방재연구 - 스마트폰 기반 실시간 침수 안전경로 안내시스템 개발

신정석,Sin, Jeong-Seok 한국방재협회 2012 방재저널 Vol.14 No.4

방재연구 - 스마트폰 기반 실시간 침수 안전경로 안내시스템 개발

신정석,Sin, Jeong-Seok 한국방재협회 2013 방재저널 Vol.15 No.4

Analysis of changes in dose distribution due to respiration during IMRT

신정석,신은혁,한영이,주상규,김진성,안성환,김태규,정배권,박희철,안용찬,최두호 대한방사선종양학회 2011 Radiation Oncology Journal Vol.29 No.3

Purpose: Intensity modulated radiation therapy (IMRT) is a high precision therapy technique that can achieve a conformal dose distribution on a given target. However, organ motion induced by respiration can result in signifi cant dosimetric error. Therefore,this study explores the dosimetric error that result from various patterns of respiration. Materials and Methods: Experiments were designed to deliver a treatment plan made for a real patient to an in-house developed motion phantom. The motion pattern; the amplitude and period as well as inhale-exhale period, could be controlled by in-house developed software. Dose distribution was measured using EDR2 fi lm and analysis was performed by RIT113 software. Three respiratory patterns were generated for the purpose of this study; fi rst the ‘even inhale-exhale pattern’, second the slightly long exhale pattern (0.35 seconds longer than inhale period) named ‘general signal pattern’, and third a ‘long exhale pattern’ (0.7seconds longer than inhale period). One dimensional dose profi le comparisons and gamma index analysis on 2 dimensions were performed. Results: In one-dimensional dose profi le comparisons, 5% in the target and 30% dose difference at the boundary were observed in the long exhale pattern. The center of high dose region in the profi le was shifted 1 mm to inhale (caudal) direction for the ‘even inhale-exhale pattern’, 2 mm and 5 mm shifts to exhale (cranial) direction were observed for ‘slightly long exhale pattern’ and ‘long exhale pattern’, respectively. The areas of gamma index >1 were 11.88 %, 15.11%, and 24.33% for ‘even inhale-exhale pattern’,‘general pattern’, and ‘long exhale pattern’, respectively. The long exhale pattern showed largest errors. Conclusion: To reduce the dosimetric error due to respiratory motions, controlling patient’s breathing to be closer to even inhaleexhale period is helpful with minimizing the motion amplitude.

영상유도 및 호흡동조 방사선치료에서의 영상장비에 의한 흡수선량 분석

신정석,한영이,주상규,신은혁,홍채선,안용찬 대한방사선종양학회 2009 Radiation Oncology Journal Vol.27 No.1

Purpose: The introduction of image guided radiation therapy/four-dimensional radiation therapy (IGRT/4DRT) potentially increases the accumulated dose to patients from imaging and verification processes as compared to conventional practice. It is therefore essential to investigate the level of the imaging dose to patients when IGRT/4DRT devices are installed. The imaging dose level was monitored and was compared with the use of pre-IGRT practice. Materials and Methods: A four-dimensional CT (4DCT) unit (GE, Ultra Light Speed 16), a simulator (Varian Acuity) and Varian IX unit with an on-board imager (OBI) and cone beam CT (CBCT) were installed. The surface doses to a RANDO phantom (The Phantom Laboratory, Salem, NY USA) were measured with the newly installed devices and with pre-existing devices including a single slice CT scanner (GE, Light Speed), a simulator (Varian Ximatron) and L-gram linear accelerator (Varian, 2100C Linac). The surface doses were measured using thermo luminescent dosimeters (TLDs) at eight sites-the brain, eye, thyroid, chest, abdomen, ovary, prostate and pelvis. Results: Compared to imaging with the use of single slice non-gated CT, the use of 4DCT imaging increased the dose to the chest and abdomen approximately ten-fold (1.74±0.34 cGy versus 23.23±3.67 cGy ). Imaging doses with the use of the Acuity simulator were smaller than doses with the use of the Ximatron simulator, which were 0.91±0.89 cGy versus 6.77±3.56 cGy, respectively. The dose with the use of the electronic portal imaging device (EPID; Varian IX unit) was approximately 50% of the dose with the use of the L-gram linear accelerator (1.83±0.36 cGy versus 3.80±1.67 cGy). The dose from the OBI for fluoroscopy and low-dose mode CBCT were 0.97±0.34 cGy and 2.3±0.67 cGy, respectively. Conclusion: The use of 4DCT is the major source of an increase of the radiation (imaging) dose to patients. OBI and CBCT doses were small, but the accumulated dose associated with everyday verification need to be considered 목 적: 영상유도방사선치료(IGRT)와 호흡동조방사선치료(4DRT)의 도입은 치료계획 및 치료부위 확인에서 환자에게 방사선 조사량을 증가시킬 가능성이 있다. 따라서 IGRT/4DRT용 영상장비와 기존 장비에서 영상선량을 측정 및 비교 하였다. 대상 및 방법: IGRT 및 4DRT를 위해 새로이 도입된 4DCT (GE, Ultra Light Speed 16)와 모의치료기(Varian Acuity), 그리고 치료기(Varian IX)에 장착된 kVp (OBI)의 영상장비 및 EPID (aSi 1000)를 대상으로, RANDO 팬톰의 표면 선량을 측정하여 기존의 장비들(single slice CT (GE, Light Speed), 모의치료기(Varian, Ximatron), L-gram (Varian 2100C))과 비교하였다. 측정은 열형광선량계를 이용하여 두뇌부, 눈, 갑상선, 흉부, 복부 및 골반부의 표면에서 측정하였다. 결 과: 기존 CT와 비교하여 4DCT모드에서는 흉부와 복부에서 10배 이상의 선량증가를 보였다(1.74±0.34 vs 23.23±3.67 cGy). Acuity에서의 선량은 모든 측정부위에서 Ximatron보다 감소하였다(0.91±0.89 vs 6.77±3.56 cGy). EPID는 기존 L-gram 선량의 약 50% (1.83±0.36 vs 3.80±1.67 cGy)였다. OBI의 투시영상선량은 0.97±0.34 cGy며, CBCT 선량은 2.3±0.67 cGy였다. 결 론: 4DCT가 선량증가의 가장 큰 원인이며, OBI와 CBCT에 의한 선량은 적으나 매번 치료에 적용 시 총 선량 증가에 대한 고려가 필요하다.

