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J. Radiat. Prot. Res > Volume 47(1); 2022 > Article
List of Recent Graduates

KARP

Name of graduate: Kim, Younghak
Affiliation: Department of Bio-convergence Engineering/Korea University/Korea
Graduation date: Feb. 2022
Degree: Doctor of Philosophy
Name of academic advisor: Lee, Wonho
Title of thesis: Development of a Compton Camera based on 3D Position-sensitive Virtual Frisch-grid CZT Detectors
Abstract: Cadmium zinc telluride (CZT) is the most promising material to detect X-ray and gamma-ray due to its high detection efficiency, good energy resolution, and operability at room temperature without any cooling device. However, detector responses of the CZT depend on the interaction position because of the distributions of weighting potential in a planar electrode structure and material defects, and it causes the degradation of the performance. We developed a detection system based on a 3D position-sensitive detector to overcome this problem. A 5 × 5 × 12 mm3 CZT was used, and the virtual Frisch-grid (VFG) method was applied. 3D position information was calculated by signals from the anode, cathode, and side electrodes. The detector responses were corrected by the position information, and as a result, the energy resolution of 0.83% at 662 keV was achieved. We developed a prototype Compton camera by expanding the single VFG CZT detector to a 2 × 2 array. This array structure allows us to use small but high-yielding crystals, so a large-area detection system with a low cost can be achievable. Four 6 × 6 × 19 mm3 CZTs and a commercialized signal processing system were used. Positional information acquisition and response correction were performed the same way as the previous system. Various sources were used for spectroscopy, and the energy resolutions at 356, 511, 662, 1,275, and 1,332 keV were 3.17, 2.37, 2.03, 1.49, and 1.14%, respectively. In Compton imaging experiments, single and multiple sources at various positions were measured, and the weighted list-mode MLEM method was applied for image reconstruction. The results showed that our Compton camera could correctly reconstruct the source positions of either single or multiple sources. The intrinsic efficiency and spatial resolution evaluated by single 137Cs results were (1.43 ± 0.28) × 10-3 and 16.42 ± 5.35°, respectively. It was also identified that the different sources could be distinguished by applying energy windows.
Name of graduate: Lee, Chanki
Affiliation: Department of Nuclear Engineering/Ulsan National Institute of Science and Technology/Korea
Graduation date: Feb. 2022
Degree: Doctor of Philosophy
Name of academic advisor: Kim, Hee Reyoung
Title of thesis: In Situ YAlO3(Ce) Gamma Spectrometry System for Underwater Survey by Remotely Operated Vehicle
Abstract: Rapid surveys and assessments of environmental radioactivity and radiation doses are required for efficient and effective response to radiological emergencies. Emergency responses under underwater conditions to illegal ocean dumping, accidents, or sabotage of marine nuclear reactors are probably going to increase in the future. Therefore, in this study, we designed, developed, and tested a mechanical, chemical, and radiologically robust in situ YAlO3(Ce) gamma spectrometer survey system, that is remotely operated by an unmanned vehicle to be used for short-range and high-dose contaminations. In particular, the system is optimally designed by prediction based on the figure of merit, which is developed by correlating the scan minimum detectable concentrations (MDCs). After calibration by Monte Carlo simulation and a water tank experiment, the response function and relevant G-factor of the spectrometer were estimated to calculate the static and scan MDCs. The calculation results show that it can satisfy concentration and dose target values for four cases (i.e., static sealed source characterization, sealed source scanning, static effluent measurement, and localized hotspot mapping) within 10 min with 95 % confidence, and 0.2 m/s scan speed with 95 % true positive and 60% false positive. In addition, the complete system operation when mounted on an underwater vehicle with a 200 m length wired communication was tested in a laboratory mockup facility by controlling the salt concentration, flow, wave, and temperature. It was found that the standard deviation of the mechanical noise (in the CPS) was proportional to the drag force, which followed a quadratically increasing trend. Temperature coefficient was found to be -0.193 ± 0.020 %/°C, and overall noise effects to spectra were minor, except for electrical noise formed in the low-energy region below tens of keV. In summary, the developed system based on YAlO3(Ce) gamma spectrometry could be used for various radiological emergencies.
