• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.2 no.1
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• pp.1-11
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• 2004

The hot cell facility for research activities related to the lithium reduction of spent fuel, which is designed to permit safe handling of source materials with radioactivity levels up to 1,385 TBq, is planned to be built. To meet this goal, the facility is designed to keep gamma and neutron radiation lower than the recommended dose-rate in normally occupied areas. The calculations peformed with QAD-CGGP and MCNP-4C are used to evaluate the proposed engineering design concepts that would provide acceptable dose-rates during a normal operation in hot cell facility. The maximum effective gamma dose-rates on the surfaces of the facility at operation area and at service area calculated by QAD-CGGP are estimated to be $2.10{\times}10^{-3}, 2.97{\times}10^{-3} and 1.01{\times}10{-1}$ mSv/h, respectively. And those calculated by MCNP-4C are $1.60{\times}10^{-3}, 2.99{\times}10^{-3} and 7.88{\times}10^{-2}$ mSv/h, respectively, The dose-rates contributed by neutrons are one order of magnitude less than that of gamma sources. Therefore, it is confirmed that the radiological design for hot cell facility satisfies the Korean criterion of 0.01 mSv/h for the operation area and 0.15 mSv/h for the service (maintenance) area.

• The Korean Journal of Nuclear Medicine
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• v.29 no.1
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• pp.54-60
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• 1995

Medical Internal Radiation Dose(MIRD) schema was developed for calculating the absorbed dose from the administered radiopharmaceuticals. With the biological distribution data and the physical properties of the radionuclide we can estimate the absorbed dose by the MIRD schema. For the thyroid cancer patients received $^{131}I$ therapy, the absorbed dose to the bone marrow is the limiting factor to the administered dose, and the duration of admission is deter-mined by the retained activity in the whole body. To monitor the whole body radioactivity, we used Eberline Smart 200 system using ionization chamber as a detector. With the time activity curve of the whole body, total body residence time was obtained. From the ICRP publication 53, the residence times of the source organs, such as kidney, urinary bladder content and stomach, were used to calculate the absorbed doses of the target organs, such as stomach, red marrow, bladder wall and remaineder total body. In 8 thyroid cancer patients with 175 mci of $^{131}I$ administered orally, the mean absorbed dose in the bladder wall was 375.1, in the stomach 285.1, red marrow 25.4 and total body 22.4 rad respectively. For the monitoring of the large administered activity, this method seemed to be quite useful.

• Journal of radiological science and technology
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• v.40 no.4
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• pp.613-620
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• 2017

Planning dose must be delivered accurately for radiation therapy. Also, It must be needed accurately setup. However, patient positioning images were need for accuracy setup. Then patient positioning images is followed by additional exposure to radiation. For 45 points in the phantom, we measured the doses for 6 MV and 10 MV photon beams, OBI(On Board Imager) and CBCT(Conebeam Computed Tomography) using OSLD(Optically Stimulated Luminescent Dosimeter). We compared the differences in the cases where posture confirmation imaging at each point was added to the treatment dose. Also, we tried to propose a photography cycle that satisfies the 5% recommended by AAPM(The American Association of Physicists in Medicine). As a result, a maximum of 98.6 cGy was obtained at a minimum of 45.27 cGy at the 6 MV, a maximum of 99.66 cGy at a minimum of 53.34 cGy at the 10 MV, a maximum of 2.64 cGy at the minimum of 0.19 cGy for the OBI and a maximum of 17.18 cGy at the minimum of 0.54 cGy for the CBCT.The ratio of the radiation dose to the treatment dose is 3.49% in the case of 2D imaging and the maximum is 22.65% in the case of 3D imaging. Therefore, tolerance of 2D image is 1 exposure per day, and 3D image is 1 exposure per week. And it is need to calculation of separate in the parallelism at additional study.

• The Journal of Korean Society for Radiation Therapy
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• v.17 no.1
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• pp.57-71
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• 2005

Purpose : To evaluate radiation dose and accuracy with TLD and diode detector when treat total skin with electron beam. Materials and Methods : Using Stanford Technique, we treated patient with Mycosis Fungoides. 6 MeV electron beam of LINAC was used and the SSD was 300 cm. Also, acrylic speller(0.8 cm) was used. The patient position was 6 types and the gantry angle was 64, 90 and $116^{\circ}$. The patient's skin dose and the output were detected 5 to 6 times with TLD and diode. Result : The deviations of dose detected with TLD from tumor dose were CA $+\;6\%$, thigh $+\;8\%$, umbilicus $+\;4\%$, calf $-\;8\%$, vertex $-\;74.4\%$, deep axillae $-\;10.2\%$, anus and testis $-\;87\%$, sole $-\;86\%$ and nails shielded with 4mm lead $+4\%$. The deviations of dose detected with diode were $-4.5\%{\sim}+5\%$ at the patient center and $-1.1\%{\sim}+1\%$ at the speller. Conclusion : The deviation of total skin dose was $+\;8\%{\sim}-\;8\%$ and that deviation was within the acceptable range(${\pm}\;10\%$). The boost dose was irradiated for the low dose areas(vertex, anus, sole). The electron beam output detected at the sootier was stable. It is thought that the deviation of dose at patient center detected with diode was induced by detection point and patient position.

