• Journal of the Korean Society of Radiology
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• v.17 no.3
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• pp.367-373
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• 2023

Aircrews and passengers are exposed to radiation from cosmic rays and secondary scattered rays generated by reactions with air or aircraft. For aircrews, radiation safety management is based on the exposure dose calculated using a space-weather environment simulation. However, the exposure dose varies depending on solar activity, altitude, flight path, etc., so measuring by route is more suggestive than the calculation. In this study, we developed an instrument to measure the cosmic radiation dose using a general-purpose Si sensor and a multichannel analyzer. The dose calculation applied the algorithm of CRaTER (Cosmic Ray Telescope for the Effects of Radiation), a space radiation measuring device of NASA. Energy and dose calibration was performed with Cs-137 662 keV gamma rays at a standard calibration facility, and good dose rate dependence was confirmed in the experimental range. Using the instrument, the dose was directly measured on the international line between Dubai and Incheon in May 2023, and it was similar to the result calculated by KREAM (Korean Radiation Exposure Assessment Model for Aviation Route Dose) within 12%. It was confirmed that the dose increased as the altitude and latitude increased, consistent with the calculation results by KREAM. Some limitations require more verification experiments. However, we confirmed it has sufficient utilization potential as a cost-effective measuring instrument for monitoring exposure dose inside or on personal aircraft.

• Progress in Medical Physics
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• v.20 no.1
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• pp.1-6
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• 2009

For HDR intracavitary brachytherapy with ovoids and a tandem, we compared the dose discrepancy of treatment plans using two different Ir-192 sources (microSelectron, Varian) and generated on two different treatment planning systems (PLATO, BrachyVision). The treatment plans of ten patient treated from Oct. 2007 to Jan. 2008 were selected for these comparisons. For the comparison of dose calculation using different sources, the average discrepancies were $-0.91{\pm}0.09%$, $-0.27{\pm}0.07%$, $0.22{\pm}0.39%$, and $0.88{\pm}0.37%$ in total treatment time and at B-point and ICRU bladder and rectum reference point, respectively. Comparing the two systems, the average dose discrepancies between treatment planning programs were $-0.22{\pm}0.42%$, $-0.25{\pm}0.29%$, $-0.23{\pm}0.63%$, and $-0.17{\pm}0.76%$, and the average dose discrepancies between positioning methods (PLATO with film and BrachyVision with digitial image) were $-0.61{\pm}0.59%$, $-0.77{\pm}0.45%$, $-0.72{\pm}1.70%$, and $0.35{\pm}2.82%$ at A-point, B-point, and ICRU bladder and rectum reference points, respectively. The rectal dose discrepancies between two systems were reached 5.87%. The difference in the dwell position expected by each TPS are mainly affected by the differences in the positioning method in TPSs and have an effect on dose calculations of rectal and bladder located in AP direction.

• The Journal of Engineering Geology
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• v.29 no.4
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• pp.461-468
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• 2019

Gamma-radiation dose rates were measured at 77 points around the Ogcheon lower phyllite zone (og2) in Goesan County, Korea, using gamma-ray spectrometry. Sample K contents were in the range 1.8-8.8% (average 4.6%), highest in Kgr. The eU contents were 0.2-217.9 ppm (average 16.7 ppm), highest in og2 (median 29.6 ppm). The eTh contents were 11.9-76.5 ppm (average 29.5 ppm) and the average eTh content of Kgr was 45.4 ppm, higher than those of Ogcheon meta-sedimentary rocks (og1, og2, and og3) (26.6-30.6 ppm). Except for some high-uranium sites in og2, ⁴⁰K is the main radioactive material contributing to the gamma-radiation dose in the study area. Our results indicate that the outdoor effective dose rate of the area is 0.08-1.71 mSv y^-1 (average 0.28 mSv y^-1), with most areas apart from three points in og2 displaying dose rates <1 mSv y^-1, which is the normal natural radiation background level.

