
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• 2024

The linear no-threshold (LNT) model is an assumption that explains the dose-response relationship for health risks, allowing for linear extrapolation from high doses to low doses without a threshold. The selection of an appropriate model for low-dose risk evaluation is a critical component in the risk assessment process for hazardous agents. This paper reviews the LNT model in light of epidemiological evidence from major international consortia studying ionizing radiation. From a scientific perspective, substantial evidence supporting the LNT model has been observed in epidemiological studies of low-dose ionizing radiation exposure, although some findings suggest non-linear dose relationships for certain cancer sites and variations across populations. From a practical standpoint, the LNT remains the most useful model for radiation protection purposes, with no alternative dose-response relationship proving more appropriate. It is important to note that the LNT model does not directly reflect the magnitude of risk at the population level, and this distinction should be clearly communicated to the public. While applying the LNT model as the principal basis for radiation protection, continuous research into various dose-response relationships is crucial for advancing our understanding.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.6
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• pp.2979-2982
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• 2016

Background: High dose ionizing radiation can induce ovarian cancer, but the effect of low dose radiation on the development of ovarian cancer has not been extensively studied. We evaluated the effect of low dose radiation and total background radiation, and the radiation delivered to the ovaries during the treatment of rectosigmoid cancer and breast cancer on ovarian cancer incidence. Materials and Methods: Background radiation measurements are from Assessment of Variations in Radiation Exposure in the United States, 2011. Ovarian cancer incidence data are from the Centers for Disease Control and Prevention. Standardized incidence ratios (SIR) of ovarian cancer following breast cancer and rectosigmoid cancer are from Surveillance, Epidemiology, and End Results (SEER) data. Obesity data by US state are from the Centers for Disease Control and Prevention. Mean ages of US state populations are from the United States Census Bureau. Results: We calculated standardized incidence ratios (SIR) from Surveillance, Epidemiology, and End Results (SEER) data, which reveal that in 194,042 cases of breast cancer treated with beam radiation, there were 796 cases of ovarian cancer by 120+ months of treatment (0.41%); in 283, 875 cases of breast cancer not treated with radiation, there were 1,531 cases of ovarian cancer by 120+ months (0.54%). The difference in ovarian cancer incidence in the two groups was significant (p < 0.001, two tailed Fisher exact test). The small dose of scattered ovarian radiation (about 3.09 cGy) from beam radiation to the breast appears to have reduced the risk of ovarian cancer by 24%. In 13,099 cases of rectal or rectosigmoid junction cancer treated with beam radiation in the SEER data, there were 20 cases of ovarian cancer by 120+ months of treatment (0.15%). In 33,305 cases of rectal or rectosigmoid junction cancer not treated with radiation, there were 91 cases of ovarian cancer by 120+ months (0.27%). The difference in ovarian cancer incidence in the two groups was significant (p = 0.017, two tailed Fisher exact test). In other words, the beam radiation to rectum and rectosigmoid that also reached the ovaries reduced the risk of ovarian cancer by 44%. In addition, there was a significant inverse relationship between ovarian cancer in white women and radon background radiation (r = - 0.465. p = 0.002) and total background radiation (r = -0.456, p = 0.002). Because increasing age and obesity are risk factors for ovarian cancer, multivariate linear regression was performed. The inverse relationship between ovarian cancer incidence and radon background was significant (${\beta}=-0.463$, p = 0.002) but unrelated to age (${\beta}=-0.080$, p = 0.570) or obesity (${\beta}=-0.180$, p = 0.208). Conclusions: The reduction of ovarian cancer risk following low dose radiation may be the result of radiation hormesis. Hormesis is a favorable biological response to low toxin exposure. A pollutant or toxin demonstrating hormesis has the opposite effect in small doses as in large doses. In the case of radiation, large doses are carcinogenic. However, lower overall cancer rates are found in U.S. states with high impact radiation. Moreover, there is reduced lung cancer incidence in high radiation background US states where nuclear weapons testing was done. Women at increased risk of ovarian cancer have two choices. They may be closely followed (surveillance) or undergo immediate prophylactic bilateral salpingo-oophorectomy. However, the efficacy of surveillance is questionable. Bilateral salpingo-oophorectomy is considered preferable, although it carries the risk of surgical complications. The data analysis above suggests that low-dose pelvic irradiation might be a good third choice to reduce ovarian cancer risk. Further studies would be worthwhile to establish the lowest optimum radiation dose.

