세기조절 방사선 치료에서 CORVUS TPS를 이용한 IMFAST/sup TM/ Segmentation Algorithm의 연구

이세병,박진호,조광환,추성실,이창궐,이석,표홍릴,서창옥 한국의학물리학회 2002 의학물리 Vol.13 No.4

Monte Carlo Modeling and Simulation of a Passive Treatment Proton Beam Delivery System using a Modulation Wheel

이세병,Jungwook Shin,김동욱,Young Kyung Lim,Sunghwan Ahn,신동호,윤명근,Sung-Yong Park,곽정원,손동철 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.1

As the first phase of applying the Monte Carlo technique, specifically using the GEANT4 toolkit,to clinical patient support, we modeled and simulated the beam delivery system of the proton therapy facility installed at the National Cancer Center (NCC), Korea. Thanks to the properly designed architecture of the GEANT4 toolkit to extend its application area, modeling the elements of the beam delivery system and of their dynamic behaviors was efficiently implemented. The simulation was validated over a treatment range of passive scattering mode in a water phantom by estimating the initial beam energy and by applying this information to a simulated therapeutic proton beam (termed the spread-out Bragg peak), resulting in good correlations with the measurement data.

Depth Dose Measurement using a Scintillating Fiber Optic Dosimeter for Proton Therapy Beam of the Passive-Scattering Mode Having Range Modulator Wheel

황의중,신동호,이세병,임영경,정종휘,김학수,김기환 한국물리학회 2018 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.72 No.9

To apply a scintillating fiber dosimetry system to measure the range of a proton therapy beam, a new method was proposed to correct for the quenching effect on measuring an spread out Bragg peak (SOBP) proton beam whose range is modulated by a range modulator wheel. The scintillating fiber dosimetry system was composed of a plastic scintillating fiber (BCF-12), optical fiber (SH 2001), photo multiplier tube (H7546), and data acquisition system (PXI6221 and SCC68). The proton beam was generated by a cyclotron (Proteus-235) in the National Cancer Center in Korea. It operated in the double-scattering mode and the spread out of the Bragg peak was achieved by a spinning range modulation wheel. Bragg peak beams and SOBP beams of various ranges were measured, corrected, and compared to the ion chamber data. For the Bragg peak beam, quenching equation was used to correct the quenching effect. On the proposed process of correcting SOBP beams, the measured data using a scintillating fiber were separated by the Bragg peaks that the SOBP beam contained, and then recomposed again to reconstruct an SOBP after correcting for each Bragg peak. The measured depth-dose curve for the single Bragg peak beam was well corrected by using a simple quenching equation. Correction for SOBP beam was conducted with a newly proposed method. The corrected SOBP signal was in accordance with the results measured with an ion chamber. We propose a new method to correct for the SOBP beam from the quenching effect in a scintillating fiber dosimetry system. This method can be applied to other scintillator dosimetry for radiation beams in which the quenching effect is shown in the scintillator.

Calculation of Beam Quality Correction Factor for Relative Positions of SOBP and Ionization Chamber Using Monte Carlo Simulations

권용철,조현석,이세병,신욱근 한국물리학회 2021 새물리 Vol.71 No.10

In proton radiotherapy, the dosimetry protocol TRS-398 does not provide the beam quality correction factors kQ;Q0 for all areas of the spread out Bragg peak (SOBP). Monte Carlo simulations using the TOPAS simulation toolkit were performed to calculate the beam quality correction factors at various depths of the SOBP to observe any variations. The SOBP of the generated proton beam had a range of 15 cm and a width of 15 cm. The beam quality correction factors kQ;Q0 were calculated not only at the reference depth of 7.5 g/cm2 recommended by TRS-398 but also at depths of 4 g/cm2 and 13 g/cm2. The comparison of the simulation results for the absorbed dose with actual measurements showed a slight difference at the surface above the water phantom, but the width of the SOBP was well matched with a difference of less than 1%. The kQ;Q0 factor calculated at the reference depth of 7.5 g/cm2 was 1.045, which is within the error range of the value of 1.030 provided by the TRS-398 protocol. The kQ;Q0 factors calculated at the depths of 4 g/cm2 and 13 g/cm2 were 1.041 and 1.048, respectively. While all the calculated values were within the error range of the value suggested by TRS-398, the observed increase in the kQ;Q0 factor with increasing depth suggests that a position-dependent beam quality correction factor determined through precise measurements may be required to calculate the correct dose.