• Radiation Oncology Journal
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• v.14 no.3
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• pp.201-209
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• 1996

Purpose : To assess the efficacy of high dose rate - intracavitary radio-therapy (HDR-ICR) in the radiotherapy of FIGO stage IB squamous cell carcinoma of uterine cervix and to determine the optimum dose combination scheme of external radiotherapy and ICR to achieve acceptable local control without severe complication. Materials and Methods : One hundred and sixty two patients with FIGO stage Ib squamous cell carcinoma of uterine cervix who received definitive radiotherapy between May 1979 and December 1990 were retrospectively analyzed. All the patients received external radiotherapy combined with HDR-ICR. External dose of 40-46 Gy in 4.5-5 weeks was given to whole pelvis(median 45 Gy) and ICR dose of 30-39 Gy in 10-13 times was given to the point A. Midline shielding was done after 20-45 Gy of external radiotherapy(median 40 Gy) Summation of external dose Plus ICR dose to the point A range were 64.20-95.00 Gy. and mean was 83.94 Gy. We analyzed the local control rate, survival rate, and late complication rate. Rusults : Initial complete response rate was $99.4\%$ for all patients. Overall 5-year survival rate was $91.1\%$ and 5-year disease free survival rate was $90.9\%$. Local failure rate was $4.9\%$ and distant failure rate was $4.3\%$. Tumor size was the only significant prognostic factor. When tumor size greater than 3cm, 5-rear survival rate was $92.6\%$ and less than 3cm, that was $79.6\%$. Late complication rate was $23.5\%$ with $18.5\%$ of rectal complication and $4.9\%$ of bladder complication. Mean rectal dose summation of external midline dose plus ICR rectal point dose was lower in the patients without rectal complication(74.88 Gr) than those with rectal complication (78.87 Gy). Complication rate was increased with low rate of improvement of survival rate when summation of external midline dose plus point A or point R dose by ICR was greater than 70-75 Gy. Conclusion : The definitive radiation therapy using high dose rate ICR in FIGO stage IB uterine cervical cancer is effective treatment modality with good local control and survival rate without severe complication.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.564-567
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• 2012

Optical fibers are going to be used for telecommunication, image fibers, sensors under irradiation in nuclear power plants and various irradiation facilities. Especially, Temperature detection sensors using Raman light scattering, temperature or strain sensors using fiber gratings, magnet-optical sensors using photo-magnetic effect, are already commercialized. However, When fibers are exposed to ionizing radiation, color centers are formed in fibers which reduces their light transmission, and it is limited in applying under radiation environments. In this study, $Co^{60}$ gamma-ray induced optical attenuation on Ge-doped single mode(SM) fiber has been measured. Gamma-ray is irradiated for 4hours at the dose rate of 0.5kGy/hr, 2kGy/hr, 8kGy/hr. Consequently, gamma-ray induced loss based on radiation effects in Ge-doped SM fiber occur precisely. Furthermore, dose rate effect that the higher dose rate in the same total dose, the more increase loss of optical fiber and annealing effect that the higher the loss after irradiation, the more increase the recovery rate of the loss are observed in the fiber. This results plan to make use of bases in the study of the radiation-hardened optical fiber.

• Journal of radiological science and technology
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• v.34 no.4
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• pp.333-339
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• 2011

The purpose of this study is to compare DNA repair characteristics of normal fibroblast cell (MRC-5) and neuroblastoma cell (SK-N-SH) induced by proton beam. Cells were irradiated with 2Gy, 5Gy and 8Gy proton beam. The rate of DNA rejoining was measured by alkaline version of the comet assay. After a repair time, tail moment was measured again. The tail moment of MRC-5 was lower than SK-N-SH. However, after 8Gy of exposure, the tail moment of MRC-5 was measured as 50.320223.17155 which represents dangerous level of DNA damage. The cells were repaired practically within 25 hours after 2 and 5Gy of exposure while they were not fully recovered after 8Gy of exposure. Especially, tail moment of MRC-5 after 25 hours was 18.15364.42849. In the distal declining edge of SOBP, the RBE value is increased by high LET. The RBE differences of SOBP in high-dose were greater than low-dose. After the high-dose exposure, MRC-5 of normal fibroblast cell could lead to lasting DNA damage as shown in this study. In conclusion, we has to pay special attention when the region of the treatment volume is close to sensitive tissues.