VOXEL 팬텀과 BOMAB 팬텀을 이용한 인체내 Na-23 방사화 시뮬레이션 모사 및 비교 연구

신정석,김정인,이병일,임영기,김종순,이춘식,이재기 한국방사성폐기물학회 2004 한국방사성폐기물학회 학술논문요약집 Vol.2 No.2

공간정보 공유체계를 위한 모듈기반 WebGIS 플랫폼 연구

신정석(Jeong-Seog Shin),최영락(Yeong-Rak Choi) 한국멀티미디어학회 2022 멀티미디어학회논문지 Vol.25 No.11

Feasibility Study of the Neutron Dose for Real-time Image-guided Proton Therapy: A Monte Carlo Study

김진성,신정석,김대현,신은혁,정광주,조성구,안성환,주상규,정윤선,정상훈,한영이 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.67 No.1

Two full rotating gantries with different nozzles (multipurpose nozzle with MLC, scanning dedicated nozzle) for a conventional cyclotron system are installed and being commissioned for various proton treatment options at Samsung Medical Center in Korea. The purpose of this study is to use Monte Carlo simulation to investigate the neutron dose equivalent per therapeutic dose, H/D, for X-ray imaging equipment under various treatment conditions. At first, we investigated the H/D for various modifications of the beamline devices (scattering, scanning, multi-leaf collimator, aperture, compensator) at the isocenter and at 20, 40 and 60 cm distances from the isocenter, and we compared our results with those of other research groups. Next, we investigated the neutron dose at the X-ray equipment used for real-time imaging under various treatment conditions. Our investigation showed doses of 0.07 0.19 mSv/Gy at the X-ray imaging equipment, depending on the treatment option and interestingly, the 50% neutron dose reduction was observed due to multileaf collimator during proton scanning treatment with the multipurpose nozzle. In future studies, we plan to measure the neutron dose experimentally and to validate the simulation data for X-ray imaging equipment for use as an additional neutron dose reduction method.

몬테카를로 시뮬레이션을 이용한 BOMAB 모의 피폭체내 Na23 농도에 따른 중성자 방사화율 평가

김정인,신정석,이병일,임영기,김종순 한국방사성폐기물학회 2004 한국방사성폐기물학회 학술논문요약집 Vol.2 No.2

Feasibility of Using Geant4 Monte Carlo Simulation for IMRT Dose Calculations for the Novalis Tx with a HD-120 Multi-leaf Collimator

정현욱,신정석,정광주,한영이,김진성,최두호 한국물리학회 2015 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.66 No.10

