Epigenomics 연구동향 리포트: Cancer와 inflammation과의 연관성

배재범 생화학분자생물학회 2008 생화학분자생물학회 소식 Vol.28 No.1

Monte Carlo Simulation of the Carbon Beam Nozzle for the Biomedical Research Facility in RAON

배재범,조병철,곽정원,박우윤,임영경,정현태,Bae, Jae-Beom,Cho, Byung-Cheol,Kwak, Jung-Won,Park, Woo-Yoon,Lim, Young-Kyung,Chung, Hyun-Tai Korean Society of Medical Physics 2015 의학물리 Vol.26 No.1

본 연구에서 한국형 중이온 가속기 RAON에서의 의생물 실험을 위하여 요구되는 빔 조건을 만족할 수 있도록 Monte Carlo 전산모사를 통한 노즐 설계를 최적화하고자 하였다. 의생명 실험을 위한 빔 조건으로 최대 조사면 크기, 선량균일도 그리고 빔 오염도의 특정 조건을 만족하는 $C^{12}$ 빔 생산이 요구되었다. 이때 최적화된 빔 노즐 설계를 위하여 Monte Carlo 시뮬레이션인 GEANT4 toolkit이 사용되었다. $15{\times}15cm^2$ 이상의 빔 조사면 크기와 3% 이내의 선량 균일도 그리고 전체 선량의 5% 보다 낮은 빔 오염도를 기본적인 조건으로 설정 되었다. 조사면 크기는 쌍극자 자석에 의해서 빔의 각도를 기울여 원형으로 회전하면서 쌍극자 자석의 아래쪽에 위치한 산란판의 두께를 조정하여 최적화 하였다. 빔 스캐닝 각도와 산란판의 두께는 Monte Carlo 시뮬레이션 분석에 의해서 각각 $0.5^{\circ}$와 0.05 cm로 최적의 값을 나타내었다. 선량 균일도와 최대 조사면 크기를 만족하기 위하여 static과 scanning beam을 복합하는 기술을 이용한 새로운 빔 전달 방법을 소개하였다. 중앙 고정용 빔과 빔 축으로부터 $0.5^{\circ}$ 경사각을 가지고 회전하는 빔과 경사각이 없이 바로 들어오는 빔을 조합하여 선량균일도가 1.1%와 빔 조사면의 최대크기가 $15{\times}15cm^2$가 되는 것을 확인하였다. 빔 오염도는 $C^{12}$ 이온과 다른 입자들에 의해서 전달된 흡수선량의 비율로 나타내었다. 물등가 깊이(water equivalent depth) 5 cm에서 17 cm 사이에서의 빔 오염도는 전체 선량에서의 2.5% 미만임을 확인하였으며 이와 같은 결과를 바탕으로, 본 연구에서는 의생명 실험을 위하여 요구되는 빔 조건을 만족하는 노즐 구조를 설정할 수 있었다. The purpose of the Monte Carlo simulation study was to provide the optimized nozzle design to satisfy the beam conditions for biomedical researches in the Korean heavy-ion accelerator, RAON. The nozzle design was required to produce $C^{12}$ beam satisfying the three conditions; the maximum field size, the dose uniformity and the beam contamination. We employed the GEANT4 toolkit in Monte Carlo simulation to optimize the nozzle design. The beams for biomedical researches were required that the maximum field size should be more than $15{\times}15cm^2$, the dose uniformity was to be less than 3% and the level of beam contamination due to the scattered radiation from collimation systems was less than 5% of total dose. For the field size, we optimized the tilting angle of the circularly rotating beam controlled by a pair of dipole magnets at the most upstream of the user beam line unit and the thickness of the scatter plate located downstream of the dipole magnets. The values of beam scanning angle and the thickness of the scatter plate could be successfully optimized to be $0.5^{\circ}$ and 0.05 cm via this Monte Carlo simulation analysis. For the dose uniformity and the beam contamination, we introduced the new beam configuration technique by the combination of scanning and static beams. With the combination of a central static beam and a circularly rotating beam with the tilting angle of $0.5^{\circ}$ to beam axis, the dose uniformity could be established to be 1.1% in $15{\times}15cm^2$ sized maximum field. For the beam contamination, it was determined by the ratio of the absorbed doses delivered by $C^{12}$ ion and other particles. The level of the beam contamination could be achieved to be less than 2.5% of total dose in the region from 5 cm to 17 cm water equivalent depth in the combined beam configuration. Based on the results, we could establish the optimized nozzle design satisfying the beam conditions which were required for biomedical researches.