• Journal of Radiation Protection and Research
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• v.26 no.3
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• pp.197-201
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• 2001

A risk analysis consists of a triplet, , where Si is the scenario identification; Pi is the probability of each scenario; and Xi is the consequences of each scenario. A new computing framework, OMAM (ORIGEN-MAAP4-MMCS), has been developed and applied for assessing the risk of a reference plant as well as radiation source terms using the concept of risk triplet. The result of this study using the OMAM framework presented in this paper, can contribute to producing domestic nuclear power plant's risk data base as well as to establishing severe accident management plans.

• Progress in Medical Physics
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• v.27 no.3
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• pp.139-145
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• 2016

With the development in field of industry and medicine, new machines and techniques are being launched. Moreover, the complexity of the techniques is associated to an increasing risk of incident. Especially, a small error in radiotherapy can lead to a serious patient-related incident, risk management is necessary in radiotherapy in order to reduce the risk of incident. However, in field of radiotherapy, there are no legally binding clauses for risk management and there is an absence of risk management systems at an institutional level. Therefore, we analyzed institutional status of risk management, reporting & classification systems, and risk assessment & analysis in 31 countries. For risk management and reporting systems, 65% of countries investigated had legislation or regulations; however, only 35% of countries used classification systems. It was found that 43% more countries had legislation for risk management in healthcare than those for radiotherapy; 19% more countries had reporting systems for healthcare than those for radiotherapy. For classification systems, 60% more countries had legislation, recommendation, and guidelines in the field of radiotherapy than those for healthcare. Recently, international institutes have published several reports for risk management and patient safety in radiotherapy, owing to which, countries adopting risk management for radiotherapy will gradually increase. Before adopting risk management in Korea, we should precisely understand the procedures and functions of risk management, in order to increase efficiency of risk management because classification & reporting system and risk assessment & analysis are connected organically, and institutional management is needed for high quality of risk management in Korea.

• Radiation Oncology Journal
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• v.35 no.1
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• pp.39-47
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• 2017

Purpose: The purpose of this study was to analyze clinical outcomes from cervical cancer and stratify patients into risk groups for prognostic factors for early-stage disease. Materials and Methods: We retrospectively reviewed patients with stage IB or IIA cervical cancer treated with adjuvant radiotherapy (RT) or concurrent chemoradiotherapy (CCRT) following primary surgery at Samsung Medical Center from 2001 to 2011. Adjuvant RT was added for patients with intermediate-risk factors, and adjuvant CCRT was performed on high-risk patients after surgery. Results: We reviewed 247 patients-149 in the high-risk group and 98 in intermediate-risk group. The median follow-up was 62 months. Loco-regional failure (LRF) alone occurred in 7 patients (2.8%), distant metastasis alone in 37 patients (15.0%) and LRF with DM in 4 patients (1.6%). The 5-year disease-free survival (DFS) and overall survival (OS) rates for both groups were 79.7% and 87.6%, respectively. In the high-risk group, the 5-year DFS and OS probabilities were 72.5% and 81.9%, respectively. Histologic type, pathologic tumor size, and the number of pelvic lymph node (PLN) metastasis were significant prognostic factors for DFS and OS. We suggest a scoring system (0-3) using these prognostic factors to predict poor prognosis in high-risk patients. Using this system, patients with higher scores have higher recurrence and lower survival rates. Conclusion: In the high-risk cervical-cancer group who received primary surgery and adjuvant CCRT, non-squamous type, large tumor size and the number of PLN metastasis were significant prognostic factors, and the number of these factors was associated with survival rates.