The aim of this study was to develop an independent dose verification system by using a Monte Carlo (MC) calculation method for intensity modulated radiation therapy (IMRT) conducted by using a Varian Novalis Tx (Varian Medical Systems, Palo Alto, CA, USA) equipped with a highdefinition multi-leaf collimator (HD-120 MLC). The Geant4 framework was used to implement a dose calculation system that accurately predicted the delivered dose. For this purpose, the Novalis Tx Linac head was modeled according to the specifications acquired from the manufacturer. Subsequently, MC simulations were performed by varying the mean energy, energy spread, and electron spot radius to determine optimum values of irradiation with 6-MV X-ray beams by using the Novalis Tx system. Computed percentage depth dose curves (PDDs) and lateral profiles were compared to the measurements obtained by using an ionization chamber (CC13). To validate the IMRT simulation by using the MC model we developed, we calculated a simple IMRT field and compared the result with the EBT3 film measurements in a water-equivalent solid phantom. Clinical cases, such as prostate cancer treatment plans, were then selected, and MC simulations were performed. The accuracy of the simulation was assessed against the EBT3 film measurements by using a gamma-index criterion. The optimal MC model parameters to specify the beam characteristics were a 6.8-MeV mean energy, a 0.5-MeV energy spread, and a 3-mm electron radius. The accuracy of these parameters was determined by comparison of MC simulations with measurements. The PDDs and the lateral profiles of the MC simulation deviated from the measurements by 1% and 2%, respectively, on average. The computed simple MLC fields agreed with the EBT3 measurements with a 95% passing rate with 3%/3-mm gamma-index criterion. Additionally, in applying our model to clinical IMRT plans, we found that the MC calculations and the EBT3 measurements agreed well with a passing rate of greater than 95% on average with a 3%/3-mm gamma-index criterion. In summary, the Novalis Tx Linac head equipped with a HD-120 MLC was successfully modeled by using a Geant4 platform, and the accuracy of the Geant4 platform was successfully validated by comparisons with measurements. The MC model we have developed can be a useful tool for pretreatment quality assurance of IMRT plans and for commissioning of radiotherapy treatment planning.

호흡동조 방사선치료의 2차원 선량 분포 정도관리를 위한 4D 정도관리 시스템 개발

김진성,신은혁,신정석,주상규,한영이,박희철,최두호,Kim, Jin-Sung,Shin, Eun-Hyuk,Shin, Jung-Suk,Ju, Sang-Gyu,Han, Young-Yih,Park, Hee-Chul,Choi, Doo-Ho 한국의학물리학회 2010 의학물리 Vol.21 No.2

Emerging technologies such as four-dimensional computed tomography (4D CT) is expected to allow clinicians to accurately model interfractional motion and to quantitatively estimate internal target volumes (ITVs) for radiation therapy involving moving targets. A need exists for a 4D radiation therapy quality assurance (QA) device that can incorporate and analyze the patient specific intrafractional motion as it relate to dose delivery and respiratory gating. We built a 4D RT prototype device and analyzed the patient-specific 4D radiation therapy QA for 2D dose distributions successfully. With more improvements, the 4D RT QA prototype device could be an integral part of a 4D RT decision process to confirm the dose delivery. 최근 시행되고 있는 호흡동조 방사선치료는 환자의 호흡의 주기를 이용하여 일정 주기에만 방사선을 조사하는 최신 방사선치료기술로 4D Computed Tomography와 RPM (Real-time Position Management) 시스템과 같은 호흡 모니터링 시스템의 개발로 환자들에게 시행이 되고 있다. 그러나 이러한 호흡동조 방사선치료에 대한 정도 관리는 아직 체계적으로 수행되고 있지 않으며 특히 환자에게 계획된 방사선치료선량이 환자의 호흡에 따라서 치료계획된 대로 조사되는지에 대한 정도관리에 대한 필요성이 요구되고 있다. 따라서 본 기관에서는 환자의 호흡신호를 사용하여 환자의 움직임을 동일하게 모사할 수 있는 팬텀을 제작하여 호흡동조 방사선치료의 2차원적 선량 분포를 평가할 수 있는 시스템을 구축하였고 특정환자의 호흡신호와 방사선치료계획을 이용하여 검증하였다. 환자의 호흡신호는 LabVIEW 7.0을 이용하여 모사하였고, 자체 제작한 팬텀 및 Kodak EDR2 필름을 사용하여 방사선을 조사한 뒤 gamma index를 사용하여 2차원 선량 분포를 비교 분석하였다. 본 연구에서 개발된 4D 정도관리 시스템을 좀 더 보완하여 호흡동조 방사선치료 과정에 있어서 조사선량의 적정성을 평가할 수 있는 정도관리 시스템으로 사용할 수 있을 것이라 생각된다.