• Nuclear Engineering and Technology
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• v.53 no.4
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• pp.1289-1296
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• 2021

In this study, an electron-scattering device was fabricated to practically use the ultra-high dose rate electron beams for the FLASH preclinical research in Dongnam Institute of Radiological and Medical Sciences. The Dongnam Institute of Radiological and Medical Sciences has been involved in the investigation of linear accelerators for preclinical research and has recently implemented FLASH electron beams. To determine the geometry of the scattering device for the FLASH preclinical research with a 6-MeV linear accelerator, the Monte Carlo N-particle transport code was exploited. By employing the fabricated scattering device, the off-axis and depth dose distributions were measured with radiochromic films. The generated mean energy of electron beams via the scattering device was 4.3 MeV, and the symmetry and flatness of the off-axis dose distribution were 0.11% and 2.33%, respectively. Finally, the doses per pulse were obtained as a function of the source to surface distance (SSD); the measured dose per pulse varied from 4.0 to 0.2 Gy/pulse at an SSD range of 20-90 cm. At an SSD of 30 cm with a 100-Hz repetition rate, the dose rate was 180 Gy/s, which is sufficient for the preclinical FLASH studies.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3417-3422
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• 2023

Recently, as the clinically positive biological effects of ultra-high dose rate (UHDR) radiation beams have been revealed, interest in flash radiation therapy has increased. Generally, FLASH preclinical experiments are performed using UHDR electron beams generated by linear accelerators. Real-time monitoring of UHDR beams is required to deliver the correct dose to a sample. However, it is difficult to use typical transmission-type ionization chambers for primary beam monitoring because there is no suitable electrometer capable of reading high pulsed currents, and collection efficiency is drastically reduced in pulsed radiation beams with ultra-high doses. In this study, a monitoring method using bremsstrahlung photons generated by irradiation devices and a water phantom was proposed. Charges collected in an ionization chamber located at the back of a water phantom were analyzed using the bremsstrahlung tail on electron depth dose curves obtained using radiochromic films. The dose conversion factor for converting a monitored charge into a delivered dose was determined analytically for the Advanced Markus® chamber and compared with experimentally determined values. It is anticipated that the method proposed in this study can be useful for monitoring sample doses in UHDR electron beam irradiation.

• Progress in Medical Physics
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• v.31 no.2
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• pp.9-19
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• 2020

Purpose: This study aims to develop a multi-purpose electron beam irradiation device for preclinical research and material testing using the research electron linear accelerator installed at the Dongnam Institute of Radiological and Medical Sciences. Methods: The fabricated irradiation device comprises a dual scattering foil and collimator. The correct scattering foil thickness, in terms of the energy loss and beam profile uniformity, was determined using Monte Carlo calculations. The ion-chamber and radiochromic films were used to determine the reference dose-rate (Gy/s) and beam profiles as functions of the source to surface distance (SSD) and pulse frequency. Results: The dose-rates for the electron beams were evaluated for the range from 59.16 Gy/s to 5.22 cGy/s at SSDs of 40-120 cm, by controlling the pulse frequency. Furthermore, uniform dose distributions in the electron fields were achieved up to approximately 10 cm in diameter. An empirical formula for the systematic dose-rate calculation for the irradiation system was established using the measured data. Conclusions: A wide dose-rate range electron beam irradiation device was successfully developed in this study. The pre-clinical studies relating to FLASH radiotherapy to the conventional level were made available. Additionally, material studies were made available using a quantified irradiation system. Future studies are required to improve the energy, dose-rate, and field uniformity of the irradiation system.

• Progress in Medical Physics
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• v.9 no.2
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• pp.105-113
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• 1998

Accurate radiation dosimetric characters is very important to determine of dose to a radiotherapeutic patient. Medical linear accelerators have been developed not only its new quality of convenient operation but also electric moderation. It is reliable to measure more detail physical parameter that linac's internal ability. Typically, radiation dosimetric tool is classified ionization chamber, film, thermoluminescence dosimeter, etc. Nowaday, Electronic Portal Imaging Device is smeared in radiation field to verification of treatment region. EPID's image was focused that using both on-line image verification and absolutely minimum absorbed dose during radiotherapy. So, Electronic Portal Imaging was tested for quality evaluation of medical linear accelerator had its pure conditional flash. This study has performed symmetry, Light/Radiation field congruence, and energy check, geometry difference on wedge filter using a liquid filled ion chamber (EPID). Prior to irradiated on EPID, high energy photon beam is checked with ion chamber. Using these results more convenient dosimetric method is accomplished by EPID that taken digital image. Medical image is acquired with EPID too. Therefore, EPID can be analyzed by numerical information for what want to see or get more knowledge for natural human condition.

• The Journal of Korean Obstetrics and Gynecology
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• v.32 no.4
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• pp.132-143
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• 2019

Objectives: The purpose of this study is to provide basic information on Korean medical research and treatment through analysis of breast cancer patients, who visited ${\bigcirc}{\bigcirc}$ university Korean medicine hospital. Methods: To analyze characteristics of breast cancer patients who visited korean medicine hospital, we searched medical records from January 1, 2016 to May 13, 2019, and 86 breast cancer patients were analyzed. Results: 1. The general characteristics of the subjects are as follows. The average age was $47.65{\pm}9.62years$ and 40's was the most (46.51%). The average height was $159.78{\pm}4.91cm$ and the average weight was $57.29{\pm}9.34kg$. The average body mass index (BMI) of the patients was $22.40{\pm}3.50kg/m^2$. 2. The stage distribution record indicated stage０ (9.72%), stageI (31.94%), stageII (34.72%), stageIII (20.83%) and stageIV (2.78%). 14 patients with unknown stage were excluded. 3. Before coming to the korean medicine hospital, of the 86 patients, 72 (83.72%) patients received surgical therapy, 55 (63.95%) patients received chemotherapy and 44 (51.16%) patients received radiotherapy. 11 (12.79%) patients chose oriental medicine as their primary treatment option. 4. The mean duration from diagnosis to hospital visit was $13.87{\pm}15.53months$. Among the total 86 patients, 46 (53.49%) patients visited for symptom relief during the follow-up period. 5. The most common symptom was general weakness in 29 (33.72%) patients, followed by hot flash, myalgia, insomnia, digestion disorder, numbness, edema, arthralgia, operation site pain, cold sensation and mastalgia. 6. Among 86 patients, 55 (63.95%) patients received acupuncture and moxibustion together. The most prescribed herbal medicine to subjects was Sibjeondaebo-tang-gamibang and Cheonhye-dan (25%). Conclusions: These results could be helpful to provide basic data on the Korean medical approach of breast cancer patients.