국립 암 센터 치료용 가속기를 위한 빔라인의 광학계 연구

황지광,김은산,이세병,황왕신,현상헌 한국물리학회 2013 새물리 Vol.63 No.4

The proton accelerator which was constructed in 2007 at the NCC (National Cancel Center) consists of an ion source for high-intensity proton beams, a cyclotron for acceleration of the proton beam produced by the ion source up to 230 MeV, an energy degrader to decrease the energy of the proton beams to provide the required energy, an energy selection section to decrease the energy spread, a beam transport line for the transport of the beam to the gantry, and a gantry for adjusting the beam distribution so as to be suitable for treatment. A high-stability proton accelerator is required for cancel therapy. If high-stability beams are to be achieved,the beams must have an accurate energy, a small energy spread and a small beam size at exit of the gantry. To achieve a high-stability beam,we investigated of the specifications for a beam line which consisted of a quadrupole and a dipole magnet, and we simulated the design of the beam line that could produce a round beam with a beam size of 2 mm rms at the exit of the gantry. 암 치료를 목적으로 2007년 완공된 국립 암센터의 치료용 양성자가속기는 양성자를 만들어내는 이온원과 이온원에서 발생된 양성자를 230MeV의 에너지까지 가속시키는 사이클로트론, 가속된 양성자의 에너지를원하는 에너지로 만들기위한 에너지 감속재 (Degrader), 빔의 에너지퍼짐도를 줄이기 위한 에너지 선택구간, 낮은 에너지 퍼짐도를 가지는양성자 빔을 갠트리 (Gantry)까지 전송해주는 빔 전송라인, 전송 된양성자 빔을 치료의 목적에 알맞게 해주는 갠트리구간 등으로 이루어져있다. 이러한 가속기에서 만들어진 양성자 빔을 환자에게 조사하여 암치료에 이용하기 위해서는 높은 안정성이 요구된다. 빔의 높은 안정성을얻기 위해서는 발생되는 양성자 빔 에너지를 정확하게 알아야하며 동시에낮은 에너지 퍼짐도를 가지져야 하고, 갠트리의 출구에서 가능한 작은 빔사이즈를 만드는 것이 좋다. 우리는 앞에서 말한 빔의 높은 안정성을성취하기 위하여 갠트리 최종단에서 가능한 작은 사이즈를 가지는 양성자빔 생산을 위한 양성자 가속기의 빔 라인의 사극자석 및 이극자석이만들어 내는 광학적 특성의 조사와 이를 이론적으로 설명하기위한시뮬레이션을 수행하여 갠트리 최종단에서 2 mm rms 빔 사이즈를 가지는원형 빔을 생성 할 수 있는 광학 격자를 설계하였다.

An Assessment of the Secondary Neutron Dose in the Passive Scattering Proton Beam Facility of the National Cancer Center

한상은,조규성,이세병 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.4

The purpose of this study is to assess the additional neutron effective dose during passivescattering proton therapy. Monte Carlo code (Monte Carlo N-Particle 6) simulation wasconducted based on a precise modeling of the National Cancer Center's proton therapyfacility. A three-dimensional neutron effective dose profile of the interior of the treatmentroom was acquired via a computer simulation of the 217.8-MeV proton beam. Measurementswere taken with a 3He neutron detector to support the simulation results, whichwere lower than the simulation results by 16% on average. The secondary photon dose wasabout 0.8% of the neutron dose. The dominant neutron source was deduced based on fluxcalculation. The secondary neutron effective dose per proton absorbed dose ranged from4.942 ± 0.031 mSv/Gy at the end of the field to 0.324 ± 0.006 mSv/Gy at 150 cm in axialdistance.

즉발감마선의 시간적 발생분포 특성 기반 양성자 빔의 비정 측정시스템의 최적화 연구

신욱근,정종휘,이세병,민철희 대한방사선방어학회 2016 대한방사선방어학회 학술발표회 논문요약집 Vol.2016 No.04

양성자 빔의 비정 평가를 위해 즉발감마선의 시간적 발생분포 특성을 측정하는 검출 시스템의 최적화 연구

신욱근,정종휘,이세병,민철희 대한방사선방어학회 2016 대한방사선방어학회 학술발표회 논문요약집 Vol.2016 No.12

A Monte Carlo Study of the Relationship between the Time Structures of Prompt Gammas and the In-vivo Radiation Dose in Proton Therapy

신욱근,민철희,신재익,정종휘,이세병 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.1

For in-vivo range verification in proton therapy, attempts have been made to measure the spatial distribution of the prompt gammas generated by the proton-induced interactions and to determine the proton dose distribution. However, the high energies of prompt gammas and background gammas are still problematic in measuring the distribution. In this study, we suggested a new method for determining the in-vivo range by utilizing the time structure of the prompt gammas formed during the rotation of a range modulation wheel (RMW) in passive scattering proton therapy. To validate the Monte Carlo code simulating the proton beam nozzle, we compared the axial percent depth doses (PDDs) with the measured PDDs for varying beam range from 4.73 to 24.01 cm. Also, we assessed the relationship between the proton dose rate and the time structure of the prompt gammas in a water phantom. The results of the PDD showed agreement within relative errors of 1.1% in the distal range and 2.9% in the modulation width. The average dose difference in the modulation was assessed as less than 1.3% by comparison with the measurements. The time structure of prompt gammas was well-matched, within 0.39 ms, with the proton dose rate, and this enabled an accurate prediction of the in-vivo range.

A Study on a Method for Measuring the Alpha Emitters from 242Cm in Neutron Capture Reactions of 241Am

Liu DONG,우종관,고석태,이세병 한국물리학회 2015 새물리 Vol.65 No.12

The reaction rate of neutron capture reaction of 241Am can be evaluated through measurements of the alpha (α) particles from 242Cm. However, alpha spectrometry requires the adjustment of samples into a chemically-isolated form to prevent or reduce interferences due to α emitted by multiple α-emitting nuclides. To avoid the need for a complex chemical separation process, we propose a new method for detecting the α emitted from 242Cm. In this method, a filter device is employed to absorb the α emitted from 241Am and its products, but not the α emitted by 242Cm. In order to determine the thickness of the filter, we used a Monte Carlo program to calculate the penetration depths of the α particles of interest and of unrelated α particles for various thicknesses of the filter. The calculation results suggested that a 25.75 μm thick aluminum absorber is an ideal filter. With this filter, the α’s emitted from 242Cm can be measured by using ordinary detectors, and the accuracy of measurement made by using high-resolution semiconductor detectors can be increased.