Name of graduate: Kwon, Tae-Eun
Affiliation: Department of Nuclear Engineering/Hanyang University/Korea
Graduation date: Aug. 2021
Degree: Doctor of Philosophy
Name of academic advisor: Chung, Yoonsun
Title of thesis: Korean-specific internal dose assessment for radioiodine
Abstract: For radioiodine, of which physiological behavior varies greatly depending on levels of dietary iodine intakes, the internal doses evaluated based on the ICRP reference data may significantly differ from actual doses for Koreans, one of the high dietary iodine-consuming populations. Therefore, this study developed fundamental data associated with internal dose assessment reflecting the Korean physical characteristics and estabilished an overall system of Korean-specific internal dose assessment for radioiodine by producing the Korean-specific dosimetric data. orean-specific iodine biokinetic model was developed based on the data on iodine biokinetics in Korean’s body, and S coefficients (i.e., doses to target regions per unit disintegration in a source region) were calcualted by Monte Calro simulation of mesh-type Korean reference computational phantoms (MRKPs). Using the Korean biokinetic model and S coefficients, Korean-specific dosimetric data that could be directly applied to practical internal dose assessment for iodine were calculated. Thyroid retention functions for Koreans were significantly lower than those provided in ICRP Publication 137, but intenral dose coefficients for short-lived isotopes (e.g., 131I, 133I, and 134I) were comparable to ICRP reference values; however, it was found that the use of Korean dosimetric data in retrospective dose assessment based on thyroid measurement might result in 1.5-2 times higher doses than those evaluated based on the ICRP reference data. This study successfully established the Korean-specific dose assessment system for iodine and quantified the bias resulting from using the ICRP reference data for Koreans by comparing the Korean data with ICRP reference data. The Korean-specific dose assessment can definitely improve the accuracy of internal dose for Koreans but should be more stressed in case that a high exposure that may approach or exceed dose limits is predicted.
Name of graduate: Kim, Jinwoo
Affiliation: School of Mechanical Engineering/Pusan National University/Korea
Graduation date: Aug. 2021
Degree: Doctor of Philosophy
Name of academic advisor: Kim, Ho Kyung
Title of thesis: Dose Estimation and Optimization for Dental Cone-Beam Computed Tomography
Abstract: There is an increasing call for radiation dose tracking from medical examinations and patient-specific dose management has become a great concern. Especially, since the computed tomography (CT) can lead to a significant amount of patient dose, fast and accurate CT dose estimation has become an important issue. For the purpose of real-time scan-protocol optimization and patient-specific dose management in cone-beam CT (CBCT), we introduce a hybrid approach that estimates the absorbed dose distributions in reconstructed images. The proposed method employs a numerical algorithm for the estimation of primary dose distributions and a deep learning technique for the estimation of secondary ones. The validation of the proposed method is performed by comparative analysis with the Monte Carlo (MC) and conventional model-based dose reconstruction methods for typical dentoalveolar CBCT protocols which consider the simple cylindrical water and anthropomorphic head phantoms as a patient. To verify each stage of the proposed method, we have developed the list-mode MC methodology for CT dose reconstructions and applied it to dental CBCT to analyze the dose distributions in terms of local primary and remote secondary doses. The proposed method shows good agreement with the MC method and consumes a significantly lower computational cost. While the direct MC simulation takes several hours for estimating an absorbed energy map for a complete CBCT scan, the proposed method can generate an absorbed dose map from a CT image in few seconds. The patient-dose benefits in CBCT due to the width-truncated detector geometry and the beam-intensity modulation are also investigated for a wide range of parameters. The dose benefit with the width-truncated geometry linearly increases as the detector-offset width is decreased. Considering both patient dose and voxel noise, the gain from the modulation techniques is marginal compared to the conventional uniform power scanning. This study will be useful for the development of dental CBCT imaging techniques in terms of patient-specific dose.
