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( Ajin Lee ),( Su Hyun Chae ),( Seung-hyuk Shim ),( Sun Joo Lee ),( Ji Young Lee ),( Soo-nyung Kim ),( Soon-beom Kang ) 대한산부인과학회 2018 대한산부인과학회 학술대회 Vol.104 No.-
Objective: Efficacy of adjuvant treatments in early stage leiomyosarcoma (LMS) after hysterectomy is not proved enough. We investigated the effect of adjuvant treatments(chemotherapy(CT) and radiotherapy(RT), in early stage leiomyosarcoma patients after hysterectomy, through meta-analysis. Methods: A systematic search was done in Cochrane, Embase, and Pubmed from 1975 through August 2017 to include studies which was related to adjuvant CT or adjuvant RT after hysterectomy in early stage LMS. The endpoints were mortality and recurrence rates in observation versus adjuvant CT(group A) and RT (group B) after hysterectomy. Results: Eleven studies (8 studies for adjuvant CT; 2540 patients, 9 studies for adjuvant RT; 580 patients) between 1946 and 2017 were included. Fixed-effects model-based meta-analysis indicated no significant difference in recurrence rate between the A (obs vs CT) and B (obs vs RT) groups (odds ratio [OR]=1.0; 95% confidence interval [CI]=0.38-1.51; p=0.968, and OR=1.1; 95% confidence interval [CI]=0.65-1.69; p=0.891) with low cross-study heterogeneity (p=0.48 and I=0.0). There was no significant difference in mortality rate between the A and B groups (OR=2.2; 95%, CI=0.89-2.68; p=0.12, and OR=0.85; 95%, CI=0.32-1.21; p=0.54) with low cross-study heterogeneity (p=0.76 and I=0.0). This pattern was observed in subgroup analysis for study design, whether done hysterectomy with or without pelvic lymph node dissection, omentectomy, bilateral salphyngo-oophorectomy, mitotic grade, chemo-regimen, radiation type. However, this pattern was not observed in the subgroup analysis for the randomized trials. There was no evidence of publication bias. Conclusion: In this meta-analysis, adjuvant treatments (both CT and RT) after hysterectomy in early stage leiomyosarcoma did not reduce the recurrence rate or mortality rate. Concerning the recurrence rate in early stage leiomyosarcoma, other adjuvant treatment strategy must be proposed in future studies.
( Hayne Cho Park ),( Young-ki Lee ),( Kyung Don Yoo ),( Hee Jung Jeon ),( Seung Jun Kim ),( Ajin Cho ),( Jacob Lee ),( Yang-gyun Kim ),( Sang-ho Lee ),( Sang-oh Lee ) 대한신장학회 2018 Kidney Research and Clinical Practice Vol.37 No.1
Patients receiving hemodialysis are vulnerable to infectious diseases due to their impaired immunity and high risk of exposure to pathogens. To protect patients, staff, and visitors from potential infections, each hemodialysis unit should establish and follow standard infection control and prevention measures. Therefore, clinical practice guidelines were developed by a working group of nephrologists and infection control specialists to provide evidence-based guidance for dialysis physicians and nurses, with the aim of preventing infection transmission and controlling infection sources in hemodialysis facilities. The areas of infection control covered by these guidelines include standard precautions, isolation strategies, vascular access, water treatment, cleaning/disinfecting/sterilizing, and vaccination. This special report summarizes the key recommendations from the Korean clinical practice guidelines for preventing the transmission of infections in hemodialysis facilities.
An Inner-Crystal Neutron-Scatter Camera: Monte Carlo Simulation
Ajin Jo,Won Ho Lee 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.68 No.9
Neutron energy emitted from special nuclear materials (SNMs) can be measured by using neutronproton scattering; also, the scattering angle can be calculated from the ratio of the scattered energy to the incident energy. By using position and energy information, we can image the original source position by using the backprojection and list-mode maximum-likelihood expectation maximization (MLEM) method. In this paper, we propose an inner-crystal neutron scatter camera system in which the detectors are not separated to obtain interactions at a variety of scatter angles; based on this system, we analyzed the characteristics of the corresponding neutron-scattering camera. The factors that affected the neutron-scatter image were the neutron velocity after scattering, the cut-off level of the time of flight (ToF), and the width of the cones used for image reconstruction. To determine the optimal point for the reconstruction of an image, we estimated the performance of the system by using the figure of merit (FoM). The optimal neutron-velocity (d/ToF) was 0.3 × 107 m/s according to our simulation result, while the optimal cut-off level of the ToF was 4 ns as the latter minimized the noise while maintaining the required efficiency. The widths of the cones (") also affected the full width at half maximum (FWHM) and the noise of the image. In terms of a simple source-geometry, whereby concepts such as “point source” were used, a large " value was suitable to achieve noise reduction; however, regarding the complicated source geometry, a small " value was favorable for precise reconstruction of the original source geometry for both the backprojection and the list-mode MLEM methods.