• Progress in Medical Physics
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• v.9 no.2
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• pp.65-71
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• 1998

The aims are to evaluate the effects of an 1.0 cm acrylic plate and SSD on the dose profile and depth dose distribution of 9 MeV electron beam and to analyse adequacy for using an acrylic plate to reduce energy of electron beams. An acrylic plate of 1.0 cm thickness was used to reduce energy of 9 MeV electron beam to 7 MeV. The plate was put on an electron applicator at 65.4 cm distance from x-ray target. The size of the applicator was 10${\times}$l0cm at 100 cm SSD. For 100cm, l05cm and 110cm SSD, depth dose on beam axis and dose profiles at d$\_$max/ on two principal axes were measured using a 3D water phantom. From depth dose distributions, d$\_$max/, d$\_$85/, d$\_$50/ and R$\_$p/, surface dose, and mean energy and peak energy at surface were compared. From dose profiles flatness, penumbra width and actual field size were compared. For comparison, 9 MeV electron beams were measured. Surface dose of 7 MeV electron beams was changed from 85.5% to 82.2% increasing SSD from 100 cm to 110 cm, and except for dose buildup region, depth dose distributions were independent of SSD. Flatness of 7 MeV ranged from 4.7% to 10.4% increasing SSD, comparing 1.4% to 3.5% for 9 MeV. Penumbra width of 7 MeV ranged from 1.52 cm to 3.03 cm, comparing 1.14 cm to 1.63 cm for 9 MeV. Actual field size increased from 10.75 cm to 12.85 cm with SSD, comparing 10.32 cm to 11.46 cm for 9 MeV. Virtual SSD's of 7 and 9 MeV were respectively 49.8 cm and 88.5cm. In using energy reducer in electron therapy, depth dose distribution were independent of SSD except for buildup region as well as open field. In case of using energy reducer, increasing SSD made flatness to deteriorate more severely, penumbra width more wide, field size to increase more rapidly and virtual SSD more short comparing with original electron beam. In conclusion, it is desirable to use no energy reducer for electron beam, especially for long SSD.

• Journal of Radiation Protection and Research
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• v.32 no.3
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• pp.111-115
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• 2007

A deuterium oxide leakage accident occurred on October 4, 1999, at nuclear power plant in Korea. The concentration of tritium in air increased and 22 workers were exposed by tritium at that time. It is well known that tritium causes internal exposure. Therefore, we examined complete blood cell count, physical and biological dosimetry fur 13 workers among whole 22 workers to check the health effect and to evaluate the dose estimation of tritium exposure. The leukocyte count test, one of general blood test, was normal. The estimated doses were 0 - 4.44 mSv by physical dosimetry and 0-37 mGy by biological dosimetry. This dose does not exceed radiation dose limit, and the clinical symptoms of the exposed workers were not shown. The consistency between clinical sign and estimated dose means that physical and biological dosimetry were very useful especially in accident evaluation.

• Journal of radiological science and technology
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• v.35 no.4
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• pp.345-352
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• 2012

As the breast cancer rate is increasing fast in Korean women, people pay more attention to mammography and number of mammography have been increasing dramatically over the last few years. Mammography is the only means to diagnose breast cancer early, but harms caused by radiation exposure shouldn't be overlooked. Therefore, it is important to calculate the radiation dose being absorbed into the breast tissue during the process of mammography for a protective measure against radiation exposure. Because it is impossible to directly measure the radiation dose being absorbed into the human body, statistical calculation methods are commonly used, and most of them are supposed to simulate the interaction between radiation and matter by describing the human body internal structure with anthropomorphic phantoms. However, a simulation using Geant4 Code of Monte Carlo Method, which is well-known as most accurate in calculating the absorbed dose inside the human body, helps calculate exact dose by recreating the anatomical human body structure as it is through the DICOM file of CT. To calculate the absorbed dose in the breast tissue, therefore, this study carried out a simulation using Geant4 Code, and by using the DICOM converted file provided by Geant4, this study changed the human body structure expressed on the CT image data into geometry needed for this simulation. Besides, this study attempted to verify if the dose calculation of Geant4 interlocking with the DICOM file is useful, by comparing the calculated dose provided by this simulation and the measured dose provided by the PTW ion chamber. As a result, under the condition of 28kVp/190mAs, the Difference(%) between the measured dose and the calculated dose was found to be 0.08 %~0.33 %, and at 28 kVp/70 mAs, the Difference(%) of dose was 0.01 %~0.16 %, both of which showed results within 2%, the effective difference range. Therefore, this study found out that calculation of the absorbed dose using Geant4 Simulation is useful in measuring the absorbed dose in the breast tissue for mammography.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.57-61
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• 2014

