http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Cheon, Bo-Wi,Yoo, Do-Hyeon,Shin, Wook-Geun,Choi, Hyun-Joon,Park, Hyo-Jun,Kim, Jung-In,Min, Chul Hee Institute of Physics in association with the Ameri 2019 Physics in medicine & biology Vol.64 No.16
<P>Incorrect prediction of skin dose in external beam radiotherapy (EBR) can have normal tissue complication such as acute skin desquamation and skin necrosis. The absorbed dose of skin should be evaluated within basal layer, placed between the epidermis and dermis layers. However, current treatment planning systems (TPS) cannot correctly define the skin layer because of the limitation of voxel resolution in computed tomography (CT). Recently, a new tetrahedral-mesh (TM) phantom was developed to evaluate radiation dose realistically. This study aims to develop a technique to evaluate realistic skin dose using the TM phantom in EBR. The TM phantom was modeled with thin skin layers, including the epidermis, basal layer, and dermis from CT images. Using the Geant4 toolkit, the simulation was performed to evaluate the skin dose according to the radiation treatment conditions. The skin dose was evaluated at a surface depth of 50 <I>µ</I>m and 2000 <I>µ</I>m. The difference in average skin dose between depths was up to 37%, depending on the thickness and region of the skin to be measured. The results indicate that the skin dose has been overestimated when the skin is evaluated using commercial TPS. Although it is not possible with traditional TPS, our skin dose evaluation technique can realistically express the absorbed dose at thin skin layers from a patient-specific phantom.</P>
Bo-Wi Cheon,Hyun Cheol Lee,Sei Hwan You,Hee Seo,Chul Hee Min,Hyun Joon Choi Korean Nuclear Society 2023 Nuclear Engineering and Technology Vol.55 No.6
In our previous study, we proposed an integrated PG-PET-based imaging method to increase the prediction accuracy for patient dose distributions. The purpose of the present study is to experimentally validate the feasibility of the PG-PET system. Based on the detector geometry optimized in the previous study, we constructed a dual-head PG-PET system consisting of a 16 × 16 GAGG scintillator and KETEK SiPM arrays, BaSO<sub>4</sub> reflectors, and an 8 × 8 parallel-hole tungsten collimator. The performance of this system as equipped with a proof of principle, we measured the PG and positron emission (PE) distributions from a 3 × 6 × 10 cm<sup>3</sup> PMMA phantom for a 45 MeV proton beam. The measured depth was about 17 mm and the expected depth was 16 mm in the computation simulation under the same conditions as the measurements. In the comparison result, we can find a 1 mm difference between computation simulation and measurement. In this study, our results show the feasibility of the PG-PET system for in-vivo range verification. However, further study should be followed with the consideration of the typical measurement conditions in the clinic application.
Cheon, Bo-Wi,Yoo, Dohyeon,Park, Hyojun,Lee, Hyun Cheol,Shin, Wook-Geun,Choi, Hyun Joon,Hong, Bong Hwan,Chung, Heejun,Min, Chul Hee Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.6
The aim of this study was to optimize the target, moderator, and collimator (TMC) in a neutron beam generator for the accelerator-based BNCT (A-BNCT) system. The optimization employed the Monte Carlo Neutron and Photon (MCNP) simulation. The optimal geometry for the target was decided as the one with the highest neutron flux among nominates, which were called as angled, rib, and tube in this study. The moderator was optimized in terms of consisting material to produce appropriate neutron energy distribution for the treatment. The optimization of the collimator, which wrapped around the target, was carried out by deciding the material to effectively prevent the leakage radiations. As results, characteristic of the neutron beam from the optimized TMC was compared to the recommendation by the International Atomic Energy Agent (IAEA). The tube type target showed the highest neutron flux among nominates. The optimal material for the moderator and collimator were combination of Fluental (Al<sub>2</sub>0<sub>3</sub>+AlF<sub>3</sub>) with <sup>60</sup>Ni filter and lead, respectively. The optimized TMC satisfied the IAEA recommendations such as the minimum production rate of epithermal neutrons from thermal neutrons: that was 2.5 times higher. The results can be used as source terms for shielding designs of treatment rooms.
Se Hyung Lee,Bo-Wi Cheon,Chul Hee Min,Haegin Han,Chan Hyeong Kim,Min Cheol Han,Seonghoon Kim Korean Society of Medical Physics 2022 의학물리 Vol.33 No.4
Recently, tetrahedral phantoms have been newly adopted as international standard mesh-type reference computational phantoms (MRCPs) by the International Commission on Radiological Protection, and a program has been developed to convert them to computational tomography images and DICOM-RT structure files for application of radiotherapy. Through this program, the use of the tetrahedral standard phantom has become available in clinical practice, but utilization has been difficult due to various library dependencies requiring a lot of time and effort for installation. To overcome this limitation, in this study a newly developed TET2DICOM-GUI, a TET2DICOM program based on a graphical user interface (GUI), was programmed using only the MATLAB language so that it can be used without additional library installation and configuration. The program runs in the same order as TET2DICOM and has been optimized to run on a personal computer in a GUI environment. A tetrahedron-based male international standard human phantom, MRCP-AM, was used to evaluate TET2DICOM-GUI. Conversion into a DICOM-RT dataset applicable in clinical practice in about one hour with a personal computer as a basis was confirmed. Also, the generated DICOM-RT dataset was confirmed to be effectively implemented in the radiotherapy planning system. The program developed in this study is expected to replace actual patient data in future studies.
Development of light and radiation fields coincidence test toolkit for LINAC quality assurance
Lee Se Hyung,Cheon Bo-Wi,Min Chul Hee,Kim ChanHyeong,Kim Seonghoon,Han Min Cheol 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.4
The coincidence of light and radiation felds is an important quality assurance test for accurate beam delivery in a linear accelerator (LINAC), and is recommended to be checked monthly by the American Association of Physicists in Medicine (AAPM). The test-related conventional tools may yield diferent results, especially without a commercial software, depending on the user, even if the tolerance suggested by the AAPM is very tight. This study was conducted to develop a semiautomatic flm analyzer, called FSChecker, for a simple, easy, and consistent quantitative evaluation of the LINAC light and radiation feld coincidence, without commercial tools. The FSChecker has two components, a dedicated grid paper and an analyzing software based on MATLAB. Comparing the results obtained from the FSChecker with those of a commercial software revealed that the FSChecker could provide a reasonable and reliable analysis for the coincidence test of light and radiation felds in a LINAC with various scan parameters, including an ofce-level confguration.