Name of graduate: Park, Sunghyun
Affiliation: Department of Nuclear Engineering/Hanyang University/Korea
Graduation date: Feb. 2022
Degree: Doctor of Philosophy
Name of academic advisor: Jae, Moosung
Title of thesis: Evaluation of Early Protective Actions on the New Principle of Radiation Protection
Abstract: Nuclear power industries have made numerous technological advances in the past 70 years to help humanity take a prosperous and advanced life. Nowadays, many countries are using the nuclear power as a base-power energy source to achieve net-zero carbon successfully. Just as everything in the world always has advantages and disadvantages, nuclear power also has both. It has tremendous efficiency for generating electricity and has a risk of severe accidents that can impact the environment and people. Accordingly, protective actions for severe accidents have been improved by many researchers in the world. However, what we have learned from the Fukushima Daiichi accident was the phenomenon of ‘putting the cart before the horse.’ For example, people who were evacuated to avoid radiation suffer from other reasons. This phenomenon occurred because the recommendation of evacuation or sheltering-in-place was based on the single criterion, projected dose. This study quantitatively evaluated the early protective actions by health effects calculated from MELCOR Accident Consequence Code System (MACCS). In order to gain insights from the consideration of health effects, threshold Evacuation Time Estimate (ETE) was used. In summary, for the close area, the threshold ETE can be used as the limit time value for the completion of the evacuation strategy. On the other hand, the possibility of acute effects is relatively low for the remote area, so the risk of latent cancer fatality should be used for this area. However, threshold ETE based on the latent cancer fatality has limitations that cannot provide appropriateness of evacuation. In order to overcome these limitations, the protective actions were re-evaluated based on the principle of radiation protection. Recently, a new standard for reference level of early protective actions was suggested by IAEA. The re-evaluation was performed with the new standard of health effects, and cost. Degree of Benefit (DOB) measures has been developed to consider these factors. In summary, it was confirmed that immediate evacuation was selected as the optimal strategy in the near area. The effectiveness of sheltering-in-place in the remote area was sufficiently shown regarding health effects and the possibility of evacuation. Various studies are being conducted on the effectiveness and dynamic characteristics of evacuation and shelter worldwide. The studies include radiation effects on the body, microscopic traffic simulations, uncertainty in decision-making, etc. The characteristic of this study is to consider health effects with the possibility of evacuation. Finally, I believe that this study can be used as primary data for improving emergency preparedness plans in Korea.
Name of graduate: Choi, Chansoo
Affiliation: Department of Nuclear Engineering/Hanyang University/Korea
Graduation date: Feb. 2022
Degree: Doctor of Philosophy
Name of academic advisor: Kim, Chan Hyeong
Title of thesis: Next-generation ICRP Pediatric Mesh-type Reference Computational Phantoms
Abstract: The present study developed the pediatric mesh-type reference computational phantoms (MRCPs) of the International Commission on Radiological Protection (ICRP), comprising ten phantoms (newborn, 1-, 5-, 10-, and 15-year-old males and female). The pediatric MRCPs overcome the dosimetric limitations of the pediatric voxel-type reference computational phantoms (VRCPs) of ICRP Publication 143 coming from the limited voxel resolutions and the nature of the voxel geometry. The pediatric MRCPs were constructed by converting the pediatric VRCPs to a high-quality mesh format with significant anatomical improvement for the complex and/or small organs which were not properly represented in the pediatric VRCPs (i.e., skeletal system, colon, thyroid, lymphatic nodes, extra-thoracic region, eyes, teeth, blood in large vessels, muscle, and lung airways). In addition, the pediatric MRCPs were developed to have all the radiosensitive target and source tissues required for calculation of effective dose, including the micrometer-scale regions situated in the skin, lens, urinary bladder, alimentary tract organs, and respiratory tract organs. The pediatric MRCPs can be directly used in general-purpose Monte Carlo codes such as Geant4, PHITS, and MCNP6, fully maintaining the high fidelity of the mesh geometry in Monte Carlo dose calculations. For both the external and internal exposures, the pediatric MRCPs generally provide similar dose values to those from the pediatric VRCPs for highly penetrating radiations (e.g., photons ≥ 50 keV) but provide more accurate and reliable dose values for exposures to weakly penetrating radiations (e.g., photons < 50 keV and electrons). The pediatric MRCPs will be used in all other future calculations following the next set of general ICRP recommendations and will provide a resource for wider use in radiological protection applications.