Purpose Iodine (I-131) is one of the most widely used radioactive isotopes for therapeutic in the field of nuclear medicine. Therapeutic I-131 capsule is made out of lead to shield high energy radiation. Accurate dosimetry is necessarily required to perform safe and effective work for relative workers. The Monte Carlo method is known as a method to predict the absorbed dose distribution most accurately in radiation therapy and many researchers constantly attempt to apply this method to the dose calculation of radiotherapy recently. This paper aims to calculate distance dependent and activity dependent therapeutic I-131 capsule using GEANT4. Materials and Methods Therapeutic capsules was implemented on the basis of the design drawings. The simulated dose was determined by generating of gamma rays of energy to more than 364 keV. The simulated dose from the capsule at the distance of 10 cm and 100 cm was measured and calculated in the model of water phantom. The simulated dose were separately calculated for each position of each detector. Results According to the domestic regulation on radiation safety, the dose at 10 cm and 100 cm away from the surface of therapeutic I-131 capsule should not exceed 2.0 mSv/h and 0.02 mSv/h, respectively. The simulated doses turned out to be less than the limit, satisfying the domestic regulation. Conclusion These simulation results may serve as useful data in the prediction of hands dose absorbed by I-131 capsule handling. GEANT4 is considered that it will be effectively used in order to check the radiation dose.

• Progress in Medical Physics
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• v.16 no.2
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• pp.62-69
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• 2005

The purpose of this study has been performed to investigate the possibility of external audit program using thermoluminescence dosimetry for electron beam in korea. The TLD system consists of LiF powder, type TLD-700 read with a PCL 3 reader. In order to determine a calibration coefficient of the TLD system, the reference dosimeters are irradiated to 2 Gy in a $^{60}CO$ beam at the KFDA The irradiation is performed under reference conditions is water phantom using the IAEA standard holder for TLD of electron beam. The energy correction factor is determined for LiF powder irradiated of dose to water 2 Gy in electron beams of 6, 9, 12, 16 and 20 MeV (Varian CL 2100C). The dose is determined according to the IAEA TRS-398 and by measurement with a PTW Roos type plane-parallel chamber. The TLD for each electron energy are positioned in water at reference depth. In this study, to verify of the accuracy of dose determination by the TLD system are performed through a 'blind' TLD irradiation. The results of blind test are $2.98\%,\;3.39\%\;and\;0.01\%(1\sigma)$ at 9, 16, 20 MeV, respectively. The value generally agrees within the acceptance level of $5\%$ for electron beam. The results of this study prove the possibility of the TLD quality assurance program for electron beams. It has contributed to the improvement of clinical electron dosimetry in radiotherapy centers.

• Progress in Medical Physics
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• v.12 no.2
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• pp.161-169
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• 2001

For the head and neck radiotherapy, the technique of half beam using independent collimator is very useful to avoid overlapping of fields particularly when the lateral neck fields are placed adjacent to anterior supraclavicular field. Also abutting photon field with electron field is frequently used for the irradiation of posterior neck when tolerable dose on spinal cord has been reached. Using 6 MV X-ray and 9 MeV electron beams of Clinac1800(Varian, USA) linear accelerator, we performed film dosimetry by the X-OMAT V film of Kodak in solid water phantom and the dose distribution at beam center of 2 half beams further examined according to depths(0 cm, 1.5 cm, 3 cm, 5 cm) for single anterior half beam and anterior/posterior half beam. The dose distribution to the junction line between photon and electron fields was also measured. For the single anterior half beam, the absorption doses at 0.3 cm, 0.5 cm and 1 cm distances from beam center were 88%, 93% and 95% of open beam, respectively. In the anterior/posterior half beams, the absorption doses at 0.3 cm, 0.5 cm and 1 cm distances from beam center were 92%, 93% and 95% of open beam, respectively At the junction line between photon and electron fields, hot spot was developed on the side of the photon field and a cold spot was developed on that of the electron field. The hot spot in the photon side was developed at depth 1.5 cm with 7 mm width. The maximum dose of hot spot was increased to 6% of reference doses in the photon field. The cold spot in the electron side was developed at all measured depths(0.5 cm-3 cm) with 1-12.5 mm widths. The decreased dose in the cold spot was 4.5-30% of reference dose in the electron field. With above results, we concluded that when using electron beam or independent jaw for head and neck radiotherapy, the hot and cold dose area should be considered as critical point.