• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.91-91
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• 2006

• Progress in Medical Physics
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• v.33 no.4
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• pp.164-171
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• 2022

The number of facilities using radiation generators increases and related regulations are strengthened, the establishment of a shielding management and evaluation technology has become important. The characteristics of the radiation generator used in previous report differ from those of currently available high-frequency radiation generators. This study aimed to manufacture lead, iron, and concrete shielding materials for the re-verification of half-value layers, tenth-value layers, and attenuation curve. For a comparison of attenuation ratio, iron, lead, and concrete shields were manufactured in this study. The initial dose was measured without shielding materials, and doses measured under different types and thicknesses of shielding material were compared with the initial dose to calculate the transmission rate on 50-300 kVp X-ray. All the three shielding materials showed a tendency to require greater shielding thickness for higher energy. The attenuation graph showed an exponential shape as the thickness decreased and a straight line as the thickness increased. The difference between the measurement results and the previous study, except in extrapolated parts, may be due to the differences in the radiation generation characteristics between the generators used in the two studies. The attenuated graph measured in this study better reflects the characteristics of current radiation generators, which would be more effective for shield designing.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4576-4582
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• 2023

The Korea retrospective dosimetry (KREDOS)-electron paramagnetic resonance (EPR) group undertook an intercomparison investigation utilizing hydroxyapatite. This analysis involved four institutions: the Korea Institute of Radiological and Medical Sciences, Dongnam Institute of Radiological and Medical Sciences, Korean Association for Radiation Application, and Radiation Health Institute of Korea Hydro & Nuclear Power. Following the irradiation of the hydroxyapatite sample, the recorded build-up was analyzed. To validate the reliability of the EPR dosimetry findings and enhance its operational performance, a hydroxyapatite dose-response curve was plotted and dosimetry was performed for a blind sample. The proficiency of each laboratory was assessed by employing an interlaboratory comparison methodology. This involved a comparative analysis of the measurement results by calculating the relative bias, z-score, and En value. The results submitted by the participating laboratories demonstrated satisfactory ratings for doses of 1.006, 3.999, and 6.993 Gy. Following the second intercomparison, efforts to optimize their hydroxyapatite-EPR dosimetry systems are underway in the participating laboratories. The current assessment of hydroxyapatite dose yielded the foundational data required to establish the parameters of dental dosimetry. In future, the third intercomparison experiment will be conducted for exploring other materials.

• Radiation Oncology Journal
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• v.35 no.3
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• pp.233-240
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• 2017

Purpose: To validate the 8th edition of the American Joint Committee on Cancer/Union for International Cancer Control (AJCC/UICC) TNM staging system for human papillomavirus (HPV)-related oropharyngeal squamous cell carcinoma (OPSCC) and investigate whether a modified classification better reflects the prognosis. Materials and Methods: Medical records of patients diagnosed with non-metastatic HPV-related OPSCC between 2010 and 2016 at a single institution were retrospectively reviewed. HPV status was determined by immunohistochemical analysis of p16 and/or HPV DNA polymerase chain reaction (PCR). We reclassified TNM stage T0-1 and N0-1 as group A, T2-3 or N2 as B, and T4 or N3 as C. Survival analysis according to 8th AJCC/UICC TNM staging and the modified classification was performed. Results: Of 383 OPSCC patients, 211 were positive for HPV DNA PCR or p16. After exclusion, 184 patients were included in this analysis. Median age was 56 years (range, 31 to 81 years). Most primary tumors were in the palatine tonsil (148 tumors, 80%). The eighth AJCC/UICC TNM classification could not differentiate between stage I and II (p = 0.470) or II and III (p = 0.209). Applying modified grouping, the 3-year overall survival rate of group A was significantly higher than that of group B and C (98% vs. 91%, p = 0.039 and 98% vs. 78%, p < 0.001, respectively). Differentiation between group B and C was marginally significant (p = 0.053). Conclusion: The 8th AJCC/UICC TNM staging system did not clearly distinguish the prognosis of stage II from that of other stages. Including the T2N0-1 group in stage II may improve prognostic stratification.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.94-94
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• 2006

• 대한방사선방어학회:학술대회논문집
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• 2011.11a
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• pp.344-345
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• 2011

• Proceedings of the Korean Society of Medical Physics Conference
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• 2006.08a
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• pp.134-134
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• 2006

• Progress in Medical Physics
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• v.33 no.4
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• pp.53-62
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• 2022

In this study, we have investigated the shielding evaluation methodology for facilities using kV energy generators. We have collected and analysis of safety evaluation criteria and methodology for overseas facilities using radiation generators. And we investigated the current status of shielding evaluation of domestic industrial radiation generators. According to the statistical data from the Radiation Safety Information System, as of 2022, a total of 7,679 organizations are using radiation generating devices. Among them, 6,299 facilities use these devices for industrial purposes, which accounts for a considerable portion of radiation. The organizations that use these devices evaluate whether the exposure dose for workers and frequent visitors is suitable as per the limit regulated by the Nuclear Safety Act. Moreover, during this process, the safety shields are evaluated at the facilities that use the radiation generating devices. However, the facilities that use radiating devices having energy less than or equal to 6 MV for industrial purposes are still mostly evaluated and analyzed according to the National Council on Radiation Protection and Measurements 49 (NCRP 49) report published in 1976. We have investigated the technical standards of safety management, including the maximum permissible dose and parameters assessment criteria for facilities using radiation generating devices, based on the NCRP 49 and the American National Standards Institute/Health Physics Society N.43.3 reports, which are the representative reports related to radiation shielding management cases overseas.

• Korean Journal of Head & Neck Oncology
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• v.19 no.1
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• pp.9-15
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• 2003

Purpose: To introduce our early experience with intensity-modulated radiotherapy (IMRT) in the treatment of nasopharyngeal carcinoma. Methods and Materials: Eight patients who underwent IMRT for no disseminated nasopharyngeal carcinoma at the Asan Medical Center between September 2001 and November 2002 were evaluate by prospective analysis. According to the 1997 American Joint Committee on Cancer staging classification, 5 had Stage III, and 3 had Stage IVB disease. The IMRT plans were designed to be delivered as a 'Simultaneous Modulated Accelerated Radiation Therapy' (SMART) using the 'step and shoot' technique with a MLC (multileaf collimator). Daily fractions of 2.2-2.5Gy and 1.9-2Gy were prescribed and delivered to the GTV and CTV and clinically negative neck node, respectively. The prescribed dose was 70A-79.0Gy to the gross tumor volume (GTV), 60Gy to the clinical target volume (CTV) and metastatic nodal station, and 46Gy to the clinically negative neck. All patients also received weekly cisplatin during radiotherapy. Acute and late normal tissue effects were graded according to the Radiation Therapy Oncology Group (RTOG) radiation morbidity scoring criteria. Results: Follow-up period was ranging from 5 to 18 months. All patients showed complete response and loco-regional control rate was 100% but one patient died of malnutrition due to treatment related toxicity. There were no Grade 3 or 4 xerostomia and all patients had experienced improvement of salivary gland function. Conclusion: 'Simultaneous Modulated Accelerated Radiation Therapy' (SMART) boost intensity-modulated radiotherapy technique allows parotid sparing as evidenced both clinically and by dosimetry. Initial tumor response and loco-regional control was promising. It is clinically feasible. A larger population of patients and a long-term follow-up are needed to evaluate ultimate tumor control and late toxicity.

• Progress in Medical Physics
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• v.34 no.1
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• pp.14-14
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• 2023