Name of graduate: Lee, Hyun Su
Affiliation: Department of Nuclear Engineering/Hanyang University/Korea
Graduation date: Aug. 2021
Degree: Doctor of Philosophy
Name of academic advisor: Kim, Chan Hyeong
Title of thesis: Large-area Hybrid Gamma Imager: Fast Localization of Gamma-ray Sources
Abstract: This thesis reports the development of a gamma-ray imaging device, named Large-Area Hybrid Gamma Imager (LAHGI), featuring high imaging sensitivity, good imaging resolution over a broad energy range. A hybrid collimation method, which combines mechanical and electronic collimation, is employed for a stable imaging performance over a range of gamma ray energies. High imaging sensitivity was accomplished by large-area scintillation detectors. The system comprises position-sensitive NaI(Tl) scintillation detectors, dedicated electronics, a tungsten coded aperture mask, and a 3D camera. Each component was specifically designed for the LAHGI system, after a thorough consideration on the performance on field application. The imaging performance of the LAHGI was evaluated through experiments in various source conditions with gamma energies, source positions and measurement time. It was able to acquire clear images of the source locations through the hybrid imaging on energies ranging from low as 59.5 keV (241Am), to high as 1,330 keV (60Co), some of which were difficult when the coded aperture imaging or the Compton imaging used separately. The imaging resolution ranged 6.0–8.9°, when maximum likelihood estimation maximization (MLEM) image reconstruction was applied. From the high sensitivity of the developed system, the 137Cs source at distance, incurring dose rate lower than background level (~0.1 µSv/h), can be imaged in a short measurement time: it required 3 s and 30 s when the dose rate from the source was about 25% and 3% of the background level, respectively. The LAHGI was also demonstrated in circumstances simulating decontamination site, where the dose rate is known to be 1–4 µSv/h. It was able to image the sources of interest in the field of view (FOV), even when other sources distributed in and out of the FOV incurred increased background radiation.
Name of graduate: Jo, Ajin
Affiliation: Department of Bio-Convergence Engineering/Korea University/Korea
Graduation date: Feb. 2022
Degree: Doctor of Philosophy
Name of academic advisor: Lee, Wonho
Title of thesis: Development of an XRF system Using a CdTe Detector Array and the Deep Learning Method
Abstract: The X-ray fluorescence (XRF) system is a material analysis system which uses characteristic X-rays emitted from the atoms when photoelectric effect happens. The conventional XRF system which uses silicon drift detector and the maximum-likelihood expectation maximization (MLEM) method, one of energy deconvolution method, has difficulties in discriminating all types of overlapping characteristic X-ray peaks. A deep learning method were expected to improve the performance of the XRF systems instead of conventional material analyzing method due to its abilities to learn the patterns of the data. In this study, material discrimination and quantitation of element fractions were performed with deep learning method. A simulation study was performed to verify the feasibility of the deep learning method when all elements from Ti (atomic number: 22) to Bi (atomic number: 83) except for Tc (atomic number: 43) were used for the training of deep learning models. Training and test data for the simulation study was obtained with the Monte Carlo simulation code (MCNPX) and arranged. The data were combined by weighting and summing two or three pure material data to imitate the compound or mixture data which have various fractions and combination of elements because collecting all types of compounds or mixtures which have various fractions is very difficult.