Monte Carlo Simulation on the 4π Field of a View Compact Compton Camera by Using Scintillators
이원호,Ajin Jo,Taewoong Lee,Dongmyeong Chu,Yong Hyun Chung 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.1
A compact LaCl3(Ce) Compton camera with a 4πfield of view (FOV) was introduced, and the optimized design parameters with the effective choice of the γ-ray interaction order were obtained by using Monte Carlo simulation. The camera consisted of six LaCl3(Ce) planar scintillators with pixelized structure, which could be coupled with position sensitive photomultiplier tubes. Since γ-rays were incident from all direction (4π), all of the scintillators were both scattering and absorbing detectors for Compton image reconstruction, and the interaction sequence was decided based on the deposited energy. According to the simulation results, the reconstructed image showed better angular resolution and smaller variance for all incident radiation energies (300 keV 2 MeV) when the energy of the scattering interaction was assumed to be smaller than that of the absorbing interaction. The optimum thickness of the scintillators to maintain high image resolution and large sensitivity was 1 1.5 cm, and the difference between the center of the camera and the scintillators was set to 7 cm to minimize degradation of image resolution and the loss of detection efficiency. With the optimized conditions, the effect of each parameter causing blurring and variance was estimated. At low energy, the finite energy resolution was the main factor increasing the uncertainties of the reconstructed image. However, at high energy, the pixelization effect and the incorrect choice of interaction sequences also were significant factors in the degraded angular resolution and relative standard deviation of the reconstructed image.
Wonho Lee,Ajin Jo,Changyeon Yoon IEEE 2010 IEEE transactions on nuclear science Vol.57 No.3
<P>Multiple modality γ-ray imaging using mechanical and electronic collimation with different detection methods was proposed and tested by simulation. Although conventional mechanical collimators, which are made from high atomic number and density materials, passively filter the incident radiation, the mechanical collimator reported in this study consisted of LaCl<SUB>3</SUB>(Ce) scintillators, which actively collimate the radiation and are used as the 1st detector of an electronic collimator to reconstruct a Compton image. A detector box made from six planar LaCl<SUB>3</SUB>(Ce) scintillators was positioned behind the active collimator. The LaCl<SUB>3</SUB>(Ce) scintillator arrays used as the active collimator and box detector consisted of voxels, each 2 mm × 2 mm × 5 mm<SUP>3</SUP> in size. A combination of active collimators and box detectors can produce multiple modalities for both mechanical and electronic collimation. The information from each modality was combined effectively using the maximum likelihood expectation maximization (MLEM) method. Therefore, a reconstructed image from multiple modalities has inherently higher efficiency than each conventional modality. The reconstructed images were evaluated using the resolution-variance curve as a quantitative method. Although mechanical collimation is effective at low γ-ray energy and electronic collimation shows high performance at high γ-ray energy, multiple modalities are superior to the conventional single modalities for intermediate γ-ray energies (364 keV). The angular resolution and absolute efficiency were calculated for each modality and source energy.</P>
학습자 참여형 현장방문교육을 위한 교수설계모형 개발연구
조아진(Ajin Cho),이예경(Yekyung Lee) 중앙대학교 한국인적자원개발전략연구소 2012 역량개발학습연구 Vol.7 No.4
본 연구는 ‘S’통신사에서 시행 중인 현장방문교육의 문제점을 극복하기 위하여 학습자 참여형 현장방문교육 교수설계모형을 개발하는 데 목적을 두었다. 이를 위해 현재 시행되고 있는 현장방문교육 전문가들의 검증, ISD 모형에 대한 문헌고찰과 ISD전문가를 통한 모형검증을 통하여 ‘현장 방문교육 교수설계모형’을 개발하였다. 개발된 모형은 다음의 특징을 지닌다: 1)현장 중심형 교수설계모형으로, 예비 분석, 예비 설계, 예비 개발과 현장 분석, 현장 설계, 현장 개발의 2번의 Analysis, Development, Design을 거치며, 2) 현장 방문 전 개발된 자료의 활용도를 높이기 위해 현장 방문 시 즉시 변형이 가능한 보조 자료를 개발할 수 있게 하였으며, 3) 교수설계에 학습자가 참여할 수 있는 체제를 설계함으로써 학습자의 능동적 참여가 가능한 학습 환경을 구축하도록 하였다. This study aimed at developing an instructional systems design model optimized for on-site training where trainers visit the site and conduct instruction. This study analyzed current problems of on-site visit training with instructors in the field and also analyzed literature related to ISD and on-site training to identify solutions that could be used to develop an ISD model for this situation. Verification of the ISD model was carried out by in-service training instructors for final development. The ISD model developed in this study has the following characteristics. First, it has two piloting and primary flows and each flow has its own instructional system flow of analysis, design and development. This makes the model have its strengths on in-service training focused ISD with its repeated flow display. Second, it makes use of versatile forms that can be used for different purposes regardless of goals, teaching materials, assessment items or methods. Third, it provides a learning environments where learners can actively participate and enhances their effectiveness.