• The Journal of Korean Society for Radiation Therapy
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• v.16 no.1
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• pp.29-37
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• 2004

Purpose : A rectum and a bladder should be carefully considered in order to decrease side effects when HDR patient of uterine cervix cancer. Generally speaking, the value of dosimeter at a rectum and a bladder only depends on the value of a planning equipment, while some analyses of the value of dosimetry at rectum with TLD has been reported Or the contrary, it is hardly to find a report with in vivo dosimetry(diode detector). On this thesis, we would like to suggest the following. When a patient of uterine cervix cancer is in therapy, it is helpful to put a diode detector inside of a rectum in order to measure the rectal dose Based upon the result of the dosimetry, the result can be used as basic data at decreasing side effects. Materials and Methods : Six patients of uterine cervix cancer(four with tandem and ovoid, one with cylinder, and the other one with tandem and cylinder) who had been irradiated with HDR. Ir-192 totally 28 times from February 2003 to June 2003. We irradiated twice in the same distant spots with anterior film and lateral film whenever we measured with a diode detector. Then we did planning and compared each film. Results : The result of the measurement 4 patients with a diode detector is the following. The average and deviation from 3 patients with tandem and ovoid were $274.1{\pm}13.4cGy$, from 1 patient with tandem and ovoid were $126.1{\pm}7.2cGy$, from 1 patient with cylinder were $99.7{\pm}7.1cGy$, and from 1 patient with tandem and cylinder were $77.7{\pm}11.5cGy$. Conclusion : It is difficult to predict how the side effect of a rectum since the result of measurement with a diode detector depends on the state of a rectum. According to the result of the study, it is effective to use a TLD or an in vivo dosimetry and measure a rectum in order to consider the side effect. It is very necessary to decrease the amount of irradiation by controlling properly the duration of the irradiation and gauze packing, and by using shield equipments especially when side effects can be expected.

• The Journal of the Korea Contents Association
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• v.14 no.2
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• pp.467-474
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• 2014

The relative dose calculated by MCNPX and the relative dose measured by ionization chamber and solid phantoms evaluated the accuracy comparing with Monte Carlo simulation. In order to apply Monte Carlo simulation the intraluminal brachytherapy of extrahepatic bile duct cancer, 192Ir sealed radioactive source replicate, Bile duct and surrounding organs were made using KMIRD phantom based on a South Korea standard man. To check the absorbed dose of normal organs around bile duct, we set the specific effective energy and initial radioactivity to 1 Ci using MCNPX. Evaluation of the accuracy of the Monte Carlo simulation, the difference of the relative dose is the most 1.96% that satisfy the criteria that is the relative error less than 2% suggested by MCNPX code. In addition, The specific effective energy and absorbed dose of normal organs that were relatively adjacent to bile duct such as right side of kidney, liver, pancreas, transverse colon, spinal cord, stomach and small intestine were relatively high. on the contrary, the organs that were relatively distant to bile duct such as left side of kidney, spleen, ascending colon, descending colon and sigmoid colon were relatively low.

• Progress in Medical Physics
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• v.13 no.2
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• pp.79-84
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• 2002

In this study, a cylindrical ultrasound applicator is developed for the treatment of vagina and rectum in combination with high dose rate brachytherapy. A cylindrical transducer (PZT-8, 1=1.5 cm, thickness=1.5mm OD=2.5 cm) was used as an energy source for induction of hyperthermia. Three single-element applicators were constructed to examine the performance of the PZT material. Vector impedance was measured to determine driving frequency. The efficiencies of the elements were determined using a radiation force technique to evaluate the feasibility of using the applicator as a hyperthermia source. A multi-element ultrasound applicator was designed using the PZT-8 material for the treatment of vagina. Results from the vector impedance measurements showed maximum magnitude at 1.78, 1.77, and 1.77 MHz for applicator 1,2, and 3, respectively. The radiation force measurements showed that the acoustic power of 40 watts was obtained in all three elements. The average efficiencies of the elements were 61.4, 65.2, and 54.0% for element 1, 2, and 3, respectively. The designed ultrasound hyperthermia applicator could be used in combination with high dose rate brachytherapy for the treatment of vagina and rectum. The use of this applicator with intracavitary brachytherapy could offer improved tumor control by increasing radiosensitiyity of the tumor.

• Journal of radiological science and technology
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• v.45 no.1
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• pp.49-55
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• 2022

This study is to develop a mobile type environmental radiation measurement system for emergency response or environmental radiation monitoring of local governments near nuclear facilities. A mobile radiation measurement system can monitor radiation by field beyond the spatial constraints of a fixed environmental radiation monitor. If installed in local government infrastructure such as public transportation, environmental radiation can be monitored without additional manpower and measurement work. In addition, it is designed to enable monitoring and measurement of radiation from low to high doses as well as the environment in preparation for radioactive disasters such as nuclear power plant accidents. It is expected that this system will be utilized not only in normal times but also in the event of a radiation accident to improve the disaster prevention capabilities of local governments.