An experiment study was also performed with Fe, Ni, Cu, Zn and brass phantoms for performance estimation of the deep learning models. Pure material data from four metal phantoms were obtained with a CdTe semiconductor detector array. Those data were also combined by weighting and summing pure material energy spectra as it was in the simulation study. Two CNN models for Cu and Zn material discrimination were composed and trained. The performance estimation was also performed with the same methods in the simulation study.
Name of graduate: Kim, Jae Hyun
Affiliation: Department of Nuclear Engineering/Hanyang University/Korea
Graduation date: Aug. 2021
Degree: Doctor of Philosophy
Name of academic advisor: Hong, Ser Gi and Kim, Jong Kyung
Title of thesis: A Study on Residual Dose Analysis for Giant Radiation Facilities Using an Automated Mesh-based Rigorous-2-Step (R2S) Approach
Abstract: In giant radiation facilities, lots of neutrons can be produced by nuclear reactions, which produce unstable nuclides emitting gamma rays in various components of fission and fusion energy systems. So, estimation of residual dose rates in such facilities is very important to check if the dose rates are below the radiational safety limits. Generally, two computational analysis schemes of the cell-based Rigorous-2-Step (R2S) method and the Direct-1-Step (D1S) method have been used widely in evaluating the residual dose rates. These previous methods have several notable problems in residual dose rate calculations. Representatively, the cell-based R2S method has low computational efficiency due to spatial resolution issues, and the D1S method cannot directly calculate the induced activity, and at least once R2S calculation is required for the D1S calculation. In this study, an automated mesh-based R2S approach to improve computational calculation efficiency and accuracy is introduced to analyze residual dose rates in giant radiation facilities. This proposed approach using coupled with the particle transport code MCNP5 and the activation inventory code FISPACT was developed for the first time in Korea to improve the computational efficiency and accuracy of the residual dose rate calculations of giant radiation facilities This automated mesh-based R2S approach is applied to several problems to verify the applicability of this approach. From the several verification calculation problems, it is shown that the automated mesh-based R2S more accurately estimates the residual dose rates than the cell-based R2S method due to its higher spatial resolution both in the neutron flux tallies and gamma sources. Furthermore, it is shown that the calculation efficiency of the automated mesh-based R2S method is considerably improved compared to the cell-based R2S in terms of FOM.
Name of graduate: Kim, Kyeong-Hyeon
Affiliation: Major of Medical Physics & Engineering, Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea/Korea
Graduation date: Aug. 2021
Degree: Doctor of Philosophy
Name of academic advisor: Suh, Tae Suk
Title of thesis: Four-dimensional inverse-geometry computed tomography: a preliminary study
Abstract: Four-dimensional (4D) cone-beam computed tomography (CBCT) has been widely used in clinics; however, several limitations remain to be addressed. Multisource inverse geometry computed tomography (IGCT) has been developed to overcome the several limitations of conventional CBCT, such as cone beam artefact and massive scattered radiation. This study introduces and evaluates respiratory-correlated 4D IGCT. The projection data of the IGCT were acquired in a single gantry rotation over 120 seconds. Three virtual phantoms—static Defrise, 4D Shepp–Logan, and 4D extended cardiac- torso (XCAT)—were used to obtain projection data for the IGCT and CBCT. The projection acquisition parameters were determined to eliminate vacancies in the Radon space for an accurate rebinning process. Phase-based sorting was conducted within 10 phase bins, and the sorted projection data were binned into a cone beam geometry. Finally, Feldkamp–Davis–Kress reconstruction was conducted independently at each phase. The reconstructed images were compared using the structural similarity index measure (SSIM) and root mean square error (RMSE). The vertical profile of the Defrise reconstruction image was uniform, and the cone beam artefact was reduced in the IGCT image. Under an ideal projection acquisition condition, the mean coronal plane SSIMs of the Shepp–Logan and 4D XCAT phantoms were 0.899 and 0.706, respectively, which were higher than those of the CBCT (0.784 and 0.623, respectively). Similarly, the mean RMSEs of the coronal plane IGCT (0.036 and 0.158) exhibited an improvement over those of the CBCT (0.165 and 0.261, respectively). The mean standard deviations of the SSIM and RMSE were lower for IGCT than for CBCT. In particular, the SSIM and RMSE of the sagittal and coronal planes of the Shepp–Logan IGCT images were stable in all phase bins; however, those of the CBCT changed depending on the phase bins. Poor image quality was observed for IGCT under inappropriate conditions. This was caused by a vacancy in the Radon space, owing to an inappropriate scan setting. Overall, the proposed 4D IGCT exhibited better image quality than conventional CBCT. Based on the excellence of IGCT, presented 4D IGCT system can evolve into an advanced imaging technique that can replace conventional CBCT in the future.