• Asian Pacific Journal of Cancer Prevention
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• v.14 no.5
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• pp.2783-2787
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• 2013

To assess the risk of cancer incidence after medical radiation exposure for coronary artery disease (CAD), a retrospective cohort study was conducted based on Taiwan's National Health Insurance Research Database (NHIRD). Patients with CAD were identified according to the International Classification of Diseases code, 9th Revision, Clinical Modification (ICD-9-CM), and their records of medical radiation procedures were collected from 1997 to 2010. A total of 18,697 subjects with radiation exposure from cardiac imaging or therapeutic procedures for CAD were enrolled, and 19,109 subjects receiving cardiac diagnostic procedures without radiation were adopted as the control group. The distributions of age and gender were similar between the two populations. Cancer risks were evaluated by age-adjusted incidence rate ratio (aIRR) and association with cumulative exposure were further evaluated with relative risks by Poisson regression analysis. A total of 954 and 885 subjects with various types of cancers in both cohorts after following up for over 10 years were found, with incidences of 409.8 and 388.0 per 100,000 person-years, respectively. The risk of breast cancer (aIRR=1.85, 95% confidence interval: 1.14-3.00) was significantly elevated in the exposed female subjects, but no significant cancer risk was found in the exposed males. In addition, cancer risks of the breast and lung were increased with the exposure level. The study suggests that radiation exposure from cardiac imaging or therapeutic procedures for CAD may be associated with the increased risk of breast and lung cancers in CAD patients.

• Journal of radiological science and technology
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• v.45 no.2
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• pp.171-177
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• 2022

The purpose of this study was to investigate the effect of the characteristics of patients who underwent spinal nerve block on the fear of injection and the risk of radiation. Subjects were 137 patients (67 males, 70 females) who visited the Department of Anesthesiology and Pain Medicine in Cheongju. The method was conducted as a research study using a total of 28 questionnaires consisting of patient characteristics, experience characteristics of nerve block surgery, nerve block fear scale, and radiation risk perception scale. The reliability of the questionnaire response was secured with a Cronbach's alpha coefficient of 0.6 or higher. For statistical analysis, correlation was tested by descriptive statistics, frequency analysis, independent sample T-test, and Pearson and Spearman correlation coefficients by measurement scale and factor. As a result, the fear scale of nerve block was significantly higher in women than in men (p<0.05). The fear scale of nerve block injection was significantly higher in the first-visit patients than in the second-visited patients (p<0.05). However, there was no significant difference among all variables in radiation risk perception. In conclusion, patients undergoing spinal nerve block were more aware of the fear of injection than the risk of radiation exposure during the procedure.

• Nuclear Engineering and Technology
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• v.46 no.4
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• pp.467-474
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• 2014

The aim of this paper is to describe a relatively recent international agreement on the widely debated concepts of: (i) attributing effects to low dose radiation exposure situations that have occurred in the past and, (ii) inferring radiation risk to situations that are planned to occur in the future. An important global consensus has been recently achieved on these fundamental issues at the level of the highest international intergovernmental body: the General Assembly of the United Nations. The General Assembly has welcomed with appreciation a scientific report on attributing health effects to radiation exposure and inferring risks that had been prepared the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) following a formal request by the General Assembly.

• Radiation Oncology Journal
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• v.37 no.3
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• pp.224-231
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• 2019

Purpose: To investigate the patterns of recurrence in patients with neuroblastoma treated with radiation therapy to the primary tumor site. Materials and Methods: We retrospectively analyzed patients with high-risk neuroblastoma managed with definitive treatment with radiation therapy to the primary tumor site between January 2003 and June 2017. These patients underwent three-dimensional conformal radiation therapy or intensity-modulated radiation therapy. A total of 14-36 Gy was delivered to the planning target volume, which included the primary tumor bed and the selected metastatic site. The disease stage was determined according to the International Neuroblastoma Staging System (INSS). We evaluated the recurrence pattern (i.e., local or systemic), progression-free survival, and overall survival. Results: A total of 40 patients with high-risk neuroblastoma were included in this study. The median patient age was 4 years (range, 1 to 11 years). Thirty patients (75%) had INSS stage 4 neuroblastoma. At the median follow-up of 58 months, there were 6 cases of local recurrence and 10 cases of systemic recurrence. Among the 6 local failure cases, 4 relapsed adjacent to the radiation field. The other 2 relapsed in the radiation field (i.e., para-aortic and retroperitoneal areas). The main sites of distant metastasis were the bone, lymph nodes, and bone marrow. The 5-year progression-free survival was 70.9% and the 5-year overall survival was 74.3%. Conclusion: Radiation therapy directed at the primary tumor site provides good local control. It seems to be adequate for disease control in patients with high-risk neuroblastoma after chemotherapy and surgical resection.