Perspectives of International Human Epigenome Consortium

배재범 한국유전체학회 2013 Genomics & informatics Vol.11 No.1

As the International Human Epigenome Consortium (IHEC) launched officially at the 2010 Washington meeting, a giant step toward the conquest of unexplored regions of the human genome has begun. IHEC aims at the production of 1,000reference epigenomes to the international scientific community for next 7-10 years. Seven member institutions, including South Korea, Korea National Institute of Health (KNIH), will produce 25-200 reference epigenomes individually, and the produced data will be publically available by using a data center. Epigenome data will cover from whole genome bisulfite sequencing, histone modification, and chromatin access information to miRNA-seq. The final goal of IHEC is the production of reference maps of human epigenomes for key cellular status relevant to health and disease.

Measurement of Radiation Damage on a Back-illuminated Silicon PIN Photodiode Caused by a 35 MeV Proton Beam

배재범,현효정,가동하,김현옥,박환배,정명환,라세진 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.22

We develop a backside illuminated photo-sensor that is fabricated on a <100>-oriented, high resistivity n-type 400 μm thick silicon wafer. The PIN photodiode is designed and manufactured as a radiation detector for alpha particles and low energy gamma-rays. The silicon photo-sensor is susceptible to radiation damage. Therefore, it is important to investigate the effects of radiation damage to the fabricated PIN photodiode. We measure the radiation damage to a PIN photodiode by a 35 MeV proton beam at the Korea Institute of Radiological and Medical Sciences (KIRAMS). We present the effects of proton radiation on the electrical properties of the PIN photodiode.

Electrical Characteristics and Radiation Detection Performance of Large-area Photodiodes

배재범,현효정,가동하,강국현,박환배 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.7

Photodiodes with the size of 2.3 × 2.3 cm2 are fabricated on n-type silicon wafers with highresistivity (>5 k·cm) for physics applications. The photodiodes are fully depleted to collect signalsproduced by incoming particles. We measure the leakage currents and the capacitances of thephotodiodes as functions of the reverse bias voltage. The photodiodes with leakage currents < 70nA/cm2 are used to measure the signal-to-noise ratio (SNR) by using a 45 MeV proton beam fromthe MC-50 cyclotron at the Korea Institute of Radiological and Medical Sciences (KIRAMS) and a90Sr radioactive source. The SNRs are measured for the photodiode only and for photodiode coupledwith a 5 mm thick plastic scintillator. The proton beam energy is controlled by using a degrader,and the pulse heights are measured for different energies of the proton beam. The radiation damageeffect is also measured in an environment of 1.18 × 1010 protons/cm2. In this paper, we present notonly the SNR measurements using the proton beam and the radioactive source but also the resultof the radiation damage test.

초임계 유체 상태에서 부분몰 부피 계산

배재범,김선욱 ( Jae Beom Bae,Sun Wook Kim ) 한국화학공학회 1996 화학공학의이론과응용 Vol.2 No.2

부동산신탁과 임대차의 대항력

도건철,배재범 서울대학교 금융법센터 2019 BFL Vol.94 No.-

Cancer and Epigenetics

김영준,배재범 한국통합생물학회 2008 Animal cells and systems Vol.12 No.3

Comparison Between the Capacitance and the Signal-to-noise Ratio of a PIN Diode

가동하,김현옥,배재범,현효정,박환배 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.1

PIN diodes with areas of 1 × 1 cm^2 were fabricated on 5-in., high-resistivity, <100>-orientation, and 380-μm-thick n-type silicon wafers. When a charged particle passes through the PIN diode and a reverse voltage is applied, electron-hole pairs are created and collected into the electrodes by the electric field. The capacitance and the signal-to-noise ratio of the PIN diode were measured as functions of the reverse bias voltage. The reciprocal of the capacitance has the same electrical behavior as the signal-to-noise ratio.