Name of graduate: Kim, Tae Hoon
Affiliation: Department of Nuclear Engineering/Hanyang University/Korea
Graduation date: Feb. 2022
Degree: Doctor of Philosophy
Name of academic advisor: Kim, Yong Kyun
Title of thesis: Absorbed Energy Measurement in Radiotherapy Using Shape-Customized Plastic Scintillation Detector
Abstract: An isodose-shaped scintillator (ISS) detector was developed using 3D printing to evaluate the output factor (OF) of the Leksell Gamma Knife (LGK). Because the shape of the ISS is based on the known dose distribution, the volume averaging effect for small fields could be corrected by summation of the dose distribution. The volume averaging correction factor calculated based on the dose distribution was compared with that calculated by the Monte Carlo (MC) simulation. The calculated factor was within 0.3% of the value obtained through the MC simulation, and the correction factor due to the density difference of the scintillation material was calculated to be between 1.003 and 1.005. The 8 mm collimator OF averaged 0.899 ± 0.003, with a 0.1 ± 0.3% difference from that provided by the treatment planning system (TPS). The 4 mm collimator OF was measured to be 0.826 ± 0.005, which was 1.5 ± 0.6% higher than the value from the TPS, but similar to values in recently published papers. A tumor model scintillator (TMS) was fabricated using 3D printing based on the shape of the treatment plan tumor volume. The output signal of the TMS was calibrated to the absorbed dose rate calculated by the MC simulation. The absorbed energy in the treatment plan was measured for three TMS samples, which was, on average, 1.9 ± 0.7% higher than the calculated value from the TPS. In addition, nine different TMSs were also tested, and the averaged value differed from the calculated value by 0.8 ± 2.5%. As such, these results were within a few percent of the TPS, but within the acceptable error range ( < 3%) provided by AAPM Report 142.
Name of graduate: Ahn, Jihyun
Affiliation: Department of Applied Plasma and Quantum Beam Engineering/Jeonbuk National University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Seo, Hee
Title of thesis: Evaluation of Gamma Spectroscopy for Quantification of Uranium in Radioactive Waste drums
Name of graduate: An, Geunyeong
Affiliation: Department of Applied Plasma Engineering/Jeonbuk National University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Seo, Hee
Title of thesis: Optimization of Pencil-beam-based Backscatter X-ray Security Scanner
Name of graduate: Park, Hyunseok
Affiliation: Department of Health and Safety Convergence Science/Korea University/Republic of Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Lee, Wonho
Title of thesis: Feasibility of BNCT using Photon Induced Neutron: Monte Carlo Simulation
Name of graduate: Park, Seoryeong
Affiliation: Department of Energy and Chemical Engineering major/ Jeju National University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Jeong, Manhee
Title of thesis: Development of coded-aperture based gamma-ray imaging system
Name of graduate: Park, Junsung
Affiliation: Department of Applied Plasma and Quantum Beam Engineering/Jeonbuk National University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Seo, Hee
Title of thesis: Optimization of Dual Energy X-ray Security Scanner by Monte Carlo Simulation
Name of graduate: Lee, Chang-Min
Affiliation: Division of Advanced Nuclear Engineering/POSTECH/Korea
Graduation date: Aug. 2021
Degree: Master of Science
Name of academic advisor: Lee, Hee-Seock/Yoon, Gunsu
Title of thesis: Development of a dose estimation code for BNCT with GPU accelerated Monte Carlo and
collapsed cone Convolution method
Name of graduate: Ha, Sangseok
Affiliation: Department of Nuclear Engineering/Hanyang University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Kim, Chan Hyeong
Title of thesis: Development of mesh-type pediatric phantom set with various body fat percentages
Name of graduate: Heo, Jae seung
Affiliation: Department of Health & Safety Convergence Science/Korea University/Korea
Graduation date: Aug. 2021
Degree: Master of Science
Name of academic advisor: Kim, Jung Min
Title of thesis: Evaluation of the decontamination efficiency of radioactive wastes generated during the production of 201Tl
Name of graduate: Lee, Eun Ji
Affiliation: Department of Nuclear Engineering/Chosun University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Kong, Tae Young
Title of thesis: A Study of Radiation Dose Reduction for Workers in Decommissioning Nuclear Power Plants using Overseas Cases
Name of graduate: Boo, Jihwan
Affiliation: Department of Nuclear and Energy Engineering/ Jeju National University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Jeong, Manhee
Title of thesis: Development of a Coded Aperture Based Hand-held Dual Particle Imager
Name of graduate: Lee, Jooyub
Affiliation: Department of Nuclear Engineering/Sejong University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Kim,Geehyun
Title of thesis: A Study of Image Reconstruction Methodology based on Graphical Approach for H-RMC
Name of graduate: Sim, Hayoung
Affiliation: Department of Applied Plasma and Quantum Beam Engineering/Jeonbuk National University/Korea
Graduation date: Feb. 2022
Degree: Master of Science
Name of academic advisor: Seo, Hee
Title of thesis: Development of Background Simulation Technique for Radiation Portal Monitors at Domestic Airports and Ports

JHPS

Name of graduate: Nimelan Veerasamy
Affiliation: Tokyo Metropolitan University
Graduation date: Sep. 2020
Degree: Doctor of Philosophy
Name of academic advisor: Inoue Kazumasa, Fukushi Masahiro
Title of thesis: Distribution of Naturally Occurring Radionuclides and Rare Earth Elements in Monazite Soils of a Natural High Background Radiation Area in India
Abstract: The main objective of this study is to understand the distribution pattern of absorbed dose in a high background radiation area, Odisha coast, India and to explore the behavior of the physical and geochemical processes that enriched primordial radionuclides and rare earth elements in the environment. The study area is one of the well-known placer deposits that is rich in monazite and ilmenite and covers nine coastal villages of Chhatrapur - Gopalpur region, Odisha. There are very few investigations in this region to correlate with the source and nature of minerals causing enhanced levels of natural radiation. To estimate radiological risks, a car-borne (vehicle-mounted NaI(Tl) gamma spectrometer) survey was undertaken to measure absorbed dose. Measurement of activity concentration of naturally occurring radionuclides in sand and soil were carried out using a high purity germanium (HPGe) gamma spectroscopy. Major elements such as TiO2 , Fe2O3 and P2O5 were measured using X-ray fluorescence (XRF) spectroscopy. Concentrations of thorium (Th), uranium (U), and rare earth elements (REEs) in samples were measured using inductively coupled plasma mass spectrometry (ICP-MS). 234U/238U and 235U/238U were measured using Multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). This research study serves as radiological and geochemical aspects of a natural high background radiation area, India and it is useful primarily for environmental radioactivity monitoring and radiological risk assessment.