동적 세기조절방사선치료에서 깊이에 따른 DLG변화 분석

장경환,곽정원,조병철,정치영,배재범,윤상민,이상욱,Chang, Kyung Hwan,Kwak, Jungwon,Cho, Byungchul,Jeong, Chiyoung,Bae, Jae Beom,Yoon, Sang Min,Lee, Sang-wook 한국의학물리학회 2015 의학물리 Vol.26 No.3

본 연구에서는 동적 세기조절방사선치료에서 깊이에 따른 DLG (Dosimetric Leaf Gap)의 변화가 치료계획시스템에서의 선량계산의 정확성에 미치는 영향을 평가하고자 하였다. 6 MV와 15 MV광자선에 대하여 동일한 SAD 조건하에 4개의 다른 깊이(2 cm, 5 cm, 10 cm, 15 cm)에서 측정된 다엽콜리메이터의 투과계수와 DLG 값을 치료계획시스템에 적용하여 DLG 측정 과정을 모사하였을 때 계산된 투과계수와 DLG 값들을 각각의 측정값들과 비교하여 분석하였다. 이를 위하여 Millenium 120 MLC시스템이 장착 된 단일 선형가속기가 사용되었다. 각각 다른 깊이에서 측정된 DLG와 투과계수 값을 적용하였을 때 치료계획시스템을 이용한 모사에서는 투과계수의 경우 1% 이내로 계산과 측정이 일치함을 보이는 반면에 DLG 값은 15 MV 경우 5% 이내의 차이를 보이고 6 MV에서는 최대 깊이인 15 cm에서 15% 이상 차이가 보였다. 실제의 경우 15 MV 경우 15 cm 깊이까지 DLG의 변화에 의한 실험과 계산의 차이가 작은 반면 6 MV 경우, 10 cm 이상의 깊이에서는 치료계획 시스템에서 계산된 값이 측정과 크게 차이를 나타냈다. 다엽콜리메이터 투과계수를 기준 조건하에서 측정한 고정된 값을 치료계획시스템에 적용하였을 때 측정 깊이에 따른 고정된 투과계수 값과 변화된 투과계수 값의 차이는 크지는 않지만 종양이 위치하는 깊이에 따라서 선량학적 영향이 나타날 수 있으므로 깊이에 따른 다엽콜리메이터 투과계수 및 DLG 값을 각각의 치료계획에 반영하여 환자 맞춤형 치료계획이 될 수 있도록 해야 할 것이다. This study is to evaluate thedosiemtric leaf gap (DLG) at different depths for dynamic intensity-modulated radiation therapy (IMRT) in order to evaluate the absolute dose and dose distribution according to the different positions of tumors and compare the measured and planned the multileaf collimator (MLC) transmission factor (T.F.) and DLG values. We used the 6 MV and 15 MV photon beam from linear accelerator with a Millenium 120 MLC system. After the import the DICOM RT files, we measured the absolute dose at different depths (2 cm, 5 cm, 10 cm, and 15 cm) to calculate the MLC T. F. and DLG. For 6 MV photon beam, the measured both MLC T. F. and DLG were increased with the increase the measured depths. When applying to treatment planning systemas fixed transmission factor with its value measured under the reference condition at depth of 5 cm, although the difference fixed and varied transmission factor is not significant, the dosiemtric effect could be presented according to the depth that the tumor is placed. Therefore, we are planning to investigate the treatment planning system whichthe T. F. and DLG factor according to at the different depths can be applied in the patient-specific treatment plan.