Name of graduate: Kimura, Tatsuki
Affiliation: Graduated School of Engineering /Kyoto University/Japan
Graduation date: March. 2021
Degree: Doctor of Philosophy
Name of academic advisor: Yoneda Minoru
Title of thesis: Studies of the effect of bacterial siderophores on the cesium behavior in the soil
Abstract: It is well known that radioactive cesium released to the environment is fixed tightly on the clay minerals in the soil. Because of strong fixation, cesium decontamination is difficult. Recently, bacterial products, especially siderophores which is the chelate for Fe3+, affect the cesium dissolution from clay minerals. This thesis examined the mechanism of the cesium dissolution and the interaction between bacterial activities and the cesium dissolution. For this purpose, siderophore producing bacteria was separated from the soil, and dissolution test and cultivation test were carried out.
Name of graduate: Miwa Kazuji
Affiliation: Graduate school of frontier sciences/The university of Tokyo/Japan
Graduation date: June. 2020
Degree: Doctor of Philosophy
Name of academic advisor: Iimoto Takeshi
Title of thesis: Development of radiation protection concept and safety evaluation method for reusing of radionuclides contaminated material
Abstract: The purpose of this paper is to propose a new application method of the concept of radiation protection for reusing of radionuclides contaminated material in existing exposure situation. Specifically, this paper proposes an interpretation of source related management for reusing of radionuclide contaminated material in existing exposure situation, which are not clearly described in international standards. In addition, dose evaluation method is developed in assuming that radiocesium-contaminated soil and rubble are reused in various environment after the Fukushima daiichi NPS accident. The concept and dose evaluation method proposed in this paper are expected to be widely applied to general radiation protection in existing exposure situation.
Name of graduate: Pham Dang Khoa
Affiliation: Tokyo Metropolitan University
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Inoue Kazumasa, Fukushi Masahiro
Title of thesis: Internal Dose Assessment in 99mTc-GSA Hepatic Scintigraphy using Multiple-compartment Biokinetic Models
Name of graduate: Kubota Jo
Affiliation: Tokyo Metropolitan University
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Inoue Kazumasa, Fukushi Masahiro
Title of thesis: Effect of Radiation on Breast Cancer Risk in a Model Rat of Hereditary Breast Cancer
Name of graduate: Sagara Yuusuke
Affiliation: Tokyo Metropolitan University
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Inoue Kazumasa, Fukushi Masahiro
Title of thesis: A Multivariate Data Analysis Study for Dose Optimization in FDG-PET/CT Scans
Name of graduate: Arimoto Akihiro
Affiliation: Fujita Health University
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Inoue Kazumasa, Asada Yashuki
Title of thesis: Evaluation of Backscatter Factor Using an Anthropomorphic Phantom
Name of graduate: Itoh Mitsuyo
Affiliation: Fujita Health University
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Yokoyama Sumi
Title of thesis: Radiation education based on radiation literacy and needs analysis for medical staff
Name of graduate: Hayashi Ryuta
Affiliation: Fujita Health University
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Yokoyama Sumi
Title of thesis: Calculation of absorbed dose to the eye lens for patients during head IVR procedures by using the Monte Carlo simulation
Name of graduate: Asai, Tomoki
Affiliation: Department of Applied Energy/Nagoya University/Japan
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Moriizumi, Jun; Yamazawa, Hiromi
Title of thesis: Analysis of fates of short-lived radon decay product nuclides in indoor environment
Name of graduate: Kamida, Shunsuke
Affiliation: Department of Applied Energy/Nagoya University/Japan
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Yamazawa, Hiromi; Moriizumi, Jun
Title of thesis: Analysis of behavior of several forms of airborne radioiodine discharged by the nuclear accidents
Name of graduate: Koike Hiromi
Affiliation: Graduate School of Frontier Sciences/The University of Tokyo/Japan
Graduation date: March. 2021
Degree: Master of Science
Name of academic advisor: Iimoto Takeshi
Title of thesis: Development and Application of NORM Sources for Radiation Education Experiments
Name of graduate: Nakamura,Kaori
Affiliation: Graduate School of Engineering and Science, University of the Ryukyus
Graduation date: March 2021
Degree: Master of Science
Name of academic advisor: Furukawa,Masahide
Title of thesis: Seasonal variation of 7Be and 210Pb concentrations in fallout collected in Okinawa Island
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